[PATCH 0/5] mm: clarify nofail memory allocation

[PATCH 0/5] mm: clarify nofail memory allocation

[Barry Song]

From: Barry Song <v-songbaohua@oppo.com>

__GFP_NOFAIL carries the semantics of never failing, so its callers
do not check the return value:
  %__GFP_NOFAIL: The VM implementation _must_ retry infinitely: the caller
  cannot handle allocation failures. The allocation could block
  indefinitely but will never return with failure. Testing for
  failure is pointless.

However, __GFP_NOFAIL can sometimes fail if it exceeds size limits
or is used with GFP_ATOMIC/GFP_NOWAIT in a non-sleepable context.
This can expose security vulnerabilities due to potential NULL
dereferences.

Since __GFP_NOFAIL does not support non-blocking allocation, we introduce
GFP_NOFAIL with inclusive blocking semantics and encourage using GFP_NOFAIL
as a replacement for __GFP_NOFAIL in non-mm.

If we must still fail a nofail allocation, we should trigger a BUG rather
than exposing NULL dereferences to callers who do not check the return
value.

* The discussion started from this topic:
 [PATCH RFC] mm: warn potential return NULL for kmalloc_array and
             kvmalloc_array with __GFP_NOFAIL

 https://lore.kernel.org/linux-mm/20240717230025.77361-1-21cnbao@gmail.com/

Thank you to Michal, Christoph, Vlastimil, and Hailong for all the
comments.

Barry Song (5):
  vpda: try to fix the potential crash due to misusing __GFP_NOFAIL
  mm: Document __GFP_NOFAIL must be blockable
  mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails
  mm: Introduce GFP_NOFAIL with the inclusion of __GFP_RECLAIM
  non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

 arch/powerpc/sysdev/xive/common.c             |  2 +-
 drivers/gpu/drm/drm_modeset_lock.c            |  2 +-
 drivers/gpu/drm/nouveau/nouveau_dmem.c        |  8 +++----
 drivers/gpu/drm/virtio/virtgpu_vq.c           |  2 +-
 drivers/hv/vmbus_drv.c                        |  2 +-
 drivers/infiniband/hw/cxgb4/mem.c             |  4 ++--
 drivers/md/dm-region-hash.c                   |  2 +-
 .../chelsio/inline_crypto/chtls/chtls_cm.c    |  6 ++---
 .../chelsio/inline_crypto/chtls/chtls_hw.c    |  2 +-
 drivers/target/iscsi/cxgbit/cxgbit_cm.c       |  2 +-
 drivers/tty/tty_ldisc.c                       |  2 +-
 drivers/vdpa/vdpa_user/iova_domain.c          | 24 +++++++++++++++----
 fs/bcachefs/btree_iter.c                      |  2 +-
 fs/bcachefs/fs-io-buffered.c                  |  2 +-
 fs/bcachefs/io_write.c                        |  2 +-
 fs/btrfs/extent_io.c                          |  8 +++----
 fs/buffer.c                                   |  6 ++---
 fs/erofs/fscache.c                            |  2 +-
 fs/erofs/zdata.c                              | 10 ++++----
 fs/ext4/extents.c                             |  8 +++----
 fs/ext4/extents_status.c                      |  4 ++--
 fs/ext4/mballoc.c                             | 12 +++++-----
 fs/ext4/page-io.c                             |  2 +-
 fs/f2fs/checkpoint.c                          |  2 +-
 fs/f2fs/data.c                                |  4 ++--
 fs/f2fs/f2fs.h                                |  2 +-
 fs/f2fs/node.c                                |  2 +-
 fs/fuse/dev.c                                 |  2 +-
 fs/fuse/file.c                                |  4 ++--
 fs/fuse/inode.c                               |  4 ++--
 fs/fuse/virtio_fs.c                           |  4 ++--
 fs/gfs2/meta_io.c                             |  2 +-
 fs/gfs2/rgrp.c                                |  6 ++---
 fs/gfs2/trans.c                               |  2 +-
 fs/iomap/buffered-io.c                        |  2 +-
 fs/jbd2/journal.c                             |  4 ++--
 fs/jbd2/revoke.c                              |  2 +-
 fs/jbd2/transaction.c                         |  6 ++---
 fs/notify/fanotify/fanotify.c                 |  2 +-
 fs/reiserfs/journal.c                         |  2 +-
 fs/udf/directory.c                            |  2 +-
 fs/xfs/libxfs/xfs_alloc.c                     |  2 +-
 fs/xfs/libxfs/xfs_attr_leaf.c                 |  8 +++----
 fs/xfs/libxfs/xfs_bmap.c                      |  2 +-
 fs/xfs/libxfs/xfs_btree.h                     |  2 +-
 fs/xfs/libxfs/xfs_btree_staging.c             |  2 +-
 fs/xfs/libxfs/xfs_da_btree.c                  |  8 +++----
 fs/xfs/libxfs/xfs_defer.c                     |  4 ++--
 fs/xfs/libxfs/xfs_dir2.c                      | 10 ++++----
 fs/xfs/libxfs/xfs_dir2_block.c                |  2 +-
 fs/xfs/libxfs/xfs_dir2_sf.c                   |  8 +++----
 fs/xfs/libxfs/xfs_exchmaps.c                  |  4 ++--
 fs/xfs/libxfs/xfs_iext_tree.c                 |  4 ++--
 fs/xfs/libxfs/xfs_inode_fork.c                | 14 +++++------
 fs/xfs/libxfs/xfs_refcount.c                  |  4 ++--
 fs/xfs/libxfs/xfs_rmap.c                      |  2 +-
 fs/xfs/xfs_attr_item.c                        |  8 +++----
 fs/xfs/xfs_attr_list.c                        |  2 +-
 fs/xfs/xfs_bmap_item.c                        |  6 ++---
 fs/xfs/xfs_buf.c                              |  8 +++----
 fs/xfs/xfs_buf_item.c                         |  4 ++--
 fs/xfs/xfs_buf_item_recover.c                 |  2 +-
 fs/xfs/xfs_dquot.c                            |  2 +-
 fs/xfs/xfs_exchmaps_item.c                    |  4 ++--
 fs/xfs/xfs_extent_busy.c                      |  2 +-
 fs/xfs/xfs_extfree_item.c                     | 10 ++++----
 fs/xfs/xfs_icache.c                           |  2 +-
 fs/xfs/xfs_icreate_item.c                     |  2 +-
 fs/xfs/xfs_inode_item.c                       |  2 +-
 fs/xfs/xfs_inode_item_recover.c               |  2 +-
 fs/xfs/xfs_iunlink_item.c                     |  2 +-
 fs/xfs/xfs_iwalk.c                            |  2 +-
 fs/xfs/xfs_log.c                              |  2 +-
 fs/xfs/xfs_log_cil.c                          |  2 +-
 fs/xfs/xfs_log_recover.c                      |  6 ++---
 fs/xfs/xfs_mount.c                            |  2 +-
 fs/xfs/xfs_mru_cache.c                        |  4 ++--
 fs/xfs/xfs_qm.c                               |  4 ++--
 fs/xfs/xfs_refcount_item.c                    |  8 +++----
 fs/xfs/xfs_rmap_item.c                        |  8 +++----
 fs/xfs/xfs_rtalloc.c                          |  2 +-
 fs/xfs/xfs_super.c                            |  2 +-
 fs/xfs/xfs_trans.c                            |  4 ++--
 fs/xfs/xfs_trans_dquot.c                      |  2 +-
 include/linux/buffer_head.h                   |  4 ++--
 include/linux/gfp_types.h                     |  7 ++++++
 include/linux/slab.h                          |  4 +++-
 kernel/resource.c                             |  2 +-
 lib/list-test.c                               |  8 +++----
 lib/ref_tracker.c                             |  2 +-
 lib/rhashtable.c                              |  6 ++---
 lib/test_hmm.c                                |  6 ++---
 mm/page_alloc.c                               | 10 ++++----
 mm/util.c                                     |  1 +
 net/ceph/osd_client.c                         |  2 +-
 net/ceph/osdmap.c                             |  4 ++--
 net/core/sock.c                               |  4 ++--
 net/ipv4/inet_connection_sock.c               |  2 +-
 net/ipv4/tcp_output.c                         |  2 +-
 security/smack/smackfs.c                      |  2 +-
 100 files changed, 222 insertions(+), 196 deletions(-)

-- 
2.34.1

[PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL

[Barry Song]

From: Barry Song <v-songbaohua@oppo.com>

mm doesn't support non-blockable __GFP_NOFAIL allocation. Because
__GFP_NOFAIL without direct reclamation may just result in a busy
loop within non-sleepable contexts.

static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
                                                struct alloc_context *ac)
{
        ...
        /*
         * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
         * we always retry
         */
        if (gfp_mask & __GFP_NOFAIL) {
                /*
                 * All existing users of the __GFP_NOFAIL are blockable, so warn
                 * of any new users that actually require GFP_NOWAIT
                 */
                if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
                        goto fail;
                ...
        }
        ...
fail:
        warn_alloc(gfp_mask, ac->nodemask,
                        "page allocation failure: order:%u", order);
got_pg:
        return page;
}

Let's move the memory allocation out of the atomic context and use
the normal sleepable context to get pages.

[RFC]: This has only been compile-tested; I'd prefer if the VDPA maintainers
handles it.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: "Eugenio Pérez" <eperezma@redhat.com>
Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
 drivers/vdpa/vdpa_user/iova_domain.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
index 791d38d6284c..eff700e5f7a2 100644
--- a/drivers/vdpa/vdpa_user/iova_domain.c
+++ b/drivers/vdpa/vdpa_user/iova_domain.c
@@ -287,28 +287,44 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
 {
 	struct vduse_bounce_map *map;
 	unsigned long i, count;
+	struct page **pages = NULL;
 
 	write_lock(&domain->bounce_lock);
 	if (!domain->user_bounce_pages)
 		goto out;
-
 	count = domain->bounce_size >> PAGE_SHIFT;
+	write_unlock(&domain->bounce_lock);
+
+	pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
+	for (i = 0; i < count; i++)
+		pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
+
+	write_lock(&domain->bounce_lock);
+	if (!domain->user_bounce_pages) {
+		for (i = 0; i < count; i++)
+			put_page(pages[i]);
+		kfree(pages);
+		goto out;
+	}
+
 	for (i = 0; i < count; i++) {
-		struct page *page = NULL;
+		struct page *page = pages[i];
 
 		map = &domain->bounce_maps[i];
-		if (WARN_ON(!map->bounce_page))
+		if (WARN_ON(!map->bounce_page)) {
+			put_page(page);
 			continue;
+		}
 
 		/* Copy user page to kernel page if it's in use */
 		if (map->orig_phys != INVALID_PHYS_ADDR) {
-			page = alloc_page(GFP_ATOMIC | __GFP_NOFAIL);
 			memcpy_from_page(page_address(page),
 					 map->bounce_page, 0, PAGE_SIZE);
 		}
 		put_page(map->bounce_page);
 		map->bounce_page = page;
 	}
+	kfree(pages);
 	domain->user_bounce_pages = false;
 out:
 	write_unlock(&domain->bounce_lock);
-- 
2.34.1

Re: [PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL

[Michal Hocko]

On Wed 24-07-24 20:55:40, Barry Song wrote:
> From: Barry Song <v-songbaohua@oppo.com>
> 
> mm doesn't support non-blockable __GFP_NOFAIL allocation. Because
> __GFP_NOFAIL without direct reclamation may just result in a busy
> loop within non-sleepable contexts.
> 
> static inline struct page *
> __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
>                                                 struct alloc_context *ac)
> {
>         ...
>         /*
>          * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
>          * we always retry
>          */
>         if (gfp_mask & __GFP_NOFAIL) {
>                 /*
>                  * All existing users of the __GFP_NOFAIL are blockable, so warn
>                  * of any new users that actually require GFP_NOWAIT
>                  */
>                 if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
>                         goto fail;
>                 ...
>         }
>         ...
> fail:
>         warn_alloc(gfp_mask, ac->nodemask,
>                         "page allocation failure: order:%u", order);
> got_pg:
>         return page;
> }
> 
> Let's move the memory allocation out of the atomic context and use
> the normal sleepable context to get pages.
> 
> [RFC]: This has only been compile-tested; I'd prefer if the VDPA maintainers
> handles it.
> 
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> Cc: "Eugenio Pérez" <eperezma@redhat.com>
> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> ---
>  drivers/vdpa/vdpa_user/iova_domain.c | 24 ++++++++++++++++++++----
>  1 file changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> index 791d38d6284c..eff700e5f7a2 100644
> --- a/drivers/vdpa/vdpa_user/iova_domain.c
> +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> @@ -287,28 +287,44 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
>  {
>  	struct vduse_bounce_map *map;
>  	unsigned long i, count;
> +	struct page **pages = NULL;
>  
>  	write_lock(&domain->bounce_lock);
>  	if (!domain->user_bounce_pages)
>  		goto out;
> -
>  	count = domain->bounce_size >> PAGE_SHIFT;
> +	write_unlock(&domain->bounce_lock);
> +
> +	pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> +	for (i = 0; i < count; i++)
> +		pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);

AFAICS vduse_domain_release calls this function with
spin_lock(&domain->iotlb_lock) so dropping &domain->bounce_lock is not
sufficient.

-- 
Michal Hocko
SUSE Labs

Re: [PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL

[Barry Song]

On Thu, Jul 25, 2024 at 12:27 AM Michal Hocko <mhocko@suse.com> wrote:
>
> On Wed 24-07-24 20:55:40, Barry Song wrote:
> > From: Barry Song <v-songbaohua@oppo.com>
> >
> > mm doesn't support non-blockable __GFP_NOFAIL allocation. Because
> > __GFP_NOFAIL without direct reclamation may just result in a busy
> > loop within non-sleepable contexts.
> >
> > static inline struct page *
> > __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> >                                                 struct alloc_context *ac)
> > {
> >         ...
> >         /*
> >          * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
> >          * we always retry
> >          */
> >         if (gfp_mask & __GFP_NOFAIL) {
> >                 /*
> >                  * All existing users of the __GFP_NOFAIL are blockable, so warn
> >                  * of any new users that actually require GFP_NOWAIT
> >                  */
> >                 if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
> >                         goto fail;
> >                 ...
> >         }
> >         ...
> > fail:
> >         warn_alloc(gfp_mask, ac->nodemask,
> >                         "page allocation failure: order:%u", order);
> > got_pg:
> >         return page;
> > }
> >
> > Let's move the memory allocation out of the atomic context and use
> > the normal sleepable context to get pages.
> >
> > [RFC]: This has only been compile-tested; I'd prefer if the VDPA maintainers
> > handles it.
> >
> > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > Cc: Jason Wang <jasowang@redhat.com>
> > Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > Cc: "Eugenio Pérez" <eperezma@redhat.com>
> > Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> > Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> > ---
> >  drivers/vdpa/vdpa_user/iova_domain.c | 24 ++++++++++++++++++++----
> >  1 file changed, 20 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > index 791d38d6284c..eff700e5f7a2 100644
> > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > @@ -287,28 +287,44 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> >  {
> >       struct vduse_bounce_map *map;
> >       unsigned long i, count;
> > +     struct page **pages = NULL;
> >
> >       write_lock(&domain->bounce_lock);
> >       if (!domain->user_bounce_pages)
> >               goto out;
> > -
> >       count = domain->bounce_size >> PAGE_SHIFT;
> > +     write_unlock(&domain->bounce_lock);
> > +
> > +     pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> > +     for (i = 0; i < count; i++)
> > +             pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
>
> AFAICS vduse_domain_release calls this function with
> spin_lock(&domain->iotlb_lock) so dropping &domain->bounce_lock is not
> sufficient.

yes. this is true:

static int vduse_domain_release(struct inode *inode, struct file *file)
{
        struct vduse_iova_domain *domain = file->private_data;

        spin_lock(&domain->iotlb_lock);
        vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
        vduse_domain_remove_user_bounce_pages(domain);
        vduse_domain_free_kernel_bounce_pages(domain);
        spin_unlock(&domain->iotlb_lock);
        put_iova_domain(&domain->stream_iovad);
        put_iova_domain(&domain->consistent_iovad);
        vhost_iotlb_free(domain->iotlb);
        vfree(domain->bounce_maps);
        kfree(domain);

        return 0;
}

This is quite a pain. I admit I don't have knowledge of this driver, and I don't
think it's safe to release two locks and then reacquire them. The situation is
rather complex. Therefore, I would prefer if the VDPA maintainers could
take the lead in implementing a proper fix.

>
> --
> Michal Hocko
> SUSE Labs

Thanks
Barry

Re: [PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL

[Michal Hocko]

On Thu 25-07-24 10:50:45, Barry Song wrote:
> On Thu, Jul 25, 2024 at 12:27 AM Michal Hocko <mhocko@suse.com> wrote:
> >
> > On Wed 24-07-24 20:55:40, Barry Song wrote:
[...]
> > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > > index 791d38d6284c..eff700e5f7a2 100644
> > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > @@ -287,28 +287,44 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> > >  {
> > >       struct vduse_bounce_map *map;
> > >       unsigned long i, count;
> > > +     struct page **pages = NULL;
> > >
> > >       write_lock(&domain->bounce_lock);
> > >       if (!domain->user_bounce_pages)
> > >               goto out;
> > > -
> > >       count = domain->bounce_size >> PAGE_SHIFT;
> > > +     write_unlock(&domain->bounce_lock);
> > > +
> > > +     pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> > > +     for (i = 0; i < count; i++)
> > > +             pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> >
> > AFAICS vduse_domain_release calls this function with
> > spin_lock(&domain->iotlb_lock) so dropping &domain->bounce_lock is not
> > sufficient.
> 
> yes. this is true:
> 
> static int vduse_domain_release(struct inode *inode, struct file *file)
> {
>         struct vduse_iova_domain *domain = file->private_data;
> 
>         spin_lock(&domain->iotlb_lock);
>         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
>         vduse_domain_remove_user_bounce_pages(domain);
>         vduse_domain_free_kernel_bounce_pages(domain);
>         spin_unlock(&domain->iotlb_lock);
>         put_iova_domain(&domain->stream_iovad);
>         put_iova_domain(&domain->consistent_iovad);
>         vhost_iotlb_free(domain->iotlb);
>         vfree(domain->bounce_maps);
>         kfree(domain);
> 
>         return 0;
> }
> 
> This is quite a pain. I admit I don't have knowledge of this driver, and I don't
> think it's safe to release two locks and then reacquire them. The situation is
> rather complex. Therefore, I would prefer if the VDPA maintainers could
> take the lead in implementing a proper fix.

Would it be possible to move all that work to a deferred context?
-- 
Michal Hocko
SUSE Labs

Re: [PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL

[Barry Song]

On Thu, Jul 25, 2024 at 6:08 PM Michal Hocko <mhocko@suse.com> wrote:
>
> On Thu 25-07-24 10:50:45, Barry Song wrote:
> > On Thu, Jul 25, 2024 at 12:27 AM Michal Hocko <mhocko@suse.com> wrote:
> > >
> > > On Wed 24-07-24 20:55:40, Barry Song wrote:
> [...]
> > > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > index 791d38d6284c..eff700e5f7a2 100644
> > > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > @@ -287,28 +287,44 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> > > >  {
> > > >       struct vduse_bounce_map *map;
> > > >       unsigned long i, count;
> > > > +     struct page **pages = NULL;
> > > >
> > > >       write_lock(&domain->bounce_lock);
> > > >       if (!domain->user_bounce_pages)
> > > >               goto out;
> > > > -
> > > >       count = domain->bounce_size >> PAGE_SHIFT;
> > > > +     write_unlock(&domain->bounce_lock);
> > > > +
> > > > +     pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> > > > +     for (i = 0; i < count; i++)
> > > > +             pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> > >
> > > AFAICS vduse_domain_release calls this function with
> > > spin_lock(&domain->iotlb_lock) so dropping &domain->bounce_lock is not
> > > sufficient.
> >
> > yes. this is true:
> >
> > static int vduse_domain_release(struct inode *inode, struct file *file)
> > {
> >         struct vduse_iova_domain *domain = file->private_data;
> >
> >         spin_lock(&domain->iotlb_lock);
> >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> >         vduse_domain_remove_user_bounce_pages(domain);
> >         vduse_domain_free_kernel_bounce_pages(domain);
> >         spin_unlock(&domain->iotlb_lock);
> >         put_iova_domain(&domain->stream_iovad);
> >         put_iova_domain(&domain->consistent_iovad);
> >         vhost_iotlb_free(domain->iotlb);
> >         vfree(domain->bounce_maps);
> >         kfree(domain);
> >
> >         return 0;
> > }
> >
> > This is quite a pain. I admit I don't have knowledge of this driver, and I don't
> > think it's safe to release two locks and then reacquire them. The situation is
> > rather complex. Therefore, I would prefer if the VDPA maintainers could
> > take the lead in implementing a proper fix.
>
> Would it be possible to move all that work to a deferred context?

My understanding is that we need to be aware of both the iotlb_lock and
bounce_lock to implement the correct changes. As long as we still need
to acquire these two locks in a deferred context, there doesn't seem to
be any difference.

I can do the memory pre-allocation before spin_lock(&domain->iotlb_lock),
but I have no knowledge whether the "count" will change after I make
the preallocation.

diff --git a/drivers/vdpa/vdpa_user/iova_domain.c
b/drivers/vdpa/vdpa_user/iova_domain.c
index 791d38d6284c..7ec87ef33d42 100644
--- a/drivers/vdpa/vdpa_user/iova_domain.c
+++ b/drivers/vdpa/vdpa_user/iova_domain.c
@@ -544,9 +544,12 @@ static int vduse_domain_release(struct inode
*inode, struct file *file)
 {
        struct vduse_iova_domain *domain = file->private_data;

+      struct page **pages;
+      spin_lock(&domain->iotlb_lock); maybe also + bounce_lock?
+      count = domain->bounce_size >> PAGE_SHIFT;
+      spin_unlock(&domain->iotlb_lock);
+
+       preallocate_count_pages(pages, count);
+
....
        spin_lock(&domain->iotlb_lock);
        vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
-       vduse_domain_remove_user_bounce_pages(domain);
+       vduse_domain_remove_user_bounce_pages(domain, pages);
        vduse_domain_free_kernel_bounce_pages(domain);
        spin_unlock(&domain->iotlb_lock);
        put_iova_domain(&domain->stream_iovad);


> --
> Michal Hocko
> SUSE Labs

Re: [PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL

[Jason Wang]

On Thu, Jul 25, 2024 at 3:00 PM Barry Song <21cnbao@gmail.com> wrote:
>
> On Thu, Jul 25, 2024 at 6:08 PM Michal Hocko <mhocko@suse.com> wrote:
> >
> > On Thu 25-07-24 10:50:45, Barry Song wrote:
> > > On Thu, Jul 25, 2024 at 12:27 AM Michal Hocko <mhocko@suse.com> wrote:
> > > >
> > > > On Wed 24-07-24 20:55:40, Barry Song wrote:
> > [...]
> > > > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > index 791d38d6284c..eff700e5f7a2 100644
> > > > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > @@ -287,28 +287,44 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> > > > >  {
> > > > >       struct vduse_bounce_map *map;
> > > > >       unsigned long i, count;
> > > > > +     struct page **pages = NULL;
> > > > >
> > > > >       write_lock(&domain->bounce_lock);
> > > > >       if (!domain->user_bounce_pages)
> > > > >               goto out;
> > > > > -
> > > > >       count = domain->bounce_size >> PAGE_SHIFT;
> > > > > +     write_unlock(&domain->bounce_lock);
> > > > > +
> > > > > +     pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> > > > > +     for (i = 0; i < count; i++)
> > > > > +             pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> > > >
> > > > AFAICS vduse_domain_release calls this function with
> > > > spin_lock(&domain->iotlb_lock) so dropping &domain->bounce_lock is not
> > > > sufficient.
> > >
> > > yes. this is true:
> > >
> > > static int vduse_domain_release(struct inode *inode, struct file *file)
> > > {
> > >         struct vduse_iova_domain *domain = file->private_data;
> > >
> > >         spin_lock(&domain->iotlb_lock);
> > >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > >         vduse_domain_remove_user_bounce_pages(domain);
> > >         vduse_domain_free_kernel_bounce_pages(domain);
> > >         spin_unlock(&domain->iotlb_lock);
> > >         put_iova_domain(&domain->stream_iovad);
> > >         put_iova_domain(&domain->consistent_iovad);
> > >         vhost_iotlb_free(domain->iotlb);
> > >         vfree(domain->bounce_maps);
> > >         kfree(domain);
> > >
> > >         return 0;
> > > }
> > >
> > > This is quite a pain. I admit I don't have knowledge of this driver, and I don't
> > > think it's safe to release two locks and then reacquire them. The situation is
> > > rather complex. Therefore, I would prefer if the VDPA maintainers could
> > > take the lead in implementing a proper fix.
> >
> > Would it be possible to move all that work to a deferred context?
>
> My understanding is that we need to be aware of both the iotlb_lock and
> bounce_lock to implement the correct changes. As long as we still need
> to acquire these two locks in a deferred context, there doesn't seem to
> be any difference.
>
> I can do the memory pre-allocation before spin_lock(&domain->iotlb_lock),
> but I have no knowledge whether the "count" will change after I make
> the preallocation.
>
> diff --git a/drivers/vdpa/vdpa_user/iova_domain.c
> b/drivers/vdpa/vdpa_user/iova_domain.c
> index 791d38d6284c..7ec87ef33d42 100644
> --- a/drivers/vdpa/vdpa_user/iova_domain.c
> +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> @@ -544,9 +544,12 @@ static int vduse_domain_release(struct inode
> *inode, struct file *file)
>  {
>         struct vduse_iova_domain *domain = file->private_data;
>
> +      struct page **pages;
> +      spin_lock(&domain->iotlb_lock); maybe also + bounce_lock?
> +      count = domain->bounce_size >> PAGE_SHIFT;
> +      spin_unlock(&domain->iotlb_lock);

We probably don't need any lock here as bounce_size won't be changed .

> +
> +       preallocate_count_pages(pages, count);
> +
> ....
>         spin_lock(&domain->iotlb_lock);
>         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> -       vduse_domain_remove_user_bounce_pages(domain);
> +       vduse_domain_remove_user_bounce_pages(domain, pages);
>         vduse_domain_free_kernel_bounce_pages(domain);
>         spin_unlock(&domain->iotlb_lock);
>         put_iova_domain(&domain->stream_iovad);

This seems to work.

Thanks

>
>
> > --
> > Michal Hocko
> > SUSE Labs
>

Re: [PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL

[Barry Song]

On Mon, Jul 29, 2024 at 3:42 PM Jason Wang <jasowang@redhat.com> wrote:
>
> On Thu, Jul 25, 2024 at 3:00 PM Barry Song <21cnbao@gmail.com> wrote:
> >
> > On Thu, Jul 25, 2024 at 6:08 PM Michal Hocko <mhocko@suse.com> wrote:
> > >
> > > On Thu 25-07-24 10:50:45, Barry Song wrote:
> > > > On Thu, Jul 25, 2024 at 12:27 AM Michal Hocko <mhocko@suse.com> wrote:
> > > > >
> > > > > On Wed 24-07-24 20:55:40, Barry Song wrote:
> > > [...]
> > > > > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > index 791d38d6284c..eff700e5f7a2 100644
> > > > > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > @@ -287,28 +287,44 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> > > > > >  {
> > > > > >       struct vduse_bounce_map *map;
> > > > > >       unsigned long i, count;
> > > > > > +     struct page **pages = NULL;
> > > > > >
> > > > > >       write_lock(&domain->bounce_lock);
> > > > > >       if (!domain->user_bounce_pages)
> > > > > >               goto out;
> > > > > > -
> > > > > >       count = domain->bounce_size >> PAGE_SHIFT;
> > > > > > +     write_unlock(&domain->bounce_lock);
> > > > > > +
> > > > > > +     pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> > > > > > +     for (i = 0; i < count; i++)
> > > > > > +             pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> > > > >
> > > > > AFAICS vduse_domain_release calls this function with
> > > > > spin_lock(&domain->iotlb_lock) so dropping &domain->bounce_lock is not
> > > > > sufficient.
> > > >
> > > > yes. this is true:
> > > >
> > > > static int vduse_domain_release(struct inode *inode, struct file *file)
> > > > {
> > > >         struct vduse_iova_domain *domain = file->private_data;
> > > >
> > > >         spin_lock(&domain->iotlb_lock);
> > > >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > > >         vduse_domain_remove_user_bounce_pages(domain);
> > > >         vduse_domain_free_kernel_bounce_pages(domain);
> > > >         spin_unlock(&domain->iotlb_lock);
> > > >         put_iova_domain(&domain->stream_iovad);
> > > >         put_iova_domain(&domain->consistent_iovad);
> > > >         vhost_iotlb_free(domain->iotlb);
> > > >         vfree(domain->bounce_maps);
> > > >         kfree(domain);
> > > >
> > > >         return 0;
> > > > }
> > > >
> > > > This is quite a pain. I admit I don't have knowledge of this driver, and I don't
> > > > think it's safe to release two locks and then reacquire them. The situation is
> > > > rather complex. Therefore, I would prefer if the VDPA maintainers could
> > > > take the lead in implementing a proper fix.
> > >
> > > Would it be possible to move all that work to a deferred context?
> >
> > My understanding is that we need to be aware of both the iotlb_lock and
> > bounce_lock to implement the correct changes. As long as we still need
> > to acquire these two locks in a deferred context, there doesn't seem to
> > be any difference.
> >
> > I can do the memory pre-allocation before spin_lock(&domain->iotlb_lock),
> > but I have no knowledge whether the "count" will change after I make
> > the preallocation.
> >
> > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c
> > b/drivers/vdpa/vdpa_user/iova_domain.c
> > index 791d38d6284c..7ec87ef33d42 100644
> > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > @@ -544,9 +544,12 @@ static int vduse_domain_release(struct inode
> > *inode, struct file *file)
> >  {
> >         struct vduse_iova_domain *domain = file->private_data;
> >
> > +      struct page **pages;
> > +      spin_lock(&domain->iotlb_lock); maybe also + bounce_lock?
> > +      count = domain->bounce_size >> PAGE_SHIFT;
> > +      spin_unlock(&domain->iotlb_lock);
>
> We probably don't need any lock here as bounce_size won't be changed .
>
> > +
> > +       preallocate_count_pages(pages, count);
> > +
> > ....
> >         spin_lock(&domain->iotlb_lock);
> >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > -       vduse_domain_remove_user_bounce_pages(domain);
> > +       vduse_domain_remove_user_bounce_pages(domain, pages);
> >         vduse_domain_free_kernel_bounce_pages(domain);
> >         spin_unlock(&domain->iotlb_lock);
> >         put_iova_domain(&domain->stream_iovad);
>
> This seems to work.

Thanks, Jason. I personally have no knowledge of vDPA. Could you please help
review and test the patch below?

From 1f3cae091159bfcaffdb4a999a4a8e37db2eacf1 Mon Sep 17 00:00:00 2001
From: Barry Song <v-songbaohua@oppo.com>
Date: Wed, 24 Jul 2024 20:55:40 +1200
Subject: [PATCH RFC v2] vpda: try to fix the potential crash due to misusing
 __GFP_NOFAIL
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

mm doesn't support non-blockable __GFP_NOFAIL allocation. Because
__GFP_NOFAIL without direct reclamation may just result in a busy
loop within non-sleepable contexts.

static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
                                                struct alloc_context *ac)
{
        ...
        /*
         * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
         * we always retry
         */
        if (gfp_mask & __GFP_NOFAIL) {
                /*
                 * All existing users of the __GFP_NOFAIL are blockable, so warn
                 * of any new users that actually require GFP_NOWAIT
                 */
                if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
                        goto fail;
                ...
        }
        ...
fail:
        warn_alloc(gfp_mask, ac->nodemask,
                        "page allocation failure: order:%u", order);
got_pg:
        return page;
}

Let's move the memory allocation out of the atomic context and use
the normal sleepable context to get pages.

