* [PATCH 10/17] jbd2: replace __get_free_pages() with kmalloc()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
In-Reply-To: <20260523-b4-fs-v1-0-275e36a83f0e@kernel.org>
jbd2_alloc() falls back from kmem_cache_alloc() to __get_free_pages() for
allocations larger than PAGE_SIZE.
But kmalloc() can handle such cases with essentially the same fallback.
Replace use of __get_free_pages() with kmalloc() and simplify
jbd2_free() as both kmem_cache_alloc() and kmalloc() allocations can be
freed with kfree().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
fs/jbd2/journal.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 4f397fcdb13c..1137b471e490 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2784,7 +2784,7 @@ void *jbd2_alloc(size_t size, gfp_t flags)
if (size < PAGE_SIZE)
ptr = kmem_cache_alloc(get_slab(size), flags);
else
- ptr = (void *)__get_free_pages(flags, get_order(size));
+ ptr = kmalloc(size, flags);
/* Check alignment; SLUB has gotten this wrong in the past,
* and this can lead to user data corruption! */
@@ -2795,10 +2795,7 @@ void *jbd2_alloc(size_t size, gfp_t flags)
void jbd2_free(void *ptr, size_t size)
{
- if (size < PAGE_SIZE)
- kmem_cache_free(get_slab(size), ptr);
- else
- free_pages((unsigned long)ptr, get_order(size));
+ kfree(ptr);
};
/*
--
2.53.0
^ permalink raw reply related
* [PATCH 09/17] jfs: replace __get_free_page() with kmalloc()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
In-Reply-To: <20260523-b4-fs-v1-0-275e36a83f0e@kernel.org>
jfs_readdir() allocates dirent_buf with __get_free_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
fs/jfs/jfs_dtree.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/fs/jfs/jfs_dtree.c b/fs/jfs/jfs_dtree.c
index ac0f79fafaca..8ce6e4458cc2 100644
--- a/fs/jfs/jfs_dtree.c
+++ b/fs/jfs/jfs_dtree.c
@@ -2729,7 +2729,7 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
struct ldtentry *d;
struct dtslot *t;
int d_namleft, len, outlen;
- unsigned long dirent_buf;
+ void *dirent_buf;
char *name_ptr;
u32 dir_index;
int do_index = 0;
@@ -2884,7 +2884,7 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
}
}
- dirent_buf = __get_free_page(GFP_KERNEL);
+ dirent_buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (dirent_buf == 0) {
DT_PUTPAGE(mp);
jfs_warn("jfs_readdir: __get_free_page failed!");
@@ -2893,7 +2893,7 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
}
while (1) {
- jfs_dirent = (struct jfs_dirent *) dirent_buf;
+ jfs_dirent = dirent_buf;
jfs_dirents = 0;
overflow = fix_page = 0;
@@ -2903,7 +2903,7 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
if (stbl[i] < 0) {
jfs_err("JFS: Invalid stbl[%d] = %d for inode %ld, block = %lld",
i, stbl[i], (long)ip->i_ino, (long long)bn);
- free_page(dirent_buf);
+ kfree(dirent_buf);
DT_PUTPAGE(mp);
return -EIO;
}
@@ -2911,7 +2911,7 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
d = (struct ldtentry *) & p->slot[stbl[i]];
if (((long) jfs_dirent + d->namlen + 1) >
- (dirent_buf + PAGE_SIZE)) {
+ ((long)dirent_buf + PAGE_SIZE)) {
/* DBCS codepages could overrun dirent_buf */
index = i;
overflow = 1;
@@ -3014,7 +3014,7 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
/* unpin previous leaf page */
DT_PUTPAGE(mp);
- jfs_dirent = (struct jfs_dirent *) dirent_buf;
+ jfs_dirent = dirent_buf;
while (jfs_dirents--) {
ctx->pos = jfs_dirent->position;
if (!dir_emit(ctx, jfs_dirent->name,
@@ -3037,13 +3037,13 @@ int jfs_readdir(struct file *file, struct dir_context *ctx)
DT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
if (rc) {
- free_page(dirent_buf);
+ kfree(dirent_buf);
return rc;
}
}
out:
- free_page(dirent_buf);
+ kfree(dirent_buf);
return rc;
}
--
2.53.0
^ permalink raw reply related
* [PATCH 08/17] libfs: simple_transaction_get(): replace get_zeroed_page() with kzalloc()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
In-Reply-To: <20260523-b4-fs-v1-0-275e36a83f0e@kernel.org>
simple_transaction_get() allocates memory with get_zeroed_page(). That
memory is used as a file local buffer that is accessed using
copy_from_user() and simple_read_from_buffer().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of get_zeroed_page() with kzalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
fs/libfs.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/libfs.c b/fs/libfs.c
index 1bbea5e7bae3..80a330c8296f 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -1258,7 +1258,7 @@ char *simple_transaction_get(struct file *file, const char __user *buf, size_t s
if (size > SIMPLE_TRANSACTION_LIMIT - 1)
return ERR_PTR(-EFBIG);
- ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL);
+ ar = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (!ar)
return ERR_PTR(-ENOMEM);
@@ -1267,7 +1267,7 @@ char *simple_transaction_get(struct file *file, const char __user *buf, size_t s
/* only one write allowed per open */
if (file->private_data) {
spin_unlock(&simple_transaction_lock);
- free_page((unsigned long)ar);
+ kfree(ar);
return ERR_PTR(-EBUSY);
}
@@ -1294,7 +1294,7 @@ EXPORT_SYMBOL(simple_transaction_read);
int simple_transaction_release(struct inode *inode, struct file *file)
{
- free_page((unsigned long)file->private_data);
+ kfree(file->private_data);
return 0;
}
EXPORT_SYMBOL(simple_transaction_release);
--
2.53.0
^ permalink raw reply related
* [PATCH 07/17] NFSD: replace __get_free_page() with kmalloc() in nfsd_buffered_readdir()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
In-Reply-To: <20260523-b4-fs-v1-0-275e36a83f0e@kernel.org>
nfsd_buffered_readdir() allocates a staging buffer with __get_free_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
fs/nfsd/vfs.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index eafdf7b7890f..c99e54b23cd9 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -2407,7 +2407,7 @@ static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
loff_t offset;
struct readdir_data buf = {
.ctx.actor = nfsd_buffered_filldir,
- .dirent = (void *)__get_free_page(GFP_KERNEL)
+ .dirent = kmalloc(PAGE_SIZE, GFP_KERNEL)
};
if (!buf.dirent)
@@ -2458,7 +2458,7 @@ static __be32 nfsd_buffered_readdir(struct file *file, struct svc_fh *fhp,
offset = vfs_llseek(file, 0, SEEK_CUR);
}
- free_page((unsigned long)(buf.dirent));
+ kfree((buf.dirent));
if (host_err)
return nfserrno(host_err);
--
2.53.0
^ permalink raw reply related
* [PATCH 06/17] NFS: remove unused page and page2 in nfs4_replace_transport()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
In-Reply-To: <20260523-b4-fs-v1-0-275e36a83f0e@kernel.org>
Temporary buffers page and page2 allocated by nfs4_replace_transport() and
passed to nfs4_try_replacing_one_location() are never used.
Remove them and the code that allocates and frees memory for these buffers.
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
fs/nfs/nfs4namespace.c | 15 +--------------
1 file changed, 1 insertion(+), 14 deletions(-)
diff --git a/fs/nfs/nfs4namespace.c b/fs/nfs/nfs4namespace.c
index 14f72baf3b30..2a03f02bba7c 100644
--- a/fs/nfs/nfs4namespace.c
+++ b/fs/nfs/nfs4namespace.c
@@ -481,7 +481,6 @@ int nfs4_submount(struct fs_context *fc, struct nfs_server *server)
* Returns zero on success, or a negative errno value.
*/
static int nfs4_try_replacing_one_location(struct nfs_server *server,
- char *page, char *page2,
const struct nfs4_fs_location *location)
{
struct net *net = rpc_net_ns(server->client);
@@ -541,21 +540,12 @@ static int nfs4_try_replacing_one_location(struct nfs_server *server,
int nfs4_replace_transport(struct nfs_server *server,
const struct nfs4_fs_locations *locations)
{
- char *page = NULL, *page2 = NULL;
int loc, error;
error = -ENOENT;
if (locations == NULL || locations->nlocations <= 0)
goto out;
- error = -ENOMEM;
- page = (char *) __get_free_page(GFP_USER);
- if (!page)
- goto out;
- page2 = (char *) __get_free_page(GFP_USER);
- if (!page2)
- goto out;
-
for (loc = 0; loc < locations->nlocations; loc++) {
const struct nfs4_fs_location *location =
&locations->locations[loc];
@@ -564,14 +554,11 @@ int nfs4_replace_transport(struct nfs_server *server,
location->rootpath.ncomponents == 0)
continue;
- error = nfs4_try_replacing_one_location(server, page,
- page2, location);
+ error = nfs4_try_replacing_one_location(server, location);
if (error == 0)
break;
}
out:
- free_page((unsigned long)page);
- free_page((unsigned long)page2);
return error;
}
--
2.53.0
^ permalink raw reply related
* [PATCH 05/17] NFS: replace __get_free_page() with kmalloc() in nfs_show_devname()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
In-Reply-To: <20260523-b4-fs-v1-0-275e36a83f0e@kernel.org>
nfs_show_devname() allocates a tmemporary buffer __get_free_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
fs/nfs/super.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 4cd420b14ce3..8f8a03a68d3d 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -623,7 +623,7 @@ static void show_implementation_id(struct seq_file *m, struct nfs_server *nfss)
int nfs_show_devname(struct seq_file *m, struct dentry *root)
{
- char *page = (char *) __get_free_page(GFP_KERNEL);
+ char *page = kmalloc(PAGE_SIZE, GFP_KERNEL);
char *devname, *dummy;
int err = 0;
if (!page)
@@ -633,7 +633,7 @@ int nfs_show_devname(struct seq_file *m, struct dentry *root)
err = PTR_ERR(devname);
else
seq_escape(m, devname, " \t\n\\");
- free_page((unsigned long)page);
+ kfree(page);
return err;
}
EXPORT_SYMBOL_GPL(nfs_show_devname);
--
2.53.0
^ permalink raw reply related
* [PATCH 04/17] nilfs2: replace get_zeroed_page() with kzalloc()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
In-Reply-To: <20260523-b4-fs-v1-0-275e36a83f0e@kernel.org>
nilfs_ioctl_wrap_copy() allocates a temporary buffer with
get_zeroed_page().
kzalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of get_zeroed_page() with kzalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
fs/nilfs2/ioctl.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index e0a606643e87..b73f2c5d10f0 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -69,7 +69,7 @@ static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
if (argv->v_index > ~(__u64)0 - argv->v_nmembs)
return -EINVAL;
- buf = (void *)get_zeroed_page(GFP_NOFS);
+ buf = kzalloc(PAGE_SIZE, GFP_NOFS);
if (unlikely(!buf))
return -ENOMEM;
maxmembs = PAGE_SIZE / argv->v_size;
@@ -107,7 +107,7 @@ static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
}
argv->v_nmembs = total;
- free_pages((unsigned long)buf, 0);
+ kfree(buf);
return ret;
}
--
2.53.0
^ permalink raw reply related
* [PATCH 03/17] ocfs2/dlm: replace __get_free_page() with kmalloc()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
In-Reply-To: <20260523-b4-fs-v1-0-275e36a83f0e@kernel.org>
A few places in ocsfs2 allocate temporary buffers with __get_free_page() or
get_zeroed_page().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() and get_zeroed_page() with kmalloc() and
kzalloc() respectively.