[RFC]: This has only been compile-tested; I'd prefer if the VDPA maintainers
handles it.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: "Eugenio Pérez" <eperezma@redhat.com>
Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
 drivers/vdpa/vdpa_user/iova_domain.c | 21 ++++++++++++++++-----
 drivers/vdpa/vdpa_user/iova_domain.h |  3 ++-
 drivers/vdpa/vdpa_user/vduse_dev.c   | 13 ++++++++++++-
 3 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
index 791d38d6284c..014809ac2b7c 100644
--- a/drivers/vdpa/vdpa_user/iova_domain.c
+++ b/drivers/vdpa/vdpa_user/iova_domain.c
@@ -283,7 +283,7 @@ int vduse_domain_add_user_bounce_pages(struct vduse_iova_domain *domain,
 	return ret;
 }
 
-void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
+void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain, struct page **pages)
 {
 	struct vduse_bounce_map *map;
 	unsigned long i, count;
@@ -294,15 +294,16 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
 
 	count = domain->bounce_size >> PAGE_SHIFT;
 	for (i = 0; i < count; i++) {
-		struct page *page = NULL;
+		struct page *page = pages[i];
 
 		map = &domain->bounce_maps[i];
-		if (WARN_ON(!map->bounce_page))
+		if (WARN_ON(!map->bounce_page)) {
+			put_page(page);
 			continue;
+		}
 
 		/* Copy user page to kernel page if it's in use */
 		if (map->orig_phys != INVALID_PHYS_ADDR) {
-			page = alloc_page(GFP_ATOMIC | __GFP_NOFAIL);
 			memcpy_from_page(page_address(page),
 					 map->bounce_page, 0, PAGE_SIZE);
 		}
@@ -543,10 +544,19 @@ static int vduse_domain_mmap(struct file *file, struct vm_area_struct *vma)
 static int vduse_domain_release(struct inode *inode, struct file *file)
 {
 	struct vduse_iova_domain *domain = file->private_data;
+	struct page **pages = NULL;
+	unsigned long count, i;
+
+	if (domain->user_bounce_pages) {
+		count = domain->bounce_size >> PAGE_SHIFT;
+		pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
+		for (i = 0; i < count; i++)
+			pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
+	}
 
 	spin_lock(&domain->iotlb_lock);
 	vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
-	vduse_domain_remove_user_bounce_pages(domain);
+	vduse_domain_remove_user_bounce_pages(domain, pages);
 	vduse_domain_free_kernel_bounce_pages(domain);
 	spin_unlock(&domain->iotlb_lock);
 	put_iova_domain(&domain->stream_iovad);
@@ -554,6 +564,7 @@ static int vduse_domain_release(struct inode *inode, struct file *file)
 	vhost_iotlb_free(domain->iotlb);
 	vfree(domain->bounce_maps);
 	kfree(domain);
+	kfree(pages);
 
 	return 0;
 }
diff --git a/drivers/vdpa/vdpa_user/iova_domain.h b/drivers/vdpa/vdpa_user/iova_domain.h
index f92f22a7267d..db0b793d86db 100644
--- a/drivers/vdpa/vdpa_user/iova_domain.h
+++ b/drivers/vdpa/vdpa_user/iova_domain.h
@@ -74,7 +74,8 @@ void vduse_domain_reset_bounce_map(struct vduse_iova_domain *domain);
 int vduse_domain_add_user_bounce_pages(struct vduse_iova_domain *domain,
 				       struct page **pages, int count);
 
-void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain);
+void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain,
+					   struct page **pages);
 
 void vduse_domain_destroy(struct vduse_iova_domain *domain);
 
diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 7ae99691efdf..df7c1b6f1350 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -1030,6 +1030,8 @@ static int vduse_dev_queue_irq_work(struct vduse_dev *dev,
 static int vduse_dev_dereg_umem(struct vduse_dev *dev,
 				u64 iova, u64 size)
 {
+	struct page **pages = NULL;
+	unsigned long count, i;
 	int ret;
 
 	mutex_lock(&dev->mem_lock);
@@ -1044,13 +1046,22 @@ static int vduse_dev_dereg_umem(struct vduse_dev *dev,
 	if (dev->umem->iova != iova || size != dev->domain->bounce_size)
 		goto unlock;
 
-	vduse_domain_remove_user_bounce_pages(dev->domain);
+	if (dev->domain->user_bounce_pages) {
+		count = dev->domain->bounce_size >> PAGE_SHIFT;
+		pages = kmalloc_array(count, sizeof(*pages),
+				      GFP_KERNEL | __GFP_NOFAIL);
+		for (i = 0; i < count; i++)
+			pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
+	}
+
+	vduse_domain_remove_user_bounce_pages(dev->domain, pages);
 	unpin_user_pages_dirty_lock(dev->umem->pages,
 				    dev->umem->npages, true);
 	atomic64_sub(dev->umem->npages, &dev->umem->mm->pinned_vm);
 	mmdrop(dev->umem->mm);
 	vfree(dev->umem->pages);
 	kfree(dev->umem);
+	kfree(pages);
 	dev->umem = NULL;
 	ret = 0;
 unlock:
-- 
2.34.1

>
> Thanks
>
> >
> >
> > > --
> > > Michal Hocko
> > > SUSE Labs
> >

Thanks
Barry

Re: [PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL

[Jason Wang]

On Mon, Jul 29, 2024 at 2:05 PM Barry Song <21cnbao@gmail.com> wrote:
>
> On Mon, Jul 29, 2024 at 3:42 PM Jason Wang <jasowang@redhat.com> wrote:
> >
> > On Thu, Jul 25, 2024 at 3:00 PM Barry Song <21cnbao@gmail.com> wrote:
> > >
> > > On Thu, Jul 25, 2024 at 6:08 PM Michal Hocko <mhocko@suse.com> wrote:
> > > >
> > > > On Thu 25-07-24 10:50:45, Barry Song wrote:
> > > > > On Thu, Jul 25, 2024 at 12:27 AM Michal Hocko <mhocko@suse.com> wrote:
> > > > > >
> > > > > > On Wed 24-07-24 20:55:40, Barry Song wrote:
> > > > [...]
> > > > > > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > > index 791d38d6284c..eff700e5f7a2 100644
> > > > > > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > > @@ -287,28 +287,44 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> > > > > > >  {
> > > > > > >       struct vduse_bounce_map *map;
> > > > > > >       unsigned long i, count;
> > > > > > > +     struct page **pages = NULL;
> > > > > > >
> > > > > > >       write_lock(&domain->bounce_lock);
> > > > > > >       if (!domain->user_bounce_pages)
> > > > > > >               goto out;
> > > > > > > -
> > > > > > >       count = domain->bounce_size >> PAGE_SHIFT;
> > > > > > > +     write_unlock(&domain->bounce_lock);
> > > > > > > +
> > > > > > > +     pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> > > > > > > +     for (i = 0; i < count; i++)
> > > > > > > +             pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> > > > > >
> > > > > > AFAICS vduse_domain_release calls this function with
> > > > > > spin_lock(&domain->iotlb_lock) so dropping &domain->bounce_lock is not
> > > > > > sufficient.
> > > > >
> > > > > yes. this is true:
> > > > >
> > > > > static int vduse_domain_release(struct inode *inode, struct file *file)
> > > > > {
> > > > >         struct vduse_iova_domain *domain = file->private_data;
> > > > >
> > > > >         spin_lock(&domain->iotlb_lock);
> > > > >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > > > >         vduse_domain_remove_user_bounce_pages(domain);
> > > > >         vduse_domain_free_kernel_bounce_pages(domain);
> > > > >         spin_unlock(&domain->iotlb_lock);
> > > > >         put_iova_domain(&domain->stream_iovad);
> > > > >         put_iova_domain(&domain->consistent_iovad);
> > > > >         vhost_iotlb_free(domain->iotlb);
> > > > >         vfree(domain->bounce_maps);
> > > > >         kfree(domain);
> > > > >
> > > > >         return 0;
> > > > > }
> > > > >
> > > > > This is quite a pain. I admit I don't have knowledge of this driver, and I don't
> > > > > think it's safe to release two locks and then reacquire them. The situation is
> > > > > rather complex. Therefore, I would prefer if the VDPA maintainers could
> > > > > take the lead in implementing a proper fix.
> > > >
> > > > Would it be possible to move all that work to a deferred context?
> > >
> > > My understanding is that we need to be aware of both the iotlb_lock and
> > > bounce_lock to implement the correct changes. As long as we still need
> > > to acquire these two locks in a deferred context, there doesn't seem to
> > > be any difference.
> > >
> > > I can do the memory pre-allocation before spin_lock(&domain->iotlb_lock),
> > > but I have no knowledge whether the "count" will change after I make
> > > the preallocation.
> > >
> > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c
> > > b/drivers/vdpa/vdpa_user/iova_domain.c
> > > index 791d38d6284c..7ec87ef33d42 100644
> > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > @@ -544,9 +544,12 @@ static int vduse_domain_release(struct inode
> > > *inode, struct file *file)
> > >  {
> > >         struct vduse_iova_domain *domain = file->private_data;
> > >
> > > +      struct page **pages;
> > > +      spin_lock(&domain->iotlb_lock); maybe also + bounce_lock?
> > > +      count = domain->bounce_size >> PAGE_SHIFT;
> > > +      spin_unlock(&domain->iotlb_lock);
> >
> > We probably don't need any lock here as bounce_size won't be changed .
> >
> > > +
> > > +       preallocate_count_pages(pages, count);
> > > +
> > > ....
> > >         spin_lock(&domain->iotlb_lock);
> > >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > > -       vduse_domain_remove_user_bounce_pages(domain);
> > > +       vduse_domain_remove_user_bounce_pages(domain, pages);
> > >         vduse_domain_free_kernel_bounce_pages(domain);
> > >         spin_unlock(&domain->iotlb_lock);
> > >         put_iova_domain(&domain->stream_iovad);
> >
> > This seems to work.
>
> Thanks, Jason. I personally have no knowledge of vDPA. Could you please help
> review and test the patch below?
>
> From 1f3cae091159bfcaffdb4a999a4a8e37db2eacf1 Mon Sep 17 00:00:00 2001
> From: Barry Song <v-songbaohua@oppo.com>
> Date: Wed, 24 Jul 2024 20:55:40 +1200
> Subject: [PATCH RFC v2] vpda: try to fix the potential crash due to misusing
>  __GFP_NOFAIL
> MIME-Version: 1.0
> Content-Type: text/plain; charset=UTF-8
> Content-Transfer-Encoding: 8bit
>
> mm doesn't support non-blockable __GFP_NOFAIL allocation. Because
> __GFP_NOFAIL without direct reclamation may just result in a busy
> loop within non-sleepable contexts.
>
> static inline struct page *
> __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
>                                                 struct alloc_context *ac)
> {
>         ...
>         /*
>          * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
>          * we always retry
>          */
>         if (gfp_mask & __GFP_NOFAIL) {
>                 /*
>                  * All existing users of the __GFP_NOFAIL are blockable, so warn
>                  * of any new users that actually require GFP_NOWAIT
>                  */
>                 if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
>                         goto fail;
>                 ...
>         }
>         ...
> fail:
>         warn_alloc(gfp_mask, ac->nodemask,
>                         "page allocation failure: order:%u", order);
> got_pg:
>         return page;
> }
>
> Let's move the memory allocation out of the atomic context and use
> the normal sleepable context to get pages.
>
> [RFC]: This has only been compile-tested; I'd prefer if the VDPA maintainers
> handles it.
>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Jason Wang <jasowang@redhat.com>
> Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> Cc: "Eugenio Pérez" <eperezma@redhat.com>
> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> ---
>  drivers/vdpa/vdpa_user/iova_domain.c | 21 ++++++++++++++++-----
>  drivers/vdpa/vdpa_user/iova_domain.h |  3 ++-
>  drivers/vdpa/vdpa_user/vduse_dev.c   | 13 ++++++++++++-
>  3 files changed, 30 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> index 791d38d6284c..014809ac2b7c 100644
> --- a/drivers/vdpa/vdpa_user/iova_domain.c
> +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> @@ -283,7 +283,7 @@ int vduse_domain_add_user_bounce_pages(struct vduse_iova_domain *domain,
>         return ret;
>  }
>
> -void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> +void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain, struct page **pages)
>  {
>         struct vduse_bounce_map *map;
>         unsigned long i, count;
> @@ -294,15 +294,16 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
>
>         count = domain->bounce_size >> PAGE_SHIFT;
>         for (i = 0; i < count; i++) {
> -               struct page *page = NULL;
> +               struct page *page = pages[i];
>
>                 map = &domain->bounce_maps[i];
> -               if (WARN_ON(!map->bounce_page))
> +               if (WARN_ON(!map->bounce_page)) {
> +                       put_page(page);
>                         continue;
> +               }
>
>                 /* Copy user page to kernel page if it's in use */
>                 if (map->orig_phys != INVALID_PHYS_ADDR) {
> -                       page = alloc_page(GFP_ATOMIC | __GFP_NOFAIL);
>                         memcpy_from_page(page_address(page),
>                                          map->bounce_page, 0, PAGE_SIZE);
>                 }
> @@ -543,10 +544,19 @@ static int vduse_domain_mmap(struct file *file, struct vm_area_struct *vma)
>  static int vduse_domain_release(struct inode *inode, struct file *file)
>  {
>         struct vduse_iova_domain *domain = file->private_data;
> +       struct page **pages = NULL;
> +       unsigned long count, i;
> +
> +       if (domain->user_bounce_pages) {
> +               count = domain->bounce_size >> PAGE_SHIFT;
> +               pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> +               for (i = 0; i < count; i++)
> +                       pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> +       }
>
>         spin_lock(&domain->iotlb_lock);
>         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> -       vduse_domain_remove_user_bounce_pages(domain);
> +       vduse_domain_remove_user_bounce_pages(domain, pages);
>         vduse_domain_free_kernel_bounce_pages(domain);
>         spin_unlock(&domain->iotlb_lock);
>         put_iova_domain(&domain->stream_iovad);
> @@ -554,6 +564,7 @@ static int vduse_domain_release(struct inode *inode, struct file *file)
>         vhost_iotlb_free(domain->iotlb);
>         vfree(domain->bounce_maps);
>         kfree(domain);
> +       kfree(pages);
>
>         return 0;
>  }
> diff --git a/drivers/vdpa/vdpa_user/iova_domain.h b/drivers/vdpa/vdpa_user/iova_domain.h
> index f92f22a7267d..db0b793d86db 100644
> --- a/drivers/vdpa/vdpa_user/iova_domain.h
> +++ b/drivers/vdpa/vdpa_user/iova_domain.h
> @@ -74,7 +74,8 @@ void vduse_domain_reset_bounce_map(struct vduse_iova_domain *domain);
>  int vduse_domain_add_user_bounce_pages(struct vduse_iova_domain *domain,
>                                        struct page **pages, int count);
>
> -void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain);
> +void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain,
> +                                          struct page **pages);
>
>  void vduse_domain_destroy(struct vduse_iova_domain *domain);
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index 7ae99691efdf..df7c1b6f1350 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -1030,6 +1030,8 @@ static int vduse_dev_queue_irq_work(struct vduse_dev *dev,
>  static int vduse_dev_dereg_umem(struct vduse_dev *dev,
>                                 u64 iova, u64 size)
>  {
> +       struct page **pages = NULL;
> +       unsigned long count, i;
>         int ret;
>
>         mutex_lock(&dev->mem_lock);
> @@ -1044,13 +1046,22 @@ static int vduse_dev_dereg_umem(struct vduse_dev *dev,
>         if (dev->umem->iova != iova || size != dev->domain->bounce_size)
>                 goto unlock;
>
> -       vduse_domain_remove_user_bounce_pages(dev->domain);
> +       if (dev->domain->user_bounce_pages) {
> +               count = dev->domain->bounce_size >> PAGE_SHIFT;
> +               pages = kmalloc_array(count, sizeof(*pages),
> +                                     GFP_KERNEL | __GFP_NOFAIL);
> +               for (i = 0; i < count; i++)
> +                       pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> +       }

Nit: there's some code duplication with vduse_domain_release().

Others look good to me.

Would you like to post a formal patch?

Thanks

> +
> +       vduse_domain_remove_user_bounce_pages(dev->domain, pages);
>         unpin_user_pages_dirty_lock(dev->umem->pages,
>                                     dev->umem->npages, true);
>         atomic64_sub(dev->umem->npages, &dev->umem->mm->pinned_vm);
>         mmdrop(dev->umem->mm);
>         vfree(dev->umem->pages);
>         kfree(dev->umem);
> +       kfree(pages);
>         dev->umem = NULL;
>         ret = 0;
>  unlock:
> --
> 2.34.1
>
> >
> > Thanks
> >
> > >
> > >
> > > > --
> > > > Michal Hocko
> > > > SUSE Labs
> > >
>
> Thanks
> Barry
>

Re: [PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL

[Barry Song]

On Tue, Jul 30, 2024 at 10:49 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Mon, Jul 29, 2024 at 2:05 PM Barry Song <21cnbao@gmail.com> wrote:
> >
> > On Mon, Jul 29, 2024 at 3:42 PM Jason Wang <jasowang@redhat.com> wrote:
> > >
> > > On Thu, Jul 25, 2024 at 3:00 PM Barry Song <21cnbao@gmail.com> wrote:
> > > >
> > > > On Thu, Jul 25, 2024 at 6:08 PM Michal Hocko <mhocko@suse.com> wrote:
> > > > >
> > > > > On Thu 25-07-24 10:50:45, Barry Song wrote:
> > > > > > On Thu, Jul 25, 2024 at 12:27 AM Michal Hocko <mhocko@suse.com> wrote:
> > > > > > >
> > > > > > > On Wed 24-07-24 20:55:40, Barry Song wrote:
> > > > > [...]
> > > > > > > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > > > index 791d38d6284c..eff700e5f7a2 100644
> > > > > > > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > > > @@ -287,28 +287,44 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> > > > > > > >  {
> > > > > > > >       struct vduse_bounce_map *map;
> > > > > > > >       unsigned long i, count;
> > > > > > > > +     struct page **pages = NULL;
> > > > > > > >
> > > > > > > >       write_lock(&domain->bounce_lock);
> > > > > > > >       if (!domain->user_bounce_pages)
> > > > > > > >               goto out;
> > > > > > > > -
> > > > > > > >       count = domain->bounce_size >> PAGE_SHIFT;
> > > > > > > > +     write_unlock(&domain->bounce_lock);
> > > > > > > > +
> > > > > > > > +     pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> > > > > > > > +     for (i = 0; i < count; i++)
> > > > > > > > +             pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> > > > > > >
> > > > > > > AFAICS vduse_domain_release calls this function with
> > > > > > > spin_lock(&domain->iotlb_lock) so dropping &domain->bounce_lock is not
> > > > > > > sufficient.
> > > > > >
> > > > > > yes. this is true:
> > > > > >
> > > > > > static int vduse_domain_release(struct inode *inode, struct file *file)
> > > > > > {
> > > > > >         struct vduse_iova_domain *domain = file->private_data;
> > > > > >
> > > > > >         spin_lock(&domain->iotlb_lock);
> > > > > >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > > > > >         vduse_domain_remove_user_bounce_pages(domain);
> > > > > >         vduse_domain_free_kernel_bounce_pages(domain);
> > > > > >         spin_unlock(&domain->iotlb_lock);
> > > > > >         put_iova_domain(&domain->stream_iovad);
> > > > > >         put_iova_domain(&domain->consistent_iovad);
> > > > > >         vhost_iotlb_free(domain->iotlb);
> > > > > >         vfree(domain->bounce_maps);
> > > > > >         kfree(domain);
> > > > > >
> > > > > >         return 0;
> > > > > > }
> > > > > >
> > > > > > This is quite a pain. I admit I don't have knowledge of this driver, and I don't
> > > > > > think it's safe to release two locks and then reacquire them. The situation is
> > > > > > rather complex. Therefore, I would prefer if the VDPA maintainers could
> > > > > > take the lead in implementing a proper fix.
> > > > >
> > > > > Would it be possible to move all that work to a deferred context?
> > > >
> > > > My understanding is that we need to be aware of both the iotlb_lock and
> > > > bounce_lock to implement the correct changes. As long as we still need
> > > > to acquire these two locks in a deferred context, there doesn't seem to
> > > > be any difference.
> > > >
> > > > I can do the memory pre-allocation before spin_lock(&domain->iotlb_lock),
> > > > but I have no knowledge whether the "count" will change after I make
> > > > the preallocation.
> > > >
> > > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c
> > > > b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > index 791d38d6284c..7ec87ef33d42 100644
> > > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > @@ -544,9 +544,12 @@ static int vduse_domain_release(struct inode
> > > > *inode, struct file *file)
> > > >  {
> > > >         struct vduse_iova_domain *domain = file->private_data;
> > > >
> > > > +      struct page **pages;
> > > > +      spin_lock(&domain->iotlb_lock); maybe also + bounce_lock?
> > > > +      count = domain->bounce_size >> PAGE_SHIFT;
> > > > +      spin_unlock(&domain->iotlb_lock);
> > >
> > > We probably don't need any lock here as bounce_size won't be changed .
> > >
> > > > +
> > > > +       preallocate_count_pages(pages, count);
> > > > +
> > > > ....
> > > >         spin_lock(&domain->iotlb_lock);
> > > >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > > > -       vduse_domain_remove_user_bounce_pages(domain);
> > > > +       vduse_domain_remove_user_bounce_pages(domain, pages);
> > > >         vduse_domain_free_kernel_bounce_pages(domain);
> > > >         spin_unlock(&domain->iotlb_lock);
> > > >         put_iova_domain(&domain->stream_iovad);
> > >
> > > This seems to work.
> >
> > Thanks, Jason. I personally have no knowledge of vDPA. Could you please help
> > review and test the patch below?
> >
> > From 1f3cae091159bfcaffdb4a999a4a8e37db2eacf1 Mon Sep 17 00:00:00 2001
> > From: Barry Song <v-songbaohua@oppo.com>
> > Date: Wed, 24 Jul 2024 20:55:40 +1200
> > Subject: [PATCH RFC v2] vpda: try to fix the potential crash due to misusing
> >  __GFP_NOFAIL
> > MIME-Version: 1.0
> > Content-Type: text/plain; charset=UTF-8
> > Content-Transfer-Encoding: 8bit
> >
> > mm doesn't support non-blockable __GFP_NOFAIL allocation. Because
> > __GFP_NOFAIL without direct reclamation may just result in a busy
> > loop within non-sleepable contexts.
> >
> > static inline struct page *
> > __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> >                                                 struct alloc_context *ac)
> > {
> >         ...
> >         /*
> >          * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
> >          * we always retry
> >          */
> >         if (gfp_mask & __GFP_NOFAIL) {
> >                 /*
> >                  * All existing users of the __GFP_NOFAIL are blockable, so warn
> >                  * of any new users that actually require GFP_NOWAIT
> >                  */
> >                 if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
> >                         goto fail;
> >                 ...
> >         }
> >         ...
> > fail:
> >         warn_alloc(gfp_mask, ac->nodemask,
> >                         "page allocation failure: order:%u", order);
> > got_pg:
> >         return page;
> > }
> >
> > Let's move the memory allocation out of the atomic context and use
> > the normal sleepable context to get pages.
> >
> > [RFC]: This has only been compile-tested; I'd prefer if the VDPA maintainers
> > handles it.
> >
> > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > Cc: Jason Wang <jasowang@redhat.com>
> > Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > Cc: "Eugenio Pérez" <eperezma@redhat.com>
> > Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> > Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> > ---
> >  drivers/vdpa/vdpa_user/iova_domain.c | 21 ++++++++++++++++-----
> >  drivers/vdpa/vdpa_user/iova_domain.h |  3 ++-
> >  drivers/vdpa/vdpa_user/vduse_dev.c   | 13 ++++++++++++-
> >  3 files changed, 30 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > index 791d38d6284c..014809ac2b7c 100644
> > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > @@ -283,7 +283,7 @@ int vduse_domain_add_user_bounce_pages(struct vduse_iova_domain *domain,
> >         return ret;
> >  }
> >
> > -void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> > +void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain, struct page **pages)
> >  {
> >         struct vduse_bounce_map *map;
> >         unsigned long i, count;
> > @@ -294,15 +294,16 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> >
> >         count = domain->bounce_size >> PAGE_SHIFT;
> >         for (i = 0; i < count; i++) {
> > -               struct page *page = NULL;
> > +               struct page *page = pages[i];
> >
> >                 map = &domain->bounce_maps[i];
> > -               if (WARN_ON(!map->bounce_page))
> > +               if (WARN_ON(!map->bounce_page)) {
> > +                       put_page(page);
> >                         continue;
> > +               }
> >
> >                 /* Copy user page to kernel page if it's in use */
> >                 if (map->orig_phys != INVALID_PHYS_ADDR) {
> > -                       page = alloc_page(GFP_ATOMIC | __GFP_NOFAIL);
> >                         memcpy_from_page(page_address(page),
> >                                          map->bounce_page, 0, PAGE_SIZE);
> >                 }
> > @@ -543,10 +544,19 @@ static int vduse_domain_mmap(struct file *file, struct vm_area_struct *vma)
> >  static int vduse_domain_release(struct inode *inode, struct file *file)
> >  {
> >         struct vduse_iova_domain *domain = file->private_data;
> > +       struct page **pages = NULL;
> > +       unsigned long count, i;
> > +
> > +       if (domain->user_bounce_pages) {
> > +               count = domain->bounce_size >> PAGE_SHIFT;
> > +               pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> > +               for (i = 0; i < count; i++)
> > +                       pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> > +       }
> >
> >         spin_lock(&domain->iotlb_lock);
> >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > -       vduse_domain_remove_user_bounce_pages(domain);
> > +       vduse_domain_remove_user_bounce_pages(domain, pages);
> >         vduse_domain_free_kernel_bounce_pages(domain);
> >         spin_unlock(&domain->iotlb_lock);
> >         put_iova_domain(&domain->stream_iovad);
> > @@ -554,6 +564,7 @@ static int vduse_domain_release(struct inode *inode, struct file *file)
> >         vhost_iotlb_free(domain->iotlb);
> >         vfree(domain->bounce_maps);
> >         kfree(domain);
> > +       kfree(pages);
> >
> >         return 0;
> >  }
> > diff --git a/drivers/vdpa/vdpa_user/iova_domain.h b/drivers/vdpa/vdpa_user/iova_domain.h
> > index f92f22a7267d..db0b793d86db 100644
> > --- a/drivers/vdpa/vdpa_user/iova_domain.h
> > +++ b/drivers/vdpa/vdpa_user/iova_domain.h
> > @@ -74,7 +74,8 @@ void vduse_domain_reset_bounce_map(struct vduse_iova_domain *domain);
> >  int vduse_domain_add_user_bounce_pages(struct vduse_iova_domain *domain,
> >                                        struct page **pages, int count);
> >
> > -void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain);
> > +void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain,
> > +                                          struct page **pages);
> >
> >  void vduse_domain_destroy(struct vduse_iova_domain *domain);
> >
> > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > index 7ae99691efdf..df7c1b6f1350 100644
> > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > @@ -1030,6 +1030,8 @@ static int vduse_dev_queue_irq_work(struct vduse_dev *dev,
> >  static int vduse_dev_dereg_umem(struct vduse_dev *dev,
> >                                 u64 iova, u64 size)
> >  {
> > +       struct page **pages = NULL;
> > +       unsigned long count, i;
> >         int ret;
> >
> >         mutex_lock(&dev->mem_lock);
> > @@ -1044,13 +1046,22 @@ static int vduse_dev_dereg_umem(struct vduse_dev *dev,
> >         if (dev->umem->iova != iova || size != dev->domain->bounce_size)
> >                 goto unlock;
> >
> > -       vduse_domain_remove_user_bounce_pages(dev->domain);
> > +       if (dev->domain->user_bounce_pages) {
> > +               count = dev->domain->bounce_size >> PAGE_SHIFT;
> > +               pages = kmalloc_array(count, sizeof(*pages),
> > +                                     GFP_KERNEL | __GFP_NOFAIL);
> > +               for (i = 0; i < count; i++)
> > +                       pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> > +       }
>
> Nit: there's some code duplication with vduse_domain_release().
>
> Others look good to me.
>
> Would you like to post a formal patch?

 Jason, thanks!

I haven't tested this patch and I don't have the setup to test. I
wonder if you can
post a tested-by tag before I send a formal patch.

BTW, if we want to have a common function to remove the duplicated code,
what is the name you suggest to have for this function?