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
fs/ocfs2/dlm/dlmdebug.c | 24 +++++++++---------------
fs/ocfs2/dlm/dlmdomain.c | 8 +++++---
fs/ocfs2/dlm/dlmmaster.c | 5 ++---
fs/ocfs2/dlm/dlmrecovery.c | 4 ++--
4 files changed, 18 insertions(+), 23 deletions(-)
diff --git a/fs/ocfs2/dlm/dlmdebug.c b/fs/ocfs2/dlm/dlmdebug.c
index fe4fdd09bae3..6ca8b3b68eef 100644
--- a/fs/ocfs2/dlm/dlmdebug.c
+++ b/fs/ocfs2/dlm/dlmdebug.c
@@ -260,10 +260,10 @@ void dlm_print_one_mle(struct dlm_master_list_entry *mle)
{
char *buf;
- buf = (char *) get_zeroed_page(GFP_ATOMIC);
+ buf = kzalloc(PAGE_SIZE, GFP_ATOMIC);
if (buf) {
dump_mle(mle, buf, PAGE_SIZE - 1);
- free_page((unsigned long)buf);
+ kfree(buf);
}
}
@@ -280,7 +280,7 @@ static struct dentry *dlm_debugfs_root;
/* begin - utils funcs */
static int debug_release(struct inode *inode, struct file *file)
{
- free_page((unsigned long)file->private_data);
+ kfree(file->private_data);
return 0;
}
@@ -327,17 +327,15 @@ static int debug_purgelist_open(struct inode *inode, struct file *file)
struct dlm_ctxt *dlm = inode->i_private;
char *buf = NULL;
- buf = (char *) get_zeroed_page(GFP_NOFS);
+ buf = kzalloc(PAGE_SIZE, GFP_NOFS);
if (!buf)
- goto bail;
+ return -ENOMEM;
i_size_write(inode, debug_purgelist_print(dlm, buf, PAGE_SIZE - 1));
file->private_data = buf;
return 0;
-bail:
- return -ENOMEM;
}
static const struct file_operations debug_purgelist_fops = {
@@ -384,17 +382,15 @@ static int debug_mle_open(struct inode *inode, struct file *file)
struct dlm_ctxt *dlm = inode->i_private;
char *buf = NULL;
- buf = (char *) get_zeroed_page(GFP_NOFS);
+ buf = kzalloc(PAGE_SIZE, GFP_NOFS);
if (!buf)
- goto bail;
+ return -ENOMEM;
i_size_write(inode, debug_mle_print(dlm, buf, PAGE_SIZE - 1));
file->private_data = buf;
return 0;
-bail:
- return -ENOMEM;
}
static const struct file_operations debug_mle_fops = {
@@ -775,17 +771,15 @@ static int debug_state_open(struct inode *inode, struct file *file)
struct dlm_ctxt *dlm = inode->i_private;
char *buf = NULL;
- buf = (char *) get_zeroed_page(GFP_NOFS);
+ buf = kzalloc(PAGE_SIZE, GFP_NOFS);
if (!buf)
- goto bail;
+ return -ENOMEM;
i_size_write(inode, debug_state_print(dlm, buf, PAGE_SIZE - 1));
file->private_data = buf;
return 0;
-bail:
- return -ENOMEM;
}
static const struct file_operations debug_state_fops = {
diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index dc9da9133c8e..97bb9400e24b 100644
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -63,7 +63,7 @@ static inline void byte_copymap(u8 dmap[], unsigned long smap[],
static void dlm_free_pagevec(void **vec, int pages)
{
while (pages--)
- free_page((unsigned long)vec[pages]);
+ kfree(vec[pages]);
kfree(vec);
}
@@ -75,9 +75,11 @@ static void **dlm_alloc_pagevec(int pages)
if (!vec)
return NULL;
- for (i = 0; i < pages; i++)
- if (!(vec[i] = (void *)__get_free_page(GFP_KERNEL)))
+ for (i = 0; i < pages; i++) {
+ vec[i] = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!vec[i])
goto out_free;
+ }
mlog(0, "Allocated DLM hash pagevec; %d pages (%lu expected), %lu buckets per page\n",
pages, (unsigned long)DLM_HASH_PAGES,
diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 93eff38fdadd..aee3b4c56dcc 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -2548,7 +2548,7 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
/* preallocate up front. if this fails, abort */
ret = -ENOMEM;
- mres = (struct dlm_migratable_lockres *) __get_free_page(GFP_NOFS);
+ mres = kmalloc(PAGE_SIZE, GFP_NOFS);
if (!mres) {
mlog_errno(ret);
goto leave;
@@ -2725,8 +2725,7 @@ static int dlm_migrate_lockres(struct dlm_ctxt *dlm,
if (wake)
wake_up(&res->wq);
- if (mres)
- free_page((unsigned long)mres);
+ kfree(mres);
dlm_put(dlm);
diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
index 128872bd945d..9b97bf73df22 100644
--- a/fs/ocfs2/dlm/dlmrecovery.c
+++ b/fs/ocfs2/dlm/dlmrecovery.c
@@ -837,7 +837,7 @@ int dlm_request_all_locks_handler(struct o2net_msg *msg, u32 len, void *data,
}
/* this will get freed by dlm_request_all_locks_worker */
- buf = (char *) __get_free_page(GFP_NOFS);
+ buf = kmalloc(PAGE_SIZE, GFP_NOFS);
if (!buf) {
kfree(item);
dlm_put(dlm);
@@ -933,7 +933,7 @@ static void dlm_request_all_locks_worker(struct dlm_work_item *item, void *data)
}
}
leave:
- free_page((unsigned long)data);
+ kfree(data);
}
--
2.53.0
^ permalink raw reply related
* [PATCH 02/17] proc: replace __get_free_page() with kmalloc()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
In-Reply-To: <20260523-b4-fs-v1-0-275e36a83f0e@kernel.org>
A few functions in fs/proc/base.c use __get_free_page() to allocate a
temporary buffer.
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_page() with kmalloc().
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
fs/proc/base.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index d9acfa89c894..e129dc509b79 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -261,7 +261,7 @@ static ssize_t get_mm_proctitle(struct mm_struct *mm, char __user *buf,
if (pos >= PAGE_SIZE)
return 0;
- page = (char *)__get_free_page(GFP_KERNEL);
+ page = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!page)
return -ENOMEM;
@@ -284,7 +284,7 @@ static ssize_t get_mm_proctitle(struct mm_struct *mm, char __user *buf,
ret = len;
}
}
- free_page((unsigned long)page);
+ kfree(page);
return ret;
}
@@ -347,7 +347,7 @@ static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf,
if (count > arg_end - pos)
count = arg_end - pos;
- page = (char *)__get_free_page(GFP_KERNEL);
+ page = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!page)
return -ENOMEM;
@@ -371,7 +371,7 @@ static ssize_t get_mm_cmdline(struct mm_struct *mm, char __user *buf,
count -= got;
}
- free_page((unsigned long)page);
+ kfree(page);
return len;
}
@@ -908,7 +908,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
if (!mm)
return 0;
- page = (char *)__get_free_page(GFP_KERNEL);
+ page = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!page)
return -ENOMEM;
@@ -949,7 +949,7 @@ static ssize_t mem_rw(struct file *file, char __user *buf,
mmput(mm);
free:
- free_page((unsigned long) page);
+ kfree(page);
return copied;
}
@@ -1016,7 +1016,7 @@ static ssize_t environ_read(struct file *file, char __user *buf,
if (!mm || !mm->env_end)
return 0;
- page = (char *)__get_free_page(GFP_KERNEL);
+ page = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!page)
return -ENOMEM;
@@ -1062,7 +1062,7 @@ static ssize_t environ_read(struct file *file, char __user *buf,
mmput(mm);
free:
- free_page((unsigned long) page);
+ kfree(page);
return ret;
}
--
2.53.0
^ permalink raw reply related
* [PATCH 01/17] quota: allocate dquot_hash with kmalloc()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
In-Reply-To: <20260523-b4-fs-v1-0-275e36a83f0e@kernel.org>
dquot_init() allocates a single page for dquot_hash with
__get_free_pages().
kmalloc() is a better API for such use and it also provides better
scalability and more debugging possibilities.
Replace use of __get_free_pages() with kmalloc() and get rid of the order
variable that remained 0 for more than 20 years.
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
fs/quota/dquot.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 64cf42721496..9850de3955d3 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -3022,7 +3022,7 @@ static const struct ctl_table fs_dqstats_table[] = {
static int __init dquot_init(void)
{
int i, ret;
- unsigned long nr_hash, order;
+ unsigned long nr_hash;
struct shrinker *dqcache_shrinker;
printk(KERN_NOTICE "VFS: Disk quotas %s\n", __DQUOT_VERSION__);
@@ -3035,8 +3035,7 @@ static int __init dquot_init(void)
SLAB_PANIC),
NULL);
- order = 0;
- dquot_hash = (struct hlist_head *)__get_free_pages(GFP_KERNEL, order);
+ dquot_hash = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (!dquot_hash)
panic("Cannot create dquot hash table");
@@ -3046,7 +3045,7 @@ static int __init dquot_init(void)
panic("Cannot create dquot stat counters");
/* Find power-of-two hlist_heads which can fit into allocation */
- nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head);
+ nr_hash = PAGE_SIZE / sizeof(struct hlist_head);
dq_hash_bits = ilog2(nr_hash);
nr_hash = 1UL << dq_hash_bits;
@@ -3054,8 +3053,8 @@ static int __init dquot_init(void)
for (i = 0; i < nr_hash; i++)
INIT_HLIST_HEAD(dquot_hash + i);
- pr_info("VFS: Dquot-cache hash table entries: %ld (order %ld,"
- " %ld bytes)\n", nr_hash, order, (PAGE_SIZE << order));
+ pr_info("VFS: Dquot-cache hash table entries: %ld (%ld bytes)\n",
+ nr_hash, PAGE_SIZE);
dqcache_shrinker = shrinker_alloc(0, "dquota-cache");
if (!dqcache_shrinker)
--
2.53.0
^ permalink raw reply related
* [PATCH 00/17] fs: replace __get_free_pages() call with kmalloc()
From: Mike Rapoport (Microsoft) @ 2026-05-23 17:54 UTC (permalink / raw)
To: Jan Kara, Mark Fasheh, Joel Becker, Joseph Qi, Ryusuke Konishi,
Viacheslav Dubeyko, Trond Myklebust, Anna Schumaker, Chuck Lever,
Jeff Layton, NeilBrown, Olga Kornievskaia, Dai Ngo, Tom Talpey,
Alexander Viro, Christian Brauner, Jan Kara, Dave Kleikamp,
Theodore Ts'o, Miklos Szeredi, Andreas Hindborg, Breno Leitao,
Kees Cook, Tigran A. Aivazian
Cc: linux-kernel, linux-fsdevel, ocfs2-devel, linux-nilfs, linux-nfs,
jfs-discussion, linux-ext4, linux-mm, Mike Rapoport (Microsoft)
This is a (small) part of larger work of replacing page allocator calls
with kmalloc.