>
> Thanks
>
> > +
> > +       vduse_domain_remove_user_bounce_pages(dev->domain, pages);
> >         unpin_user_pages_dirty_lock(dev->umem->pages,
> >                                     dev->umem->npages, true);
> >         atomic64_sub(dev->umem->npages, &dev->umem->mm->pinned_vm);
> >         mmdrop(dev->umem->mm);
> >         vfree(dev->umem->pages);
> >         kfree(dev->umem);
> > +       kfree(pages);
> >         dev->umem = NULL;
> >         ret = 0;
> >  unlock:
> > --
> > 2.34.1
> >
> > >
> > > Thanks
> > >
> > > >
> > > >
> > > > > --
> > > > > Michal Hocko
> > > > > SUSE Labs
> > > >
> >
> > Thanks
> > Barry
> >
>

Thanks
Barry

Re: [PATCH RFC 1/5] vpda: try to fix the potential crash due to misusing __GFP_NOFAIL

[Jason Wang]

On Tue, Jul 30, 2024 at 11:09 AM Barry Song <21cnbao@gmail.com> wrote:
>
> On Tue, Jul 30, 2024 at 10:49 AM Jason Wang <jasowang@redhat.com> wrote:
> >
> > On Mon, Jul 29, 2024 at 2:05 PM Barry Song <21cnbao@gmail.com> wrote:
> > >
> > > On Mon, Jul 29, 2024 at 3:42 PM Jason Wang <jasowang@redhat.com> wrote:
> > > >
> > > > On Thu, Jul 25, 2024 at 3:00 PM Barry Song <21cnbao@gmail.com> wrote:
> > > > >
> > > > > On Thu, Jul 25, 2024 at 6:08 PM Michal Hocko <mhocko@suse.com> wrote:
> > > > > >
> > > > > > On Thu 25-07-24 10:50:45, Barry Song wrote:
> > > > > > > On Thu, Jul 25, 2024 at 12:27 AM Michal Hocko <mhocko@suse.com> wrote:
> > > > > > > >
> > > > > > > > On Wed 24-07-24 20:55:40, Barry Song wrote:
> > > > > > [...]
> > > > > > > > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > > > > index 791d38d6284c..eff700e5f7a2 100644
> > > > > > > > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > > > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > > > > > @@ -287,28 +287,44 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> > > > > > > > >  {
> > > > > > > > >       struct vduse_bounce_map *map;
> > > > > > > > >       unsigned long i, count;
> > > > > > > > > +     struct page **pages = NULL;
> > > > > > > > >
> > > > > > > > >       write_lock(&domain->bounce_lock);
> > > > > > > > >       if (!domain->user_bounce_pages)
> > > > > > > > >               goto out;
> > > > > > > > > -
> > > > > > > > >       count = domain->bounce_size >> PAGE_SHIFT;
> > > > > > > > > +     write_unlock(&domain->bounce_lock);
> > > > > > > > > +
> > > > > > > > > +     pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> > > > > > > > > +     for (i = 0; i < count; i++)
> > > > > > > > > +             pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> > > > > > > >
> > > > > > > > AFAICS vduse_domain_release calls this function with
> > > > > > > > spin_lock(&domain->iotlb_lock) so dropping &domain->bounce_lock is not
> > > > > > > > sufficient.
> > > > > > >
> > > > > > > yes. this is true:
> > > > > > >
> > > > > > > static int vduse_domain_release(struct inode *inode, struct file *file)
> > > > > > > {
> > > > > > >         struct vduse_iova_domain *domain = file->private_data;
> > > > > > >
> > > > > > >         spin_lock(&domain->iotlb_lock);
> > > > > > >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > > > > > >         vduse_domain_remove_user_bounce_pages(domain);
> > > > > > >         vduse_domain_free_kernel_bounce_pages(domain);
> > > > > > >         spin_unlock(&domain->iotlb_lock);
> > > > > > >         put_iova_domain(&domain->stream_iovad);
> > > > > > >         put_iova_domain(&domain->consistent_iovad);
> > > > > > >         vhost_iotlb_free(domain->iotlb);
> > > > > > >         vfree(domain->bounce_maps);
> > > > > > >         kfree(domain);
> > > > > > >
> > > > > > >         return 0;
> > > > > > > }
> > > > > > >
> > > > > > > This is quite a pain. I admit I don't have knowledge of this driver, and I don't
> > > > > > > think it's safe to release two locks and then reacquire them. The situation is
> > > > > > > rather complex. Therefore, I would prefer if the VDPA maintainers could
> > > > > > > take the lead in implementing a proper fix.
> > > > > >
> > > > > > Would it be possible to move all that work to a deferred context?
> > > > >
> > > > > My understanding is that we need to be aware of both the iotlb_lock and
> > > > > bounce_lock to implement the correct changes. As long as we still need
> > > > > to acquire these two locks in a deferred context, there doesn't seem to
> > > > > be any difference.
> > > > >
> > > > > I can do the memory pre-allocation before spin_lock(&domain->iotlb_lock),
> > > > > but I have no knowledge whether the "count" will change after I make
> > > > > the preallocation.
> > > > >
> > > > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > index 791d38d6284c..7ec87ef33d42 100644
> > > > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > > > @@ -544,9 +544,12 @@ static int vduse_domain_release(struct inode
> > > > > *inode, struct file *file)
> > > > >  {
> > > > >         struct vduse_iova_domain *domain = file->private_data;
> > > > >
> > > > > +      struct page **pages;
> > > > > +      spin_lock(&domain->iotlb_lock); maybe also + bounce_lock?
> > > > > +      count = domain->bounce_size >> PAGE_SHIFT;
> > > > > +      spin_unlock(&domain->iotlb_lock);
> > > >
> > > > We probably don't need any lock here as bounce_size won't be changed .
> > > >
> > > > > +
> > > > > +       preallocate_count_pages(pages, count);
> > > > > +
> > > > > ....
> > > > >         spin_lock(&domain->iotlb_lock);
> > > > >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > > > > -       vduse_domain_remove_user_bounce_pages(domain);
> > > > > +       vduse_domain_remove_user_bounce_pages(domain, pages);
> > > > >         vduse_domain_free_kernel_bounce_pages(domain);
> > > > >         spin_unlock(&domain->iotlb_lock);
> > > > >         put_iova_domain(&domain->stream_iovad);
> > > >
> > > > This seems to work.
> > >
> > > Thanks, Jason. I personally have no knowledge of vDPA. Could you please help
> > > review and test the patch below?
> > >
> > > From 1f3cae091159bfcaffdb4a999a4a8e37db2eacf1 Mon Sep 17 00:00:00 2001
> > > From: Barry Song <v-songbaohua@oppo.com>
> > > Date: Wed, 24 Jul 2024 20:55:40 +1200
> > > Subject: [PATCH RFC v2] vpda: try to fix the potential crash due to misusing
> > >  __GFP_NOFAIL
> > > MIME-Version: 1.0
> > > Content-Type: text/plain; charset=UTF-8
> > > Content-Transfer-Encoding: 8bit
> > >
> > > mm doesn't support non-blockable __GFP_NOFAIL allocation. Because
> > > __GFP_NOFAIL without direct reclamation may just result in a busy
> > > loop within non-sleepable contexts.
> > >
> > > static inline struct page *
> > > __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> > >                                                 struct alloc_context *ac)
> > > {
> > >         ...
> > >         /*
> > >          * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
> > >          * we always retry
> > >          */
> > >         if (gfp_mask & __GFP_NOFAIL) {
> > >                 /*
> > >                  * All existing users of the __GFP_NOFAIL are blockable, so warn
> > >                  * of any new users that actually require GFP_NOWAIT
> > >                  */
> > >                 if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
> > >                         goto fail;
> > >                 ...
> > >         }
> > >         ...
> > > fail:
> > >         warn_alloc(gfp_mask, ac->nodemask,
> > >                         "page allocation failure: order:%u", order);
> > > got_pg:
> > >         return page;
> > > }
> > >
> > > Let's move the memory allocation out of the atomic context and use
> > > the normal sleepable context to get pages.
> > >
> > > [RFC]: This has only been compile-tested; I'd prefer if the VDPA maintainers
> > > handles it.
> > >
> > > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > > Cc: Jason Wang <jasowang@redhat.com>
> > > Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > > Cc: "Eugenio Pérez" <eperezma@redhat.com>
> > > Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> > > Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> > > ---
> > >  drivers/vdpa/vdpa_user/iova_domain.c | 21 ++++++++++++++++-----
> > >  drivers/vdpa/vdpa_user/iova_domain.h |  3 ++-
> > >  drivers/vdpa/vdpa_user/vduse_dev.c   | 13 ++++++++++++-
> > >  3 files changed, 30 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > > index 791d38d6284c..014809ac2b7c 100644
> > > --- a/drivers/vdpa/vdpa_user/iova_domain.c
> > > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > > @@ -283,7 +283,7 @@ int vduse_domain_add_user_bounce_pages(struct vduse_iova_domain *domain,
> > >         return ret;
> > >  }
> > >
> > > -void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> > > +void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain, struct page **pages)
> > >  {
> > >         struct vduse_bounce_map *map;
> > >         unsigned long i, count;
> > > @@ -294,15 +294,16 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
> > >
> > >         count = domain->bounce_size >> PAGE_SHIFT;
> > >         for (i = 0; i < count; i++) {
> > > -               struct page *page = NULL;
> > > +               struct page *page = pages[i];
> > >
> > >                 map = &domain->bounce_maps[i];
> > > -               if (WARN_ON(!map->bounce_page))
> > > +               if (WARN_ON(!map->bounce_page)) {
> > > +                       put_page(page);
> > >                         continue;
> > > +               }
> > >
> > >                 /* Copy user page to kernel page if it's in use */
> > >                 if (map->orig_phys != INVALID_PHYS_ADDR) {
> > > -                       page = alloc_page(GFP_ATOMIC | __GFP_NOFAIL);
> > >                         memcpy_from_page(page_address(page),
> > >                                          map->bounce_page, 0, PAGE_SIZE);
> > >                 }
> > > @@ -543,10 +544,19 @@ static int vduse_domain_mmap(struct file *file, struct vm_area_struct *vma)
> > >  static int vduse_domain_release(struct inode *inode, struct file *file)
> > >  {
> > >         struct vduse_iova_domain *domain = file->private_data;
> > > +       struct page **pages = NULL;
> > > +       unsigned long count, i;
> > > +
> > > +       if (domain->user_bounce_pages) {
> > > +               count = domain->bounce_size >> PAGE_SHIFT;
> > > +               pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
> > > +               for (i = 0; i < count; i++)
> > > +                       pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> > > +       }
> > >
> > >         spin_lock(&domain->iotlb_lock);
> > >         vduse_iotlb_del_range(domain, 0, ULLONG_MAX);
> > > -       vduse_domain_remove_user_bounce_pages(domain);
> > > +       vduse_domain_remove_user_bounce_pages(domain, pages);
> > >         vduse_domain_free_kernel_bounce_pages(domain);
> > >         spin_unlock(&domain->iotlb_lock);
> > >         put_iova_domain(&domain->stream_iovad);
> > > @@ -554,6 +564,7 @@ static int vduse_domain_release(struct inode *inode, struct file *file)
> > >         vhost_iotlb_free(domain->iotlb);
> > >         vfree(domain->bounce_maps);
> > >         kfree(domain);
> > > +       kfree(pages);
> > >
> > >         return 0;
> > >  }
> > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.h b/drivers/vdpa/vdpa_user/iova_domain.h
> > > index f92f22a7267d..db0b793d86db 100644
> > > --- a/drivers/vdpa/vdpa_user/iova_domain.h
> > > +++ b/drivers/vdpa/vdpa_user/iova_domain.h
> > > @@ -74,7 +74,8 @@ void vduse_domain_reset_bounce_map(struct vduse_iova_domain *domain);
> > >  int vduse_domain_add_user_bounce_pages(struct vduse_iova_domain *domain,
> > >                                        struct page **pages, int count);
> > >
> > > -void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain);
> > > +void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain,
> > > +                                          struct page **pages);
> > >
> > >  void vduse_domain_destroy(struct vduse_iova_domain *domain);
> > >
> > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > index 7ae99691efdf..df7c1b6f1350 100644
> > > --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> > > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > > @@ -1030,6 +1030,8 @@ static int vduse_dev_queue_irq_work(struct vduse_dev *dev,
> > >  static int vduse_dev_dereg_umem(struct vduse_dev *dev,
> > >                                 u64 iova, u64 size)
> > >  {
> > > +       struct page **pages = NULL;
> > > +       unsigned long count, i;
> > >         int ret;
> > >
> > >         mutex_lock(&dev->mem_lock);
> > > @@ -1044,13 +1046,22 @@ static int vduse_dev_dereg_umem(struct vduse_dev *dev,
> > >         if (dev->umem->iova != iova || size != dev->domain->bounce_size)
> > >                 goto unlock;
> > >
> > > -       vduse_domain_remove_user_bounce_pages(dev->domain);
> > > +       if (dev->domain->user_bounce_pages) {
> > > +               count = dev->domain->bounce_size >> PAGE_SHIFT;
> > > +               pages = kmalloc_array(count, sizeof(*pages),
> > > +                                     GFP_KERNEL | __GFP_NOFAIL);
> > > +               for (i = 0; i < count; i++)
> > > +                       pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
> > > +       }
> >
> > Nit: there's some code duplication with vduse_domain_release().
> >
> > Others look good to me.
> >
> > Would you like to post a formal patch?
>
>  Jason, thanks!
>
> I haven't tested this patch and I don't have the setup to test. I
> wonder if you can
> post a tested-by tag before I send a formal patch.

Maybe a RFT tag then I can do a test?

>
> BTW, if we want to have a common function to remove the duplicated code,
> what is the name you suggest to have for this function?

Something like vduse_alloc_pages()? (not a native speaker)

Thanks

>
> >
> > Thanks
> >
> > > +
> > > +       vduse_domain_remove_user_bounce_pages(dev->domain, pages);
> > >         unpin_user_pages_dirty_lock(dev->umem->pages,
> > >                                     dev->umem->npages, true);
> > >         atomic64_sub(dev->umem->npages, &dev->umem->mm->pinned_vm);
> > >         mmdrop(dev->umem->mm);
> > >         vfree(dev->umem->pages);
> > >         kfree(dev->umem);
> > > +       kfree(pages);
> > >         dev->umem = NULL;
> > >         ret = 0;
> > >  unlock:
> > > --
> > > 2.34.1
> > >
> > > >
> > > > Thanks
> > > >
> > > > >
> > > > >
> > > > > > --
> > > > > > Michal Hocko
> > > > > > SUSE Labs
> > > > >
> > >
> > > Thanks
> > > Barry
> > >
> >
>
> Thanks
> Barry
>

[PATCH 2/5] mm: Document __GFP_NOFAIL must be blockable

[Barry Song]

From: Barry Song <v-songbaohua@oppo.com>

Non-blocking allocation with __GFP_NOFAIL is not supported and may
still result in NULL pointers (if we don't return NULL, we result
in busy-loop within non-sleepable contexts):

static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
						struct alloc_context *ac)
{
	...
	/*
	 * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
	 * we always retry
	 */
	if (gfp_mask & __GFP_NOFAIL) {
		/*
		 * All existing users of the __GFP_NOFAIL are blockable, so warn
		 * of any new users that actually require GFP_NOWAIT
		 */
		if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
			goto fail;
		...
	}
	...
fail:
	warn_alloc(gfp_mask, ac->nodemask,
			"page allocation failure: order:%u", order);
got_pg:
	return page;
}

Highlight this in the documentation of __GFP_NOFAIL so that non-mm
subsystems can reject any illegal usage of __GFP_NOFAIL with
GFP_ATOMIC, GFP_NOWAIT, etc.

Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
 include/linux/gfp_types.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h
index 313be4ad79fd..0dad2c7914be 100644
--- a/include/linux/gfp_types.h
+++ b/include/linux/gfp_types.h
@@ -246,6 +246,8 @@ enum {
  * cannot handle allocation failures. The allocation could block
  * indefinitely but will never return with failure. Testing for
  * failure is pointless.
+ * It _must_ be blockable and used together with __GFP_DIRECT_RECLAIM.
+ * It should _never_ be used in non-sleepable contexts.
  * New users should be evaluated carefully (and the flag should be
  * used only when there is no reasonable failure policy) but it is
  * definitely preferable to use the flag rather than opencode endless
-- 
2.34.1

Re: [PATCH 2/5] mm: Document __GFP_NOFAIL must be blockable

[Michal Hocko]

On Wed 24-07-24 20:55:41, Barry Song wrote:
> From: Barry Song <v-songbaohua@oppo.com>
> 
> Non-blocking allocation with __GFP_NOFAIL is not supported and may
> still result in NULL pointers (if we don't return NULL, we result
> in busy-loop within non-sleepable contexts):
> 
> static inline struct page *
> __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> 						struct alloc_context *ac)
> {
> 	...
> 	/*
> 	 * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
> 	 * we always retry
> 	 */
> 	if (gfp_mask & __GFP_NOFAIL) {
> 		/*
> 		 * All existing users of the __GFP_NOFAIL are blockable, so warn
> 		 * of any new users that actually require GFP_NOWAIT
> 		 */
> 		if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
> 			goto fail;
> 		...
> 	}
> 	...
> fail:
> 	warn_alloc(gfp_mask, ac->nodemask,
> 			"page allocation failure: order:%u", order);
> got_pg:
> 	return page;
> }
> 
> Highlight this in the documentation of __GFP_NOFAIL so that non-mm
> subsystems can reject any illegal usage of __GFP_NOFAIL with
> GFP_ATOMIC, GFP_NOWAIT, etc.
> 
> Signed-off-by: Barry Song <v-songbaohua@oppo.com>

Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  include/linux/gfp_types.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h
> index 313be4ad79fd..0dad2c7914be 100644
> --- a/include/linux/gfp_types.h
> +++ b/include/linux/gfp_types.h
> @@ -246,6 +246,8 @@ enum {
>   * cannot handle allocation failures. The allocation could block
>   * indefinitely but will never return with failure. Testing for
>   * failure is pointless.
> + * It _must_ be blockable and used together with __GFP_DIRECT_RECLAIM.
> + * It should _never_ be used in non-sleepable contexts.
>   * New users should be evaluated carefully (and the flag should be
>   * used only when there is no reasonable failure policy) but it is
>   * definitely preferable to use the flag rather than opencode endless
> -- 
> 2.34.1

Do you think the following addendum should be folded in just for
completness?

diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h
index 313be4ad79fd..d024cfd1af8e 100644
--- a/include/linux/gfp_types.h
+++ b/include/linux/gfp_types.h
@@ -215,7 +215,8 @@ enum {
  * the caller still has to check for failures) while costly requests try to be
  * not disruptive and back off even without invoking the OOM killer.
  * The following three modifiers might be used to override some of these
- * implicit rules.
+ * implicit rules. Please note that all of them must be used along with
+ * %__GFP_DIRECT_RECLAIM flag.
  *
  * %__GFP_NORETRY: The VM implementation will try only very lightweight
  * memory direct reclaim to get some memory under memory pressure (thus

-- 
Michal Hocko
SUSE Labs

Re: [PATCH 2/5] mm: Document __GFP_NOFAIL must be blockable

[Davidlohr Bueso]

On Wed, 24 Jul 2024, Barry Song wrote:\n
>From: Barry Song <v-songbaohua@oppo.com>
>
>Non-blocking allocation with __GFP_NOFAIL is not supported and may
>still result in NULL pointers (if we don't return NULL, we result
>in busy-loop within non-sleepable contexts):
>
>static inline struct page *
>__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
>						struct alloc_context *ac)
>{
>	...
>	/*
>	 * Make sure that __GFP_NOFAIL request doesn't leak out and make sure
>	 * we always retry
>	 */
>	if (gfp_mask & __GFP_NOFAIL) {
>		/*
>		 * All existing users of the __GFP_NOFAIL are blockable, so warn
>		 * of any new users that actually require GFP_NOWAIT
>		 */
>		if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
>			goto fail;
>		...
>	}
>	...
>fail:
>	warn_alloc(gfp_mask, ac->nodemask,
>			"page allocation failure: order:%u", order);
>got_pg:
>	return page;
>}
>
>Highlight this in the documentation of __GFP_NOFAIL so that non-mm
>subsystems can reject any illegal usage of __GFP_NOFAIL with
>GFP_ATOMIC, GFP_NOWAIT, etc.
>

Acked-by: Davidlohr Bueso <dave@stgolabs.net>

[PATCH 3/5] mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails

[Barry Song]

From: Barry Song <v-songbaohua@oppo.com>

We have cases we still fail though callers might have __GFP_NOFAIL.
Since they don't check the return, we are exposed to the security
risks for NULL deference.

Though BUG_ON() is not encouraged by Linus, this is an unrecoverable
situation.

Christoph Hellwig:
The whole freaking point of __GFP_NOFAIL is that callers don't handle
allocation failures.  So in fact a straight BUG is the right thing
here.

Vlastimil Babka:
It's just not a recoverable situation (WARN_ON is for recoverable
situations). The caller cannot handle allocation failure and at the same
time asked for an impossible allocation. BUG_ON() is a guaranteed oops
with stracktrace etc. We don't need to hope for the later NULL pointer
dereference (which might if really unlucky happen from a different
context where it's no longer obvious what lead to the allocation failing).

Michal Hocko:
Linus tends to be against adding new BUG() calls unless the failure is
absolutely unrecoverable (e.g. corrupted data structures etc.). I am
not sure how he would look at simply incorrect memory allocator usage to
blow up the kernel. Now the argument could be made that those failures
could cause subtle memory corruptions or even be exploitable which might
be a sufficient reason to stop them early.

Cc: Michal Hocko <mhocko@suse.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
 include/linux/slab.h |  4 +++-
 mm/page_alloc.c      | 10 +++++-----
 mm/util.c            |  1 +
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index c9cb42203183..4a4d1fdc2afe 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -827,8 +827,10 @@ kvmalloc_array_node_noprof(size_t n, size_t size, gfp_t flags, int node)
 {
 	size_t bytes;
 
-	if (unlikely(check_mul_overflow(n, size, &bytes)))
+	if (unlikely(check_mul_overflow(n, size, &bytes))) {
+		BUG_ON(flags & __GFP_NOFAIL);
 		return NULL;
+	}
 
 	return kvmalloc_node_noprof(bytes, flags, node);
 }
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 45d2f41b4783..4d6af00fccd4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4435,11 +4435,11 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 	 */
 	if (gfp_mask & __GFP_NOFAIL) {
 		/*
-		 * All existing users of the __GFP_NOFAIL are blockable, so warn
-		 * of any new users that actually require GFP_NOWAIT
+		 * All existing users of the __GFP_NOFAIL are blockable
+		 * otherwise we introduce a busy loop with inside the page
+		 * allocator from non-sleepable contexts
 		 */
-		if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
-			goto fail;
+		BUG_ON(!can_direct_reclaim);
 
 		/*
 		 * PF_MEMALLOC request from this context is rather bizarre
@@ -4470,7 +4470,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 		cond_resched();
 		goto retry;
 	}
-fail:
+
 	warn_alloc(gfp_mask, ac->nodemask,
 			"page allocation failure: order:%u", order);
 got_pg:
diff --git a/mm/util.c b/mm/util.c
index 0ff5898cc6de..a1be50c243f1 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -668,6 +668,7 @@ void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), gfp_t flags, int node)
 	/* Don't even allow crazy sizes */
 	if (unlikely(size > INT_MAX)) {
 		WARN_ON_ONCE(!(flags & __GFP_NOWARN));
+		BUG_ON(flags & __GFP_NOFAIL);
 		return NULL;
 	}
 
-- 
2.34.1

Re: [PATCH 3/5] mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails

[Vlastimil Babka]

On 7/24/24 10:55 AM, Barry Song wrote:
> From: Barry Song <v-songbaohua@oppo.com>
> 
> We have cases we still fail though callers might have __GFP_NOFAIL.
> Since they don't check the return, we are exposed to the security
> risks for NULL deference.
> 
> Though BUG_ON() is not encouraged by Linus, this is an unrecoverable
> situation.
> 
> Christoph Hellwig:
> The whole freaking point of __GFP_NOFAIL is that callers don't handle
> allocation failures.  So in fact a straight BUG is the right thing
> here.
> 
> Vlastimil Babka:
> It's just not a recoverable situation (WARN_ON is for recoverable
> situations). The caller cannot handle allocation failure and at the same
> time asked for an impossible allocation. BUG_ON() is a guaranteed oops
> with stracktrace etc. We don't need to hope for the later NULL pointer
> dereference (which might if really unlucky happen from a different
> context where it's no longer obvious what lead to the allocation failing).

Note that quote was meant specifically for the "too large" allocation, which
is truly impossible. That includes the kvmalloc_array() overflow, order >
MAX_ORDER etc.

The "can't sleep/reclaim" is a bit more nuanced as there's the alternative
in just warning and looping and hoping kswapd or some other direct reclaimer
saves the day. If yes, great, we have a system that still works and a
warning to repor. If no, there's still a warning, but later soft/hardlockup
hits. These might be eventually worse than an immediate BUG_ON so it's not a
clear cut. At least I think these cases should be handled in two different
patches and not together.

> Michal Hocko:
> Linus tends to be against adding new BUG() calls unless the failure is
> absolutely unrecoverable (e.g. corrupted data structures etc.). I am
> not sure how he would look at simply incorrect memory allocator usage to
> blow up the kernel. Now the argument could be made that those failures
> could cause subtle memory corruptions or even be exploitable which might
> be a sufficient reason to stop them early.
> 
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Lorenzo Stoakes <lstoakes@gmail.com>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Pekka Enberg <penberg@kernel.org>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Vlastimil Babka <vbabka@suse.cz>
> Cc: Roman Gushchin <roman.gushchin@linux.dev>
> Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Kees Cook <kees@kernel.org>
> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> ---
>  include/linux/slab.h |  4 +++-
>  mm/page_alloc.c      | 10 +++++-----
>  mm/util.c            |  1 +
>  3 files changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index c9cb42203183..4a4d1fdc2afe 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -827,8 +827,10 @@ kvmalloc_array_node_noprof(size_t n, size_t size, gfp_t flags, int node)
>  {
>  	size_t bytes;
>  
> -	if (unlikely(check_mul_overflow(n, size, &bytes)))
> +	if (unlikely(check_mul_overflow(n, size, &bytes))) {
> +		BUG_ON(flags & __GFP_NOFAIL);
>  		return NULL;
> +	}
>  
>  	return kvmalloc_node_noprof(bytes, flags, node);
>  }
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 45d2f41b4783..4d6af00fccd4 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -4435,11 +4435,11 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
>  	 */
>  	if (gfp_mask & __GFP_NOFAIL) {
>  		/*
> -		 * All existing users of the __GFP_NOFAIL are blockable, so warn
> -		 * of any new users that actually require GFP_NOWAIT
> +		 * All existing users of the __GFP_NOFAIL are blockable
> +		 * otherwise we introduce a busy loop with inside the page
> +		 * allocator from non-sleepable contexts
>  		 */
> -		if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
> -			goto fail;
> +		BUG_ON(!can_direct_reclaim);
>  
>  		/*
>  		 * PF_MEMALLOC request from this context is rather bizarre
> @@ -4470,7 +4470,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
>  		cond_resched();
>  		goto retry;
>  	}
> -fail:
> +
>  	warn_alloc(gfp_mask, ac->nodemask,
>  			"page allocation failure: order:%u", order);
>  got_pg:
> diff --git a/mm/util.c b/mm/util.c
> index 0ff5898cc6de..a1be50c243f1 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -668,6 +668,7 @@ void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), gfp_t flags, int node)
>  	/* Don't even allow crazy sizes */
>  	if (unlikely(size > INT_MAX)) {
>  		WARN_ON_ONCE(!(flags & __GFP_NOWARN));
> +		BUG_ON(flags & __GFP_NOFAIL);
>  		return NULL;
>  	}
>  

Re: [PATCH 3/5] mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails

[Barry Song]

On Wed, Jul 24, 2024 at 10:03 PM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 7/24/24 10:55 AM, Barry Song wrote:
> > From: Barry Song <v-songbaohua@oppo.com>
> >
> > We have cases we still fail though callers might have __GFP_NOFAIL.
> > Since they don't check the return, we are exposed to the security
> > risks for NULL deference.
> >
> > Though BUG_ON() is not encouraged by Linus, this is an unrecoverable
> > situation.
> >
> > Christoph Hellwig:
> > The whole freaking point of __GFP_NOFAIL is that callers don't handle
> > allocation failures.  So in fact a straight BUG is the right thing
> > here.
> >
> > Vlastimil Babka:
> > It's just not a recoverable situation (WARN_ON is for recoverable
> > situations). The caller cannot handle allocation failure and at the same
> > time asked for an impossible allocation. BUG_ON() is a guaranteed oops
> > with stracktrace etc. We don't need to hope for the later NULL pointer
> > dereference (which might if really unlucky happen from a different
> > context where it's no longer obvious what lead to the allocation failing).
>
> Note that quote was meant specifically for the "too large" allocation, which
> is truly impossible. That includes the kvmalloc_array() overflow, order >
> MAX_ORDER etc.

I equally quote this for two cases because non-sleepable is also returning NULL,
in this means, they are currently facing the same problems.

>
> The "can't sleep/reclaim" is a bit more nuanced as there's the alternative
> in just warning and looping and hoping kswapd or some other direct reclaimer
> saves the day. If yes, great, we have a system that still works and a
> warning to repor. If no, there's still a warning, but later soft/hardlockup
> hits. These might be eventually worse than an immediate BUG_ON so it's not a
> clear cut. At least I think these cases should be handled in two different
> patches and not together.

But I fully agree these two can be separated and judged separately.

After more thinking, I am concerned that this issue might be difficult to be
rescued, as the misuse of GFP_ATOMIC | __GFP_NOFAIL typically occurs
in atomic contexts with strict time requirements. Even if some other
components release memory to satisfy the one busy-looping to obtain
memory, it might already be too late?

>
> > Michal Hocko:
> > Linus tends to be against adding new BUG() calls unless the failure is
> > absolutely unrecoverable (e.g. corrupted data structures etc.). I am
> > not sure how he would look at simply incorrect memory allocator usage to
> > blow up the kernel. Now the argument could be made that those failures
> > could cause subtle memory corruptions or even be exploitable which might
> > be a sufficient reason to stop them early.
> >
> > Cc: Michal Hocko <mhocko@suse.com>
> > Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
> > Cc: Christoph Hellwig <hch@infradead.org>
> > Cc: Lorenzo Stoakes <lstoakes@gmail.com>
> > Cc: Christoph Lameter <cl@linux.com>
> > Cc: Pekka Enberg <penberg@kernel.org>
> > Cc: David Rientjes <rientjes@google.com>
> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > Cc: Vlastimil Babka <vbabka@suse.cz>
> > Cc: Roman Gushchin <roman.gushchin@linux.dev>
> > Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> > Cc: Linus Torvalds <torvalds@linux-foundation.org>
> > Cc: Kees Cook <kees@kernel.org>
> > Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> > ---
> >  include/linux/slab.h |  4 +++-
> >  mm/page_alloc.c      | 10 +++++-----
> >  mm/util.c            |  1 +
> >  3 files changed, 9 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/linux/slab.h b/include/linux/slab.h
> > index c9cb42203183..4a4d1fdc2afe 100644
> > --- a/include/linux/slab.h
> > +++ b/include/linux/slab.h
> > @@ -827,8 +827,10 @@ kvmalloc_array_node_noprof(size_t n, size_t size, gfp_t flags, int node)
> >  {
> >       size_t bytes;
> >
> > -     if (unlikely(check_mul_overflow(n, size, &bytes)))
> > +     if (unlikely(check_mul_overflow(n, size, &bytes))) {
> > +             BUG_ON(flags & __GFP_NOFAIL);
> >               return NULL;
> > +     }
> >
> >       return kvmalloc_node_noprof(bytes, flags, node);
> >  }
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 45d2f41b4783..4d6af00fccd4 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -4435,11 +4435,11 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> >        */
> >       if (gfp_mask & __GFP_NOFAIL) {
> >               /*
> > -              * All existing users of the __GFP_NOFAIL are blockable, so warn
> > -              * of any new users that actually require GFP_NOWAIT
> > +              * All existing users of the __GFP_NOFAIL are blockable
> > +              * otherwise we introduce a busy loop with inside the page
> > +              * allocator from non-sleepable contexts
> >                */
> > -             if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
> > -                     goto fail;
> > +             BUG_ON(!can_direct_reclaim);
> >
> >               /*
> >                * PF_MEMALLOC request from this context is rather bizarre
> > @@ -4470,7 +4470,7 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> >               cond_resched();
> >               goto retry;
> >       }
> > -fail:
> > +
> >       warn_alloc(gfp_mask, ac->nodemask,
> >                       "page allocation failure: order:%u", order);
> >  got_pg:
> > diff --git a/mm/util.c b/mm/util.c
> > index 0ff5898cc6de..a1be50c243f1 100644
> > --- a/mm/util.c
> > +++ b/mm/util.c
> > @@ -668,6 +668,7 @@ void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), gfp_t flags, int node)
> >       /* Don't even allow crazy sizes */
> >       if (unlikely(size > INT_MAX)) {
> >               WARN_ON_ONCE(!(flags & __GFP_NOWARN));
> > +             BUG_ON(flags & __GFP_NOFAIL);
> >               return NULL;
> >       }
> >
>

Re: [PATCH 3/5] mm: BUG_ON to avoid NULL deference while __GFP_NOFAIL fails

[Michal Hocko]

On Wed 24-07-24 20:55:42, Barry Song wrote:
> From: Barry Song <v-songbaohua@oppo.com>
> 
> We have cases we still fail though callers might have __GFP_NOFAIL.
> Since they don't check the return, we are exposed to the security
> risks for NULL deference.
> 
> Though BUG_ON() is not encouraged by Linus, this is an unrecoverable
> situation.
> 
> Christoph Hellwig:
> The whole freaking point of __GFP_NOFAIL is that callers don't handle
> allocation failures.  So in fact a straight BUG is the right thing
> here.
> 
> Vlastimil Babka:
> It's just not a recoverable situation (WARN_ON is for recoverable
> situations). The caller cannot handle allocation failure and at the same
> time asked for an impossible allocation. BUG_ON() is a guaranteed oops
> with stracktrace etc. We don't need to hope for the later NULL pointer
> dereference (which might if really unlucky happen from a different
> context where it's no longer obvious what lead to the allocation failing).
> 
> Michal Hocko:
> Linus tends to be against adding new BUG() calls unless the failure is
> absolutely unrecoverable (e.g. corrupted data structures etc.). I am
> not sure how he would look at simply incorrect memory allocator usage to
> blow up the kernel. Now the argument could be made that those failures
> could cause subtle memory corruptions or even be exploitable which might
> be a sufficient reason to stop them early.

I think it is worth adding that size checks are not really actionable
because they either cause unexpected failure or BUG_ON. It is not too
much of a stretch to expect some of the user triggerable codepaths could
hit this - e.g. when input is not checked properly. Silent failure is
then a potential security risk.

The page allocator, on the other hand, can chose to keep retrying even
if that means that there is not reclaim going on and essentially cause a
busy loop in the kernel space. That would eventually cause soft/hard
lockup detector to fire (if an architecture offers a reliable one).
So essentially there is choice between two bad solutions and you have
chosen one that reliably bugs on rather than rely on something external
to intervene. The reasoning for that should be mentioned in the
changelog.