Also in git:
https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git gfp-to-kmalloc/fs
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
Mike Rapoport (Microsoft) (17):
quota: allocate dquot_hash with kmalloc()
proc: replace __get_free_page() with kmalloc()
ocfs2/dlm: replace __get_free_page() with kmalloc()
nilfs2: replace get_zeroed_page() with kzalloc()
NFS: replace __get_free_page() with kmalloc() in nfs_show_devname()
NFS: remove unused page and page2 in nfs4_replace_transport()
NFSD: replace __get_free_page() with kmalloc() in nfsd_buffered_readdir()
libfs: simple_transaction_get(): replace get_zeroed_page() with kzalloc()
jfs: replace __get_free_page() with kmalloc()
jbd2: replace __get_free_pages() with kmalloc()
isofs: replace __get_free_page() with kmalloc()
fuse: replace __get_free_page() with kmalloc()
fs/select: replace __get_free_page() with kmalloc()
fs/namespace: use __getname() to allocate mntpath buffer
configfs: replace __get_free_pages() with kzalloc()
binfmt_misc: replace __get_free_page() with kmalloc()
bfs: replace get_zeroed_page() with kzalloc()
fs/bfs/inode.c | 4 ++--
fs/binfmt_misc.c | 4 ++--
fs/configfs/file.c | 7 +++----
fs/fuse/ioctl.c | 5 +++--
fs/isofs/dir.c | 5 +++--
fs/jbd2/journal.c | 7 ++-----
fs/jfs/jfs_dtree.c | 16 ++++++++--------
fs/libfs.c | 6 +++---
fs/namespace.c | 4 ++--
fs/nfs/nfs4namespace.c | 15 +--------------
fs/nfs/super.c | 4 ++--
fs/nfsd/vfs.c | 4 ++--
fs/nilfs2/ioctl.c | 4 ++--
fs/ocfs2/dlm/dlmdebug.c | 24 +++++++++---------------
fs/ocfs2/dlm/dlmdomain.c | 8 +++++---
fs/ocfs2/dlm/dlmmaster.c | 5 ++---
fs/ocfs2/dlm/dlmrecovery.c | 4 ++--
fs/proc/base.c | 16 ++++++++--------
fs/quota/dquot.c | 11 +++++------
fs/select.c | 4 ++--
20 files changed, 68 insertions(+), 89 deletions(-)
---
base-commit: 5d6919055dec134de3c40167a490f33c74c12581
change-id: 20260522-b4-fs-5e5c70f31664
Best regards,
--
Sincerely yours,
Mike.
^ permalink raw reply
* Re: DEPT (the dependency tracker) as AI review prompt?
From: Yunseong Kim @ 2026-05-23 15:04 UTC (permalink / raw)
To: Harry Yoo, Yunseong Kim
Cc: Byungchul Park, linux-kernel, kernel_team, torvalds,
damien.lemoal, linux-ide, adilger.kernel, linux-ext4, mingo,
peterz, will, tglx, rostedt, joel, sashal, daniel.vetter,
duyuyang, johannes.berg, tj, tytso, willy, david, amir73il,
gregkh, kernel-team, linux-mm, akpm, mhocko, minchan, hannes,
vdavydov.dev, sj, jglisse, dennis, cl, penberg, rientjes, vbabka,
ngupta, linux-block, linux-fsdevel, jack, jlayton, dan.j.williams,
hch, djwong, dri-devel, rodrigosiqueiramelo, melissa.srw,
hamohammed.sa, harry.yoo, chris.p.wilson, gwan-gyeong.mun,
max.byungchul.park, boqun.feng, longman, yunseong.kim,
yeoreum.yun, netdev, matthew.brost, her0gyugyu, corbet,
catalin.marinas, bp, x86, hpa, luto, sumit.semwal, gustavo,
christian.koenig, andi.shyti, arnd, lorenzo.stoakes, Liam.Howlett,
rppt, surenb, mcgrof, petr.pavlu, da.gomez, samitolvanen, paulmck,
frederic, neeraj.upadhyay, joelagnelf, josh, urezki,
mathieu.desnoyers, jiangshanlai, qiang.zhang, juri.lelli,
vincent.guittot, dietmar.eggemann, bsegall, mgorman, vschneid,
chuck.lever, neil, okorniev, Dai.Ngo, tom, trondmy, anna, kees,
bigeasy, clrkwllms, mark.rutland, ada.coupriediaz,
kristina.martsenko, wangkefeng.wang, broonie, kevin.brodsky, dwmw,
shakeel.butt, ast, ziy, yuzhao, baolin.wang, usamaarif642,
joel.granados, richard.weiyang, geert+renesas, tim.c.chen, linux,
alexander.shishkin, lillian, chenhuacai, francesco,
guoweikang.kernel, link, jpoimboe, masahiroy, brauner,
thomas.weissschuh, oleg, mjguzik, andrii, wangfushuai, linux-doc,
linux-arm-kernel, linux-media, linaro-mm-sig, linux-i2c,
linux-arch, linux-modules, rcu, linux-nfs, linux-rt-devel,
2407018371, dakr, miguel.ojeda.sandonis, neilb, bagasdotme,
wsa+renesas, dave.hansen, geert, ojeda, alex.gaynor, gary,
bjorn3_gh, lossin, a.hindborg, aliceryhl, tmgross, rust-for-linux,
Chris Mason, Roman Gushchin, Josef Bacik
In-Reply-To: <0592b09b-a084-4d9d-bcbf-1b77e45226cf@kernel.org>
Hi Harry,
On 5/23/26 16:34, Harry Yoo wrote:
>
>
> On 5/23/26 11:00 PM, Yunseong Kim wrote:
>> I've previously experimented with running DEPT alongside syzkaller fuzzing,
>> and many hung tasks missed by lockdep are caught by DEPT, but the resulting
>> high volume of reports makes it easy for issues to get lost in the massive
>> log output. Sorting through that output manually is a huge bottleneck, so
>> leveraging a well-crafted AI prompt to triage the warnings and filter out
>> the false positives would be incredibly valuable.
>
> I mean both 1) detection of deadlock issues AND 2) false positive elimination with AI.
I completely agree. Implanting DEPT's model into an AI review prompt
is a great idea. As you suggested, the patterns we develop for the AI
could provide valuable feedback to enhance DEPT's itself.
> If the review prompt is only used to eliminate DEPT's false positives, I think that would be quite hard to get broad use.
>
> Someone would have to build out-of-tree DEPT, collect the reports, and then feed those back into the AI. I don't think building that kind of pipeline would actually work well in practice.
I also have a huge dept report of DEPT reports, and manually
reviewing all of them is makes me sigh. The constant kernel rebuilds
required for lockup testing every time are also quite expensive.
Thanks for the summary!
Best Regards,
Yunseong
^ permalink raw reply
* Re: DEPT (the dependency tracker) as AI review prompt?
From: Harry Yoo @ 2026-05-23 14:34 UTC (permalink / raw)
To: Yunseong Kim
Cc: Byungchul Park, linux-kernel, kernel_team, torvalds,
damien.lemoal, linux-ide, adilger.kernel, linux-ext4, mingo,
peterz, will, tglx, rostedt, joel, sashal, daniel.vetter,
duyuyang, johannes.berg, tj, tytso, willy, david, amir73il,
gregkh, kernel-team, linux-mm, akpm, mhocko, minchan, hannes,
vdavydov.dev, sj, jglisse, dennis, cl, penberg, rientjes, vbabka,
ngupta, linux-block, linux-fsdevel, jack, jlayton, dan.j.williams,
hch, djwong, dri-devel, rodrigosiqueiramelo, melissa.srw,
hamohammed.sa, harry.yoo, chris.p.wilson, gwan-gyeong.mun,
max.byungchul.park, boqun.feng, longman, yunseong.kim,
yeoreum.yun, netdev, matthew.brost, her0gyugyu, corbet,
catalin.marinas, bp, x86, hpa, luto, sumit.semwal, gustavo,
christian.koenig, andi.shyti, arnd, lorenzo.stoakes, Liam.Howlett,
rppt, surenb, mcgrof, petr.pavlu, da.gomez, samitolvanen, paulmck,
frederic, neeraj.upadhyay, joelagnelf, josh, urezki,
mathieu.desnoyers, jiangshanlai, qiang.zhang, juri.lelli,
vincent.guittot, dietmar.eggemann, bsegall, mgorman, vschneid,
chuck.lever, neil, okorniev, Dai.Ngo, tom, trondmy, anna, kees,
bigeasy, clrkwllms, mark.rutland, ada.coupriediaz,
kristina.martsenko, wangkefeng.wang, broonie, kevin.brodsky, dwmw,
shakeel.butt, ast, ziy, yuzhao, baolin.wang, usamaarif642,
joel.granados, richard.weiyang, geert+renesas, tim.c.chen, linux,
alexander.shishkin, lillian, chenhuacai, francesco,
guoweikang.kernel, link, jpoimboe, masahiroy, brauner,
thomas.weissschuh, oleg, mjguzik, andrii, wangfushuai, linux-doc,
linux-arm-kernel, linux-media, linaro-mm-sig, linux-i2c,
linux-arch, linux-modules, rcu, linux-nfs, linux-rt-devel,
2407018371, dakr, miguel.ojeda.sandonis, neilb, bagasdotme,
wsa+renesas, dave.hansen, geert, ojeda, alex.gaynor, gary,
bjorn3_gh, lossin, a.hindborg, aliceryhl, tmgross, rust-for-linux,
Chris Mason, Roman Gushchin, Josef Bacik, Yunseong Kim
In-Reply-To: <CA+7O06GxeDLR9RcKDN2i-Rgc4kgzz6BfF4b0XAH4tFx=A723Nw@mail.gmail.com>
On 5/23/26 11:00 PM, Yunseong Kim wrote:
> I've previously experimented with running DEPT alongside syzkaller fuzzing,
> and many hung tasks missed by lockdep are caught by DEPT, but the resulting
> high volume of reports makes it easy for issues to get lost in the massive
> log output. Sorting through that output manually is a huge bottleneck, so
> leveraging a well-crafted AI prompt to triage the warnings and filter out
> the false positives would be incredibly valuable.
I mean both 1) detection of deadlock issues AND 2) false positive
elimination with AI.
If the review prompt is only used to eliminate DEPT's false positives, I
think that would be quite hard to get broad use.
Someone would have to build out-of-tree DEPT, collect the reports, and
then feed those back into the AI. I don't think building that kind of
pipeline would actually work well in practice.
--
Cheers,
Harry / Hyeonggon
^ permalink raw reply
* Re: DEPT (the dependency tracker) as AI review prompt? (was: DEPT v18)
From: Yunseong Kim @ 2026-05-23 14:00 UTC (permalink / raw)
To: Harry Yoo
Cc: Byungchul Park, linux-kernel, kernel_team, torvalds,
damien.lemoal, linux-ide, adilger.kernel, linux-ext4, mingo,
peterz, will, tglx, rostedt, joel, sashal, daniel.vetter,
duyuyang, johannes.berg, tj, tytso, willy, david, amir73il,
gregkh, kernel-team, linux-mm, akpm, mhocko, minchan, hannes,
vdavydov.dev, sj, jglisse, dennis, cl, penberg, rientjes, vbabka,
ngupta, linux-block, linux-fsdevel, jack, jlayton, dan.j.williams,
hch, djwong, dri-devel, rodrigosiqueiramelo, melissa.srw,
hamohammed.sa, harry.yoo, chris.p.wilson, gwan-gyeong.mun,
max.byungchul.park, boqun.feng, longman, yunseong.kim, ysk,
yeoreum.yun, netdev, matthew.brost, her0gyugyu, corbet,
catalin.marinas, bp, x86, hpa, luto, sumit.semwal, gustavo,
christian.koenig, andi.shyti, arnd, lorenzo.stoakes, Liam.Howlett,
rppt, surenb, mcgrof, petr.pavlu, da.gomez, samitolvanen, paulmck,
frederic, neeraj.upadhyay, joelagnelf, josh, urezki,
mathieu.desnoyers, jiangshanlai, qiang.zhang, juri.lelli,
vincent.guittot, dietmar.eggemann, bsegall, mgorman, vschneid,
chuck.lever, neil, okorniev, Dai.Ngo, tom, trondmy, anna, kees,
bigeasy, clrkwllms, mark.rutland, ada.coupriediaz,
kristina.martsenko, wangkefeng.wang, broonie, kevin.brodsky, dwmw,
shakeel.butt, ast, ziy, yuzhao, baolin.wang, usamaarif642,
joel.granados, richard.weiyang, geert+renesas, tim.c.chen, linux,
alexander.shishkin, lillian, chenhuacai, francesco,
guoweikang.kernel, link, jpoimboe, masahiroy, brauner,
thomas.weissschuh, oleg, mjguzik, andrii, wangfushuai, linux-doc,
linux-arm-kernel, linux-media, linaro-mm-sig, linux-i2c,
linux-arch, linux-modules, rcu, linux-nfs, linux-rt-devel,
2407018371, dakr, miguel.ojeda.sandonis, neilb, bagasdotme,
wsa+renesas, dave.hansen, geert, ojeda, alex.gaynor, gary,
bjorn3_gh, lossin, a.hindborg, aliceryhl, tmgross, rust-for-linux,
Chris Mason, Roman Gushchin, Josef Bacik, Yunseong Kim
In-Reply-To: <6b2a816f-eb3b-4e0c-a024-ee2e3743eb04@kernel.org>
Hi Harry,
On Sat, May 23, 2026 at 2:33 PM Harry Yoo <harry@kernel.org> wrote:
>
> Can we start DEPT as an AI review prompt, by documenting DEPT's
> dependency tracking model and false positive elimination rules as a
> carefully crafted prompt?
>
> While DEPT can identify deadlock issues beyond lockdep's capabilities,
> it is hard to enable in automated testing; without fine-grained
> annotations it can produce a high rate of false positives, and verifying
> them requires significant human effort.
>
> The open source AI Review Prompt has locking.md file [1] that teaches
> the AI how to review locks and detect misuse.
>
> If we can write a review prompt for DEPT in a similar manner and have
> the AI do the deadlock detection and false positive elimination, I think
> we could identify those problems more effectively with much less human
> effort.
>
> [1]
> https://github.com/masoncl/review-prompts/blob/main/kernel/subsystem/locking.md
>
> --
> Cheers,
> Harry / Hyeonggon
I think this is an excellent idea, Harry.
I've previously experimented with running DEPT alongside syzkaller fuzzing,
and many hung tasks missed by lockdep are caught by DEPT, but the resulting
high volume of reports makes it easy for issues to get lost in the massive
log output. Sorting through that output manually is a huge bottleneck, so
leveraging a well-crafted AI prompt to triage the warnings and filter out
the false positives would be incredibly valuable.
Leveraging an AI prompt to triage these warnings would be incredibly valuable.
I'd be happy to help translate DEPT's tracking model into specific rules for
reducing false positives and establishing solid filtering patterns.
> On 12/5/25 4:18 PM, Byungchul Park wrote:
> > I'm happy to see that DEPT reported real problems in practice:
> >
> > https://lore.kernel.org/lkml/6383cde5-cf4b-facf-6e07-1378a485657d@I-love.SAKURA.ne.jp/
> > https://lore.kernel.org/lkml/1674268856-31807-1-git-send-email-byungchul.park@lge.com/
> > https://lore.kernel.org/all/b6e00e77-4a8c-4e05-ab79-266bf05fcc2d@igalia.com/
> >
> > I’ve added documentation describing DEPT — this should help you
> > understand what DEPT is and how it works. You can use DEPT simply by
> > enabling CONFIG_DEPT and checking dmesg at runtime.
> > ---
> >
> > Hi Linus and folks,
> >
> > I’ve been developing a tool to detect deadlock possibilities by tracking
> > waits/events — rather than lock acquisition order — to cover all the
> > synchronization mechanisms. To summarize the design rationale, starting
> > from the problem statement, through analysis, to the solution:
> >
> > CURRENT STATUS
> > --------------
> > Lockdep tracks lock acquisition order to identify deadlock conditions.
> > Additionally, it tracks IRQ state changes — via {en,dis}able — to
> > detect cases where locks are acquired unintentionally during
> > interrupt handling.
> >
> > PROBLEM
> > -------
> > Waits and their associated events that are never reachable can
> > eventually lead to deadlocks. However, since Lockdep focuses solely
> > on lock acquisition order, it has inherent limitations when handling
> > waits and events.
> >
> > Moreover, by tracking only lock acquisition order, Lockdep cannot
> > properly handle read locks or cross-event scenarios — such as
> > wait_for_completion() and complete() — making it increasingly
> > inadequate as a general-purpose deadlock detection tool.
> >
> > SOLUTION
> > --------
> > Once again, waits and their associated events that are never
> > reachable can eventually lead to deadlocks. The new solution, DEPT,
> > focuses directly on waits and events. DEPT monitors waits and events,
> > and reports them when any become unreachable.
> >
> > DEPT provides:
> >
> > * Correct handling of read locks.
> > * Support for general waits and events.
> > * Continuous operation, even after multiple reports.
> > * Simple, intuitive annotation APIs.
> >
> > There are still false positives, and some are already being worked on
> > for suppression. Especially splitting the folio class into several
> > appropriate classes e.g. block device mapping class and regular file
> > mapping class, is currently under active development by me and Yeoreum
> > Yun.
> >> Anyway, these efforts will need to continue for a while, as we’ve seen
> > with lockdep over two decades. DEPT is tagged as EXPERIMENTAL in
> > Kconfig — meaning it’s not yet suitable for use as an automation tool.
> >
> > However, for those who are interested in using DEPT to analyze complex
> > synchronization patterns and extract dependency insights, DEPT would be
> > a great tool for the purpose.
Best regards,
Yunseong
^ permalink raw reply
* DEPT (the dependency tracker) as AI review prompt? (was: DEPT v18)
From: Harry Yoo @ 2026-05-23 12:32 UTC (permalink / raw)
To: Byungchul Park, linux-kernel
Cc: kernel_team, torvalds, damien.lemoal, linux-ide, adilger.kernel,
linux-ext4, mingo, peterz, will, tglx, rostedt, joel, sashal,
daniel.vetter, duyuyang, johannes.berg, tj, tytso, willy, david,
amir73il, gregkh, kernel-team, linux-mm, akpm, mhocko, minchan,
hannes, vdavydov.dev, sj, jglisse, dennis, cl, penberg, rientjes,
vbabka, ngupta, linux-block, josef, linux-fsdevel, jack, jlayton,
dan.j.williams, hch, djwong, dri-devel, rodrigosiqueiramelo,
melissa.srw, hamohammed.sa, harry.yoo, chris.p.wilson,
gwan-gyeong.mun, max.byungchul.park, boqun.feng, longman,
yunseong.kim, ysk, yeoreum.yun, netdev, matthew.brost, her0gyugyu,
corbet, catalin.marinas, bp, x86, hpa, luto, sumit.semwal,
gustavo, christian.koenig, andi.shyti, arnd, lorenzo.stoakes,
Liam.Howlett, rppt, surenb, mcgrof, petr.pavlu, da.gomez,
samitolvanen, paulmck, frederic, neeraj.upadhyay, joelagnelf,
josh, urezki, mathieu.desnoyers, jiangshanlai, qiang.zhang,
juri.lelli, vincent.guittot, dietmar.eggemann, bsegall, mgorman,
vschneid, chuck.lever, neil, okorniev, Dai.Ngo, tom, trondmy,
anna, kees, bigeasy, clrkwllms, mark.rutland, ada.coupriediaz,
kristina.martsenko, wangkefeng.wang, broonie, kevin.brodsky, dwmw,
shakeel.butt, ast, ziy, yuzhao, baolin.wang, usamaarif642,
joel.granados, richard.weiyang, geert+renesas, tim.c.chen, linux,
alexander.shishkin, lillian, chenhuacai, francesco,
guoweikang.kernel, link, jpoimboe, masahiroy, brauner,
thomas.weissschuh, oleg, mjguzik, andrii, wangfushuai, linux-doc,
linux-arm-kernel, linux-media, linaro-mm-sig, linux-i2c,
linux-arch, linux-modules, rcu, linux-nfs, linux-rt-devel,
2407018371, dakr, miguel.ojeda.sandonis, neilb, bagasdotme,
wsa+renesas, dave.hansen, geert, ojeda, alex.gaynor, gary,
bjorn3_gh, lossin, a.hindborg, aliceryhl, tmgross, rust-for-linux,
Chris Mason, Roman Gushchin, Josef Bacik
In-Reply-To: <20251205071855.72743-1-byungchul@sk.com>
Can we start DEPT as an AI review prompt, by documenting DEPT's
dependency tracking model and false positive elimination rules as a
carefully crafted prompt?
While DEPT can identify deadlock issues beyond lockdep's capabilities,
it is hard to enable in automated testing; without fine-grained
annotations it can produce a high rate of false positives, and verifying
them requires significant human effort.
The open source AI Review Prompt has locking.md file [1] that teaches
the AI how to review locks and detect misuse.
If we can write a review prompt for DEPT in a similar manner and have
the AI do the deadlock detection and false positive elimination, I think
we could identify those problems more effectively with much less human
effort.
[1]
https://github.com/masoncl/review-prompts/blob/main/kernel/subsystem/locking.md
--
Cheers,
Harry / Hyeonggon
On 12/5/25 4:18 PM, Byungchul Park wrote:
> I'm happy to see that DEPT reported real problems in practice:
>
> https://lore.kernel.org/lkml/6383cde5-cf4b-facf-6e07-1378a485657d@I-love.SAKURA.ne.jp/
> https://lore.kernel.org/lkml/1674268856-31807-1-git-send-email-byungchul.park@lge.com/
> https://lore.kernel.org/all/b6e00e77-4a8c-4e05-ab79-266bf05fcc2d@igalia.com/
>
> I’ve added documentation describing DEPT — this should help you
> understand what DEPT is and how it works. You can use DEPT simply by
> enabling CONFIG_DEPT and checking dmesg at runtime.
> ---
>
> Hi Linus and folks,
>
> I’ve been developing a tool to detect deadlock possibilities by tracking
> waits/events — rather than lock acquisition order — to cover all the
> synchronization mechanisms. To summarize the design rationale, starting
> from the problem statement, through analysis, to the solution:
>
> CURRENT STATUS
> --------------
> Lockdep tracks lock acquisition order to identify deadlock conditions.
> Additionally, it tracks IRQ state changes — via {en,dis}able — to
> detect cases where locks are acquired unintentionally during
> interrupt handling.
>
> PROBLEM
> -------
> Waits and their associated events that are never reachable can
> eventually lead to deadlocks. However, since Lockdep focuses solely
> on lock acquisition order, it has inherent limitations when handling
> waits and events.
>
> Moreover, by tracking only lock acquisition order, Lockdep cannot
> properly handle read locks or cross-event scenarios — such as
> wait_for_completion() and complete() — making it increasingly
> inadequate as a general-purpose deadlock detection tool.
>
> SOLUTION
> --------
> Once again, waits and their associated events that are never
> reachable can eventually lead to deadlocks. The new solution, DEPT,
> focuses directly on waits and events. DEPT monitors waits and events,
> and reports them when any become unreachable.