[...]
> diff --git a/mm/util.c b/mm/util.c
> index 0ff5898cc6de..a1be50c243f1 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -668,6 +668,7 @@ void *__kvmalloc_node_noprof(DECL_BUCKET_PARAMS(size, b), gfp_t flags, int node)
>  	/* Don't even allow crazy sizes */
>  	if (unlikely(size > INT_MAX)) {
>  		WARN_ON_ONCE(!(flags & __GFP_NOWARN));
> +		BUG_ON(flags & __GFP_NOFAIL);

I guess you want to switch the ordering. WARNING on top of BUG on seems
rather pointless IMHO.

>  		return NULL;
>  	}
>  
> -- 
> 2.34.1

-- 
Michal Hocko
SUSE Labs

[PATCH 4/5] mm: Introduce GFP_NOFAIL with the inclusion of __GFP_RECLAIM

[Barry Song]

From: Barry Song <v-songbaohua@oppo.com>

Introducing GFP_NOFAIL and gradually increasing enforcement to prevent
direct use of __GFP_NOFAIL which might be misused within non-sleepable
contexts with GFP_ATOMIC and GFP_NOWAIT.

Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
 include/linux/gfp_types.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h
index 0dad2c7914be..1666db74f25c 100644
--- a/include/linux/gfp_types.h
+++ b/include/linux/gfp_types.h
@@ -339,6 +339,10 @@ enum {
  * recurse into the FS layer with a short explanation why. All allocation
  * requests will inherit GFP_NOFS implicitly.
  *
+ * %GFP_NOFAIL employs direct memory reclaim and continuously retries until
+ * successful memory allocation. It should never be used in contexts where
+ * sleeping is not allowed.
+ *
  * %GFP_USER is for userspace allocations that also need to be directly
  * accessibly by the kernel or hardware. It is typically used by hardware
  * for buffers that are mapped to userspace (e.g. graphics) that hardware
@@ -378,6 +382,7 @@ enum {
 #define GFP_NOWAIT	(__GFP_KSWAPD_RECLAIM | __GFP_NOWARN)
 #define GFP_NOIO	(__GFP_RECLAIM)
 #define GFP_NOFS	(__GFP_RECLAIM | __GFP_IO)
+#define GFP_NOFAIL	(__GFP_RECLAIM | __GFP_NOFAIL)
 #define GFP_USER	(__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL)
 #define GFP_DMA		__GFP_DMA
 #define GFP_DMA32	__GFP_DMA32
-- 
2.34.1

Re: [PATCH 4/5] mm: Introduce GFP_NOFAIL with the inclusion of __GFP_RECLAIM

[Michal Hocko]

On Wed 24-07-24 20:55:43, Barry Song wrote:
> From: Barry Song <v-songbaohua@oppo.com>
> 
> Introducing GFP_NOFAIL and gradually increasing enforcement to prevent
> direct use of __GFP_NOFAIL which might be misused within non-sleepable
> contexts with GFP_ATOMIC and GFP_NOWAIT.

I do not think this makes sense without removing __GFP_NOFAIL and
changing existing users because a new flag will very likely not be used
and therefore it will not achieve the ultimate goal to remove a
potential abuse.

> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> ---
>  include/linux/gfp_types.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/include/linux/gfp_types.h b/include/linux/gfp_types.h
> index 0dad2c7914be..1666db74f25c 100644
> --- a/include/linux/gfp_types.h
> +++ b/include/linux/gfp_types.h
> @@ -339,6 +339,10 @@ enum {
>   * recurse into the FS layer with a short explanation why. All allocation
>   * requests will inherit GFP_NOFS implicitly.
>   *
> + * %GFP_NOFAIL employs direct memory reclaim and continuously retries until
> + * successful memory allocation. It should never be used in contexts where
> + * sleeping is not allowed.
> + *
>   * %GFP_USER is for userspace allocations that also need to be directly
>   * accessibly by the kernel or hardware. It is typically used by hardware
>   * for buffers that are mapped to userspace (e.g. graphics) that hardware
> @@ -378,6 +382,7 @@ enum {
>  #define GFP_NOWAIT	(__GFP_KSWAPD_RECLAIM | __GFP_NOWARN)
>  #define GFP_NOIO	(__GFP_RECLAIM)
>  #define GFP_NOFS	(__GFP_RECLAIM | __GFP_IO)
> +#define GFP_NOFAIL	(__GFP_RECLAIM | __GFP_NOFAIL)
>  #define GFP_USER	(__GFP_RECLAIM | __GFP_IO | __GFP_FS | __GFP_HARDWALL)
>  #define GFP_DMA		__GFP_DMA
>  #define GFP_DMA32	__GFP_DMA32
> -- 
> 2.34.1

-- 
Michal Hocko
SUSE Labs

[PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Barry Song]

From: Barry Song <v-songbaohua@oppo.com>

GFP_NOFAIL includes the meaning of block and direct reclamation, which
is essential for a true no-fail allocation. We are gradually starting
to enforce this block semantics to prevent the potential misuse of
__GFP_NOFAIL in atomic contexts in the future.

A typical example of incorrect usage is in VDPA, where GFP_ATOMIC
and __GFP_NOFAIL are used together.

[RFC]: This patch seems quite large; I don't mind splitting it into
multiple patches for different subsystems after patches 1 ~ 4 have
been applied.

Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
 arch/powerpc/sysdev/xive/common.c                  |  2 +-
 drivers/gpu/drm/drm_modeset_lock.c                 |  2 +-
 drivers/gpu/drm/nouveau/nouveau_dmem.c             |  8 ++++----
 drivers/gpu/drm/virtio/virtgpu_vq.c                |  2 +-
 drivers/hv/vmbus_drv.c                             |  2 +-
 drivers/infiniband/hw/cxgb4/mem.c                  |  4 ++--
 drivers/md/dm-region-hash.c                        |  2 +-
 .../chelsio/inline_crypto/chtls/chtls_cm.c         |  6 +++---
 .../chelsio/inline_crypto/chtls/chtls_hw.c         |  2 +-
 drivers/target/iscsi/cxgbit/cxgbit_cm.c            |  2 +-
 drivers/tty/tty_ldisc.c                            |  2 +-
 drivers/vdpa/vdpa_user/iova_domain.c               |  4 ++--
 fs/bcachefs/btree_iter.c                           |  2 +-
 fs/bcachefs/fs-io-buffered.c                       |  2 +-
 fs/bcachefs/io_write.c                             |  2 +-
 fs/btrfs/extent_io.c                               |  8 ++++----
 fs/buffer.c                                        |  6 +++---
 fs/erofs/fscache.c                                 |  2 +-
 fs/erofs/zdata.c                                   | 10 +++++-----
 fs/ext4/extents.c                                  |  8 ++++----
 fs/ext4/extents_status.c                           |  4 ++--
 fs/ext4/mballoc.c                                  | 12 ++++++------
 fs/ext4/page-io.c                                  |  2 +-
 fs/f2fs/checkpoint.c                               |  2 +-
 fs/f2fs/data.c                                     |  4 ++--
 fs/f2fs/f2fs.h                                     |  2 +-
 fs/f2fs/node.c                                     |  2 +-
 fs/fuse/dev.c                                      |  2 +-
 fs/fuse/file.c                                     |  4 ++--
 fs/fuse/inode.c                                    |  4 ++--
 fs/fuse/virtio_fs.c                                |  4 ++--
 fs/gfs2/meta_io.c                                  |  2 +-
 fs/gfs2/rgrp.c                                     |  6 +++---
 fs/gfs2/trans.c                                    |  2 +-
 fs/iomap/buffered-io.c                             |  2 +-
 fs/jbd2/journal.c                                  |  4 ++--
 fs/jbd2/revoke.c                                   |  2 +-
 fs/jbd2/transaction.c                              |  6 +++---
 fs/notify/fanotify/fanotify.c                      |  2 +-
 fs/reiserfs/journal.c                              |  2 +-
 fs/udf/directory.c                                 |  2 +-
 fs/xfs/libxfs/xfs_alloc.c                          |  2 +-
 fs/xfs/libxfs/xfs_attr_leaf.c                      |  8 ++++----
 fs/xfs/libxfs/xfs_bmap.c                           |  2 +-
 fs/xfs/libxfs/xfs_btree.h                          |  2 +-
 fs/xfs/libxfs/xfs_btree_staging.c                  |  2 +-
 fs/xfs/libxfs/xfs_da_btree.c                       |  8 ++++----
 fs/xfs/libxfs/xfs_defer.c                          |  4 ++--
 fs/xfs/libxfs/xfs_dir2.c                           | 10 +++++-----
 fs/xfs/libxfs/xfs_dir2_block.c                     |  2 +-
 fs/xfs/libxfs/xfs_dir2_sf.c                        |  8 ++++----
 fs/xfs/libxfs/xfs_exchmaps.c                       |  4 ++--
 fs/xfs/libxfs/xfs_iext_tree.c                      |  4 ++--
 fs/xfs/libxfs/xfs_inode_fork.c                     | 14 +++++++-------
 fs/xfs/libxfs/xfs_refcount.c                       |  4 ++--
 fs/xfs/libxfs/xfs_rmap.c                           |  2 +-
 fs/xfs/xfs_attr_item.c                             |  8 ++++----
 fs/xfs/xfs_attr_list.c                             |  2 +-
 fs/xfs/xfs_bmap_item.c                             |  6 +++---
 fs/xfs/xfs_buf.c                                   |  8 ++++----
 fs/xfs/xfs_buf_item.c                              |  4 ++--
 fs/xfs/xfs_buf_item_recover.c                      |  2 +-
 fs/xfs/xfs_dquot.c                                 |  2 +-
 fs/xfs/xfs_exchmaps_item.c                         |  4 ++--
 fs/xfs/xfs_extent_busy.c                           |  2 +-
 fs/xfs/xfs_extfree_item.c                          | 10 +++++-----
 fs/xfs/xfs_icache.c                                |  2 +-
 fs/xfs/xfs_icreate_item.c                          |  2 +-
 fs/xfs/xfs_inode_item.c                            |  2 +-
 fs/xfs/xfs_inode_item_recover.c                    |  2 +-
 fs/xfs/xfs_iunlink_item.c                          |  2 +-
 fs/xfs/xfs_iwalk.c                                 |  2 +-
 fs/xfs/xfs_log.c                                   |  2 +-
 fs/xfs/xfs_log_cil.c                               |  2 +-
 fs/xfs/xfs_log_recover.c                           |  6 +++---
 fs/xfs/xfs_mount.c                                 |  2 +-
 fs/xfs/xfs_mru_cache.c                             |  4 ++--
 fs/xfs/xfs_qm.c                                    |  4 ++--
 fs/xfs/xfs_refcount_item.c                         |  8 ++++----
 fs/xfs/xfs_rmap_item.c                             |  8 ++++----
 fs/xfs/xfs_rtalloc.c                               |  2 +-
 fs/xfs/xfs_super.c                                 |  2 +-
 fs/xfs/xfs_trans.c                                 |  4 ++--
 fs/xfs/xfs_trans_dquot.c                           |  2 +-
 include/linux/buffer_head.h                        |  4 ++--
 kernel/resource.c                                  |  2 +-
 lib/list-test.c                                    |  8 ++++----
 lib/ref_tracker.c                                  |  2 +-
 lib/rhashtable.c                                   |  6 +++---
 lib/test_hmm.c                                     |  6 +++---
 net/ceph/osd_client.c                              |  2 +-
 net/ceph/osdmap.c                                  |  4 ++--
 net/core/sock.c                                    |  4 ++--
 net/ipv4/inet_connection_sock.c                    |  2 +-
 net/ipv4/tcp_output.c                              |  2 +-
 security/smack/smackfs.c                           |  2 +-
 96 files changed, 188 insertions(+), 188 deletions(-)

diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
index fa01818c1972..29eaf8b84b52 100644
--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -1146,7 +1146,7 @@ static int __init xive_init_ipis(void)
 	if (!ipi_domain)
 		goto out_free_fwnode;
 
-	xive_ipis = kcalloc(nr_node_ids, sizeof(*xive_ipis), GFP_KERNEL | __GFP_NOFAIL);
+	xive_ipis = kcalloc(nr_node_ids, sizeof(*xive_ipis), GFP_KERNEL | GFP_NOFAIL);
 	if (!xive_ipis)
 		goto out_free_domain;
 
diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c
index 7694b85e75e3..3564751aaff7 100644
--- a/drivers/gpu/drm/drm_modeset_lock.c
+++ b/drivers/gpu/drm/drm_modeset_lock.c
@@ -146,7 +146,7 @@ void drm_modeset_lock_all(struct drm_device *dev)
 	struct drm_modeset_acquire_ctx *ctx;
 	int ret;
 
-	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL | __GFP_NOFAIL);
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL | GFP_NOFAIL);
 	if (WARN_ON(!ctx))
 		return;
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 6719353e2e13..df799c190844 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -378,9 +378,9 @@ nouveau_dmem_evict_chunk(struct nouveau_dmem_chunk *chunk)
 	dma_addr_t *dma_addrs;
 	struct nouveau_fence *fence;
 
-	src_pfns = kvcalloc(npages, sizeof(*src_pfns), GFP_KERNEL | __GFP_NOFAIL);
-	dst_pfns = kvcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL | __GFP_NOFAIL);
-	dma_addrs = kvcalloc(npages, sizeof(*dma_addrs), GFP_KERNEL | __GFP_NOFAIL);
+	src_pfns = kvcalloc(npages, sizeof(*src_pfns), GFP_KERNEL | GFP_NOFAIL);
+	dst_pfns = kvcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL | GFP_NOFAIL);
+	dma_addrs = kvcalloc(npages, sizeof(*dma_addrs), GFP_KERNEL | GFP_NOFAIL);
 
 	migrate_device_range(src_pfns, chunk->pagemap.range.start >> PAGE_SHIFT,
 			npages);
@@ -394,7 +394,7 @@ nouveau_dmem_evict_chunk(struct nouveau_dmem_chunk *chunk)
 			 * is nothing sensible we can do if we can't copy the
 			 * data back.
 			 */
-			dpage = alloc_page(GFP_HIGHUSER | __GFP_NOFAIL);
+			dpage = alloc_page(GFP_HIGHUSER | GFP_NOFAIL);
 			dst_pfns[i] = migrate_pfn(page_to_pfn(dpage));
 			nouveau_dmem_copy_one(chunk->drm,
 					migrate_pfn_to_page(src_pfns[i]), dpage,
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 0d3d0d09f39b..95b844036925 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -93,7 +93,7 @@ virtio_gpu_get_vbuf(struct virtio_gpu_device *vgdev,
 {
 	struct virtio_gpu_vbuffer *vbuf;
 
-	vbuf = kmem_cache_zalloc(vgdev->vbufs, GFP_KERNEL | __GFP_NOFAIL);
+	vbuf = kmem_cache_zalloc(vgdev->vbufs, GFP_KERNEL | GFP_NOFAIL);
 
 	BUG_ON(size > MAX_INLINE_CMD_SIZE ||
 	       size < sizeof(struct virtio_gpu_ctrl_hdr));
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 12a707ab73f8..b2bb7dd117d7 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -1170,7 +1170,7 @@ static void vmbus_force_channel_rescinded(struct vmbus_channel *channel)
 	 * otherwise the state of the hv_sock connections ends up in limbo.
 	 */
 	ctx = kzalloc(sizeof(*ctx) + sizeof(*rescind),
-		      GFP_KERNEL | __GFP_NOFAIL);
+		      GFP_KERNEL | GFP_NOFAIL);
 
 	/*
 	 * So far, these are not really used by Linux. Just set them to the
diff --git a/drivers/infiniband/hw/cxgb4/mem.c b/drivers/infiniband/hw/cxgb4/mem.c
index a2c71a1d93d5..b9e7b902191a 100644
--- a/drivers/infiniband/hw/cxgb4/mem.c
+++ b/drivers/infiniband/hw/cxgb4/mem.c
@@ -75,7 +75,7 @@ static int _c4iw_write_mem_dma_aligned(struct c4iw_rdev *rdev, u32 addr,
 	wr_len = roundup(sizeof(*req) + sizeof(*sgl), 16);
 
 	if (!skb) {
-		skb = alloc_skb(wr_len, GFP_KERNEL | __GFP_NOFAIL);
+		skb = alloc_skb(wr_len, GFP_KERNEL | GFP_NOFAIL);
 		if (!skb)
 			return -ENOMEM;
 	}
@@ -135,7 +135,7 @@ static int _c4iw_write_mem_inline(struct c4iw_rdev *rdev, u32 addr, u32 len,
 				 16);
 
 		if (!skb) {
-			skb = alloc_skb(wr_len, GFP_KERNEL | __GFP_NOFAIL);
+			skb = alloc_skb(wr_len, GFP_KERNEL | GFP_NOFAIL);
 			if (!skb)
 				return -ENOMEM;
 		}
diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c
index a4550975c27d..9a2b3f090c93 100644
--- a/drivers/md/dm-region-hash.c
+++ b/drivers/md/dm-region-hash.c
@@ -294,7 +294,7 @@ static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region)
 
 	nreg = mempool_alloc(&rh->region_pool, GFP_ATOMIC);
 	if (unlikely(!nreg))
-		nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL);
+		nreg = kmalloc(sizeof(*nreg), GFP_NOIO | GFP_NOFAIL);
 
 	nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
 		      DM_RH_CLEAN : DM_RH_NOSYNC;
diff --git a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
index 6f6525983130..29a30b23b06c 100644
--- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_cm.c
@@ -215,7 +215,7 @@ static struct sk_buff *alloc_ctrl_skb(struct sk_buff *skb, int len)
 		__skb_trim(skb, 0);
 		refcount_inc(&skb->users);
 	} else {
-		skb = alloc_skb(len, GFP_KERNEL | __GFP_NOFAIL);
+		skb = alloc_skb(len, GFP_KERNEL | GFP_NOFAIL);
 	}
 	return skb;
 }
@@ -305,7 +305,7 @@ static void chtls_close_conn(struct sock *sk)
 	csk = rcu_dereference_sk_user_data(sk);
 	tid = csk->tid;
 
-	skb = alloc_skb(len, GFP_KERNEL | __GFP_NOFAIL);
+	skb = alloc_skb(len, GFP_KERNEL | GFP_NOFAIL);
 	req = (struct cpl_close_con_req *)__skb_put(skb, len);
 	memset(req, 0, len);
 	req->wr.wr_hi = htonl(FW_WR_OP_V(FW_TP_WR) |
@@ -1990,7 +1990,7 @@ static void send_defer_abort_rpl(struct chtls_dev *cdev, struct sk_buff *skb)
 	struct sk_buff *reply_skb;
 
 	reply_skb = alloc_skb(sizeof(struct cpl_abort_rpl),
-			      GFP_KERNEL | __GFP_NOFAIL);
+			      GFP_KERNEL | GFP_NOFAIL);
 	__skb_put(reply_skb, sizeof(struct cpl_abort_rpl));
 	set_abort_rpl_wr(reply_skb, GET_TID(req),
 			 (req->status & CPL_ABORT_NO_RST));
diff --git a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_hw.c b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_hw.c
index 1e67140b0f80..b949c901f2bc 100644
--- a/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_hw.c
+++ b/drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_hw.c
@@ -98,7 +98,7 @@ void chtls_set_tcb_field_rpl_skb(struct sock *sk, u16 word,
 	wrlen = sizeof(struct cpl_set_tcb_field) + sizeof(struct ulptx_idata);
 	wrlen = roundup(wrlen, 16);
 
-	skb = alloc_skb(wrlen, GFP_KERNEL | __GFP_NOFAIL);
+	skb = alloc_skb(wrlen, GFP_KERNEL | GFP_NOFAIL);
 	if (!skb)
 		return;
 
diff --git a/drivers/target/iscsi/cxgbit/cxgbit_cm.c b/drivers/target/iscsi/cxgbit/cxgbit_cm.c
index d9204c590d9a..a6df299e4d4f 100644
--- a/drivers/target/iscsi/cxgbit/cxgbit_cm.c
+++ b/drivers/target/iscsi/cxgbit/cxgbit_cm.c
@@ -697,7 +697,7 @@ __cxgbit_abort_conn(struct cxgbit_sock *csk, struct sk_buff *skb)
 
 void cxgbit_abort_conn(struct cxgbit_sock *csk)
 {
-	struct sk_buff *skb = alloc_skb(0, GFP_KERNEL | __GFP_NOFAIL);
+	struct sk_buff *skb = alloc_skb(0, GFP_KERNEL | GFP_NOFAIL);
 
 	cxgbit_get_csk(csk);
 	cxgbit_init_wr_wait(&csk->com.wr_wait);
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index d80e9d4c974b..dfddda94756d 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -162,7 +162,7 @@ static struct tty_ldisc *tty_ldisc_get(struct tty_struct *tty, int disc)
 	 * There is no way to handle allocation failure of only 16 bytes.
 	 * Let's simplify error handling and save more memory.
 	 */
-	ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL | __GFP_NOFAIL);
+	ld = kmalloc(sizeof(struct tty_ldisc), GFP_KERNEL | GFP_NOFAIL);
 	ld->ops = ldops;
 	ld->tty = tty;
 
diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
index eff700e5f7a2..eaf1a6049111 100644
--- a/drivers/vdpa/vdpa_user/iova_domain.c
+++ b/drivers/vdpa/vdpa_user/iova_domain.c
@@ -295,9 +295,9 @@ void vduse_domain_remove_user_bounce_pages(struct vduse_iova_domain *domain)
 	count = domain->bounce_size >> PAGE_SHIFT;
 	write_unlock(&domain->bounce_lock);
 
-	pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | __GFP_NOFAIL);
+	pages = kmalloc_array(count, sizeof(*pages), GFP_KERNEL | GFP_NOFAIL);
 	for (i = 0; i < count; i++)
-		pages[i] = alloc_page(GFP_KERNEL | __GFP_NOFAIL);
+		pages[i] = alloc_page(GFP_KERNEL | GFP_NOFAIL);
 
 	write_lock(&domain->bounce_lock);
 	if (!domain->user_bounce_pages) {
diff --git a/fs/bcachefs/btree_iter.c b/fs/bcachefs/btree_iter.c
index 36872207f09b..85d7a5393b42 100644
--- a/fs/bcachefs/btree_iter.c
+++ b/fs/bcachefs/btree_iter.c
@@ -1619,7 +1619,7 @@ static noinline void btree_paths_realloc(struct btree_trans *trans)
 			  sizeof(struct btree_trans_paths) +
 			  nr * sizeof(struct btree_path) +
 			  nr * sizeof(btree_path_idx_t) + 8 +
-			  nr * sizeof(struct btree_insert_entry), GFP_KERNEL|__GFP_NOFAIL);
+			  nr * sizeof(struct btree_insert_entry), GFP_KERNEL|GFP_NOFAIL);
 
 	unsigned long *paths_allocated = p;
 	memcpy(paths_allocated, trans->paths_allocated, BITS_TO_LONGS(trans->nr_paths) * sizeof(unsigned long));
diff --git a/fs/bcachefs/fs-io-buffered.c b/fs/bcachefs/fs-io-buffered.c
index cc33d763f722..9cbbc5dac45b 100644
--- a/fs/bcachefs/fs-io-buffered.c
+++ b/fs/bcachefs/fs-io-buffered.c
@@ -534,7 +534,7 @@ static int __bch2_writepage(struct folio *folio,
 
 	if (f_sectors > w->tmp_sectors) {
 		kfree(w->tmp);
-		w->tmp = kcalloc(f_sectors, sizeof(struct bch_folio_sector), __GFP_NOFAIL);
+		w->tmp = kcalloc(f_sectors, sizeof(struct bch_folio_sector), GFP_NOFAIL);
 		w->tmp_sectors = f_sectors;
 	}
 
diff --git a/fs/bcachefs/io_write.c b/fs/bcachefs/io_write.c
index d31c8d006d97..f5defe4dd26f 100644
--- a/fs/bcachefs/io_write.c
+++ b/fs/bcachefs/io_write.c
@@ -1279,7 +1279,7 @@ static void bch2_nocow_write(struct bch_write_op *op)
 			/* XXX allocating memory with btree locks held - rare */
 			darray_push_gfp(&buckets, ((struct bucket_to_lock) {
 						   .b = b, .gen = ptr->gen, .l = l,
-						   }), GFP_KERNEL|__GFP_NOFAIL);
+						   }), GFP_KERNEL|GFP_NOFAIL);
 
 			if (ptr->unwritten)
 				op->flags |= BCH_WRITE_CONVERT_UNWRITTEN;
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index aa7f8148cd0d..29303973143a 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -686,7 +686,7 @@ int btrfs_alloc_folio_array(unsigned int nr_folios, struct folio **folio_array)
  * @nr_pages:   number of pages to allocate
  * @page_array: the array to fill with pages; any existing non-null entries in
  *		the array will be skipped
- * @nofail:	whether using __GFP_NOFAIL flag
+ * @nofail:	whether using GFP_NOFAIL flag
  *
  * Return: 0        if all pages were able to be allocated;
  *         -ENOMEM  otherwise, the partially allocated pages would be freed and
@@ -695,7 +695,7 @@ int btrfs_alloc_folio_array(unsigned int nr_folios, struct folio **folio_array)
 int btrfs_alloc_page_array(unsigned int nr_pages, struct page **page_array,
 			   bool nofail)
 {
-	const gfp_t gfp = nofail ? (GFP_NOFS | __GFP_NOFAIL) : GFP_NOFS;
+	const gfp_t gfp = nofail ? (GFP_NOFS | GFP_NOFAIL) : GFP_NOFS;
 	unsigned int allocated;
 
 	for (allocated = 0; allocated < nr_pages;) {
@@ -2674,7 +2674,7 @@ __alloc_extent_buffer(struct btrfs_fs_info *fs_info, u64 start,
 {
 	struct extent_buffer *eb = NULL;
 
-	eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|__GFP_NOFAIL);
+	eb = kmem_cache_zalloc(extent_buffer_cache, GFP_NOFS|GFP_NOFAIL);
 	eb->start = start;
 	eb->len = len;
 	eb->fs_info = fs_info;
@@ -2982,7 +2982,7 @@ static int attach_eb_folio_to_filemap(struct extent_buffer *eb, int i,
 
 retry:
 	ret = filemap_add_folio(mapping, eb->folios[i], index + i,
-				GFP_NOFS | __GFP_NOFAIL);
+				GFP_NOFS | GFP_NOFAIL);
 	if (!ret)
 		goto finish;
 
diff --git a/fs/buffer.c b/fs/buffer.c
index e55ad471c530..64952bb73c8d 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -963,7 +963,7 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
 {
 	gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT;
 	if (retry)
-		gfp |= __GFP_NOFAIL;
+		gfp |= GFP_NOFAIL;
 
 	return folio_alloc_buffers(page_folio(page), size, gfp);
 }
@@ -1490,7 +1490,7 @@ struct buffer_head *__bread_gfp(struct block_device *bdev, sector_t block,
 	 * Prefer looping in the allocator rather than here, at least that
 	 * code knows what it's doing.
 	 */
-	gfp |= __GFP_NOFAIL;
+	gfp |= GFP_NOFAIL;
 
 	bh = bdev_getblk(bdev, block, size, gfp);
 
@@ -1666,7 +1666,7 @@ struct buffer_head *create_empty_buffers(struct folio *folio,
 		unsigned long blocksize, unsigned long b_state)
 {
 	struct buffer_head *bh, *head, *tail;
-	gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT | __GFP_NOFAIL;
+	gfp_t gfp = GFP_NOFS | __GFP_ACCOUNT | GFP_NOFAIL;
 
 	head = folio_alloc_buffers(folio, blocksize, gfp);
 	bh = head;
diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
index fda16eedafb5..759a02600dc3 100644
--- a/fs/erofs/fscache.c
+++ b/fs/erofs/fscache.c
@@ -196,7 +196,7 @@ struct bio *erofs_fscache_bio_alloc(struct erofs_map_dev *mdev)
 {
 	struct erofs_fscache_bio *io;
 
-	io = kmalloc(sizeof(*io), GFP_KERNEL | __GFP_NOFAIL);
+	io = kmalloc(sizeof(*io), GFP_KERNEL | GFP_NOFAIL);
 	bio_init(&io->bio, NULL, io->bvecs, BIO_MAX_VECS, REQ_OP_READ);
 	io->io.private = mdev->m_fscache->cookie;
 	io->io.end_io = erofs_fscache_bio_endio;
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 424f656cd765..e5192f7e75f0 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1106,7 +1106,7 @@ static void z_erofs_do_decompressed_bvec(struct z_erofs_decompress_backend *be,
 	}
 
 	/* (cold path) one pcluster is requested multiple times */
-	item = kmalloc(sizeof(*item), GFP_KERNEL | __GFP_NOFAIL);
+	item = kmalloc(sizeof(*item), GFP_KERNEL | GFP_NOFAIL);
 	item->bvec = *bvec;
 	list_add(&item->list, &be->decompressed_secondary_bvecs);
 }
@@ -1245,11 +1245,11 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
 	if (!be->decompressed_pages)
 		be->decompressed_pages =
 			kvcalloc(be->nr_pages, sizeof(struct page *),
-				 GFP_KERNEL | __GFP_NOFAIL);
+				 GFP_KERNEL | GFP_NOFAIL);
 	if (!be->compressed_pages)
 		be->compressed_pages =
 			kvcalloc(pclusterpages, sizeof(struct page *),
-				 GFP_KERNEL | __GFP_NOFAIL);
+				 GFP_KERNEL | GFP_NOFAIL);
 
 	z_erofs_parse_out_bvecs(be);
 	err2 = z_erofs_parse_in_bvecs(be, &overlapped);
@@ -1269,7 +1269,7 @@ static int z_erofs_decompress_pcluster(struct z_erofs_decompress_backend *be,
 					.partial_decoding = pcl->partial,
 					.fillgaps = pcl->multibases,
 					.gfp = pcl->besteffort ?
-						GFP_KERNEL | __GFP_NOFAIL :
+						GFP_KERNEL | GFP_NOFAIL :
 						GFP_NOWAIT | __GFP_NORETRY
 				 }, be->pagepool);
 
@@ -1496,7 +1496,7 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec,
 	folio_unlock(folio);
 	folio_put(folio);
 out_allocfolio:
-	zbv.page = erofs_allocpage(&f->pagepool, gfp | __GFP_NOFAIL);
+	zbv.page = erofs_allocpage(&f->pagepool, gfp | GFP_NOFAIL);
 	spin_lock(&pcl->obj.lockref.lock);
 	if (pcl->compressed_bvecs[nr].page) {
 		erofs_pagepool_add(&f->pagepool, zbv.page);
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index e067f2dd0335..ea636f07e7c4 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -555,7 +555,7 @@ __read_extent_tree_block(const char *function, unsigned int line,
 	ext4_fsblk_t			pblk;
 
 	if (flags & EXT4_EX_NOFAIL)
-		gfp_flags |= __GFP_NOFAIL;
+		gfp_flags |= GFP_NOFAIL;
 
 	pblk = ext4_idx_pblock(idx);
 	bh = sb_getblk_gfp(inode->i_sb, pblk, gfp_flags);
@@ -891,7 +891,7 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block,
 	gfp_t gfp_flags = GFP_NOFS;
 
 	if (flags & EXT4_EX_NOFAIL)
-		gfp_flags |= __GFP_NOFAIL;
+		gfp_flags |= GFP_NOFAIL;
 
 	eh = ext_inode_hdr(inode);
 	depth = ext_depth(inode);
@@ -1067,7 +1067,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
 	size_t ext_size = 0;
 
 	if (flags & EXT4_EX_NOFAIL)
-		gfp_flags |= __GFP_NOFAIL;
+		gfp_flags |= GFP_NOFAIL;
 