>
> DEPT provides:
>
> * Correct handling of read locks.
> * Support for general waits and events.
> * Continuous operation, even after multiple reports.
> * Simple, intuitive annotation APIs.
>
> There are still false positives, and some are already being worked on
> for suppression. Especially splitting the folio class into several
> appropriate classes e.g. block device mapping class and regular file
> mapping class, is currently under active development by me and Yeoreum
> Yun.
>> Anyway, these efforts will need to continue for a while, as we’ve seen
> with lockdep over two decades. DEPT is tagged as EXPERIMENTAL in
> Kconfig — meaning it’s not yet suitable for use as an automation tool.
>
> However, for those who are interested in using DEPT to analyze complex
> synchronization patterns and extract dependency insights, DEPT would be
> a great tool for the purpose.
^ permalink raw reply
* [PATCH] ext2: Remove deprecated DAX support
From: Ashwin Gundarapu @ 2026-05-23 12:20 UTC (permalink / raw)
To: jack; +Cc: linux-ext4, linux-kernel
DAX support in ext2 was deprecated in commit d5a2693f93e4
("ext2: Deprecate DAX") with a removal deadline of end of 2025.
Remove all DAX code from ext2 as scheduled.
This removes the DAX mount option, IOMAP DAX support, DAX file
operations, DAX address_space_operations, and the DAX fault handler.
Signed-off-by: Ashwin Gundarapu <linuxuser509@zohomail.in>
---
fs/ext2/ext2.h | 5 +-
fs/ext2/file.c | 118 ++----------------------------------------------
fs/ext2/inode.c | 60 ++----------------------
fs/ext2/super.c | 45 +++---------------
4 files changed, 16 insertions(+), 212 deletions(-)
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 3eb1f342645c..3a26308ec841 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -114,8 +114,6 @@ struct ext2_sb_info {
*/
spinlock_t s_lock;
struct mb_cache *s_ea_block_cache;
- struct dax_device *s_daxdev;
- u64 s_dax_part_off;
};
static inline spinlock_t *
@@ -373,11 +371,10 @@ struct ext2_inode {
#define EXT2_MOUNT_NO_UID32 0x000200 /* Disable 32-bit UIDs */
#define EXT2_MOUNT_XATTR_USER 0x004000 /* Extended user attributes */
#define EXT2_MOUNT_POSIX_ACL 0x008000 /* POSIX Access Control Lists */
-#define EXT2_MOUNT_XIP 0x010000 /* Obsolete, use DAX */
+#define EXT2_MOUNT_XIP 0x010000 /* Obsolete*/
#define EXT2_MOUNT_USRQUOTA 0x020000 /* user quota */
#define EXT2_MOUNT_GRPQUOTA 0x040000 /* group quota */
#define EXT2_MOUNT_RESERVATION 0x080000 /* Preallocation */
-#define EXT2_MOUNT_DAX 0x100000 /* Direct Access */
#define clear_opt(o, opt) o &= ~EXT2_MOUNT_##opt
diff --git a/fs/ext2/file.c b/fs/ext2/file.c
index d9b1eb34694a..0fd9208af062 100644
--- a/fs/ext2/file.c
+++ b/fs/ext2/file.c
@@ -21,7 +21,6 @@
#include <linux/time.h>
#include <linux/pagemap.h>
-#include <linux/dax.h>
#include <linux/filelock.h>
#include <linux/quotaops.h>
#include <linux/iomap.h>
@@ -32,111 +31,6 @@
#include "acl.h"
#include "trace.h"
-#ifdef CONFIG_FS_DAX
-static ssize_t ext2_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
-{
- struct inode *inode = iocb->ki_filp->f_mapping->host;
- ssize_t ret;
-
- if (!iov_iter_count(to))
- return 0; /* skip atime */
-
- inode_lock_shared(inode);
- ret = dax_iomap_rw(iocb, to, &ext2_iomap_ops);
- inode_unlock_shared(inode);
-
- file_accessed(iocb->ki_filp);
- return ret;
-}
-
-static ssize_t ext2_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
-{
- struct file *file = iocb->ki_filp;
- struct inode *inode = file->f_mapping->host;
- ssize_t ret;
-
- inode_lock(inode);
- ret = generic_write_checks(iocb, from);
- if (ret <= 0)
- goto out_unlock;
- ret = file_remove_privs(file);
- if (ret)
- goto out_unlock;
- ret = file_update_time(file);
- if (ret)
- goto out_unlock;
-
- ret = dax_iomap_rw(iocb, from, &ext2_iomap_ops);
- if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
- i_size_write(inode, iocb->ki_pos);
- mark_inode_dirty(inode);
- }
-
-out_unlock:
- inode_unlock(inode);
- if (ret > 0)
- ret = generic_write_sync(iocb, ret);
- return ret;
-}
-
-/*
- * The lock ordering for ext2 DAX fault paths is:
- *
- * mmap_lock (MM)
- * sb_start_pagefault (vfs, freeze)
- * address_space->invalidate_lock
- * address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
- * ext2_inode_info->truncate_mutex
- *
- * The default page_lock and i_size verification done by non-DAX fault paths
- * is sufficient because ext2 doesn't support hole punching.
- */
-static vm_fault_t ext2_dax_fault(struct vm_fault *vmf)
-{
- struct inode *inode = file_inode(vmf->vma->vm_file);
- vm_fault_t ret;
- bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
- (vmf->vma->vm_flags & VM_SHARED);
-
- if (write) {
- sb_start_pagefault(inode->i_sb);
- file_update_time(vmf->vma->vm_file);
- }
- filemap_invalidate_lock_shared(inode->i_mapping);
-
- ret = dax_iomap_fault(vmf, 0, NULL, NULL, &ext2_iomap_ops);
-
- filemap_invalidate_unlock_shared(inode->i_mapping);
- if (write)
- sb_end_pagefault(inode->i_sb);
- return ret;
-}
-
-static const struct vm_operations_struct ext2_dax_vm_ops = {
- .fault = ext2_dax_fault,
- /*
- * .huge_fault is not supported for DAX because allocation in ext2
- * cannot be reliably aligned to huge page sizes and so pmd faults
- * will always fail and fail back to regular faults.
- */
- .page_mkwrite = ext2_dax_fault,
- .pfn_mkwrite = ext2_dax_fault,
-};
-
-static int ext2_file_mmap_prepare(struct vm_area_desc *desc)
-{
- struct file *file = desc->file;
-
- if (!IS_DAX(file_inode(file)))
- return generic_file_mmap_prepare(desc);
-
- file_accessed(file);
- desc->vm_ops = &ext2_dax_vm_ops;
- return 0;
-}
-#else
-#define ext2_file_mmap_prepare generic_file_mmap_prepare
-#endif
/*
* Called when filp is released. This happens when all file descriptors
@@ -285,10 +179,7 @@ static ssize_t ext2_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
-#ifdef CONFIG_FS_DAX
- if (IS_DAX(iocb->ki_filp->f_mapping->host))
- return ext2_dax_read_iter(iocb, to);
-#endif
+
if (iocb->ki_flags & IOCB_DIRECT)
return ext2_dio_read_iter(iocb, to);
@@ -297,10 +188,7 @@ static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
-#ifdef CONFIG_FS_DAX
- if (IS_DAX(iocb->ki_filp->f_mapping->host))
- return ext2_dax_write_iter(iocb, from);
-#endif
+
if (iocb->ki_flags & IOCB_DIRECT)
return ext2_dio_write_iter(iocb, from);
@@ -321,7 +209,7 @@ const struct file_operations ext2_file_operations = {
#ifdef CONFIG_COMPAT
.compat_ioctl = ext2_compat_ioctl,
#endif
- .mmap_prepare = ext2_file_mmap_prepare,
+ .mmap_prepare = generic_file_mmap_prepare,
.open = ext2_file_open,
.release = ext2_release_file,
.fsync = ext2_fsync,
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 74aca5eb572d..91fc4709836f 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -26,7 +26,6 @@
#include <linux/time.h>
#include <linux/highuid.h>
#include <linux/pagemap.h>
-#include <linux/dax.h>
#include <linux/blkdev.h>
#include <linux/quotaops.h>
#include <linux/writeback.h>
@@ -741,27 +740,6 @@ static int ext2_get_blocks(struct inode *inode,
goto cleanup;
}
- if (IS_DAX(inode)) {
- /*
- * We must unmap blocks before zeroing so that writeback cannot
- * overwrite zeros with stale data from block device page cache.