 	/* make decision: where to split? */
 	/* FIXME: now decision is simplest: at current extent */
@@ -2912,7 +2912,7 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
 				le16_to_cpu(path[k].p_hdr->eh_entries)+1;
 	} else {
 		path = kcalloc(depth + 1, sizeof(struct ext4_ext_path),
-			       GFP_NOFS | __GFP_NOFAIL);
+			       GFP_NOFS | GFP_NOFAIL);
 		if (path == NULL) {
 			ext4_journal_stop(handle);
 			return -ENOMEM;
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index 17dcf13adde2..70423b01abe6 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -456,7 +456,7 @@ static inline struct pending_reservation *__alloc_pending(bool nofail)
 	if (!nofail)
 		return kmem_cache_alloc(ext4_pending_cachep, GFP_ATOMIC);
 
-	return kmem_cache_zalloc(ext4_pending_cachep, GFP_KERNEL | __GFP_NOFAIL);
+	return kmem_cache_zalloc(ext4_pending_cachep, GFP_KERNEL | GFP_NOFAIL);
 }
 
 static inline void __free_pending(struct pending_reservation *pr)
@@ -482,7 +482,7 @@ static inline struct extent_status *__es_alloc_extent(bool nofail)
 	if (!nofail)
 		return kmem_cache_alloc(ext4_es_cachep, GFP_ATOMIC);
 
-	return kmem_cache_zalloc(ext4_es_cachep, GFP_KERNEL | __GFP_NOFAIL);
+	return kmem_cache_zalloc(ext4_es_cachep, GFP_KERNEL | GFP_NOFAIL);
 }
 
 static void ext4_es_init_extent(struct inode *inode, struct extent_status *es,
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 9dda9cd68ab2..fc763893e4d0 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -5592,7 +5592,7 @@ void ext4_discard_preallocations(struct inode *inode)
 		group = ext4_get_group_number(sb, pa->pa_pstart);
 
 		err = ext4_mb_load_buddy_gfp(sb, group, &e4b,
-					     GFP_NOFS|__GFP_NOFAIL);
+					     GFP_NOFS|GFP_NOFAIL);
 		if (err) {
 			ext4_error_err(sb, -err, "Error %d loading buddy information for %u",
 				       err, group);
@@ -5898,7 +5898,7 @@ ext4_mb_discard_lg_preallocations(struct super_block *sb,
 
 		group = ext4_get_group_number(sb, pa->pa_pstart);
 		err = ext4_mb_load_buddy_gfp(sb, group, &e4b,
-					     GFP_NOFS|__GFP_NOFAIL);
+					     GFP_NOFS|GFP_NOFAIL);
 		if (err) {
 			ext4_error_err(sb, -err, "Error %d loading buddy information for %u",
 				       err, group);
@@ -6449,9 +6449,9 @@ static void ext4_mb_clear_bb(handle_t *handle, struct inode *inode,
 	count_clusters = EXT4_NUM_B2C(sbi, count);
 	trace_ext4_mballoc_free(sb, inode, block_group, bit, count_clusters);
 
-	/* __GFP_NOFAIL: retry infinitely, ignore TIF_MEMDIE and memcg limit. */
+	/* GFP_NOFAIL: retry infinitely, ignore TIF_MEMDIE and memcg limit. */
 	err = ext4_mb_load_buddy_gfp(sb, block_group, &e4b,
-				     GFP_NOFS|__GFP_NOFAIL);
+				     GFP_NOFS|GFP_NOFAIL);
 	if (err)
 		goto error_out;
 
@@ -6488,11 +6488,11 @@ static void ext4_mb_clear_bb(handle_t *handle, struct inode *inode,
 	     !ext4_should_writeback_data(inode))) {
 		struct ext4_free_data *new_entry;
 		/*
-		 * We use __GFP_NOFAIL because ext4_free_blocks() is not allowed
+		 * We use GFP_NOFAIL because ext4_free_blocks() is not allowed
 		 * to fail.
 		 */
 		new_entry = kmem_cache_alloc(ext4_free_data_cachep,
-				GFP_NOFS|__GFP_NOFAIL);
+				GFP_NOFS|GFP_NOFAIL);
 		new_entry->efd_start_cluster = bit;
 		new_entry->efd_group = block_group;
 		new_entry->efd_count = count_clusters;
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index ad5543866d21..4d9a557d692f 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -530,7 +530,7 @@ int ext4_bio_write_folio(struct ext4_io_submit *io, struct folio *folio,
 				if (io->io_bio)
 					ext4_io_submit(io);
 				else
-					new_gfp_flags |= __GFP_NOFAIL;
+					new_gfp_flags |= GFP_NOFAIL;
 				memalloc_retry_wait(gfp_flags);
 				gfp_flags = new_gfp_flags;
 				goto retry_encrypt;
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 55d444bec5c0..0f9d4e50373e 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -531,7 +531,7 @@ static void __add_ino_entry(struct f2fs_sb_info *sbi, nid_t ino,
 		new = f2fs_kmem_cache_alloc(ino_entry_slab,
 						GFP_NOFS, true, NULL);
 
-	radix_tree_preload(GFP_NOFS | __GFP_NOFAIL);
+	radix_tree_preload(GFP_NOFS | GFP_NOFAIL);
 
 	spin_lock(&im->ino_lock);
 	e = radix_tree_lookup(&im->ino_root, ino);
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index b9b0debc6b3d..46f95caa96f6 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -2518,7 +2518,7 @@ int f2fs_encrypt_one_page(struct f2fs_io_info *fio)
 		if (PTR_ERR(fio->encrypted_page) == -ENOMEM) {
 			f2fs_flush_merged_writes(fio->sbi);
 			memalloc_retry_wait(GFP_NOFS);
-			gfp_flags |= __GFP_NOFAIL;
+			gfp_flags |= GFP_NOFAIL;
 			goto retry_encrypt;
 		}
 		return PTR_ERR(fio->encrypted_page);
@@ -2998,7 +2998,7 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
 	if (f2fs_compressed_file(inode) &&
 		1 << cc.log_cluster_size > F2FS_ONSTACK_PAGES) {
 		pages = f2fs_kzalloc(sbi, sizeof(struct page *) <<
-				cc.log_cluster_size, GFP_NOFS | __GFP_NOFAIL);
+				cc.log_cluster_size, GFP_NOFS | GFP_NOFAIL);
 		max_pages = 1 << cc.log_cluster_size;
 	}
 #endif
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 8a9d910aa552..c8fbfb73fb95 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2814,7 +2814,7 @@ static inline void *f2fs_kmem_cache_alloc_nofail(struct kmem_cache *cachep,
 
 	entry = kmem_cache_alloc(cachep, flags);
 	if (!entry)
-		entry = kmem_cache_alloc(cachep, flags | __GFP_NOFAIL);
+		entry = kmem_cache_alloc(cachep, flags | GFP_NOFAIL);
 	return entry;
 }
 
diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
index b72ef96f7e33..919c7cb9366d 100644
--- a/fs/f2fs/node.c
+++ b/fs/f2fs/node.c
@@ -2316,7 +2316,7 @@ static bool add_free_nid(struct f2fs_sb_info *sbi,
 	i->nid = nid;
 	i->state = FREE_NID;
 
-	radix_tree_preload(GFP_NOFS | __GFP_NOFAIL);
+	radix_tree_preload(GFP_NOFS | GFP_NOFAIL);
 
 	spin_lock(&nm_i->nid_list_lock);
 
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 9eb191b5c4de..8f4012060fdc 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -490,7 +490,7 @@ ssize_t fuse_simple_request(struct fuse_mount *fm, struct fuse_args *args)
 
 	if (args->force) {
 		atomic_inc(&fc->num_waiting);
-		req = fuse_request_alloc(fm, GFP_KERNEL | __GFP_NOFAIL);
+		req = fuse_request_alloc(fm, GFP_KERNEL | GFP_NOFAIL);
 
 		if (!args->nocreds)
 			fuse_force_creds(req);
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index f39456c65ed7..7b9ff0334d51 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -116,7 +116,7 @@ static void fuse_file_put(struct fuse_file *ff, bool sync)
 		} else {
 			args->end = fuse_release_end;
 			if (fuse_simple_background(ff->fm, args,
-						   GFP_KERNEL | __GFP_NOFAIL))
+						   GFP_KERNEL | GFP_NOFAIL))
 				fuse_release_end(ff->fm, args, -ENOTCONN);
 		}
 		kfree(ff);
@@ -1816,7 +1816,7 @@ __acquires(fi->lock)
 	err = fuse_simple_background(fm, args, GFP_ATOMIC);
 	if (err == -ENOMEM) {
 		spin_unlock(&fi->lock);
-		err = fuse_simple_background(fm, args, GFP_NOFS | __GFP_NOFAIL);
+		err = fuse_simple_background(fm, args, GFP_NOFS | GFP_NOFAIL);
 		spin_lock(&fi->lock);
 	}
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index d8ab4e93916f..6861b34290b9 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -634,7 +634,7 @@ static struct fuse_sync_bucket *fuse_sync_bucket_alloc(void)
 {
 	struct fuse_sync_bucket *bucket;
 
-	bucket = kzalloc(sizeof(*bucket), GFP_KERNEL | __GFP_NOFAIL);
+	bucket = kzalloc(sizeof(*bucket), GFP_KERNEL | GFP_NOFAIL);
 	if (bucket) {
 		init_waitqueue_head(&bucket->waitq);
 		/* Initial active count */
@@ -1372,7 +1372,7 @@ void fuse_send_init(struct fuse_mount *fm)
 	struct fuse_init_args *ia;
 	u64 flags;
 
-	ia = kzalloc(sizeof(*ia), GFP_KERNEL | __GFP_NOFAIL);
+	ia = kzalloc(sizeof(*ia), GFP_KERNEL | GFP_NOFAIL);
 
 	ia->in.major = FUSE_KERNEL_VERSION;
 	ia->in.minor = FUSE_KERNEL_MINOR_VERSION;
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index dd5260141615..29ff3bf6d242 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -700,7 +700,7 @@ static void virtio_fs_requests_done_work(struct work_struct *work)
 		if (req->args->may_block) {
 			struct virtio_fs_req_work *w;
 
-			w = kzalloc(sizeof(*w), GFP_NOFS | __GFP_NOFAIL);
+			w = kzalloc(sizeof(*w), GFP_NOFS | GFP_NOFAIL);
 			INIT_WORK(&w->done_work, virtio_fs_complete_req_work);
 			w->fsvq = fsvq;
 			w->req = req;
@@ -1109,7 +1109,7 @@ __releases(fiq->lock)
 	spin_unlock(&fiq->lock);
 
 	/* Allocate a buffer for the request */
-	forget = kmalloc(sizeof(*forget), GFP_NOFS | __GFP_NOFAIL);
+	forget = kmalloc(sizeof(*forget), GFP_NOFS | GFP_NOFAIL);
 	req = &forget->req;
 
 	req->ih = (struct fuse_in_header){
diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index 2b26e8d529aa..af5bbd443543 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -131,7 +131,7 @@ struct buffer_head *gfs2_getbuf(struct gfs2_glock *gl, u64 blkno, int create)
 	if (create) {
 		folio = __filemap_get_folio(mapping, index,
 				FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
-				mapping_gfp_mask(mapping) | __GFP_NOFAIL);
+				mapping_gfp_mask(mapping) | GFP_NOFAIL);
 		bh = folio_buffers(folio);
 		if (!bh)
 			bh = create_empty_buffers(folio,
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 29c772816765..bfeb0f91e0e7 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -2273,7 +2273,7 @@ static void rgblk_free(struct gfs2_sbd *sdp, struct gfs2_rgrpd *rgd,
 		if (bi != bi_prev) {
 			if (!bi->bi_clone) {
 				bi->bi_clone = kmalloc(bi->bi_bh->b_size,
-						      GFP_NOFS | __GFP_NOFAIL);
+						      GFP_NOFS | GFP_NOFAIL);
 				memcpy(bi->bi_clone + bi->bi_offset,
 				       bi->bi_bh->b_data + bi->bi_offset,
 				       bi->bi_bytes);
@@ -2702,7 +2702,7 @@ void gfs2_rlist_add(struct gfs2_inode *ip, struct gfs2_rgrp_list *rlist,
 		new_space = rlist->rl_space + 10;
 
 		tmp = kcalloc(new_space, sizeof(struct gfs2_rgrpd *),
-			      GFP_NOFS | __GFP_NOFAIL);
+			      GFP_NOFS | GFP_NOFAIL);
 
 		if (rlist->rl_rgd) {
 			memcpy(tmp, rlist->rl_rgd,
@@ -2735,7 +2735,7 @@ void gfs2_rlist_alloc(struct gfs2_rgrp_list *rlist,
 
 	rlist->rl_ghs = kmalloc_array(rlist->rl_rgrps,
 				      sizeof(struct gfs2_holder),
-				      GFP_NOFS | __GFP_NOFAIL);
+				      GFP_NOFS | GFP_NOFAIL);
 	for (x = 0; x < rlist->rl_rgrps; x++)
 		gfs2_holder_init(rlist->rl_rgd[x]->rd_gl, state, flags,
 				 &rlist->rl_ghs[x]);
diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index 192213c7359a..8cbbdc09a46c 100644
--- a/fs/gfs2/trans.c
+++ b/fs/gfs2/trans.c
@@ -165,7 +165,7 @@ static struct gfs2_bufdata *gfs2_alloc_bufdata(struct gfs2_glock *gl,
 {
 	struct gfs2_bufdata *bd;
 
-	bd = kmem_cache_zalloc(gfs2_bufdata_cachep, GFP_NOFS | __GFP_NOFAIL);
+	bd = kmem_cache_zalloc(gfs2_bufdata_cachep, GFP_NOFS | GFP_NOFAIL);
 	bd->bd_bh = bh;
 	bd->bd_gl = gl;
 	INIT_LIST_HEAD(&bd->bd_list);
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index f420c53d86ac..0b25c5501894 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -192,7 +192,7 @@ static struct iomap_folio_state *ifs_alloc(struct inode *inode,
 	if (flags & IOMAP_NOWAIT)
 		gfp = GFP_NOWAIT;
 	else
-		gfp = GFP_NOFS | __GFP_NOFAIL;
+		gfp = GFP_NOFS | GFP_NOFAIL;
 
 	/*
 	 * ifs->state tracks two sets of state flags when the
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 1ebf2393bfb7..cbfb45cb4a0b 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -338,7 +338,7 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 	 */
 	J_ASSERT_BH(bh_in, buffer_jbddirty(bh_in));
 
-	new_bh = alloc_buffer_head(GFP_NOFS|__GFP_NOFAIL);
+	new_bh = alloc_buffer_head(GFP_NOFS|GFP_NOFAIL);
 
 	/* keep subsequent assertions sane */
 	atomic_set(&new_bh->b_count, 1);
@@ -2864,7 +2864,7 @@ static struct journal_head *journal_alloc_journal_head(void)
 		jbd2_debug(1, "out of memory for journal_head\n");
 		pr_notice_ratelimited("ENOMEM in %s, retrying.\n", __func__);
 		ret = kmem_cache_zalloc(jbd2_journal_head_cache,
-				GFP_NOFS | __GFP_NOFAIL);
+				GFP_NOFS | GFP_NOFAIL);
 	}
 	if (ret)
 		spin_lock_init(&ret->b_state_lock);
diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c
index 4556e4689024..2af21686b037 100644
--- a/fs/jbd2/revoke.c
+++ b/fs/jbd2/revoke.c
@@ -141,7 +141,7 @@ static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr,
 	gfp_t gfp_mask = GFP_NOFS;
 
 	if (journal_oom_retry)
-		gfp_mask |= __GFP_NOFAIL;
+		gfp_mask |= GFP_NOFAIL;
 	record = kmem_cache_alloc(jbd2_revoke_record_cache, gfp_mask);
 	if (!record)
 		return -ENOMEM;
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 66513c18ca29..76551cd71260 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -351,7 +351,7 @@ static int start_this_handle(journal_t *journal, handle_t *handle,
 		 * inside the fs writeback layer, so we MUST NOT fail.
 		 */
 		if ((gfp_mask & __GFP_FS) == 0)
-			gfp_mask |= __GFP_NOFAIL;
+			gfp_mask |= GFP_NOFAIL;
 		new_transaction = kmem_cache_zalloc(transaction_cache,
 						    gfp_mask);
 		if (!new_transaction)
@@ -1115,7 +1115,7 @@ do_get_write_access(handle_t *handle, struct journal_head *jh,
 			JBUFFER_TRACE(jh, "allocate memory for buffer");
 			spin_unlock(&jh->b_state_lock);
 			frozen_buffer = jbd2_alloc(jh2bh(jh)->b_size,
-						   GFP_NOFS | __GFP_NOFAIL);
+						   GFP_NOFS | GFP_NOFAIL);
 			goto repeat;
 		}
 		jh->b_frozen_data = frozen_buffer;
@@ -1393,7 +1393,7 @@ int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
 repeat:
 	if (!jh->b_committed_data)
 		committed_data = jbd2_alloc(jh2bh(jh)->b_size,
-					    GFP_NOFS|__GFP_NOFAIL);
+					    GFP_NOFS|GFP_NOFAIL);
 
 	spin_lock(&jh->b_state_lock);
 	if (!jh->b_committed_data) {
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 224bccaab4cc..2704b5b66e8e 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -794,7 +794,7 @@ static struct fanotify_event *fanotify_alloc_event(
 	 * target monitoring memcg as it may have security repercussion.
 	 */
 	if (group->max_events == UINT_MAX)
-		gfp |= __GFP_NOFAIL;
+		gfp |= GFP_NOFAIL;
 	else
 		gfp |= __GFP_RETRY_MAYFAIL;
 
diff --git a/fs/reiserfs/journal.c b/fs/reiserfs/journal.c
index e477ee0ff35d..93d3238a5d1b 100644
--- a/fs/reiserfs/journal.c
+++ b/fs/reiserfs/journal.c
@@ -2570,7 +2570,7 @@ static struct reiserfs_journal_list *alloc_journal_list(struct super_block *s)
 {
 	struct reiserfs_journal_list *jl;
 	jl = kzalloc(sizeof(struct reiserfs_journal_list),
-		     GFP_NOFS | __GFP_NOFAIL);
+		     GFP_NOFS | GFP_NOFAIL);
 	INIT_LIST_HEAD(&jl->j_list);
 	INIT_LIST_HEAD(&jl->j_working_list);
 	INIT_LIST_HEAD(&jl->j_tail_bh_list);
diff --git a/fs/udf/directory.c b/fs/udf/directory.c
index 93153665eb37..1f040ff7c15b 100644
--- a/fs/udf/directory.c
+++ b/fs/udf/directory.c
@@ -252,7 +252,7 @@ int udf_fiiter_init(struct udf_fileident_iter *iter, struct inode *dir,
 	 * fail and it can be difficult to undo without corrupting filesystem.
 	 * So just do not allow memory allocation failures here.
 	 */
-	iter->namebuf = kmalloc(UDF_NAME_LEN_CS0, GFP_KERNEL | __GFP_NOFAIL);
+	iter->namebuf = kmalloc(UDF_NAME_LEN_CS0, GFP_KERNEL | GFP_NOFAIL);
 
 	if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
 		err = udf_copy_fi(iter);
diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 59326f84f6a5..e32e95c29280 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -2649,7 +2649,7 @@ xfs_defer_extent_free(
 		return -EFSCORRUPTED;
 
 	xefi = kmem_cache_zalloc(xfs_extfree_item_cache,
-			       GFP_KERNEL | __GFP_NOFAIL);
+			       GFP_KERNEL | GFP_NOFAIL);
 	xefi->xefi_startblock = bno;
 	xefi->xefi_blockcount = (xfs_extlen_t)len;
 	xefi->xefi_agresv = type;
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index b9e98950eb3d..9cc06f758d85 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -954,7 +954,7 @@ xfs_attr_shortform_to_leaf(
 
 	trace_xfs_attr_sf_to_leaf(args);
 
-	tmpbuffer = kmalloc(size, GFP_KERNEL | __GFP_NOFAIL);
+	tmpbuffer = kmalloc(size, GFP_KERNEL | GFP_NOFAIL);
 	memcpy(tmpbuffer, ifp->if_data, size);
 	sf = (struct xfs_attr_sf_hdr *)tmpbuffer;
 
@@ -1138,7 +1138,7 @@ xfs_attr3_leaf_to_shortform(
 
 	trace_xfs_attr_leaf_to_sf(args);
 
-	tmpbuffer = kmalloc(args->geo->blksize, GFP_KERNEL | __GFP_NOFAIL);
+	tmpbuffer = kmalloc(args->geo->blksize, GFP_KERNEL | GFP_NOFAIL);
 	if (!tmpbuffer)
 		return -ENOMEM;
 
@@ -1613,7 +1613,7 @@ xfs_attr3_leaf_compact(
 
 	trace_xfs_attr_leaf_compact(args);
 
-	tmpbuffer = kmalloc(args->geo->blksize, GFP_KERNEL | __GFP_NOFAIL);
+	tmpbuffer = kmalloc(args->geo->blksize, GFP_KERNEL | GFP_NOFAIL);
 	memcpy(tmpbuffer, bp->b_addr, args->geo->blksize);
 	memset(bp->b_addr, 0, args->geo->blksize);
 	leaf_src = (xfs_attr_leafblock_t *)tmpbuffer;
@@ -2331,7 +2331,7 @@ xfs_attr3_leaf_unbalance(
 		struct xfs_attr3_icleaf_hdr tmphdr;
 
 		tmp_leaf = kzalloc(state->args->geo->blksize,
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 
 		/*
 		 * Copy the header into the temp leaf so that all the stuff
diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 7df74c35d9f9..6accbb03ec8a 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -6246,7 +6246,7 @@ __xfs_bmap_add(
 	    bmap->br_startblock == DELAYSTARTBLOCK)
 		return;
 
-	bi = kmem_cache_alloc(xfs_bmap_intent_cache, GFP_KERNEL | __GFP_NOFAIL);
+	bi = kmem_cache_alloc(xfs_bmap_intent_cache, GFP_KERNEL | GFP_NOFAIL);
 	INIT_LIST_HEAD(&bi->bi_list);
 	bi->bi_type = type;
 	bi->bi_owner = ip;
diff --git a/fs/xfs/libxfs/xfs_btree.h b/fs/xfs/libxfs/xfs_btree.h
index 10b7ddc3b2b3..4df96e12603c 100644
--- a/fs/xfs/libxfs/xfs_btree.h
+++ b/fs/xfs/libxfs/xfs_btree.h
@@ -663,7 +663,7 @@ xfs_btree_alloc_cursor(
 
 	/* BMBT allocations can come through from non-transactional context. */
 	cur = kmem_cache_zalloc(cache,
-			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+			GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 	cur->bc_ops = ops;
 	cur->bc_tp = tp;
 	cur->bc_mp = mp;
diff --git a/fs/xfs/libxfs/xfs_btree_staging.c b/fs/xfs/libxfs/xfs_btree_staging.c
index 694929703152..fa13fb00be31 100644
--- a/fs/xfs/libxfs/xfs_btree_staging.c
+++ b/fs/xfs/libxfs/xfs_btree_staging.c
@@ -303,7 +303,7 @@ xfs_btree_bload_prep_block(
 
 		/* Allocate a new incore btree root block. */
 		new_size = bbl->iroot_size(cur, level, nr_this_block, priv);
-		ifp->if_broot = kzalloc(new_size, GFP_KERNEL | __GFP_NOFAIL);
+		ifp->if_broot = kzalloc(new_size, GFP_KERNEL | GFP_NOFAIL);
 		ifp->if_broot_bytes = (int)new_size;
 
 		/* Initialize it and send it out. */
diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index 16a529a88780..846678b2ce3c 100644
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -87,7 +87,7 @@ xfs_da_state_alloc(
 	struct xfs_da_state	*state;
 
 	state = kmem_cache_zalloc(xfs_da_state_cache,
-			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+			GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 	state->args = args;
 	state->mp = args->dp->i_mount;
 	return state;
@@ -2323,7 +2323,7 @@ xfs_da_grow_inode_int(
 		 * try without the CONTIG flag.  Loop until we get it all.
 		 */
 		mapp = kmalloc(sizeof(*mapp) * count,
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 		for (b = *bno, mapi = 0; b < *bno + count; ) {
 			c = (int)(*bno + count - b);
 			nmap = min(XFS_BMAP_MAX_NMAP, c);
@@ -2702,7 +2702,7 @@ xfs_dabuf_map(
 
 	if (nfsb > 1)
 		irecs = kzalloc(sizeof(irec) * nfsb,
-				GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+				GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 
 	nirecs = nfsb;
 	error = xfs_bmapi_read(dp, bno, nfsb, irecs, &nirecs,
@@ -2716,7 +2716,7 @@ xfs_dabuf_map(
 	 */
 	if (nirecs > 1) {
 		map = kzalloc(nirecs * sizeof(struct xfs_buf_map),
-				GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+				GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 		if (!map) {
 			error = -ENOMEM;
 			goto out_free_irecs;
diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
index 40021849b42f..08c5ee66e44c 100644
--- a/fs/xfs/libxfs/xfs_defer.c
+++ b/fs/xfs/libxfs/xfs_defer.c
@@ -828,7 +828,7 @@ xfs_defer_alloc(
 	struct xfs_defer_pending	*dfp;
 
 	dfp = kmem_cache_zalloc(xfs_defer_pending_cache,
-			GFP_KERNEL | __GFP_NOFAIL);
+			GFP_KERNEL | GFP_NOFAIL);
 	dfp->dfp_ops = ops;
 	INIT_LIST_HEAD(&dfp->dfp_work);
 	list_add_tail(&dfp->dfp_list, dfops);
@@ -977,7 +977,7 @@ xfs_defer_ops_capture(
 		return ERR_PTR(error);
 
 	/* Create an object to capture the defer ops. */
-	dfc = kzalloc(sizeof(*dfc), GFP_KERNEL | __GFP_NOFAIL);
+	dfc = kzalloc(sizeof(*dfc), GFP_KERNEL | GFP_NOFAIL);
 	INIT_LIST_HEAD(&dfc->dfc_list);
 	INIT_LIST_HEAD(&dfc->dfc_dfops);
 
diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c
index 202468223bf9..1884428eda5f 100644
--- a/fs/xfs/libxfs/xfs_dir2.c
+++ b/fs/xfs/libxfs/xfs_dir2.c
@@ -248,7 +248,7 @@ xfs_dir_init(
 	if (error)
 		return error;
 
-	args = kzalloc(sizeof(*args), GFP_KERNEL | __GFP_NOFAIL);
+	args = kzalloc(sizeof(*args), GFP_KERNEL | GFP_NOFAIL);
 	if (!args)
 		return -ENOMEM;
 
@@ -341,7 +341,7 @@ xfs_dir_createname(
 		XFS_STATS_INC(dp->i_mount, xs_dir_create);
 	}
 
-	args = kzalloc(sizeof(*args), GFP_KERNEL | __GFP_NOFAIL);
+	args = kzalloc(sizeof(*args), GFP_KERNEL | GFP_NOFAIL);
 	if (!args)
 		return -ENOMEM;
 
@@ -439,7 +439,7 @@ xfs_dir_lookup(
 	XFS_STATS_INC(dp->i_mount, xs_dir_lookup);
 
 	args = kzalloc(sizeof(*args),
-			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+			GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 	args->geo = dp->i_mount->m_dir_geo;
 	args->name = name->name;
 	args->namelen = name->len;
@@ -504,7 +504,7 @@ xfs_dir_removename(
 	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
 	XFS_STATS_INC(dp->i_mount, xs_dir_remove);
 
-	args = kzalloc(sizeof(*args), GFP_KERNEL | __GFP_NOFAIL);
+	args = kzalloc(sizeof(*args), GFP_KERNEL | GFP_NOFAIL);
 	if (!args)
 		return -ENOMEM;
 
@@ -564,7 +564,7 @@ xfs_dir_replace(
 	if (rval)
 		return rval;
 
-	args = kzalloc(sizeof(*args), GFP_KERNEL | __GFP_NOFAIL);
+	args = kzalloc(sizeof(*args), GFP_KERNEL | GFP_NOFAIL);
 	if (!args)
 		return -ENOMEM;
 
diff --git a/fs/xfs/libxfs/xfs_dir2_block.c b/fs/xfs/libxfs/xfs_dir2_block.c
index 0f93ed1a4a74..555f840e8465 100644
--- a/fs/xfs/libxfs/xfs_dir2_block.c
+++ b/fs/xfs/libxfs/xfs_dir2_block.c
@@ -1116,7 +1116,7 @@ xfs_dir2_sf_to_block(
 	 * Copy the directory into a temporary buffer.
 	 * Then pitch the incore inode data so we can make extents.
 	 */
-	sfp = kmalloc(ifp->if_bytes, GFP_KERNEL | __GFP_NOFAIL);
+	sfp = kmalloc(ifp->if_bytes, GFP_KERNEL | GFP_NOFAIL);
 	memcpy(sfp, oldsfp, ifp->if_bytes);
 
 	xfs_idata_realloc(dp, -ifp->if_bytes, XFS_DATA_FORK);
diff --git a/fs/xfs/libxfs/xfs_dir2_sf.c b/fs/xfs/libxfs/xfs_dir2_sf.c
index 17a20384c8b7..4c0f65e2e0a6 100644
--- a/fs/xfs/libxfs/xfs_dir2_sf.c
+++ b/fs/xfs/libxfs/xfs_dir2_sf.c
@@ -276,7 +276,7 @@ xfs_dir2_block_to_sf(
 	 * format the data into.  Once we have formatted the data, we can free
 	 * the block and copy the formatted data into the inode literal area.
 	 */
-	sfp = kmalloc(mp->m_sb.sb_inodesize, GFP_KERNEL | __GFP_NOFAIL);
+	sfp = kmalloc(mp->m_sb.sb_inodesize, GFP_KERNEL | GFP_NOFAIL);
 	memcpy(sfp, sfhp, xfs_dir2_sf_hdr_size(sfhp->i8count));
 
 	/*
@@ -524,7 +524,7 @@ xfs_dir2_sf_addname_hard(
 	 * Copy the old directory to the stack buffer.
 	 */
 	old_isize = (int)dp->i_disk_size;
-	buf = kmalloc(old_isize, GFP_KERNEL | __GFP_NOFAIL);
+	buf = kmalloc(old_isize, GFP_KERNEL | GFP_NOFAIL);
 	oldsfp = (xfs_dir2_sf_hdr_t *)buf;
 	memcpy(oldsfp, dp->i_df.if_data, old_isize);
 	/*
@@ -1151,7 +1151,7 @@ xfs_dir2_sf_toino4(
 	 * Don't want xfs_idata_realloc copying the data here.
 	 */
 	oldsize = dp->i_df.if_bytes;
-	buf = kmalloc(oldsize, GFP_KERNEL | __GFP_NOFAIL);
+	buf = kmalloc(oldsize, GFP_KERNEL | GFP_NOFAIL);
 	ASSERT(oldsfp->i8count == 1);
 	memcpy(buf, oldsfp, oldsize);
 	/*
@@ -1223,7 +1223,7 @@ xfs_dir2_sf_toino8(
 	 * Don't want xfs_idata_realloc copying the data here.
 	 */
 	oldsize = dp->i_df.if_bytes;
-	buf = kmalloc(oldsize, GFP_KERNEL | __GFP_NOFAIL);
+	buf = kmalloc(oldsize, GFP_KERNEL | GFP_NOFAIL);
 	ASSERT(oldsfp->i8count == 0);
 	memcpy(buf, oldsfp, oldsize);
 	/*
diff --git a/fs/xfs/libxfs/xfs_exchmaps.c b/fs/xfs/libxfs/xfs_exchmaps.c
index 2021396651de..eabbb13bd02c 100644
--- a/fs/xfs/libxfs/xfs_exchmaps.c
+++ b/fs/xfs/libxfs/xfs_exchmaps.c
@@ -499,7 +499,7 @@ xfs_exchmaps_link_to_sf(
 