- */
- clean_bdev_aliases(inode->i_sb->s_bdev,
- le32_to_cpu(chain[depth-1].key),
- count);
- /*
- * block must be initialised before we put it in the tree
- * so that it's not found by another thread before it's
- * initialised
- */
- err = sb_issue_zeroout(inode->i_sb,
- le32_to_cpu(chain[depth-1].key), count,
- GFP_KERNEL);
- if (err) {
- mutex_unlock(&ei->truncate_mutex);
- goto cleanup;
- }
- }
*new = true;
ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
@@ -841,10 +819,7 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
iomap->flags = 0;
iomap->offset = (u64)first_block << blkbits;
- if (flags & IOMAP_DAX)
- iomap->dax_dev = sbi->s_daxdev;
- else
- iomap->bdev = inode->i_sb->s_bdev;
+ iomap->bdev = inode->i_sb->s_bdev;
if (ret == 0) {
/*
@@ -859,8 +834,6 @@ static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
} else {
iomap->type = IOMAP_MAPPED;
iomap->addr = (u64)bno << blkbits;
- if (flags & IOMAP_DAX)
- iomap->addr += sbi->s_dax_part_off;
iomap->length = (u64)ret << blkbits;
iomap->flags |= IOMAP_F_MERGED;
}
@@ -962,13 +935,6 @@ ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
return mpage_writepages(mapping, wbc, ext2_get_block);
}
-static int
-ext2_dax_writepages(struct address_space *mapping, struct writeback_control *wbc)
-{
- struct ext2_sb_info *sbi = EXT2_SB(mapping->host->i_sb);
-
- return dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);
-}
const struct address_space_operations ext2_aops = {
.dirty_folio = block_dirty_folio,
@@ -984,10 +950,6 @@ const struct address_space_operations ext2_aops = {
.error_remove_folio = generic_error_remove_folio,
};
-static const struct address_space_operations ext2_dax_aops = {
- .writepages = ext2_dax_writepages,
- .dirty_folio = noop_dirty_folio,
-};
/*
* Probably it should be a library function... search for first non-zero word
@@ -1186,9 +1148,6 @@ static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
blocksize = inode->i_sb->s_blocksize;
iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
-#ifdef CONFIG_FS_DAX
- WARN_ON(!rwsem_is_locked(&inode->i_mapping->invalidate_lock));
-#endif
n = ext2_block_to_path(inode, iblock, offsets, NULL);
if (n == 0)
@@ -1290,12 +1249,8 @@ static int ext2_setsize(struct inode *inode, loff_t newsize)
inode_dio_wait(inode);
- if (IS_DAX(inode))
- error = dax_truncate_page(inode, newsize, NULL,
- &ext2_iomap_ops);
- else
- error = block_truncate_page(inode->i_mapping,
- newsize, ext2_get_block);
+ error = block_truncate_page(inode->i_mapping,
+ newsize, ext2_get_block);
if (error)
return error;
@@ -1363,7 +1318,7 @@ void ext2_set_inode_flags(struct inode *inode)
unsigned int flags = EXT2_I(inode)->i_flags;
inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME |
- S_DIRSYNC | S_DAX);
+ S_DIRSYNC);
if (flags & EXT2_SYNC_FL)
inode->i_flags |= S_SYNC;
if (flags & EXT2_APPEND_FL)
@@ -1374,18 +1329,13 @@ void ext2_set_inode_flags(struct inode *inode)
inode->i_flags |= S_NOATIME;
if (flags & EXT2_DIRSYNC_FL)
inode->i_flags |= S_DIRSYNC;
- if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
- inode->i_flags |= S_DAX;
}
void ext2_set_file_ops(struct inode *inode)
{
inode->i_op = &ext2_file_inode_operations;
inode->i_fop = &ext2_file_operations;
- if (IS_DAX(inode))
- inode->i_mapping->a_ops = &ext2_dax_aops;
- else
- inode->i_mapping->a_ops = &ext2_aops;
+ inode->i_mapping->a_ops = &ext2_aops;
}
struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 19f76d8cb473..ede4ad84828c 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -34,7 +34,6 @@
#include <linux/log2.h>
#include <linux/quotaops.h>
#include <linux/uaccess.h>
-#include <linux/dax.h>
#include <linux/iversion.h>
#include "ext2.h"
#include "xattr.h"
@@ -198,7 +197,6 @@ static void ext2_put_super (struct super_block * sb)
brelse (sbi->s_sbh);
sb->s_fs_info = NULL;
kfree(sbi->s_blockgroup_lock);
- fs_put_dax(sbi->s_daxdev, NULL);
kfree(sbi);
}
@@ -332,8 +330,6 @@ static int ext2_show_options(struct seq_file *seq, struct dentry *root)
if (test_opt(sb, XIP))
seq_puts(seq, ",xip");
- if (test_opt(sb, DAX))
- seq_puts(seq, ",dax");
if (!test_opt(sb, RESERVATION))
seq_puts(seq, ",noreservation");
@@ -432,7 +428,7 @@ static const struct export_operations ext2_export_ops = {
enum {
Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid, Opt_resgid, Opt_resuid,
Opt_sb, Opt_errors, Opt_nouid32, Opt_debug, Opt_oldalloc, Opt_orlov,
- Opt_nobh, Opt_user_xattr, Opt_acl, Opt_xip, Opt_dax, Opt_ignore,
+ Opt_nobh, Opt_user_xattr, Opt_acl, Opt_xip, Opt_ignore,
Opt_quota, Opt_usrquota, Opt_grpquota, Opt_reservation,
};
@@ -462,7 +458,6 @@ static const struct fs_parameter_spec ext2_param_spec[] = {
fsparam_flag_no ("user_xattr", Opt_user_xattr),
fsparam_flag_no ("acl", Opt_acl),
fsparam_flag ("xip", Opt_xip),
- fsparam_flag ("dax", Opt_dax),
fsparam_flag ("grpquota", Opt_grpquota),
fsparam_flag ("noquota", Opt_ignore),
fsparam_flag ("quota", Opt_quota),
@@ -595,20 +590,9 @@ static int ext2_parse_param(struct fs_context *fc, struct fs_parameter *param)
ext2_msg_fc(fc, KERN_INFO, "(no)acl options not supported");
break;
#endif
- case Opt_xip:
- ext2_msg_fc(fc, KERN_INFO, "use dax instead of xip");
- ctx_set_mount_opt(ctx, EXT2_MOUNT_XIP);
- fallthrough;
- case Opt_dax:
-#ifdef CONFIG_FS_DAX
- ext2_msg_fc(fc, KERN_WARNING,
- "DAX enabled. Warning: DAX support in ext2 driver is deprecated"
- " and will be removed at the end of 2025. Please use ext4 driver instead.");
- ctx_set_mount_opt(ctx, EXT2_MOUNT_DAX);
-#else
- ext2_msg_fc(fc, KERN_INFO, "dax option not supported");
-#endif
- break;
+ case Opt_xip:
+ ext2_msg_fc(fc, KERN_ERR, "DAX support has been removed. Please use ext4 instead.");
+ return -EINVAL;
#if defined(CONFIG_QUOTA)
case Opt_quota:
@@ -906,8 +890,6 @@ static int ext2_fill_super(struct super_block *sb, struct fs_context *fc)
}
sb->s_fs_info = sbi;
sbi->s_sb_block = sb_block;
- sbi->s_daxdev = fs_dax_get_by_bdev(sb->s_bdev, &sbi->s_dax_part_off,
- NULL, NULL);
spin_lock_init(&sbi->s_lock);
ret = -EINVAL;
@@ -992,16 +974,8 @@ static int ext2_fill_super(struct super_block *sb, struct fs_context *fc)
}
blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
- if (test_opt(sb, DAX)) {
- if (!sbi->s_daxdev) {
- ext2_msg(sb, KERN_ERR,
- "DAX unsupported by block device. Turning off DAX.");
- clear_opt(sbi->s_mount_opt, DAX);
- } else if (blocksize != PAGE_SIZE) {
- ext2_msg(sb, KERN_ERR, "unsupported blocksize for DAX\n");
- clear_opt(sbi->s_mount_opt, DAX);
- }
- }
+
+
/* If the blocksize doesn't match, re-read the thing.. */
if (sb->s_blocksize != blocksize) {
@@ -1252,7 +1226,6 @@ static int ext2_fill_super(struct super_block *sb, struct fs_context *fc)
failed_mount:
brelse(bh);
failed_sbi:
- fs_put_dax(sbi->s_daxdev, NULL);
sb->s_fs_info = NULL;
kfree(sbi->s_blockgroup_lock);
kfree(sbi);
@@ -1379,11 +1352,7 @@ static int ext2_reconfigure(struct fs_context *fc)
spin_lock(&sbi->s_lock);
es = sbi->s_es;
- if ((sbi->s_mount_opt ^ new_opts.s_mount_opt) & EXT2_MOUNT_DAX) {
- ext2_msg(sb, KERN_WARNING, "warning: refusing change of "
- "dax flag with busy inodes while remounting");
- new_opts.s_mount_opt ^= EXT2_MOUNT_DAX;
- }
+
if ((bool)(flags & SB_RDONLY) == sb_rdonly(sb))
goto out_set;
if (flags & SB_RDONLY) {
--
2.43.0
^ permalink raw reply related
* Re: [PATCH 0/2] fs: refactor code to use clear_and_wake_up_bit()
From: Christian Brauner @ 2026-05-22 13:14 UTC (permalink / raw)
To: linux-fsdevel, linux-ext4, linux-kernel, Jan Kara, shuo chen,
Theodore Ts'o, linux-kernel-mentees, shuah, patch-reply,
Agatha Isabelle Moreira
Cc: Christian Brauner
In-Reply-To: <ag4PEP52c8rxrYPc@guidai>
On Wed, 20 May 2026 16:45:35 -0300, Agatha Isabelle Moreira wrote:
> Refactor code to use `clear_and_wake_up_bit()` instead of manual calls
> to:
> clear_bit_unlock();
> smp_mb__after_atomic();
> wake_up_bit();
>
> The helper function `clear_and_wake_up_bit()` was introduced in
> 'commit 8236b0ae31c83 ("bdi: wake up concurrent wb_shutdown()
> callers.")' as a generic way of doing the same sequence of operations,
> but several pieces of code still remain.
>
> [...]
Applied to the vfs-7.2.misc branch of the vfs/vfs.git tree.
Patches in the vfs-7.2.misc branch should appear in linux-next soon.
Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.
It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.
Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.
tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs-7.2.misc
[1/2] fs: buffer: use clear_and_wake_up_bit() in unlock_buffer()
https://git.kernel.org/vfs/vfs/c/89aafbd6d52b
[2/2] fs: jbd2: use clear_and_wake_up_bit() in journal_end_buffer_io_sync()
https://git.kernel.org/vfs/vfs/c/d7a7e95e5f50
^ permalink raw reply
* Re: [PATCH v10 00/22] fs-verity support for XFS with post EOF merkle tree
From: Christoph Hellwig @ 2026-05-22 12:07 UTC (permalink / raw)
To: Christian Brauner
Cc: Carlos Maiolino, Andrey Albershteyn, Christoph Hellwig,
Andrey Albershteyn, linux-xfs, fsverity, linux-fsdevel, ebiggers,
linux-ext4, linux-f2fs-devel, linux-btrfs, linux-unionfs, djwong,
david
In-Reply-To: <20260522-unbehagen-baumethode-erlesen-811a4065eeac@brauner>
On Fri, May 22, 2026 at 12:03:20PM +0200, Christian Brauner wrote:
> > I was expecting this to come through xfs tree too if Eric and Christian
> > agree.
>
> You may take it through the xfs tree if there are no conflicts with
> vfs-7.2.iomap. If there are I want to add the iomap changes into
> vfs-7.2.iomap that you can pull in.
Merging the iomap bits through the iomap branch might make sense, given
that iomap usually tends to see quite a bit of activity.
^ permalink raw reply
* Re: [PATCH v10 00/22] fs-verity support for XFS with post EOF merkle tree
From: Christian Brauner @ 2026-05-22 10:03 UTC (permalink / raw)
To: Carlos Maiolino
Cc: Andrey Albershteyn, Christoph Hellwig, Andrey Albershteyn,
linux-xfs, fsverity, linux-fsdevel, ebiggers, linux-ext4,
linux-f2fs-devel, linux-btrfs, linux-unionfs, djwong, david
In-Reply-To: <ag7uW7KQ5mVyCGEv@nidhogg.toxiclabs.cc>
On Thu, May 21, 2026 at 01:38:38PM +0200, Carlos Maiolino wrote:
> On Thu, May 21, 2026 at 11:42:13AM +0200, Andrey Albershteyn wrote:
> > On 2026-05-21 11:07:05, Christoph Hellwig wrote:
> > > On Wed, May 20, 2026 at 02:36:58PM +0200, Andrey Albershteyn wrote:
> > > > This series based on v7.1-rc4.
> > >
> > > How are we going to merge this? It touches at three subsystem trees
> > > (fsverity, vfs/iomap, xfs) so some coordination will be needed.
> >
> > As most of the patches are xfs, it's probably make sense to go
> > through xfs tree
> >
> > Carlos, what do you think?
>
> I was expecting this to come through xfs tree too if Eric and Christian
> agree.
You may take it through the xfs tree if there are no conflicts with
vfs-7.2.iomap. If there are I want to add the iomap changes into
vfs-7.2.iomap that you can pull in.
^ permalink raw reply
* [PATCH v5 v5 3/3] ext4: allow controlling mballoc stats through proc mb_stats
From: Baolin Liu @ 2026-05-22 3:59 UTC (permalink / raw)
To: tytso, adilger.kernel, libaokun, jack, ojaswin, ritesh.list,
yi.zhang, corbet, skhan
Cc: linux-ext4, linux-kernel, Baolin Liu, Andreas Dilger
In-Reply-To: <20260522035905.1145743-1-liubaolin12138@163.com>
From: Baolin Liu <liubaolin@kylinos.cn>
Make /proc/fs/ext4/<dev>/mb_stats writable. Writing 0 disables mballoc
statistics collection, writing 1 enables it, and writing -1 clears the
current statistics before enabling collection.
Update the ext4 documentation for proc mb_stats, document that the
sysfs mb_stats entry is deprecated, and point proc.rst to
Documentation/admin-guide/ext4.rst for ext4-specific /proc entries.
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Baokun Li <libaokun@linux.alibaba.com>
Reviewed-by: Ted Tso <tytso@mit.edu>
Signed-off-by: Baolin Liu <liubaolin@kylinos.cn>
---
Documentation/ABI/testing/sysfs-fs-ext4 | 3 +-
Documentation/admin-guide/ext4.rst | 9 ++++-
Documentation/filesystems/proc.rst | 13 +------
fs/ext4/ext4.h | 1 +
fs/ext4/mballoc.c | 31 +++++++++++++++-
fs/ext4/sysfs.c | 48 +++++++++++++++++++++++--
6 files changed, 88 insertions(+), 17 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-fs-ext4 b/Documentation/ABI/testing/sysfs-fs-ext4
index 2edd0a6672d3..7bf06c533343 100644
--- a/Documentation/ABI/testing/sysfs-fs-ext4
+++ b/Documentation/ABI/testing/sysfs-fs-ext4
@@ -5,7 +5,8 @@ Description:
Controls whether the multiblock allocator should
collect statistics, which are shown during the unmount.
1 means to collect statistics, 0 means not to collect
- statistics
+ statistics. This sysfs entry is deprecated, and users
+ should prefer /proc/fs/ext4/<disk>/mb_stats.
What: /sys/fs/ext4/<disk>/mb_group_prealloc
Date: March 2008
diff --git a/Documentation/admin-guide/ext4.rst b/Documentation/admin-guide/ext4.rst
index ac0c709ea9e7..ca76e981b2aa 100644
--- a/Documentation/admin-guide/ext4.rst
+++ b/Documentation/admin-guide/ext4.rst
@@ -436,6 +436,12 @@ Files in /proc/fs/ext4/<devname>
mb_groups
details of multiblock allocator buddy cache of free blocks
+ mb_stats
+ reports runtime statistics from the multiblock allocator
+ (mballoc). Writing 0 disables statistics collection, writing
+ 1 enables statistics collection, and writing -1 clears the
+ current statistics and enables statistics collection.
+
/sys entries
============
@@ -493,7 +499,8 @@ Files in /sys/fs/ext4/<devname>:
mb_stats
Controls whether the multiblock allocator should collect statistics,
which are shown during the unmount. 1 means to collect statistics, 0
- means not to collect statistics.
+ means not to collect statistics. This sysfs entry is deprecated, and
+ users should prefer /proc/fs/ext4/<devname>/mb_stats.
mb_stream_req
Files which have fewer blocks than this tunable parameter will have
diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
index b0c0d1b45b99..dd487004b862 100644
--- a/Documentation/filesystems/proc.rst
+++ b/Documentation/filesystems/proc.rst
@@ -1623,18 +1623,7 @@ softirq.
1.8 Ext4 file system parameters
-------------------------------
-Information about mounted ext4 file systems can be found in
-/proc/fs/ext4. Each mounted filesystem will have a directory in
-/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
-/proc/fs/ext4/sda9 or /proc/fs/ext4/dm-0). The files in each per-device
-directory are shown in Table 1-12, below.
-
-.. table:: Table 1-12: Files in /proc/fs/ext4/<devname>
-
- ============== ==========================================================
- File Content
- mb_groups details of multiblock allocator buddy cache of free blocks
- ============== ==========================================================
+See Documentation/admin-guide/ext4.rst for ext4-specific /proc entries.
1.9 /proc/consoles
-------------------
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index df96bcd53a59..483438d5742b 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2995,6 +2995,7 @@ int ext4_fc_record_regions(struct super_block *sb, int ino,
extern const struct seq_operations ext4_mb_seq_groups_ops;
extern const struct seq_operations ext4_mb_seq_structs_summary_ops;
extern int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset);
+extern void ext4_mb_stats_clear(struct ext4_sb_info *sbi);
extern int ext4_mb_init(struct super_block *);
extern void ext4_mb_release(struct super_block *);
extern ext4_fsblk_t ext4_mb_new_blocks(handle_t *,
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index fed6d854877b..3f6454ada587 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3214,7 +3214,7 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
seq_puts(seq, "\tmb stats collection turned off.\n");
seq_puts(
seq,
- "\tTo enable, please write \"1\" to sysfs file mb_stats.\n");
+ "\tTo enable, please write \"1\" to proc file mb_stats.\n");
return 0;
}
seq_printf(seq, "\tblocks_allocated: %u\n",
@@ -4723,6 +4723,35 @@ static void ext4_mb_collect_stats(struct ext4_allocation_context *ac)
trace_ext4_mballoc_prealloc(ac);
}
+void ext4_mb_stats_clear(struct ext4_sb_info *sbi)
+{
+ int i;
+
+ atomic_set(&sbi->s_bal_reqs, 0);
+ atomic_set(&sbi->s_bal_success, 0);
+ atomic_set(&sbi->s_bal_allocated, 0);
+ atomic_set(&sbi->s_bal_groups_scanned, 0);
+
+ for (i = 0; i < EXT4_MB_NUM_CRS; i++) {
+ atomic64_set(&sbi->s_bal_cX_hits[i], 0);
+ atomic64_set(&sbi->s_bal_cX_groups_considered[i], 0);
+ atomic_set(&sbi->s_bal_cX_ex_scanned[i], 0);
+ atomic64_set(&sbi->s_bal_cX_failed[i], 0);
+ }
+
+ atomic_set(&sbi->s_bal_ex_scanned, 0);
+ atomic_set(&sbi->s_bal_goals, 0);
+ atomic_set(&sbi->s_bal_stream_goals, 0);
+ atomic_set(&sbi->s_bal_len_goals, 0);
+ atomic_set(&sbi->s_bal_2orders, 0);
+ atomic_set(&sbi->s_bal_breaks, 0);
+ atomic_set(&sbi->s_mb_lost_chunks, 0);
+ atomic_set(&sbi->s_mb_buddies_generated, 0);
+ atomic64_set(&sbi->s_mb_generation_time, 0);
+ atomic_set(&sbi->s_mb_preallocated, 0);
+ atomic_set(&sbi->s_mb_discarded, 0);
+}
+
/*
* Called on failure; free up any blocks from the inode PA for this
* context. We don't need this for MB_GROUP_PA because we only change
diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index 47e06c32c6fb..76e6c346231a 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -53,6 +53,50 @@ typedef enum {
static const char proc_dirname[] = "fs/ext4";
static struct proc_dir_entry *ext4_proc_root;
+static int ext4_mb_stats_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, ext4_seq_mb_stats_show, pde_data(inode));
+}
+
+static ssize_t ext4_mb_stats_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct super_block *sb = pde_data(file_inode(file));
+ struct ext4_sb_info *sbi = EXT4_SB(sb);
+ int val;
+ int ret;
+
+ ret = kstrtoint_from_user(buf, count, 0, &val);
+ if (ret)
+ return ret;
+
+ switch (val) {
+ case -1:
+ WRITE_ONCE(sbi->s_mb_stats, 0);
+ ext4_mb_stats_clear(sbi);
+ WRITE_ONCE(sbi->s_mb_stats, 1);
+ break;
+ case 1:
+ WRITE_ONCE(sbi->s_mb_stats, 1);
+ break;
+ case 0:
+ WRITE_ONCE(sbi->s_mb_stats, 0);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return count;
+}
+
+static const struct proc_ops ext4_mb_stats_proc_ops = {
+ .proc_open = ext4_mb_stats_open,
+ .proc_read = seq_read,
+ .proc_lseek = seq_lseek,
+ .proc_release = single_release,
+ .proc_write = ext4_mb_stats_write,
+};
+
struct ext4_attr {
struct attribute attr;
short attr_id;
@@ -666,8 +710,8 @@ int ext4_register_sysfs(struct super_block *sb)
ext4_fc_info_show, sb);
proc_create_seq_data("mb_groups", S_IRUGO, sbi->s_proc,
&ext4_mb_seq_groups_ops, sb);
- proc_create_single_data("mb_stats", 0444, sbi->s_proc,
- ext4_seq_mb_stats_show, sb);
+ proc_create_data("mb_stats", 0644, sbi->s_proc,
+ &ext4_mb_stats_proc_ops, sb);
proc_create_seq_data("mb_structs_summary", 0444, sbi->s_proc,
&ext4_mb_seq_structs_summary_ops, sb);
}
--
2.51.0
^ permalink raw reply related
* [PATCH v5 v5 0/3] ext4: improve mballoc statistics reporting and control
From: Baolin Liu @ 2026-05-22 3:59 UTC (permalink / raw)
To: tytso, adilger.kernel, libaokun, jack, ojaswin, ritesh.list,
yi.zhang, corbet, skhan
Cc: linux-ext4, linux-kernel, Baolin Liu
This series improves mballoc statistics reporting and control by adding
blocks_allocated to /proc/fs/ext4/<dev>/mb_stats, using
READ_ONCE()/WRITE_ONCE() for concurrent accesses to s_mb_stats, and
allowing mballoc stats to be controlled through
/proc/fs/ext4/<dev>/mb_stats.
Changes in v5:
- Use READ_ONCE()/WRITE_ONCE() for s_mb_stats accesses instead of
converting s_mb_stats to atomic_t, as suggested in review.
- For proc mb_stats writes of -1, disable stats collection before
clearing the counters, then re-enable it.
Baolin Liu (3):
ext4: add blocks_allocated to mb_stats output
ext4: use READ_ONCE/WRITE_ONCE for s_mb_stats
ext4: allow controlling mballoc stats through proc mb_stats
Documentation/ABI/testing/sysfs-fs-ext4 | 3 +-
Documentation/admin-guide/ext4.rst | 9 ++-
Documentation/filesystems/proc.rst | 13 +----
fs/ext4/ext4.h | 1 +
fs/ext4/mballoc.c | 57 ++++++++++++++-----
fs/ext4/sysfs.c | 73 ++++++++++++++++++++++++-
6 files changed, 126 insertions(+), 30 deletions(-)
--
2.51.0
^ permalink raw reply
* [PATCH v5 v5 2/3] ext4: use READ_ONCE/WRITE_ONCE for s_mb_stats
From: Baolin Liu @ 2026-05-22 3:59 UTC (permalink / raw)
To: tytso, adilger.kernel, libaokun, jack, ojaswin, ritesh.list,
yi.zhang, corbet, skhan
Cc: linux-ext4, linux-kernel, Baolin Liu
In-Reply-To: <20260522035905.1145743-1-liubaolin12138@163.com>
From: Baolin Liu <liubaolin@kylinos.cn>
Use READ_ONCE()/WRITE_ONCE() for concurrent accesses to
s_mb_stats.