 	/* Read the current symlink target into a buffer. */
 	buf = kmalloc(ip->i_disk_size + 1,
-			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+			GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 	if (!buf) {
 		ASSERT(0);
 		return -ENOMEM;
@@ -978,7 +978,7 @@ xfs_exchmaps_init_intent(
 	unsigned int			rs = 0;
 
 	xmi = kmem_cache_zalloc(xfs_exchmaps_intent_cache,
-			GFP_NOFS | __GFP_NOFAIL);
+			GFP_NOFS | GFP_NOFAIL);
 	INIT_LIST_HEAD(&xmi->xmi_list);
 	xmi->xmi_ip1 = req->ip1;
 	xmi->xmi_ip2 = req->ip2;
diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
index 8796f2b3e534..367dc8dbb886 100644
--- a/fs/xfs/libxfs/xfs_iext_tree.c
+++ b/fs/xfs/libxfs/xfs_iext_tree.c
@@ -398,7 +398,7 @@ static inline void *
 xfs_iext_alloc_node(
 	int	size)
 {
-	return kzalloc(size, GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+	return kzalloc(size, GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 }
 
 static void
@@ -611,7 +611,7 @@ xfs_iext_realloc_root(
 		new_size = NODE_SIZE;
 
 	new = krealloc(ifp->if_data, new_size,
-			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+			GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 	memset(new + ifp->if_bytes, 0, new_size - ifp->if_bytes);
 	ifp->if_data = new;
 	cur->leaf = new;
diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 9d11ae015909..e087337bdaa8 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -53,7 +53,7 @@ xfs_init_local_fork(
 
 	if (size) {
 		char *new_data = kmalloc(mem_size,
-				GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+				GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 
 		memcpy(new_data, data, size);
 		if (zero_terminate)
@@ -213,7 +213,7 @@ xfs_iformat_btree(
 
 	ifp->if_broot_bytes = size;
 	ifp->if_broot = kmalloc(size,
-				GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+				GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 	ASSERT(ifp->if_broot != NULL);
 	/*
 	 * Copy and convert from the on-disk structure
@@ -411,7 +411,7 @@ xfs_iroot_realloc(
 		if (ifp->if_broot_bytes == 0) {
 			new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, rec_diff);
 			ifp->if_broot = kmalloc(new_size,
-						GFP_KERNEL | __GFP_NOFAIL);
+						GFP_KERNEL | GFP_NOFAIL);
 			ifp->if_broot_bytes = (int)new_size;
 			return;
 		}
@@ -426,7 +426,7 @@ xfs_iroot_realloc(
 		new_max = cur_max + rec_diff;
 		new_size = XFS_BMAP_BROOT_SPACE_CALC(mp, new_max);
 		ifp->if_broot = krealloc(ifp->if_broot, new_size,
-					 GFP_KERNEL | __GFP_NOFAIL);
+					 GFP_KERNEL | GFP_NOFAIL);
 		op = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
 						     ifp->if_broot_bytes);
 		np = (char *)XFS_BMAP_BROOT_PTR_ADDR(mp, ifp->if_broot, 1,
@@ -452,7 +452,7 @@ xfs_iroot_realloc(
 	else
 		new_size = 0;
 	if (new_size > 0) {
-		new_broot = kmalloc(new_size, GFP_KERNEL | __GFP_NOFAIL);
+		new_broot = kmalloc(new_size, GFP_KERNEL | GFP_NOFAIL);
 		/*
 		 * First copy over the btree block header.
 		 */
@@ -521,7 +521,7 @@ xfs_idata_realloc(
 
 	if (byte_diff) {
 		ifp->if_data = krealloc(ifp->if_data, new_size,
-					GFP_KERNEL | __GFP_NOFAIL);
+					GFP_KERNEL | GFP_NOFAIL);
 		if (new_size == 0)
 			ifp->if_data = NULL;
 		ifp->if_bytes = new_size;
@@ -701,7 +701,7 @@ xfs_ifork_init_cow(
 		return;
 
 	ip->i_cowfp = kmem_cache_zalloc(xfs_ifork_cache,
-				GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+				GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 	ip->i_cowfp->if_format = XFS_DINODE_FMT_EXTENTS;
 }
 
diff --git a/fs/xfs/libxfs/xfs_refcount.c b/fs/xfs/libxfs/xfs_refcount.c
index 198b84117df1..05d746e8939d 100644
--- a/fs/xfs/libxfs/xfs_refcount.c
+++ b/fs/xfs/libxfs/xfs_refcount.c
@@ -1430,7 +1430,7 @@ __xfs_refcount_add(
 	struct xfs_refcount_intent	*ri;
 
 	ri = kmem_cache_alloc(xfs_refcount_intent_cache,
-			GFP_KERNEL | __GFP_NOFAIL);
+			GFP_KERNEL | GFP_NOFAIL);
 	INIT_LIST_HEAD(&ri->ri_list);
 	ri->ri_type = type;
 	ri->ri_startblock = startblock;
@@ -1876,7 +1876,7 @@ xfs_refcount_recover_extent(
 	}
 
 	rr = kmalloc(sizeof(struct xfs_refcount_recovery),
-			GFP_KERNEL | __GFP_NOFAIL);
+			GFP_KERNEL | GFP_NOFAIL);
 	INIT_LIST_HEAD(&rr->rr_list);
 	xfs_refcount_btrec_to_irec(rec, &rr->rr_rrec);
 
diff --git a/fs/xfs/libxfs/xfs_rmap.c b/fs/xfs/libxfs/xfs_rmap.c
index 6ef4687b3aba..da360a213871 100644
--- a/fs/xfs/libxfs/xfs_rmap.c
+++ b/fs/xfs/libxfs/xfs_rmap.c
@@ -2650,7 +2650,7 @@ __xfs_rmap_add(
 {
 	struct xfs_rmap_intent		*ri;
 
-	ri = kmem_cache_alloc(xfs_rmap_intent_cache, GFP_KERNEL | __GFP_NOFAIL);
+	ri = kmem_cache_alloc(xfs_rmap_intent_cache, GFP_KERNEL | GFP_NOFAIL);
 	INIT_LIST_HEAD(&ri->ri_list);
 	ri->ri_type = type;
 	ri->ri_owner = owner;
diff --git a/fs/xfs/xfs_attr_item.c b/fs/xfs/xfs_attr_item.c
index f683b7a9323f..27ab8c15d666 100644
--- a/fs/xfs/xfs_attr_item.c
+++ b/fs/xfs/xfs_attr_item.c
@@ -275,7 +275,7 @@ xfs_attri_init(
 {
 	struct xfs_attri_log_item	*attrip;
 
-	attrip = kmem_cache_zalloc(xfs_attri_cache, GFP_KERNEL | __GFP_NOFAIL);
+	attrip = kmem_cache_zalloc(xfs_attri_cache, GFP_KERNEL | GFP_NOFAIL);
 
 	/*
 	 * Grab an extra reference to the name/value buffer for this log item.
@@ -673,7 +673,7 @@ xfs_attri_recover_work(
 	}
 
 	attr = kzalloc(sizeof(struct xfs_attr_intent) +
-			sizeof(struct xfs_da_args), GFP_KERNEL | __GFP_NOFAIL);
+			sizeof(struct xfs_da_args), GFP_KERNEL | GFP_NOFAIL);
 	args = (struct xfs_da_args *)(attr + 1);
 
 	attr->xattri_da_args = args;
@@ -858,7 +858,7 @@ xfs_attr_create_done(
 
 	attrip = ATTRI_ITEM(intent);
 
-	attrdp = kmem_cache_zalloc(xfs_attrd_cache, GFP_KERNEL | __GFP_NOFAIL);
+	attrdp = kmem_cache_zalloc(xfs_attrd_cache, GFP_KERNEL | GFP_NOFAIL);
 
 	xfs_log_item_init(tp->t_mountp, &attrdp->attrd_item, XFS_LI_ATTRD,
 			  &xfs_attrd_item_ops);
@@ -885,7 +885,7 @@ xfs_attr_defer_add(
 	}
 
 	new = kmem_cache_zalloc(xfs_attr_intent_cache,
-			GFP_NOFS | __GFP_NOFAIL);
+			GFP_NOFS | GFP_NOFAIL);
 	new->xattri_da_args = args;
 
 	/* Compute log operation from the higher level op and namespace. */
diff --git a/fs/xfs/xfs_attr_list.c b/fs/xfs/xfs_attr_list.c
index 5c947e5ce8b8..7161cf86ccc6 100644
--- a/fs/xfs/xfs_attr_list.c
+++ b/fs/xfs/xfs_attr_list.c
@@ -114,7 +114,7 @@ xfs_attr_shortform_list(
 	 * It didn't all fit, so we have to sort everything on hashval.
 	 */
 	sbsize = sf->count * sizeof(*sbuf);
-	sbp = sbuf = kmalloc(sbsize, GFP_KERNEL | __GFP_NOFAIL);
+	sbp = sbuf = kmalloc(sbsize, GFP_KERNEL | GFP_NOFAIL);
 
 	/*
 	 * Scan the attribute list for the rest of the entries, storing
diff --git a/fs/xfs/xfs_bmap_item.c b/fs/xfs/xfs_bmap_item.c
index e224b49b7cff..3265a74bc457 100644
--- a/fs/xfs/xfs_bmap_item.c
+++ b/fs/xfs/xfs_bmap_item.c
@@ -142,7 +142,7 @@ xfs_bui_init(
 {
 	struct xfs_bui_log_item		*buip;
 
-	buip = kmem_cache_zalloc(xfs_bui_cache, GFP_KERNEL | __GFP_NOFAIL);
+	buip = kmem_cache_zalloc(xfs_bui_cache, GFP_KERNEL | GFP_NOFAIL);
 
 	xfs_log_item_init(mp, &buip->bui_item, XFS_LI_BUI, &xfs_bui_item_ops);
 	buip->bui_format.bui_nextents = XFS_BUI_MAX_FAST_EXTENTS;
@@ -309,7 +309,7 @@ xfs_bmap_update_create_done(
 	struct xfs_bui_log_item		*buip = BUI_ITEM(intent);
 	struct xfs_bud_log_item		*budp;
 
-	budp = kmem_cache_zalloc(xfs_bud_cache, GFP_KERNEL | __GFP_NOFAIL);
+	budp = kmem_cache_zalloc(xfs_bud_cache, GFP_KERNEL | GFP_NOFAIL);
 	xfs_log_item_init(tp->t_mountp, &budp->bud_item, XFS_LI_BUD,
 			  &xfs_bud_item_ops);
 	budp->bud_buip = buip;
@@ -452,7 +452,7 @@ xfs_bui_recover_work(
 		return ERR_PTR(error);
 
 	bi = kmem_cache_zalloc(xfs_bmap_intent_cache,
-			GFP_KERNEL | __GFP_NOFAIL);
+			GFP_KERNEL | GFP_NOFAIL);
 	bi->bi_whichfork = (map->me_flags & XFS_BMAP_EXTENT_ATTR_FORK) ?
 			XFS_ATTR_FORK : XFS_DATA_FORK;
 	bi->bi_type = map->me_flags & XFS_BMAP_EXTENT_TYPE_MASK;
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index aa4dbda7b536..bf6c1a83a70d 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -196,7 +196,7 @@ xfs_buf_get_maps(
 	}
 
 	bp->b_maps = kzalloc(map_count * sizeof(struct xfs_buf_map),
-			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+			GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 	if (!bp->b_maps)
 		return -ENOMEM;
 	return 0;
@@ -229,7 +229,7 @@ _xfs_buf_alloc(
 
 	*bpp = NULL;
 	bp = kmem_cache_zalloc(xfs_buf_cache,
-			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
+			GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL);
 
 	/*
 	 * We don't want certain flags to appear in b_flags unless they are
@@ -334,7 +334,7 @@ xfs_buf_alloc_kmem(
 	struct xfs_buf	*bp,
 	xfs_buf_flags_t	flags)
 {
-	gfp_t		gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL;
+	gfp_t		gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | GFP_NOFAIL;
 	size_t		size = BBTOB(bp->b_length);
 
 	/* Assure zeroed buffer for non-read cases. */
@@ -2106,7 +2106,7 @@ xfs_alloc_buftarg(
 #if defined(CONFIG_FS_DAX) && defined(CONFIG_MEMORY_FAILURE)
 	ops = &xfs_dax_holder_operations;
 #endif
-	btp = kzalloc(sizeof(*btp), GFP_KERNEL | __GFP_NOFAIL);
+	btp = kzalloc(sizeof(*btp), GFP_KERNEL | GFP_NOFAIL);
 
 	btp->bt_mount = mp;
 	btp->bt_bdev_file = bdev_file;
diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 47549cfa61cd..c35fc6897c82 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -838,7 +838,7 @@ xfs_buf_item_get_format(
 	}
 
 	bip->bli_formats = kzalloc(count * sizeof(struct xfs_buf_log_format),
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 }
 
 STATIC void
@@ -879,7 +879,7 @@ xfs_buf_item_init(
 		return 0;
 	}
 
-	bip = kmem_cache_zalloc(xfs_buf_item_cache, GFP_KERNEL | __GFP_NOFAIL);
+	bip = kmem_cache_zalloc(xfs_buf_item_cache, GFP_KERNEL | GFP_NOFAIL);
 	xfs_log_item_init(mp, &bip->bli_item, XFS_LI_BUF, &xfs_buf_item_ops);
 	bip->bli_buf = bp;
 
diff --git a/fs/xfs/xfs_buf_item_recover.c b/fs/xfs/xfs_buf_item_recover.c
index 09e893cf563c..df4d0bfe0547 100644
--- a/fs/xfs/xfs_buf_item_recover.c
+++ b/fs/xfs/xfs_buf_item_recover.c
@@ -85,7 +85,7 @@ xlog_add_buffer_cancelled(
 		return false;
 	}
 
-	bcp = kmalloc(sizeof(struct xfs_buf_cancel), GFP_KERNEL | __GFP_NOFAIL);
+	bcp = kmalloc(sizeof(struct xfs_buf_cancel), GFP_KERNEL | GFP_NOFAIL);
 	bcp->bc_blkno = blkno;
 	bcp->bc_len = len;
 	bcp->bc_refcount = 1;
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
index c1b211c260a9..db6e78b485ea 100644
--- a/fs/xfs/xfs_dquot.c
+++ b/fs/xfs/xfs_dquot.c
@@ -494,7 +494,7 @@ xfs_dquot_alloc(
 {
 	struct xfs_dquot	*dqp;
 
-	dqp = kmem_cache_zalloc(xfs_dquot_cache, GFP_KERNEL | __GFP_NOFAIL);
+	dqp = kmem_cache_zalloc(xfs_dquot_cache, GFP_KERNEL | GFP_NOFAIL);
 
 	dqp->q_type = type;
 	dqp->q_id = id;
diff --git a/fs/xfs/xfs_exchmaps_item.c b/fs/xfs/xfs_exchmaps_item.c
index 264a121c5e16..af790026296a 100644
--- a/fs/xfs/xfs_exchmaps_item.c
+++ b/fs/xfs/xfs_exchmaps_item.c
@@ -134,7 +134,7 @@ xfs_xmi_init(
 {
 	struct xfs_xmi_log_item	*xmi_lip;
 
-	xmi_lip = kmem_cache_zalloc(xfs_xmi_cache, GFP_KERNEL | __GFP_NOFAIL);
+	xmi_lip = kmem_cache_zalloc(xfs_xmi_cache, GFP_KERNEL | GFP_NOFAIL);
 
 	xfs_log_item_init(mp, &xmi_lip->xmi_item, XFS_LI_XMI, &xfs_xmi_item_ops);
 	xmi_lip->xmi_format.xmi_id = (uintptr_t)(void *)xmi_lip;
@@ -253,7 +253,7 @@ xfs_exchmaps_create_done(
 	struct xfs_xmi_log_item		*xmi_lip = XMI_ITEM(intent);
 	struct xfs_xmd_log_item		*xmd_lip;
 
-	xmd_lip = kmem_cache_zalloc(xfs_xmd_cache, GFP_KERNEL | __GFP_NOFAIL);
+	xmd_lip = kmem_cache_zalloc(xfs_xmd_cache, GFP_KERNEL | GFP_NOFAIL);
 	xfs_log_item_init(tp->t_mountp, &xmd_lip->xmd_item, XFS_LI_XMD,
 			  &xfs_xmd_item_ops);
 	xmd_lip->xmd_intent_log_item = xmi_lip;
diff --git a/fs/xfs/xfs_extent_busy.c b/fs/xfs/xfs_extent_busy.c
index a73e7c73b664..a6c9953781fb 100644
--- a/fs/xfs/xfs_extent_busy.c
+++ b/fs/xfs/xfs_extent_busy.c
@@ -33,7 +33,7 @@ xfs_extent_busy_insert_list(
 	struct rb_node		*parent = NULL;
 
 	new = kzalloc(sizeof(struct xfs_extent_busy),
-			GFP_KERNEL | __GFP_NOFAIL);
+			GFP_KERNEL | GFP_NOFAIL);
 	new->agno = pag->pag_agno;
 	new->bno = bno;
 	new->length = len;
diff --git a/fs/xfs/xfs_extfree_item.c b/fs/xfs/xfs_extfree_item.c
index abffc74a924f..e09713ad83b5 100644
--- a/fs/xfs/xfs_extfree_item.c
+++ b/fs/xfs/xfs_extfree_item.c
@@ -148,10 +148,10 @@ xfs_efi_init(
 	ASSERT(nextents > 0);
 	if (nextents > XFS_EFI_MAX_FAST_EXTENTS) {
 		efip = kzalloc(xfs_efi_log_item_sizeof(nextents),
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 	} else {
 		efip = kmem_cache_zalloc(xfs_efi_cache,
-					 GFP_KERNEL | __GFP_NOFAIL);
+					 GFP_KERNEL | GFP_NOFAIL);
 	}
 
 	xfs_log_item_init(mp, &efip->efi_item, XFS_LI_EFI, &xfs_efi_item_ops);
@@ -421,10 +421,10 @@ xfs_extent_free_create_done(
 
 	if (count > XFS_EFD_MAX_FAST_EXTENTS) {
 		efdp = kzalloc(xfs_efd_log_item_sizeof(count),
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 	} else {
 		efdp = kmem_cache_zalloc(xfs_efd_cache,
-					GFP_KERNEL | __GFP_NOFAIL);
+					GFP_KERNEL | GFP_NOFAIL);
 	}
 
 	xfs_log_item_init(tp->t_mountp, &efdp->efd_item, XFS_LI_EFD,
@@ -573,7 +573,7 @@ xfs_efi_recover_work(
 	struct xfs_extent_free_item	*xefi;
 
 	xefi = kmem_cache_zalloc(xfs_extfree_item_cache,
-			       GFP_KERNEL | __GFP_NOFAIL);
+			       GFP_KERNEL | GFP_NOFAIL);
 	xefi->xefi_startblock = extp->ext_start;
 	xefi->xefi_blockcount = extp->ext_len;
 	xefi->xefi_agresv = XFS_AG_RESV_NONE;
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index cf629302d48e..821dfa6a4cb9 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -79,7 +79,7 @@ xfs_inode_alloc(
 	 * XXX: If this didn't occur in transactions, we could drop GFP_NOFAIL
 	 * and return NULL here on ENOMEM.
 	 */
-	ip = alloc_inode_sb(mp->m_super, xfs_inode_cache, GFP_KERNEL | __GFP_NOFAIL);
+	ip = alloc_inode_sb(mp->m_super, xfs_inode_cache, GFP_KERNEL | GFP_NOFAIL);
 
 	if (inode_init_always(mp->m_super, VFS_I(ip))) {
 		kmem_cache_free(xfs_inode_cache, ip);
diff --git a/fs/xfs/xfs_icreate_item.c b/fs/xfs/xfs_icreate_item.c
index 4345db501714..dd74eefa82f9 100644
--- a/fs/xfs/xfs_icreate_item.c
+++ b/fs/xfs/xfs_icreate_item.c
@@ -98,7 +98,7 @@ xfs_icreate_log(
 {
 	struct xfs_icreate_item	*icp;
 
-	icp = kmem_cache_zalloc(xfs_icreate_cache, GFP_KERNEL | __GFP_NOFAIL);
+	icp = kmem_cache_zalloc(xfs_icreate_cache, GFP_KERNEL | GFP_NOFAIL);
 
 	xfs_log_item_init(tp->t_mountp, &icp->ic_item, XFS_LI_ICREATE,
 			  &xfs_icreate_item_ops);
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index b509cbd191f4..a61b97ba6cfe 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -868,7 +868,7 @@ xfs_inode_item_init(
 
 	ASSERT(ip->i_itemp == NULL);
 	iip = ip->i_itemp = kmem_cache_zalloc(xfs_ili_cache,
-					      GFP_KERNEL | __GFP_NOFAIL);
+					      GFP_KERNEL | GFP_NOFAIL);
 
 	iip->ili_inode = ip;
 	spin_lock_init(&iip->ili_lock);
diff --git a/fs/xfs/xfs_inode_item_recover.c b/fs/xfs/xfs_inode_item_recover.c
index dbdab4ce7c44..bbc2c33cff07 100644
--- a/fs/xfs/xfs_inode_item_recover.c
+++ b/fs/xfs/xfs_inode_item_recover.c
@@ -292,7 +292,7 @@ xlog_recover_inode_commit_pass2(
 		in_f = item->ri_buf[0].i_addr;
 	} else {
 		in_f = kmalloc(sizeof(struct xfs_inode_log_format),
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 		need_free = 1;
 		error = xfs_inode_item_format_convert(&item->ri_buf[0], in_f);
 		if (error)
diff --git a/fs/xfs/xfs_iunlink_item.c b/fs/xfs/xfs_iunlink_item.c
index 2ddccb172fa0..bba7861c7451 100644
--- a/fs/xfs/xfs_iunlink_item.c
+++ b/fs/xfs/xfs_iunlink_item.c
@@ -161,7 +161,7 @@ xfs_iunlink_log_inode(
 		return 0;
 	}
 
-	iup = kmem_cache_zalloc(xfs_iunlink_cache, GFP_KERNEL | __GFP_NOFAIL);
+	iup = kmem_cache_zalloc(xfs_iunlink_cache, GFP_KERNEL | GFP_NOFAIL);
 	xfs_log_item_init(mp, &iup->item, XFS_LI_IUNLINK,
 			  &xfs_iunlink_item_ops);
 
diff --git a/fs/xfs/xfs_iwalk.c b/fs/xfs/xfs_iwalk.c
index 86f14ec7c31f..75c290e1dab3 100644
--- a/fs/xfs/xfs_iwalk.c
+++ b/fs/xfs/xfs_iwalk.c
@@ -659,7 +659,7 @@ xfs_iwalk_threaded(
 			break;
 
 		iwag = kzalloc(sizeof(struct xfs_iwalk_ag),
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 		iwag->mp = mp;
 
 		/*
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 817ea7e0a8ab..ed513ede0c44 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -3244,7 +3244,7 @@ xlog_ticket_alloc(
 	int			unit_res;
 
 	tic = kmem_cache_zalloc(xfs_log_ticket_cache,
-			GFP_KERNEL | __GFP_NOFAIL);
+			GFP_KERNEL | GFP_NOFAIL);
 
 	unit_res = xlog_calc_unit_res(log, unit_bytes, &tic->t_iclog_hdrs);
 
diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index 391a938d690c..c101ba39a172 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -100,7 +100,7 @@ xlog_cil_ctx_alloc(void)
 {
 	struct xfs_cil_ctx	*ctx;
 
-	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL | __GFP_NOFAIL);
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL | GFP_NOFAIL);
 	INIT_LIST_HEAD(&ctx->committing);
 	INIT_LIST_HEAD(&ctx->busy_extents.extent_list);
 	INIT_LIST_HEAD(&ctx->log_items);
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 1997981827fb..86aca82656d5 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -2087,7 +2087,7 @@ xlog_recover_add_item(
 	struct xlog_recover_item *item;
 
 	item = kzalloc(sizeof(struct xlog_recover_item),
-			GFP_KERNEL | __GFP_NOFAIL);
+			GFP_KERNEL | GFP_NOFAIL);
 	INIT_LIST_HEAD(&item->ri_list);
 	list_add_tail(&item->ri_list, head);
 }
@@ -2218,7 +2218,7 @@ xlog_recover_add_to_trans(
 
 		item->ri_total = in_f->ilf_size;
 		item->ri_buf = kzalloc(item->ri_total * sizeof(xfs_log_iovec_t),
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 	}
 
 	if (item->ri_total <= item->ri_cnt) {
@@ -2361,7 +2361,7 @@ xlog_recover_ophdr_to_trans(
 	 * This is a new transaction so allocate a new recovery container to
 	 * hold the recovery ops that will follow.
 	 */
-	trans = kzalloc(sizeof(struct xlog_recover), GFP_KERNEL | __GFP_NOFAIL);
+	trans = kzalloc(sizeof(struct xlog_recover), GFP_KERNEL | GFP_NOFAIL);
 	trans->r_log_tid = tid;
 	trans->r_lsn = be64_to_cpu(rhead->h_lsn);
 	INIT_LIST_HEAD(&trans->r_itemq);
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 09eef1721ef4..6b0cd7099fc8 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -86,7 +86,7 @@ xfs_uuid_mount(
 	if (hole < 0) {
 		xfs_uuid_table = krealloc(xfs_uuid_table,
 			(xfs_uuid_table_size + 1) * sizeof(*xfs_uuid_table),
-			GFP_KERNEL | __GFP_NOFAIL);
+			GFP_KERNEL | GFP_NOFAIL);
 		hole = xfs_uuid_table_size++;
 	}
 	xfs_uuid_table[hole] = *uuid;
diff --git a/fs/xfs/xfs_mru_cache.c b/fs/xfs/xfs_mru_cache.c
index 7443debaffd6..b53797f257e4 100644
--- a/fs/xfs/xfs_mru_cache.c
+++ b/fs/xfs/xfs_mru_cache.c
@@ -333,14 +333,14 @@ xfs_mru_cache_create(
 	if (!(grp_time = msecs_to_jiffies(lifetime_ms) / grp_count))
 		return -EINVAL;
 
-	mru = kzalloc(sizeof(*mru), GFP_KERNEL | __GFP_NOFAIL);
+	mru = kzalloc(sizeof(*mru), GFP_KERNEL | GFP_NOFAIL);
 	if (!mru)
 		return -ENOMEM;
 
 	/* An extra list is needed to avoid reaping up to a grp_time early. */
 	mru->grp_count = grp_count + 1;
 	mru->lists = kzalloc(mru->grp_count * sizeof(*mru->lists),
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 	if (!mru->lists) {
 		err = -ENOMEM;
 		goto exit;
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index 9490b913a4ab..23b02066bcee 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -630,7 +630,7 @@ xfs_qm_init_quotainfo(
 	ASSERT(XFS_IS_QUOTA_ON(mp));
 
 	qinf = mp->m_quotainfo = kzalloc(sizeof(struct xfs_quotainfo),
-					GFP_KERNEL | __GFP_NOFAIL);
+					GFP_KERNEL | GFP_NOFAIL);
 
 	error = list_lru_init(&qinf->qi_lru);
 	if (error)
@@ -1011,7 +1011,7 @@ xfs_qm_reset_dqcounts_buf(
 		return 0;
 
 	map = kmalloc(XFS_DQITER_MAP_SIZE * sizeof(*map),
-			GFP_KERNEL | __GFP_NOFAIL);
+			GFP_KERNEL | GFP_NOFAIL);
 
 	lblkno = 0;
 	maxlblkcnt = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
diff --git a/fs/xfs/xfs_refcount_item.c b/fs/xfs/xfs_refcount_item.c
index 27398512b179..8899048ae6f6 100644
--- a/fs/xfs/xfs_refcount_item.c
+++ b/fs/xfs/xfs_refcount_item.c
@@ -146,10 +146,10 @@ xfs_cui_init(
 	ASSERT(nextents > 0);
 	if (nextents > XFS_CUI_MAX_FAST_EXTENTS)
 		cuip = kzalloc(xfs_cui_log_item_sizeof(nextents),
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 	else
 		cuip = kmem_cache_zalloc(xfs_cui_cache,
-					 GFP_KERNEL | __GFP_NOFAIL);
+					 GFP_KERNEL | GFP_NOFAIL);
 
 	xfs_log_item_init(mp, &cuip->cui_item, XFS_LI_CUI, &xfs_cui_item_ops);
 	cuip->cui_format.cui_nextents = nextents;
@@ -311,7 +311,7 @@ xfs_refcount_update_create_done(
 	struct xfs_cui_log_item		*cuip = CUI_ITEM(intent);
 	struct xfs_cud_log_item		*cudp;
 
-	cudp = kmem_cache_zalloc(xfs_cud_cache, GFP_KERNEL | __GFP_NOFAIL);
+	cudp = kmem_cache_zalloc(xfs_cud_cache, GFP_KERNEL | GFP_NOFAIL);
 	xfs_log_item_init(tp->t_mountp, &cudp->cud_item, XFS_LI_CUD,
 			  &xfs_cud_item_ops);
 	cudp->cud_cuip = cuip;
@@ -427,7 +427,7 @@ xfs_cui_recover_work(
 	struct xfs_refcount_intent	*ri;
 
 	ri = kmem_cache_alloc(xfs_refcount_intent_cache,
-			GFP_KERNEL | __GFP_NOFAIL);
+			GFP_KERNEL | GFP_NOFAIL);
 	ri->ri_type = pmap->pe_flags & XFS_REFCOUNT_EXTENT_TYPE_MASK;
 	ri->ri_startblock = pmap->pe_startblock;
 	ri->ri_blockcount = pmap->pe_len;
diff --git a/fs/xfs/xfs_rmap_item.c b/fs/xfs/xfs_rmap_item.c
index 88b5580e1e19..d711d290ff02 100644
--- a/fs/xfs/xfs_rmap_item.c
+++ b/fs/xfs/xfs_rmap_item.c
@@ -145,10 +145,10 @@ xfs_rui_init(
 	ASSERT(nextents > 0);
 	if (nextents > XFS_RUI_MAX_FAST_EXTENTS)
 		ruip = kzalloc(xfs_rui_log_item_sizeof(nextents),
-				GFP_KERNEL | __GFP_NOFAIL);
+				GFP_KERNEL | GFP_NOFAIL);
 	else
 		ruip = kmem_cache_zalloc(xfs_rui_cache,
-					 GFP_KERNEL | __GFP_NOFAIL);
+					 GFP_KERNEL | GFP_NOFAIL);
 
 	xfs_log_item_init(mp, &ruip->rui_item, XFS_LI_RUI, &xfs_rui_item_ops);
 	ruip->rui_format.rui_nextents = nextents;
@@ -334,7 +334,7 @@ xfs_rmap_update_create_done(
 	struct xfs_rui_log_item		*ruip = RUI_ITEM(intent);
 	struct xfs_rud_log_item		*rudp;
 
-	rudp = kmem_cache_zalloc(xfs_rud_cache, GFP_KERNEL | __GFP_NOFAIL);
+	rudp = kmem_cache_zalloc(xfs_rud_cache, GFP_KERNEL | GFP_NOFAIL);
 	xfs_log_item_init(tp->t_mountp, &rudp->rud_item, XFS_LI_RUD,
 			  &xfs_rud_item_ops);
 	rudp->rud_ruip = ruip;
@@ -454,7 +454,7 @@ xfs_rui_recover_work(
 {
 	struct xfs_rmap_intent		*ri;
 
-	ri = kmem_cache_alloc(xfs_rmap_intent_cache, GFP_KERNEL | __GFP_NOFAIL);
+	ri = kmem_cache_alloc(xfs_rmap_intent_cache, GFP_KERNEL | GFP_NOFAIL);
 
 	switch (map->me_flags & XFS_RMAP_EXTENT_TYPE_MASK) {
 	case XFS_RMAP_EXTENT_MAP:
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 0c3e96c621a6..3a5c260a4d75 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -901,7 +901,7 @@ xfs_growfs_rt(
 	/*
 	 * Allocate a new (fake) mount/sb.
 	 */
-	nmp = kmalloc(sizeof(*nmp), GFP_KERNEL | __GFP_NOFAIL);
+	nmp = kmalloc(sizeof(*nmp), GFP_KERNEL | GFP_NOFAIL);
 	/*
 	 * Loop over the bitmap blocks.
 	 * We will do everything one bitmap block at a time.
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 27e9f749c4c7..5f01da8300fa 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -2004,7 +2004,7 @@ static int xfs_init_fs_context(
 {
 	struct xfs_mount	*mp;
 
-	mp = kzalloc(sizeof(struct xfs_mount), GFP_KERNEL | __GFP_NOFAIL);
+	mp = kzalloc(sizeof(struct xfs_mount), GFP_KERNEL | GFP_NOFAIL);
 	if (!mp)
 		return -ENOMEM;
 
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index bdf3704dc301..e67b0ef50375 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -93,7 +93,7 @@ xfs_trans_dup(
 
 	trace_xfs_trans_dup(tp, _RET_IP_);
 
-	ntp = kmem_cache_zalloc(xfs_trans_cache, GFP_KERNEL | __GFP_NOFAIL);
+	ntp = kmem_cache_zalloc(xfs_trans_cache, GFP_KERNEL | GFP_NOFAIL);
 
 	/*
 	 * Initialize the new transaction structure.
@@ -259,7 +259,7 @@ xfs_trans_alloc(
 	 * by doing GFP_KERNEL allocations inside sb_start_intwrite().
 	 */
 retry:
-	tp = kmem_cache_zalloc(xfs_trans_cache, GFP_KERNEL | __GFP_NOFAIL);
+	tp = kmem_cache_zalloc(xfs_trans_cache, GFP_KERNEL | GFP_NOFAIL);
 	if (!(flags & XFS_TRANS_NO_WRITECOUNT))
 		sb_start_intwrite(mp->m_super);
 	xfs_trans_set_context(tp);
diff --git a/fs/xfs/xfs_trans_dquot.c b/fs/xfs/xfs_trans_dquot.c
index b368e13424c4..840b3ca0804f 100644
--- a/fs/xfs/xfs_trans_dquot.c
+++ b/fs/xfs/xfs_trans_dquot.c
@@ -1013,7 +1013,7 @@ xfs_trans_alloc_dqinfo(
 	xfs_trans_t	*tp)
 {
 	tp->t_dqinfo = kmem_cache_zalloc(xfs_dqtrx_cache,
-					 GFP_KERNEL | __GFP_NOFAIL);
+					 GFP_KERNEL | GFP_NOFAIL);
 }
 
 void
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 14acf1bbe0ce..8a26d25f2274 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -365,7 +365,7 @@ static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
 	gfp_t gfp;
 
 	gfp = mapping_gfp_constraint(bdev->bd_mapping, ~__GFP_FS);
-	gfp |= __GFP_NOFAIL;
+	gfp |= GFP_NOFAIL;
 
 	return bdev_getblk(bdev, block, size, gfp);
 }
@@ -376,7 +376,7 @@ static inline struct buffer_head *__getblk(struct block_device *bdev,
 	gfp_t gfp;
 
 	gfp = mapping_gfp_constraint(bdev->bd_mapping, ~__GFP_FS);
-	gfp |= __GFP_MOVABLE | __GFP_NOFAIL;
+	gfp |= __GFP_MOVABLE | GFP_NOFAIL;
 
 	return bdev_getblk(bdev, block, size, gfp);
 }
diff --git a/kernel/resource.c b/kernel/resource.c
index 9f747bb7cd03..c4c26f54d60e 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1376,7 +1376,7 @@ void release_mem_region_adjustable(resource_size_t start, resource_size_t size)
 	 * similarly).
 	 */
 retry:
-	new_res = alloc_resource(GFP_KERNEL | (alloc_nofail ? __GFP_NOFAIL : 0));
+	new_res = alloc_resource(GFP_KERNEL | (alloc_nofail ? GFP_NOFAIL : 0));
 
 	p = &parent->child;
 	write_lock(&resource_lock);
diff --git a/lib/list-test.c b/lib/list-test.c
index 37cbc33e9fdb..21ffa455ff0e 100644
--- a/lib/list-test.c
+++ b/lib/list-test.c
@@ -26,10 +26,10 @@ static void list_test_list_init(struct kunit *test)
 
 	INIT_LIST_HEAD(&list2);
 
-	list4 = kzalloc(sizeof(*list4), GFP_KERNEL | __GFP_NOFAIL);
+	list4 = kzalloc(sizeof(*list4), GFP_KERNEL | GFP_NOFAIL);
 	INIT_LIST_HEAD(list4);
 
-	list5 = kmalloc(sizeof(*list5), GFP_KERNEL | __GFP_NOFAIL);
+	list5 = kmalloc(sizeof(*list5), GFP_KERNEL | GFP_NOFAIL);
 	memset(list5, 0xFF, sizeof(*list5));
 	INIT_LIST_HEAD(list5);
 
@@ -821,10 +821,10 @@ static void hlist_test_init(struct kunit *test)
 
 	INIT_HLIST_HEAD(&list2);
 
-	list4 = kzalloc(sizeof(*list4), GFP_KERNEL | __GFP_NOFAIL);
+	list4 = kzalloc(sizeof(*list4), GFP_KERNEL | GFP_NOFAIL);
 	INIT_HLIST_HEAD(list4);
 
-	list5 = kmalloc(sizeof(*list5), GFP_KERNEL | __GFP_NOFAIL);
+	list5 = kmalloc(sizeof(*list5), GFP_KERNEL | GFP_NOFAIL);
 	memset(list5, 0xFF, sizeof(*list5));
 	INIT_HLIST_HEAD(list5);
 
diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index cf5609b1ca79..04beeb01b478 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -199,7 +199,7 @@ int ref_tracker_alloc(struct ref_tracker_dir *dir,
 		return 0;
 	}
 	if (gfp & __GFP_DIRECT_RECLAIM)
-		gfp_mask |= __GFP_NOFAIL;
+		gfp_mask |= GFP_NOFAIL;
 	*trackerp = tracker = kzalloc(sizeof(*tracker), gfp_mask);
 	if (unlikely(!tracker)) {
 		pr_err_once("memory allocation failure, unreliable refcount tracker.\n");
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index dbbed19f8fff..994b7582976b 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -189,7 +189,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
 
 	size = nbuckets;
 
-	if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) {
+	if (tbl == NULL && (gfp & ~GFP_NOFAIL) != GFP_KERNEL) {
 		tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
 		nbuckets = 0;
 	}
@@ -1066,12 +1066,12 @@ int rhashtable_init_noprof(struct rhashtable *ht,
 	/*
 	 * This is api initialization and thus we need to guarantee the
 	 * initial rhashtable allocation. Upon failure, retry with the
-	 * smallest possible size with __GFP_NOFAIL semantics.
+	 * smallest possible size with GFP_NOFAIL semantics.
 	 */
 	tbl = bucket_table_alloc(ht, size, GFP_KERNEL);
 	if (unlikely(tbl == NULL)) {
 		size = max_t(u16, ht->p.min_size, HASH_MIN_SIZE);
-		tbl = bucket_table_alloc(ht, size, GFP_KERNEL | __GFP_NOFAIL);
+		tbl = bucket_table_alloc(ht, size, GFP_KERNEL | GFP_NOFAIL);
 	}
 
 	atomic_set(&ht->nelems, 0);
diff --git a/lib/test_hmm.c b/lib/test_hmm.c
index ee20e1f9bae9..cfad88651a1f 100644
--- a/lib/test_hmm.c
+++ b/lib/test_hmm.c
@@ -1226,8 +1226,8 @@ static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk)
 	unsigned long *src_pfns;
 	unsigned long *dst_pfns;
 
-	src_pfns = kvcalloc(npages, sizeof(*src_pfns), GFP_KERNEL | __GFP_NOFAIL);
-	dst_pfns = kvcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL | __GFP_NOFAIL);
+	src_pfns = kvcalloc(npages, sizeof(*src_pfns), GFP_KERNEL | GFP_NOFAIL);
+	dst_pfns = kvcalloc(npages, sizeof(*dst_pfns), GFP_KERNEL | GFP_NOFAIL);
 
 	migrate_device_range(src_pfns, start_pfn, npages);
 	for (i = 0; i < npages; i++) {
@@ -1241,7 +1241,7 @@ static void dmirror_device_evict_chunk(struct dmirror_chunk *chunk)
 			    !is_device_coherent_page(spage)))
 			continue;
 		spage = BACKING_PAGE(spage);
-		dpage = alloc_page(GFP_HIGHUSER_MOVABLE | __GFP_NOFAIL);
+		dpage = alloc_page(GFP_HIGHUSER_MOVABLE | GFP_NOFAIL);
 		lock_page(dpage);
 		copy_highpage(dpage, spage);
 		dst_pfns[i] = migrate_pfn(page_to_pfn(dpage));
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 9d078b37fe0b..424b543c0477 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -1285,7 +1285,7 @@ static struct ceph_osd *create_osd(struct ceph_osd_client *osdc, int onum)
 
 	WARN_ON(onum == CEPH_HOMELESS_OSD);
 
-	osd = kzalloc(sizeof(*osd), GFP_NOIO | __GFP_NOFAIL);
+	osd = kzalloc(sizeof(*osd), GFP_NOIO | GFP_NOFAIL);
 	osd_init(osd);
 	osd->o_osdc = osdc;
 	osd->o_osd = onum;
diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 295098873861..f760d47c6e99 100644
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -2142,7 +2142,7 @@ void ceph_oid_copy(struct ceph_object_id *dest,
 	if (src->name != src->inline_name) {
 		/* very rare, see ceph_object_id definition */
 		dest->name = kmalloc(src->name_len + 1,
-				     GFP_NOIO | __GFP_NOFAIL);
+				     GFP_NOIO | GFP_NOFAIL);
 	} else {
 		dest->name = dest->inline_name;
 	}
@@ -2410,7 +2410,7 @@ void __ceph_object_locator_to_pg(struct ceph_pg_pool_info *pi,
 		size_t total = nsl + 1 + oid->name_len;
 
 		if (total > sizeof(stack_buf))
-			buf = kmalloc(total, GFP_NOIO | __GFP_NOFAIL);
+			buf = kmalloc(total, GFP_NOIO | GFP_NOFAIL);
 		memcpy(buf, oloc->pool_ns->str, nsl);
 		buf[nsl] = '\037';
 		memcpy(buf + nsl + 1, oid->name, oid->name_len);
diff --git a/net/core/sock.c b/net/core/sock.c
index 9abc4fe25953..fa46b1ecab0b 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -3155,10 +3155,10 @@ int __sk_mem_raise_allocated(struct sock *sk, int size, int amt, int kind)
 		 * In this case we cannot block, so that we have to fail.
 		 */
 		if (sk->sk_wmem_queued + size >= sk->sk_sndbuf) {
-			/* Force charge with __GFP_NOFAIL */
+			/* Force charge with GFP_NOFAIL */
 			if (memcg && !charged) {
 				mem_cgroup_charge_skmem(memcg, amt,
-					gfp_memcg_charge() | __GFP_NOFAIL);
+					gfp_memcg_charge() | GFP_NOFAIL);
 			}
 			return 1;
 		}
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 64d07b842e73..e933a54db1a7 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -732,7 +732,7 @@ struct sock *inet_csk_accept(struct sock *sk, struct proto_accept_arg *arg)
 
 		if (amt)
 			mem_cgroup_charge_skmem(newsk->sk_memcg, amt,
-						GFP_KERNEL | __GFP_NOFAIL);
+						GFP_KERNEL | GFP_NOFAIL);
 
 		release_sock(newsk);
 	}
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 16c48df8df4c..8d05ed592881 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3566,7 +3566,7 @@ void sk_forced_mem_schedule(struct sock *sk, int size)
 
 	if (mem_cgroup_sockets_enabled && sk->sk_memcg)
 		mem_cgroup_charge_skmem(sk->sk_memcg, amt,
-					gfp_memcg_charge() | __GFP_NOFAIL);
+					gfp_memcg_charge() | GFP_NOFAIL);
 }
 
 /* Send a FIN. The caller locks the socket for us.
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index e22aad7604e8..9c2df7d77886 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -694,7 +694,7 @@ static void smk_cipso_doi(void)
 		printk(KERN_WARNING "%s:%d remove rc = %d\n",
 		       __func__, __LINE__, rc);
 
-	doip = kmalloc(sizeof(struct cipso_v4_doi), GFP_KERNEL | __GFP_NOFAIL);
+	doip = kmalloc(sizeof(struct cipso_v4_doi), GFP_KERNEL | GFP_NOFAIL);
 	doip->map.std = NULL;
 	doip->doi = smk_cipso_doi_value;
 	doip->type = CIPSO_V4_MAP_PASS;
-- 
2.34.1

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Vlastimil Babka]

On 7/24/24 10:55 AM, Barry Song wrote:
> From: Barry Song <v-songbaohua@oppo.com>
> 
> GFP_NOFAIL includes the meaning of block and direct reclamation, which
> is essential for a true no-fail allocation. We are gradually starting
> to enforce this block semantics to prevent the potential misuse of
> __GFP_NOFAIL in atomic contexts in the future.
> 
> A typical example of incorrect usage is in VDPA, where GFP_ATOMIC
> and __GFP_NOFAIL are used together.
> 
> [RFC]: This patch seems quite large; I don't mind splitting it into
> multiple patches for different subsystems after patches 1 ~ 4 have
> been applied.
> 
> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> 
> diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
> index fa01818c1972..29eaf8b84b52 100644
> --- a/arch/powerpc/sysdev/xive/common.c
> +++ b/arch/powerpc/sysdev/xive/common.c
> @@ -1146,7 +1146,7 @@ static int __init xive_init_ipis(void)
>  	if (!ipi_domain)
>  		goto out_free_fwnode;
>  
> -	xive_ipis = kcalloc(nr_node_ids, sizeof(*xive_ipis), GFP_KERNEL | __GFP_NOFAIL);
> +	xive_ipis = kcalloc(nr_node_ids, sizeof(*xive_ipis), GFP_KERNEL | GFP_NOFAIL);

This (and others) doesn't look great. Normally there's just one GFP_MAIN
that combines several commonly used together flags internally, with possibly
some | __GFP_EXTRA addition for less common modifications. Now you're
combining two GFP_MAIN's and that's just confusing.

So if we want to go this way, you'd need e.g.

GFP_KERNEL_NOFAIL which is GFP_KERNEL | __GFP_NOFAIL

And probably also GFP_NOFS_NOFAIL and GFP_NOIO_NOFAIL (sigh).

>  	if (!xive_ipis)
>  		goto out_free_domain;

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Barry Song]

On Wed, Jul 24, 2024 at 9:53 PM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 7/24/24 10:55 AM, Barry Song wrote:
> > From: Barry Song <v-songbaohua@oppo.com>
> >
> > GFP_NOFAIL includes the meaning of block and direct reclamation, which
> > is essential for a true no-fail allocation. We are gradually starting
> > to enforce this block semantics to prevent the potential misuse of
> > __GFP_NOFAIL in atomic contexts in the future.
> >
> > A typical example of incorrect usage is in VDPA, where GFP_ATOMIC
> > and __GFP_NOFAIL are used together.
> >
> > [RFC]: This patch seems quite large; I don't mind splitting it into
> > multiple patches for different subsystems after patches 1 ~ 4 have
> > been applied.
> >
> > Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> >
> > diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
> > index fa01818c1972..29eaf8b84b52 100644
> > --- a/arch/powerpc/sysdev/xive/common.c
> > +++ b/arch/powerpc/sysdev/xive/common.c
> > @@ -1146,7 +1146,7 @@ static int __init xive_init_ipis(void)
> >       if (!ipi_domain)
> >               goto out_free_fwnode;
> >
> > -     xive_ipis = kcalloc(nr_node_ids, sizeof(*xive_ipis), GFP_KERNEL | __GFP_NOFAIL);
> > +     xive_ipis = kcalloc(nr_node_ids, sizeof(*xive_ipis), GFP_KERNEL | GFP_NOFAIL);
>
> This (and others) doesn't look great. Normally there's just one GFP_MAIN
> that combines several commonly used together flags internally, with possibly
> some | __GFP_EXTRA addition for less common modifications. Now you're
> combining two GFP_MAIN's and that's just confusing.

This is true, but I assume this won't incur overhead at runtime since the
compiler resolves GFP_KERNEL | GFP_NOFAIL at compile-time.
Only readers might find some bits are duplicated OR twice?

>
> So if we want to go this way, you'd need e.g.
>
> GFP_KERNEL_NOFAIL which is GFP_KERNEL | __GFP_NOFAIL

I actually considered this, but it doesn't always work because we have
many cases:

variable |= __GFP_NOFAIL.

>
> And probably also GFP_NOFS_NOFAIL and GFP_NOIO_NOFAIL (sigh).
>
> >       if (!xive_ipis)
> >               goto out_free_domain;
>

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Christoph Hellwig]

On Wed, Jul 24, 2024 at 09:58:36PM +1200, Barry Song wrote:
> This is true, but I assume this won't incur overhead at runtime since the
> compiler resolves GFP_KERNEL | GFP_NOFAIL at compile-time.
> Only readers might find some bits are duplicated OR twice?

It's not really the overhead.  Having a single main flag make it very
easy to grep for and find abuses.

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Michal Hocko]

On Wed 24-07-24 11:53:49, Vlastimil Babka wrote:
> On 7/24/24 10:55 AM, Barry Song wrote:
> > From: Barry Song <v-songbaohua@oppo.com>
> > 
> > GFP_NOFAIL includes the meaning of block and direct reclamation, which
> > is essential for a true no-fail allocation. We are gradually starting
> > to enforce this block semantics to prevent the potential misuse of
> > __GFP_NOFAIL in atomic contexts in the future.
> > 
> > A typical example of incorrect usage is in VDPA, where GFP_ATOMIC
> > and __GFP_NOFAIL are used together.
> > 
> > [RFC]: This patch seems quite large; I don't mind splitting it into
> > multiple patches for different subsystems after patches 1 ~ 4 have
> > been applied.
> > 
> > Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> > 
> > diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
> > index fa01818c1972..29eaf8b84b52 100644
> > --- a/arch/powerpc/sysdev/xive/common.c
> > +++ b/arch/powerpc/sysdev/xive/common.c
> > @@ -1146,7 +1146,7 @@ static int __init xive_init_ipis(void)
> >  	if (!ipi_domain)
> >  		goto out_free_fwnode;
> >  
> > -	xive_ipis = kcalloc(nr_node_ids, sizeof(*xive_ipis), GFP_KERNEL | __GFP_NOFAIL);
> > +	xive_ipis = kcalloc(nr_node_ids, sizeof(*xive_ipis), GFP_KERNEL | GFP_NOFAIL);
> 
> This (and others) doesn't look great. Normally there's just one GFP_MAIN
> that combines several commonly used together flags internally, with possibly
> some | __GFP_EXTRA addition for less common modifications. Now you're
> combining two GFP_MAIN's and that's just confusing.

I am not sure we can expect too much consistency from our gfp flags.
This is unfortunate but something that is really hard to fix. Combining
GFP_$FOO | GFP_$BAR is not unprecedented. A quick grep shows that
GFP_KERNEL | GFP_DMA* is quite used.

So while not great, if we want to enforce sleepable NOFAIL allocations
then this seems like something that is acceptable. Adding yet another
set of GFP_$FOO_NOFAIL seems like too many flags that are likely seldom
used and make the whole thing overblown.

-- 
Michal Hocko
SUSE Labs

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Christoph Hellwig]

On Wed, Jul 24, 2024 at 11:53:49AM +0200, Vlastimil Babka wrote:
> GFP_KERNEL_NOFAIL which is GFP_KERNEL | __GFP_NOFAIL
> 
> And probably also GFP_NOFS_NOFAIL and GFP_NOIO_NOFAIL (sigh).

Let's not add these and force people to use the scope API which
we're trying to move to.  I think we should be able to simply
have GFP_NOFAIL which includes GFP_KERNEL and no variant.

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Michal Hocko]

On Wed 24-07-24 06:13:31, Christoph Hellwig wrote:
> On Wed, Jul 24, 2024 at 11:53:49AM +0200, Vlastimil Babka wrote:
> > GFP_KERNEL_NOFAIL which is GFP_KERNEL | __GFP_NOFAIL
> > 
> > And probably also GFP_NOFS_NOFAIL and GFP_NOIO_NOFAIL (sigh).
> 
> Let's not add these and force people to use the scope API which
> we're trying to move to.  I think we should be able to simply
> have GFP_NOFAIL which includes GFP_KERNEL and no variant.

Scope API is tricky here. Exactly because the scope itself could have
opportunistic GFP_NOWAIT allocations. It just takes a library function
to call from a scope that could become a risk because it doesn't know
about potential scopes it can live in.

-- 
Michal Hocko
SUSE Labs

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Christoph Hellwig]

On Wed, Jul 24, 2024 at 03:21:13PM +0200, Michal Hocko wrote:
> Scope API is tricky here. Exactly because the scope itself could have
> opportunistic GFP_NOWAIT allocations.

Really, where?  That just sounds f**cked up as callers using any kind
of nofail API can be broken by a caller higher in the stack.

And that's totally independ of adding a NOFS/NOIO helper, so it'll need
to be fixed.

Adding more NOFS/NOIO wrappers while we're trying to kill the flag just
is not helpful going forward.

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Michal Hocko]

On Wed 24-07-24 06:23:29, Christoph Hellwig wrote:
> On Wed, Jul 24, 2024 at 03:21:13PM +0200, Michal Hocko wrote:
> > Scope API is tricky here. Exactly because the scope itself could have
> > opportunistic GFP_NOWAIT allocations.
> 
> Really, where?  That just sounds f**cked up as callers using any kind
> of nofail API can be broken by a caller higher in the stack.

I do not see this a problem. There is no real reason to have a NOWAIT
allocation down the stack that has a different fallback strategy.
I am not saying that this is the current practice because I do not know
that but I am saying that this is not impossible to imagine and it makes
scoped NOFAIL context subtle and error prone.

> And that's totally independ of adding a NOFS/NOIO helper, so it'll need
> to be fixed.
> 
> Adding more NOFS/NOIO wrappers while we're trying to kill the flag just
> is not helpful going forward.

NOFS, NOIO scopes are both compatible with NOFAIL and NOWAIT contexts.

-- 
Michal Hocko
SUSE Labs

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Vlastimil Babka]

On 7/24/24 3:31 PM, Michal Hocko wrote:
> On Wed 24-07-24 06:23:29, Christoph Hellwig wrote:
>> On Wed, Jul 24, 2024 at 03:21:13PM +0200, Michal Hocko wrote:
>> > Scope API is tricky here. Exactly because the scope itself could have
>> > opportunistic GFP_NOWAIT allocations.
>> 
>> Really, where?  That just sounds f**cked up as callers using any kind
>> of nofail API can be broken by a caller higher in the stack.
> 
> I do not see this a problem. There is no real reason to have a NOWAIT
> allocation down the stack that has a different fallback strategy.
> I am not saying that this is the current practice because I do not know
> that but I am saying that this is not impossible to imagine and it makes
> scoped NOFAIL context subtle and error prone.

I don't think Christoph proposed scoped NOFAIL, just use scoped NOFS/NOIO
together with GFP_KERNEL_NOFAIL intead of introducing GFP_NOFS_NOFAIL.

>> And that's totally independ of adding a NOFS/NOIO helper, so it'll need
>> to be fixed.
>> 
>> Adding more NOFS/NOIO wrappers while we're trying to kill the flag just
>> is not helpful going forward.
> 
> NOFS, NOIO scopes are both compatible with NOFAIL and NOWAIT contexts.
> 

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Christoph Hellwig]

On Wed, Jul 24, 2024 at 03:33:19PM +0200, Vlastimil Babka wrote:
> > I do not see this a problem. There is no real reason to have a NOWAIT
> > allocation down the stack that has a different fallback strategy.
> > I am not saying that this is the current practice because I do not know
> > that but I am saying that this is not impossible to imagine and it makes
> > scoped NOFAIL context subtle and error prone.
> 
> I don't think Christoph proposed scoped NOFAIL, just use scoped NOFS/NOIO
> together with GFP_KERNEL_NOFAIL intead of introducing GFP_NOFS_NOFAIL.

Yes, exactly.

And I didn't think Michal thought I meant something different, maybe
that's why it felt really confusing.

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Michal Hocko]

On Wed 24-07-24 06:38:41, Christoph Hellwig wrote:
> On Wed, Jul 24, 2024 at 03:33:19PM +0200, Vlastimil Babka wrote:
> > > I do not see this a problem. There is no real reason to have a NOWAIT
> > > allocation down the stack that has a different fallback strategy.
> > > I am not saying that this is the current practice because I do not know
> > > that but I am saying that this is not impossible to imagine and it makes
> > > scoped NOFAIL context subtle and error prone.
> > 
> > I don't think Christoph proposed scoped NOFAIL, just use scoped NOFS/NOIO
> > together with GFP_KERNEL_NOFAIL intead of introducing GFP_NOFS_NOFAIL.
> 
> Yes, exactly.
> 
> And I didn't think Michal thought I meant something different, maybe
> that's why it felt really confusing.

OK, now it makes more sense ;) I have absolutely no objections to
prefering scoped NO{FS,IO} interfaces of course. And that would indeed
eliminate a need for defining GFP_NO{FS,IO}_NOFAIL alternatives.

Thanks for the clarification.
-- 
Michal Hocko
SUSE Labs

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Christoph Hellwig]

On Wed, Jul 24, 2024 at 03:47:46PM +0200, Michal Hocko wrote:
> OK, now it makes more sense ;) I have absolutely no objections to
> prefering scoped NO{FS,IO} interfaces of course. And that would indeed
> eliminate a need for defining GFP_NO{FS,IO}_NOFAIL alternatives.

Yes.  My proposal would be:

GFP_NOFAIL without any modifiers it the only valid nofail API.

File systems / drivers can combine іt with the scoped nofs/noio if
needed.

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Vlastimil Babka]

On 7/24/24 3:55 PM, Christoph Hellwig wrote:
> On Wed, Jul 24, 2024 at 03:47:46PM +0200, Michal Hocko wrote:
>> OK, now it makes more sense ;) I have absolutely no objections to
>> prefering scoped NO{FS,IO} interfaces of course. And that would indeed
>> eliminate a need for defining GFP_NO{FS,IO}_NOFAIL alternatives.
> 
> Yes.  My proposal would be:
> 
> GFP_NOFAIL without any modifiers it the only valid nofail API.

Where GFP_NOFAIL is GFP_KERNEL | __GFP_NOFAIL (and not the more limited one
as defined in patch 4/5).

> File systems / drivers can combine іt with the scoped nofs/noio if
> needed.

Sounds good, how quickly we can convert existing __GFP_NOFAIL users remains
to be seen...

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Christoph Hellwig]

On Wed, Jul 24, 2024 at 04:39:11PM +0200, Vlastimil Babka wrote:
> On 7/24/24 3:55 PM, Christoph Hellwig wrote:
> > On Wed, Jul 24, 2024 at 03:47:46PM +0200, Michal Hocko wrote:
> >> OK, now it makes more sense ;) I have absolutely no objections to
> >> prefering scoped NO{FS,IO} interfaces of course. And that would indeed
> >> eliminate a need for defining GFP_NO{FS,IO}_NOFAIL alternatives.
> > 
> > Yes.  My proposal would be:
> > 
> > GFP_NOFAIL without any modifiers it the only valid nofail API.
> 
> Where GFP_NOFAIL is GFP_KERNEL | __GFP_NOFAIL (and not the more limited one
> as defined in patch 4/5).

Yes.

> > File systems / drivers can combine іt with the scoped nofs/noio if
> > needed.
> 
> Sounds good, how quickly we can convert existing __GFP_NOFAIL users remains
> to be seen...

I took a quick look at the file system ones and they look pretty easy.  I
think it would be good to a quick scriped run for everything that does
GFP_KERNEL | __GFP_NOFAIL right now, and then spend a little time on
the rest.

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Barry Song]

On Thu, Jul 25, 2024 at 2:41 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Wed, Jul 24, 2024 at 04:39:11PM +0200, Vlastimil Babka wrote:
> > On 7/24/24 3:55 PM, Christoph Hellwig wrote:
> > > On Wed, Jul 24, 2024 at 03:47:46PM +0200, Michal Hocko wrote:
> > >> OK, now it makes more sense ;) I have absolutely no objections to
> > >> prefering scoped NO{FS,IO} interfaces of course. And that would indeed
> > >> eliminate a need for defining GFP_NO{FS,IO}_NOFAIL alternatives.
> > >
> > > Yes.  My proposal would be:
> > >
> > > GFP_NOFAIL without any modifiers it the only valid nofail API.
> >
> > Where GFP_NOFAIL is GFP_KERNEL | __GFP_NOFAIL (and not the more limited one
> > as defined in patch 4/5).
>
> Yes.
>
> > > File systems / drivers can combine іt with the scoped nofs/noio if
> > > needed.
> >
> > Sounds good, how quickly we can convert existing __GFP_NOFAIL users remains
> > to be seen...
>
> I took a quick look at the file system ones and they look pretty easy.  I
> think it would be good to a quick scriped run for everything that does
> GFP_KERNEL | __GFP_NOFAIL right now, and then spend a little time on
> the rest.

I am not quite sure I have understood you, could you please provide a
concrete example,
for example, for the below case?

drivers/md/dm-region-hash.c:            nreg = kmalloc(sizeof(*nreg),
GFP_NOIO | __GFP_NOFAIL);

how are you going to drop the __GFP_IO | __GFP_FS bits while
GFP_NOFAIL = GFP_KERNEL | __GFP_NOFAIL?

And for those cases in which we don't even know GFP_NOIO/GFP_NOFS
is there since gfp is a variable?

gfp |= __GFP_NOFAIL ?

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Barry Song]

On Thu, Jul 25, 2024 at 1:47 PM Barry Song <21cnbao@gmail.com> wrote:
>
> On Thu, Jul 25, 2024 at 2:41 AM Christoph Hellwig <hch@infradead.org> wrote:
> >
> > On Wed, Jul 24, 2024 at 04:39:11PM +0200, Vlastimil Babka wrote:
> > > On 7/24/24 3:55 PM, Christoph Hellwig wrote:
> > > > On Wed, Jul 24, 2024 at 03:47:46PM +0200, Michal Hocko wrote:
> > > >> OK, now it makes more sense ;) I have absolutely no objections to
> > > >> prefering scoped NO{FS,IO} interfaces of course. And that would indeed
> > > >> eliminate a need for defining GFP_NO{FS,IO}_NOFAIL alternatives.
> > > >
> > > > Yes.  My proposal would be:
> > > >
> > > > GFP_NOFAIL without any modifiers it the only valid nofail API.
> > >
> > > Where GFP_NOFAIL is GFP_KERNEL | __GFP_NOFAIL (and not the more limited one
> > > as defined in patch 4/5).
> >
> > Yes.
> >
> > > > File systems / drivers can combine іt with the scoped nofs/noio if
> > > > needed.
> > >
> > > Sounds good, how quickly we can convert existing __GFP_NOFAIL users remains
> > > to be seen...
> >
> > I took a quick look at the file system ones and they look pretty easy.  I
> > think it would be good to a quick scriped run for everything that does
> > GFP_KERNEL | __GFP_NOFAIL right now, and then spend a little time on
> > the rest.

I assume you mean something as the below?

diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c
index a4550975c27d..b90ef94b1a09 100644
--- a/drivers/md/dm-region-hash.c
+++ b/drivers/md/dm-region-hash.c
@@ -291,10 +291,13 @@ static void __rh_insert(struct dm_region_hash
*rh, struct dm_region *reg)
 static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region)
 {
        struct dm_region *reg, *nreg;
+       int orig_flags;

        nreg = mempool_alloc(&rh->region_pool, GFP_ATOMIC);
+       orig_flags = memalloc_noio_save();
        if (unlikely(!nreg))
-               nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL);
+               nreg = kmalloc(sizeof(*nreg), GFP_NOFAIL);
+       memalloc_noio_restore(orig_flags);

        nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
                      DM_RH_CLEAN : DM_RH_NOSYNC;

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Vlastimil Babka]

On 7/29/24 11:56 AM, Barry Song wrote:
> On Thu, Jul 25, 2024 at 1:47 PM Barry Song <21cnbao@gmail.com> wrote:
>>
>> On Thu, Jul 25, 2024 at 2:41 AM Christoph Hellwig <hch@infradead.org> wrote:
>> >
>> > On Wed, Jul 24, 2024 at 04:39:11PM +0200, Vlastimil Babka wrote:
>> > > On 7/24/24 3:55 PM, Christoph Hellwig wrote:
>> > > > On Wed, Jul 24, 2024 at 03:47:46PM +0200, Michal Hocko wrote:
>> > > >> OK, now it makes more sense ;) I have absolutely no objections to
>> > > >> prefering scoped NO{FS,IO} interfaces of course. And that would indeed
>> > > >> eliminate a need for defining GFP_NO{FS,IO}_NOFAIL alternatives.
>> > > >
>> > > > Yes.  My proposal would be:
>> > > >
>> > > > GFP_NOFAIL without any modifiers it the only valid nofail API.
>> > >
>> > > Where GFP_NOFAIL is GFP_KERNEL | __GFP_NOFAIL (and not the more limited one
>> > > as defined in patch 4/5).
>> >
>> > Yes.
>> >
>> > > > File systems / drivers can combine іt with the scoped nofs/noio if
>> > > > needed.
>> > >
>> > > Sounds good, how quickly we can convert existing __GFP_NOFAIL users remains
>> > > to be seen...
>> >
>> > I took a quick look at the file system ones and they look pretty easy.  I
>> > think it would be good to a quick scriped run for everything that does
>> > GFP_KERNEL | __GFP_NOFAIL right now, and then spend a little time on
>> > the rest.
> 
> I assume you mean something as the below?

This would work but looks too much like a workaround to fit with the new
rules without actually fulfiling the purpose of the scopes. I.e. it's
possible this allocation is in fact part of a larger NOIO scope that should
be marked accordingly, and not just wrap this single kmalloc.

> diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c
> index a4550975c27d..b90ef94b1a09 100644
> --- a/drivers/md/dm-region-hash.c
> +++ b/drivers/md/dm-region-hash.c
> @@ -291,10 +291,13 @@ static void __rh_insert(struct dm_region_hash
> *rh, struct dm_region *reg)
>  static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region)
>  {
>         struct dm_region *reg, *nreg;
> +       int orig_flags;
> 
>         nreg = mempool_alloc(&rh->region_pool, GFP_ATOMIC);
> +       orig_flags = memalloc_noio_save();
>         if (unlikely(!nreg))
> -               nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL);
> +               nreg = kmalloc(sizeof(*nreg), GFP_NOFAIL);
> +       memalloc_noio_restore(orig_flags);
> 
>         nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
>                       DM_RH_CLEAN : DM_RH_NOSYNC;

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Barry Song]

On Mon, Jul 29, 2024 at 10:03 PM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 7/29/24 11:56 AM, Barry Song wrote:
> > On Thu, Jul 25, 2024 at 1:47 PM Barry Song <21cnbao@gmail.com> wrote:
> >>
> >> On Thu, Jul 25, 2024 at 2:41 AM Christoph Hellwig <hch@infradead.org> wrote:
> >> >
> >> > On Wed, Jul 24, 2024 at 04:39:11PM +0200, Vlastimil Babka wrote:
> >> > > On 7/24/24 3:55 PM, Christoph Hellwig wrote:
> >> > > > On Wed, Jul 24, 2024 at 03:47:46PM +0200, Michal Hocko wrote:
> >> > > >> OK, now it makes more sense ;) I have absolutely no objections to
> >> > > >> prefering scoped NO{FS,IO} interfaces of course. And that would indeed
> >> > > >> eliminate a need for defining GFP_NO{FS,IO}_NOFAIL alternatives.
> >> > > >
> >> > > > Yes.  My proposal would be:
> >> > > >
> >> > > > GFP_NOFAIL without any modifiers it the only valid nofail API.
> >> > >
> >> > > Where GFP_NOFAIL is GFP_KERNEL | __GFP_NOFAIL (and not the more limited one
> >> > > as defined in patch 4/5).
> >> >
> >> > Yes.
> >> >
> >> > > > File systems / drivers can combine іt with the scoped nofs/noio if
> >> > > > needed.
> >> > >
> >> > > Sounds good, how quickly we can convert existing __GFP_NOFAIL users remains
> >> > > to be seen...
> >> >
> >> > I took a quick look at the file system ones and they look pretty easy.  I
> >> > think it would be good to a quick scriped run for everything that does
> >> > GFP_KERNEL | __GFP_NOFAIL right now, and then spend a little time on
> >> > the rest.
> >
> > I assume you mean something as the below?
>
> This would work but looks too much like a workaround to fit with the new
> rules without actually fulfiling the purpose of the scopes. I.e. it's
> possible this allocation is in fact part of a larger NOIO scope that should
> be marked accordingly, and not just wrap this single kmalloc.

Absolutely agreed, but the scope needs to be determined on a case-by-case
basis ? The module guys are probably the better people to set the appropriate
scope?  It is difficult to assess this solely from the mm perspective.

>
> > diff --git a/drivers/md/dm-region-hash.c b/drivers/md/dm-region-hash.c
> > index a4550975c27d..b90ef94b1a09 100644
> > --- a/drivers/md/dm-region-hash.c
> > +++ b/drivers/md/dm-region-hash.c
> > @@ -291,10 +291,13 @@ static void __rh_insert(struct dm_region_hash
> > *rh, struct dm_region *reg)
> >  static struct dm_region *__rh_alloc(struct dm_region_hash *rh, region_t region)
> >  {
> >         struct dm_region *reg, *nreg;
> > +       int orig_flags;
> >
> >         nreg = mempool_alloc(&rh->region_pool, GFP_ATOMIC);
> > +       orig_flags = memalloc_noio_save();
> >         if (unlikely(!nreg))
> > -               nreg = kmalloc(sizeof(*nreg), GFP_NOIO | __GFP_NOFAIL);
> > +               nreg = kmalloc(sizeof(*nreg), GFP_NOFAIL);
> > +       memalloc_noio_restore(orig_flags);
> >
> >         nreg->state = rh->log->type->in_sync(rh->log, region, 1) ?
> >                       DM_RH_CLEAN : DM_RH_NOSYNC;
>

Thanks
Barry

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Michal Hocko]

On Wed 24-07-24 20:55:44, Barry Song wrote:
> From: Barry Song <v-songbaohua@oppo.com>
> 
> GFP_NOFAIL includes the meaning of block and direct reclamation, which
> is essential for a true no-fail allocation. We are gradually starting
> to enforce this block semantics to prevent the potential misuse of
> __GFP_NOFAIL in atomic contexts in the future.
> 
> A typical example of incorrect usage is in VDPA, where GFP_ATOMIC
> and __GFP_NOFAIL are used together.

Ohh, so you have done the migration. Please squash those two patches.
Also if we want to preserve clean __GFP_NOFAIL for internal MM use then it
should be moved away from include/linux/gfp_types.h. But is there any
real use for that?

-- 
Michal Hocko
SUSE Labs

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Barry Song]

On Thu, Jul 25, 2024 at 12:17 AM Michal Hocko <mhocko@suse.com> wrote:
>
> On Wed 24-07-24 20:55:44, Barry Song wrote:
> > From: Barry Song <v-songbaohua@oppo.com>
> >
> > GFP_NOFAIL includes the meaning of block and direct reclamation, which
> > is essential for a true no-fail allocation. We are gradually starting
> > to enforce this block semantics to prevent the potential misuse of
> > __GFP_NOFAIL in atomic contexts in the future.
> >
> > A typical example of incorrect usage is in VDPA, where GFP_ATOMIC
> > and __GFP_NOFAIL are used together.
>
> Ohh, so you have done the migration. Please squash those two patches.
> Also if we want to preserve clean __GFP_NOFAIL for internal MM use then it
> should be moved away from include/linux/gfp_types.h. But is there any
> real use for that?

yes. currently i got two,

lib/rhashtable.c

static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
                                               size_t nbuckets,
                                               gfp_t gfp)
{
        struct bucket_table *tbl = NULL;
        size_t size;
        int i;
        static struct lock_class_key __key;

        tbl = alloc_hooks_tag(ht->alloc_tag,
                        kvmalloc_node_noprof(struct_size(tbl, buckets,
nbuckets),
                                             gfp|__GFP_ZERO, NUMA_NO_NODE));

        size = nbuckets;

        if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) {
                tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
                nbuckets = 0;
        }

        ...

        return tbl;
}

and tools/perf/builtin-kmem.c:

static const struct {
        const char *original;
        const char *compact;
} gfp_compact_table[] = {
        { "GFP_TRANSHUGE",              "THP" },
        { "GFP_TRANSHUGE_LIGHT",        "THL" },
        { "GFP_HIGHUSER_MOVABLE",       "HUM" },
        { "GFP_HIGHUSER",               "HU" },
        ...
        { "__GFP_NOFAIL",               "NF" },
       ...
};

>
> --
> Michal Hocko
> SUSE Labs

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Michal Hocko]

On Thu 25-07-24 13:38:50, Barry Song wrote:
> On Thu, Jul 25, 2024 at 12:17 AM Michal Hocko <mhocko@suse.com> wrote:
> >
> > On Wed 24-07-24 20:55:44, Barry Song wrote:
> > > From: Barry Song <v-songbaohua@oppo.com>
> > >
> > > GFP_NOFAIL includes the meaning of block and direct reclamation, which
> > > is essential for a true no-fail allocation. We are gradually starting
> > > to enforce this block semantics to prevent the potential misuse of
> > > __GFP_NOFAIL in atomic contexts in the future.
> > >
> > > A typical example of incorrect usage is in VDPA, where GFP_ATOMIC
> > > and __GFP_NOFAIL are used together.
> >
> > Ohh, so you have done the migration. Please squash those two patches.
> > Also if we want to preserve clean __GFP_NOFAIL for internal MM use then it
> > should be moved away from include/linux/gfp_types.h. But is there any
> > real use for that?
> 
> yes. currently i got two,
> 
> lib/rhashtable.c
> 
> static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
>                                                size_t nbuckets,
>                                                gfp_t gfp)
> {
>         struct bucket_table *tbl = NULL;
>         size_t size;
>         int i;
>         static struct lock_class_key __key;
> 
>         tbl = alloc_hooks_tag(ht->alloc_tag,
>                         kvmalloc_node_noprof(struct_size(tbl, buckets,
> nbuckets),
>                                              gfp|__GFP_ZERO, NUMA_NO_NODE));
> 
>         size = nbuckets;
> 
>         if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) {
>                 tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
>                 nbuckets = 0;
>         }
> 
>         ...
> 
>         return tbl;
> }

Ugh. OK this is a weird allocation fallback strategy 2d22ecf6db1c
("lib/rhashtable: guarantee initial hashtable allocation"). Maybe the
code should be just simplified and GFP_NOFAIL used from the begining?
Davidlohr WDYT? For your context Barry tries to drop all the
__GFP_NOFAIL use and replace it by GFP_NOFAIL which enforces
__GFP_DIRECT_RECLAIM so that people cannot request atomic NOFAIL.

> and tools/perf/builtin-kmem.c:
> 
> static const struct {
>         const char *original;
>         const char *compact;
> } gfp_compact_table[] = {
>         { "GFP_TRANSHUGE",              "THP" },
>         { "GFP_TRANSHUGE_LIGHT",        "THL" },
>         { "GFP_HIGHUSER_MOVABLE",       "HUM" },
>         { "GFP_HIGHUSER",               "HU" },
>         ...
>         { "__GFP_NOFAIL",               "NF" },
>        ...
> };

This is a prrintk formatting stuff. This counts as low level
functionality.

-- 
Michal Hocko
SUSE Labs

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Davidlohr Bueso]

On Thu, 25 Jul 2024, Michal Hocko wrote:\n
>On Thu 25-07-24 13:38:50, Barry Song wrote:
>> On Thu, Jul 25, 2024 at 12:17???AM Michal Hocko <mhocko@suse.com> wrote:
>> >
>> > On Wed 24-07-24 20:55:44, Barry Song wrote:
>> > > From: Barry Song <v-songbaohua@oppo.com>
>> > >
>> > > GFP_NOFAIL includes the meaning of block and direct reclamation, which
>> > > is essential for a true no-fail allocation. We are gradually starting
>> > > to enforce this block semantics to prevent the potential misuse of
>> > > __GFP_NOFAIL in atomic contexts in the future.
>> > >
>> > > A typical example of incorrect usage is in VDPA, where GFP_ATOMIC
>> > > and __GFP_NOFAIL are used together.
>> >
>> > Ohh, so you have done the migration. Please squash those two patches.
>> > Also if we want to preserve clean __GFP_NOFAIL for internal MM use then it
>> > should be moved away from include/linux/gfp_types.h. But is there any
>> > real use for that?
>>
>> yes. currently i got two,
>>
>> lib/rhashtable.c
>>
>> static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
>>                                                size_t nbuckets,
>>                                                gfp_t gfp)
>> {
>>         struct bucket_table *tbl = NULL;
>>         size_t size;
>>         int i;
>>         static struct lock_class_key __key;
>>
>>         tbl = alloc_hooks_tag(ht->alloc_tag,
>>                         kvmalloc_node_noprof(struct_size(tbl, buckets,
>> nbuckets),
>>                                              gfp|__GFP_ZERO, NUMA_NO_NODE));
>>
>>         size = nbuckets;
>>
>>         if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) {
>>                 tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
>>                 nbuckets = 0;
>>         }
>>
>>         ...
>>
>>         return tbl;
>> }
>
>Ugh. OK this is a weird allocation fallback strategy 2d22ecf6db1c
>("lib/rhashtable: guarantee initial hashtable allocation"). Maybe the
>code should be just simplified and GFP_NOFAIL used from the begining?
>Davidlohr WDYT? For your context Barry tries to drop all the
>__GFP_NOFAIL use and replace it by GFP_NOFAIL which enforces
>__GFP_DIRECT_RECLAIM so that people cannot request atomic NOFAIL.

Why is it so weird? Perhaps I'm missing your point, but the fallback
introduced in that commit attempts to avoid abusing nofail semantics
and only ask with a smaller size.

In any case, would the following be better (and also silences smatch)?
Disregarding the initial nofail request, rhashtable allocations are
always either regular GFP_KERNEL or GFP_ATOMIC (for the nested and
some insertion cases).

-----8<-----
diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index dbbed19f8fff..c9f9cce4a3c1 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -184,12 +184,12 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
  	static struct lock_class_key __key;
  
  	tbl = alloc_hooks_tag(ht->alloc_tag,
-			kvmalloc_node_noprof(struct_size(tbl, buckets, nbuckets),
-					     gfp|__GFP_ZERO, NUMA_NO_NODE));
+			kvmalloc_noprof(struct_size(tbl, buckets, nbuckets),
+					gfp|__GFP_ZERO));
  
  	size = nbuckets;
  
-	if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) {
+	if (tbl == NULL && (gfp & GFP_ATOMIC)) {
  		tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
  		nbuckets = 0;
  	}

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Michal Hocko]

On Fri 26-07-24 14:08:18, Davidlohr Bueso wrote:
> On Thu, 25 Jul 2024, Michal Hocko wrote:\n
> > On Thu 25-07-24 13:38:50, Barry Song wrote:
> > > On Thu, Jul 25, 2024 at 12:17???AM Michal Hocko <mhocko@suse.com> wrote:
> > > >
> > > > On Wed 24-07-24 20:55:44, Barry Song wrote:
> > > > > From: Barry Song <v-songbaohua@oppo.com>
> > > > >
> > > > > GFP_NOFAIL includes the meaning of block and direct reclamation, which
> > > > > is essential for a true no-fail allocation. We are gradually starting
> > > > > to enforce this block semantics to prevent the potential misuse of
> > > > > __GFP_NOFAIL in atomic contexts in the future.
> > > > >
> > > > > A typical example of incorrect usage is in VDPA, where GFP_ATOMIC
> > > > > and __GFP_NOFAIL are used together.
> > > >
> > > > Ohh, so you have done the migration. Please squash those two patches.
> > > > Also if we want to preserve clean __GFP_NOFAIL for internal MM use then it
> > > > should be moved away from include/linux/gfp_types.h. But is there any
> > > > real use for that?
> > > 
> > > yes. currently i got two,
> > > 
> > > lib/rhashtable.c
> > > 
> > > static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
> > >                                                size_t nbuckets,
> > >                                                gfp_t gfp)
> > > {
> > >         struct bucket_table *tbl = NULL;
> > >         size_t size;
> > >         int i;
> > >         static struct lock_class_key __key;
> > > 
> > >         tbl = alloc_hooks_tag(ht->alloc_tag,
> > >                         kvmalloc_node_noprof(struct_size(tbl, buckets,
> > > nbuckets),
> > >                                              gfp|__GFP_ZERO, NUMA_NO_NODE));
> > > 
> > >         size = nbuckets;
> > > 
> > >         if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) {
> > >                 tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
> > >                 nbuckets = 0;
> > >         }
> > > 
> > >         ...
> > > 
> > >         return tbl;
> > > }
> > 
> > Ugh. OK this is a weird allocation fallback strategy 2d22ecf6db1c
> > ("lib/rhashtable: guarantee initial hashtable allocation"). Maybe the
> > code should be just simplified and GFP_NOFAIL used from the begining?
> > Davidlohr WDYT? For your context Barry tries to drop all the
> > __GFP_NOFAIL use and replace it by GFP_NOFAIL which enforces
> > __GFP_DIRECT_RECLAIM so that people cannot request atomic NOFAIL.
> 
> Why is it so weird?

Because it is really hard to figure out what it is supposed to mean.
If the caller uses __GFP_NOFAIL then it is (should be) impossible and if
NOFAIL is not used then why does it need to check for 
	(gfp & ~__GFP_NOFAIL) != GFP_KERNEL?
this could be GFP_NO{IO,FS} but also GFP_ATOMIC. So what is it supposed
to mean even?

> Perhaps I'm missing your point, but the fallback
> introduced in that commit attempts to avoid abusing nofail semantics
> and only ask with a smaller size.
> 
> In any case, would the following be better (and also silences smatch)?
> Disregarding the initial nofail request, rhashtable allocations are
> always either regular GFP_KERNEL or GFP_ATOMIC (for the nested and
> some insertion cases).
> 
> -----8<-----
> diff --git a/lib/rhashtable.c b/lib/rhashtable.c
> index dbbed19f8fff..c9f9cce4a3c1 100644
> --- a/lib/rhashtable.c
> +++ b/lib/rhashtable.c
> @@ -184,12 +184,12 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
>  	static struct lock_class_key __key;
>  	tbl = alloc_hooks_tag(ht->alloc_tag,
> -			kvmalloc_node_noprof(struct_size(tbl, buckets, nbuckets),
> -					     gfp|__GFP_ZERO, NUMA_NO_NODE));
> +			kvmalloc_noprof(struct_size(tbl, buckets, nbuckets),
> +					gfp|__GFP_ZERO));
>  	size = nbuckets;
> -	if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) {
> +	if (tbl == NULL && (gfp & GFP_ATOMIC)) {

I have really hard time to follow what that is supposed to mean. First
GFP_ATOMIC is not a mask usable for this kind of tests as it is
	__GFP_HIGH|__GFP_KSWAPD_RECLAIM

so GFP_KERNEL & GFP_ATOMIC is true. If you want to explicitly ask for a
sleepable allocation then use gfpflags_allow_blocking but fundamentally
why you simply do not do
	if (!tlb)
  		tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);

Why does gfp flags play any role here?
-- 
Michal Hocko
SUSE Labs

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Davidlohr Bueso]

On Mon, 29 Jul 2024, Michal Hocko wrote:
>Because it is really hard to figure out what it is supposed to mean.
>If the caller uses __GFP_NOFAIL then it is (should be) impossible and if
>NOFAIL is not used then why does it need to check for
>	(gfp & ~__GFP_NOFAIL) != GFP_KERNEL?

Agreed, this is pointless - and cannot recall why it was justified to have
in the first place.

But I think we should revert back to the original check then, which is there
to distinguish failure cases between normal (GFP_KERNEL) and nested (GFP_ATOMIC)
contexts. Removing the check altogether would change the fallback for regular
allocations.

So this would be:

-       if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) {
+       if (tbl == NULL && gfp != GFP_KERNEL) {

Thanks,
Davidlohr

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Michal Hocko]

On Sat 03-08-24 15:15:56, Davidlohr Bueso wrote:
> On Mon, 29 Jul 2024, Michal Hocko wrote:
> > Because it is really hard to figure out what it is supposed to mean.
> > If the caller uses __GFP_NOFAIL then it is (should be) impossible and if
> > NOFAIL is not used then why does it need to check for
> > 	(gfp & ~__GFP_NOFAIL) != GFP_KERNEL?
> 
> Agreed, this is pointless - and cannot recall why it was justified to have
> in the first place.
> 
> But I think we should revert back to the original check then, which is there
> to distinguish failure cases between normal (GFP_KERNEL) and nested (GFP_ATOMIC)
> contexts. Removing the check altogether would change the fallback for regular
> allocations.
> 
> So this would be:
> 
> -       if (tbl == NULL && (gfp & ~__GFP_NOFAIL) != GFP_KERNEL) {
> +       if (tbl == NULL && gfp != GFP_KERNEL) {

If you want to tell between sleeping and atomic allocations then already
mentioned gfpflags_allow_blocking would be more readable IMHO but the
above is much better already.
-- 
Michal Hocko
SUSE Labs

Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[kernel test robot]

Hi Barry,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Barry-Song/vpda-try-to-fix-the-potential-crash-due-to-misusing-__GFP_NOFAIL/20240724-170305
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20240724085544.299090-6-21cnbao%40gmail.com
patch subject: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL
config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20240725/202407250848.1RB1y5JP-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240725/202407250848.1RB1y5JP-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202407250848.1RB1y5JP-lkp@intel.com/

All warnings (new ones prefixed by >>):

   lib/rhashtable.c: In function 'bucket_table_alloc':
>> lib/rhashtable.c:192:48: warning: bitwise comparison always evaluates to true [-Wtautological-compare]
     192 |         if (tbl == NULL && (gfp & ~GFP_NOFAIL) != GFP_KERNEL) {
         |                                                ^~


vim +192 lib/rhashtable.c

   176	
   177	static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
   178						       size_t nbuckets,
   179						       gfp_t gfp)
   180	{
   181		struct bucket_table *tbl = NULL;
   182		size_t size;
   183		int i;
   184		static struct lock_class_key __key;
   185	
   186		tbl = alloc_hooks_tag(ht->alloc_tag,
   187				kvmalloc_node_noprof(struct_size(tbl, buckets, nbuckets),
   188						     gfp|__GFP_ZERO, NUMA_NO_NODE));
   189	
   190		size = nbuckets;
   191	
 > 192		if (tbl == NULL && (gfp & ~GFP_NOFAIL) != GFP_KERNEL) {
   193			tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
   194			nbuckets = 0;
   195		}
   196	
   197		if (tbl == NULL)
   198			return NULL;
   199	
   200		lockdep_init_map(&tbl->dep_map, "rhashtable_bucket", &__key, 0);
   201	
   202		tbl->size = size;
   203	
   204		rcu_head_init(&tbl->rcu);
   205		INIT_LIST_HEAD(&tbl->walkers);
   206	
   207		tbl->hash_rnd = get_random_u32();
   208	
   209		for (i = 0; i < nbuckets; i++)
   210			INIT_RHT_NULLS_HEAD(tbl->buckets[i]);
   211	
   212		return tbl;
   213	}
   214	

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Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[Dan Carpenter]

Hi Barry,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

url:    https://github.com/intel-lab-lkp/linux/commits/Barry-Song/vpda-try-to-fix-the-potential-crash-due-to-misusing-__GFP_NOFAIL/20240724-170305
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20240724085544.299090-6-21cnbao%40gmail.com
patch subject: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL
config: i386-randconfig-141-20240725 (https://download.01.org/0day-ci/archive/20240725/202407251449.TnONiYn5-lkp@intel.com/config)
compiler: gcc-12 (Ubuntu 12.3.0-9ubuntu2) 12.3.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202407251449.TnONiYn5-lkp@intel.com/

New smatch warnings:
lib/rhashtable.c:192 bucket_table_alloc() warn: masked condition '(gfp & ~(((((((1))) << (10)) | ((((1))) << (11)))) | (((((1))) << (15))))) != (((((((1))) << (10)) | ((((1))) << (11)))) | (((((1))) << (6))) | (((((1))) << (7))))' is always true.

vim +192 lib/rhashtable.c

97defe1ecf868b Thomas Graf        2015-01-02  177  static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
b9ecfdaa1090b5 Herbert Xu         2015-03-24  178  					       size_t nbuckets,
b9ecfdaa1090b5 Herbert Xu         2015-03-24  179  					       gfp_t gfp)
7e1e77636e3607 Thomas Graf        2014-08-02  180  {
eb6d1abf1bd8bf Daniel Borkmann    2015-02-20  181  	struct bucket_table *tbl = NULL;
8f0db018006a42 NeilBrown          2019-04-02  182  	size_t size;
f89bd6f87a53ce Thomas Graf        2015-01-02  183  	int i;
149212f07856b2 NeilBrown          2019-04-02  184  	static struct lock_class_key __key;
7e1e77636e3607 Thomas Graf        2014-08-02  185  
9e54dd8b64dccd Kent Overstreet    2024-03-21  186  	tbl = alloc_hooks_tag(ht->alloc_tag,
9e54dd8b64dccd Kent Overstreet    2024-03-21  187  			kvmalloc_node_noprof(struct_size(tbl, buckets, nbuckets),
9e54dd8b64dccd Kent Overstreet    2024-03-21  188  					     gfp|__GFP_ZERO, NUMA_NO_NODE));
da20420f83ea0f Herbert Xu         2017-02-11  189  
da20420f83ea0f Herbert Xu         2017-02-11  190  	size = nbuckets;
da20420f83ea0f Herbert Xu         2017-02-11  191  
c61791509b08d1 Barry Song         2024-07-24 @192  	if (tbl == NULL && (gfp & ~GFP_NOFAIL) != GFP_KERNEL) {
                                                                                   ^^^^^^^^^^
GFP_KERNEL includes some NOFAIL bits so this condition doesn't work.

da20420f83ea0f Herbert Xu         2017-02-11  193  		tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
da20420f83ea0f Herbert Xu         2017-02-11  194  		nbuckets = 0;
da20420f83ea0f Herbert Xu         2017-02-11  195  	}
2d22ecf6db1c39 Davidlohr Bueso    2018-08-21  196  

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Re: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20240724085544.299090-6-21cnbao@gmail.com>
References: <20240724085544.299090-6-21cnbao@gmail.com>
TO: Barry Song <21cnbao@gmail.com>

Hi Barry,

[This is a private test report for your RFC patch.]
kernel test robot noticed the following build warnings:

[auto build test WARNING on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Barry-Song/vpda-try-to-fix-the-potential-crash-due-to-misusing-__GFP_NOFAIL/20240724-170305
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20240724085544.299090-6-21cnbao%40gmail.com
patch subject: [PATCH RFC 5/5] non-mm: discourage the usage of __GFP_NOFAIL and encourage GFP_NOFAIL
:::::: branch date: 22 hours ago
:::::: commit date: 22 hours ago
config: i386-randconfig-141-20240725 (https://download.01.org/0day-ci/archive/20240725/202407251449.TnONiYn5-lkp@intel.com/config)
compiler: gcc-12 (Ubuntu 12.3.0-9ubuntu2) 12.3.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202407251449.TnONiYn5-lkp@intel.com/

New smatch warnings:
lib/rhashtable.c:192 bucket_table_alloc() warn: masked condition '(gfp & ~(((((((1))) << (10)) | ((((1))) << (11)))) | (((((1))) << (15))))) != (((((((1))) << (10)) | ((((1))) << (11)))) | (((((1))) << (6))) | (((((1))) << (7))))' is always true.

Old smatch warnings:
lib/rhashtable.c:557 rhashtable_insert_one() warn: passing zero to 'ERR_CAST'
lib/rhashtable.c:624 rhashtable_try_insert() warn: passing zero to 'ERR_CAST'

vim +192 lib/rhashtable.c

da20420f83ea0f Herbert Xu         2017-02-11  176  
97defe1ecf868b Thomas Graf        2015-01-02  177  static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
b9ecfdaa1090b5 Herbert Xu         2015-03-24  178  					       size_t nbuckets,
b9ecfdaa1090b5 Herbert Xu         2015-03-24  179  					       gfp_t gfp)
7e1e77636e3607 Thomas Graf        2014-08-02  180  {
eb6d1abf1bd8bf Daniel Borkmann    2015-02-20  181  	struct bucket_table *tbl = NULL;
8f0db018006a42 NeilBrown          2019-04-02  182  	size_t size;
f89bd6f87a53ce Thomas Graf        2015-01-02  183  	int i;
149212f07856b2 NeilBrown          2019-04-02  184  	static struct lock_class_key __key;
7e1e77636e3607 Thomas Graf        2014-08-02  185  
9e54dd8b64dccd Kent Overstreet    2024-03-21  186  	tbl = alloc_hooks_tag(ht->alloc_tag,
9e54dd8b64dccd Kent Overstreet    2024-03-21  187  			kvmalloc_node_noprof(struct_size(tbl, buckets, nbuckets),
9e54dd8b64dccd Kent Overstreet    2024-03-21  188  					     gfp|__GFP_ZERO, NUMA_NO_NODE));
da20420f83ea0f Herbert Xu         2017-02-11  189  
da20420f83ea0f Herbert Xu         2017-02-11  190  	size = nbuckets;
da20420f83ea0f Herbert Xu         2017-02-11  191  
c61791509b08d1 Barry Song         2024-07-24 @192  	if (tbl == NULL && (gfp & ~GFP_NOFAIL) != GFP_KERNEL) {
da20420f83ea0f Herbert Xu         2017-02-11  193  		tbl = nested_bucket_table_alloc(ht, nbuckets, gfp);
da20420f83ea0f Herbert Xu         2017-02-11  194  		nbuckets = 0;
da20420f83ea0f Herbert Xu         2017-02-11  195  	}
2d22ecf6db1c39 Davidlohr Bueso    2018-08-21  196  
7e1e77636e3607 Thomas Graf        2014-08-02  197  	if (tbl == NULL)
7e1e77636e3607 Thomas Graf        2014-08-02  198  		return NULL;
7e1e77636e3607 Thomas Graf        2014-08-02  199  
149212f07856b2 NeilBrown          2019-04-02  200  	lockdep_init_map(&tbl->dep_map, "rhashtable_bucket", &__key, 0);
149212f07856b2 NeilBrown          2019-04-02  201  
da20420f83ea0f Herbert Xu         2017-02-11  202  	tbl->size = size;
7e1e77636e3607 Thomas Graf        2014-08-02  203  
4feb7c7a4fbb8f NeilBrown          2019-03-21  204  	rcu_head_init(&tbl->rcu);
eddee5ba34eb6c Herbert Xu         2015-03-14  205  	INIT_LIST_HEAD(&tbl->walkers);
eddee5ba34eb6c Herbert Xu         2015-03-14  206  
d48ad080ec0101 Jason A. Donenfeld 2017-06-07  207  	tbl->hash_rnd = get_random_u32();
5269b53da4d432 Herbert Xu         2015-03-14  208  
f89bd6f87a53ce Thomas Graf        2015-01-02  209  	for (i = 0; i < nbuckets; i++)
9b4f64a227b6f4 NeilBrown          2018-06-18  210  		INIT_RHT_NULLS_HEAD(tbl->buckets[i]);
f89bd6f87a53ce Thomas Graf        2015-01-02  211  
97defe1ecf868b Thomas Graf        2015-01-02  212  	return tbl;
7e1e77636e3607 Thomas Graf        2014-08-02  213  }
7e1e77636e3607 Thomas Graf        2014-08-02  214  

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