Signed-off-by: Baolin Liu <liubaolin@kylinos.cn>
---
fs/ext4/mballoc.c | 24 ++++++++++++------------
fs/ext4/sysfs.c | 25 ++++++++++++++++++++++++-
2 files changed, 36 insertions(+), 13 deletions(-)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index d36b0f7b5d7d..fed6d854877b 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -924,7 +924,7 @@ static int ext4_mb_scan_groups_xa_range(struct ext4_allocation_context *ac,
xa_for_each_range(xa, group, grp, start, end - 1) {
int err;
- if (sbi->s_mb_stats)
+ if (READ_ONCE(sbi->s_mb_stats))
atomic64_inc(&sbi->s_bal_cX_groups_considered[cr]);
err = ext4_mb_scan_group(ac, grp->bb_group);
@@ -980,7 +980,7 @@ static int ext4_mb_scan_groups_p2_aligned(struct ext4_allocation_context *ac,
goto wrap_around;
}
- if (sbi->s_mb_stats)
+ if (READ_ONCE(sbi->s_mb_stats))
atomic64_inc(&sbi->s_bal_cX_failed[ac->ac_criteria]);
/* Increment cr and search again if no group is found */
@@ -1031,7 +1031,7 @@ static int ext4_mb_scan_groups_goal_fast(struct ext4_allocation_context *ac,
goto wrap_around;
}
- if (sbi->s_mb_stats)
+ if (READ_ONCE(sbi->s_mb_stats))
atomic64_inc(&sbi->s_bal_cX_failed[ac->ac_criteria]);
/*
* CR_BEST_AVAIL_LEN works based on the concept that we have
@@ -1135,7 +1135,7 @@ static int ext4_mb_scan_groups_best_avail(struct ext4_allocation_context *ac,
/* Reset goal length to original goal length before falling into CR_GOAL_LEN_SLOW */
ac->ac_g_ex.fe_len = ac->ac_orig_goal_len;
- if (sbi->s_mb_stats)
+ if (READ_ONCE(sbi->s_mb_stats))
atomic64_inc(&sbi->s_bal_cX_failed[ac->ac_criteria]);
ac->ac_criteria = CR_GOAL_LEN_SLOW;
@@ -1184,7 +1184,7 @@ static int ext4_mb_scan_groups_linear(struct ext4_allocation_context *ac,
ac->ac_criteria++;
/* Processed all groups and haven't found blocks */
- if (sbi->s_mb_stats && i == ngroups)
+ if (READ_ONCE(sbi->s_mb_stats) && i == ngroups)
atomic64_inc(&sbi->s_bal_cX_failed[cr]);
return 0;
@@ -2541,7 +2541,7 @@ void ext4_mb_simple_scan_group(struct ext4_allocation_context *ac,
BUG_ON(ac->ac_f_ex.fe_len != ac->ac_g_ex.fe_len);
- if (EXT4_SB(sb)->s_mb_stats)
+ if (READ_ONCE(EXT4_SB(sb)->s_mb_stats))
atomic_inc(&EXT4_SB(sb)->s_bal_2orders);
break;
@@ -2786,7 +2786,7 @@ static int ext4_mb_good_group_nolock(struct ext4_allocation_context *ac,
if (!grp)
return -EFSCORRUPTED;
- if (sbi->s_mb_stats)
+ if (READ_ONCE(sbi->s_mb_stats))
atomic64_inc(&sbi->s_bal_cX_groups_considered[ac->ac_criteria]);
if (should_lock) {
ext4_lock_group(sb, group);
@@ -3097,7 +3097,7 @@ ext4_mb_regular_allocator(struct ext4_allocation_context *ac)
}
}
- if (sbi->s_mb_stats && ac->ac_status == AC_STATUS_FOUND) {
+ if (READ_ONCE(sbi->s_mb_stats) && ac->ac_status == AC_STATUS_FOUND) {
atomic64_inc(&sbi->s_bal_cX_hits[ac->ac_criteria]);
if (ac->ac_flags & EXT4_MB_STREAM_ALLOC &&
ac->ac_b_ex.fe_group == ac->ac_g_ex.fe_group)
@@ -3210,7 +3210,7 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
struct ext4_sb_info *sbi = EXT4_SB(sb);
seq_puts(seq, "mballoc:\n");
- if (!sbi->s_mb_stats) {
+ if (!READ_ONCE(sbi->s_mb_stats)) {
seq_puts(seq, "\tmb stats collection turned off.\n");
seq_puts(
seq,
@@ -3787,7 +3787,7 @@ int ext4_mb_init(struct super_block *sb)
sbi->s_mb_max_to_scan = MB_DEFAULT_MAX_TO_SCAN;
sbi->s_mb_min_to_scan = MB_DEFAULT_MIN_TO_SCAN;
- sbi->s_mb_stats = MB_DEFAULT_STATS;
+ WRITE_ONCE(sbi->s_mb_stats, MB_DEFAULT_STATS);
sbi->s_mb_stream_request = MB_DEFAULT_STREAM_THRESHOLD;
sbi->s_mb_order2_reqs = MB_DEFAULT_ORDER2_REQS;
sbi->s_mb_best_avail_max_trim_order = MB_DEFAULT_BEST_AVAIL_TRIM_ORDER;
@@ -3929,7 +3929,7 @@ void ext4_mb_release(struct super_block *sb)
kfree(sbi->s_mb_offsets);
kfree(sbi->s_mb_maxs);
iput(sbi->s_buddy_cache);
- if (sbi->s_mb_stats) {
+ if (READ_ONCE(sbi->s_mb_stats)) {
ext4_msg(sb, KERN_INFO,
"mballoc: %u blocks %u reqs (%u success)",
atomic_read(&sbi->s_bal_allocated),
@@ -4694,7 +4694,7 @@ static void ext4_mb_collect_stats(struct ext4_allocation_context *ac)
{
struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
- if (sbi->s_mb_stats && ac->ac_g_ex.fe_len >= 1) {
+ if (READ_ONCE(sbi->s_mb_stats) && ac->ac_g_ex.fe_len >= 1) {
atomic_inc(&sbi->s_bal_reqs);
atomic_add(ac->ac_b_ex.fe_len, &sbi->s_bal_allocated);
if (ac->ac_b_ex.fe_len >= ac->ac_o_ex.fe_len)
diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index afe12bcc1603..47e06c32c6fb 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -41,6 +41,7 @@ typedef enum {
attr_pointer_atomic,
attr_journal_task,
attr_err_report_sec,
+ attr_mb_stats,
} attr_id_t;
typedef enum {
@@ -241,6 +242,7 @@ EXT4_ATTR_FUNC(session_write_kbytes, 0444);
EXT4_ATTR_FUNC(lifetime_write_kbytes, 0444);
EXT4_ATTR_FUNC(reserved_clusters, 0644);
EXT4_ATTR_FUNC(sra_exceeded_retry_limit, 0444);
+EXT4_ATTR_FUNC(mb_stats, 0644);
EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, inode_readahead,
ext4_sb_info, s_inode_readahead_blks);
@@ -250,7 +252,6 @@ EXT4_ATTR_OFFSET(mb_best_avail_max_trim_order, 0644, mb_order,
ext4_sb_info, s_mb_best_avail_max_trim_order);
EXT4_ATTR_OFFSET(err_report_sec, 0644, err_report_sec, ext4_sb_info, s_err_report_sec);
EXT4_RW_ATTR_SBI_UI(inode_goal, s_inode_goal);
-EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats);
EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan);
EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
@@ -451,6 +452,24 @@ static ssize_t ext4_generic_attr_show(struct ext4_attr *a,
return 0;
}
+static ssize_t mb_stats_show(struct ext4_sb_info *sbi, char *buf)
+{
+ return sysfs_emit(buf, "%u\n", READ_ONCE(sbi->s_mb_stats));
+}
+
+static ssize_t mb_stats_store(struct ext4_sb_info *sbi,
+ const char *buf, size_t len)
+{
+ unsigned int t;
+ int ret;
+
+ ret = kstrtouint(skip_spaces(buf), 0, &t);
+ if (ret)
+ return ret;
+ WRITE_ONCE(sbi->s_mb_stats, t);
+ return len;
+}
+
static ssize_t ext4_attr_show(struct kobject *kobj,
struct attribute *attr, char *buf)
{
@@ -475,6 +494,8 @@ static ssize_t ext4_attr_show(struct kobject *kobj,
return sysfs_emit(buf, "%llu\n",
(unsigned long long)
percpu_counter_sum(&sbi->s_sra_exceeded_retry_limit));
+ case attr_mb_stats:
+ return mb_stats_show(sbi, buf);
case attr_feature:
return sysfs_emit(buf, "supported\n");
case attr_first_error_time:
@@ -559,6 +580,8 @@ static ssize_t ext4_attr_store(struct kobject *kobj,
return inode_readahead_blks_store(sbi, buf, len);
case attr_trigger_test_error:
return trigger_test_error(sbi, buf, len);
+ case attr_mb_stats:
+ return mb_stats_store(sbi, buf, len);
case attr_err_report_sec:
return err_report_sec_store(sbi, buf, len);
default:
--
2.51.0
^ permalink raw reply related
* [PATCH v5 v5 1/3] ext4: add blocks_allocated to mb_stats output
From: Baolin Liu @ 2026-05-22 3:59 UTC (permalink / raw)
To: tytso, adilger.kernel, libaokun, jack, ojaswin, ritesh.list,
yi.zhang, corbet, skhan
Cc: linux-ext4, linux-kernel, Baolin Liu, Andreas Dilger
In-Reply-To: <20260522035905.1145743-1-liubaolin12138@163.com>
From: Baolin Liu <liubaolin@kylinos.cn>
Add blocks_allocated to /proc/fs/ext4/<dev>/mb_stats so that the
reported statistics match the mballoc summary printed at unmount time.
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Baolin Liu <liubaolin@kylinos.cn>
---
fs/ext4/mballoc.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index bb58eafb87bc..d36b0f7b5d7d 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3217,6 +3217,8 @@ int ext4_seq_mb_stats_show(struct seq_file *seq, void *offset)
"\tTo enable, please write \"1\" to sysfs file mb_stats.\n");
return 0;
}
+ seq_printf(seq, "\tblocks_allocated: %u\n",
+ atomic_read(&sbi->s_bal_allocated));
seq_printf(seq, "\treqs: %u\n", atomic_read(&sbi->s_bal_reqs));
seq_printf(seq, "\tsuccess: %u\n", atomic_read(&sbi->s_bal_success));
--
2.51.0
^ permalink raw reply related
* [PATCH] jbd2: update outdated comment for jbd2_journal_try_to_free_buffers()
From: Zhang Yi @ 2026-05-22 3:05 UTC (permalink / raw)
To: linux-ext4
Cc: linux-fsdevel, linux-kernel, tytso, adilger.kernel, libaokun,
jack, ojaswin, ritesh.list, yi.zhang, yi.zhang, yizhang089,
yangerkun, yukuai
From: Zhang Yi <yi.zhang@huawei.com>
jbd2_journal_try_to_free_buffers() currently only tries to remove
checkpointed data buffers from the checkpoint list for data=journal
mode, and bails out if any buffer is still attached to a transaction.
For data=ordered and writeback modes, data buffers never have
journal_heads, so the function degenerates to a plain
try_to_free_buffers() call.
Besides, The release of metadata buffers has been delegated to the jbd2
journal shrinker in commit 4ba3fcdde7e3 ("jbd2,ext4: add a shrinker to
release checkpointed buffers"). jbd2_journal_try_to_free_buffers() is
not used for handling metadata buffers now.
However, the comment above the function still references
jbd2_journal_dirty_data(), __jbd2_journal_unfile_buffer(), t_datalist,
BKL, and BUF_CLEAN, all of which were removed in commit 87c89c232c8f
("jbd2: Remove data=ordered mode support using jbd buffer heads").
Replace it with a description of what the function actually does now.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
fs/jbd2/transaction.c | 39 ++++++++++++---------------------------
1 file changed, 12 insertions(+), 27 deletions(-)
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 4885903bbd10..239bcf88ed1c 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -2139,38 +2139,23 @@ static void __jbd2_journal_unfile_buffer(struct journal_head *jh)
}
/**
- * jbd2_journal_try_to_free_buffers() - try to free page buffers.
+ * jbd2_journal_try_to_free_buffers() - try to free folio buffers.
* @journal: journal for operation
* @folio: Folio to detach data from.
*
- * For all the buffers on this page,
- * if they are fully written out ordered data, move them onto BUF_CLEAN
- * so try_to_free_buffers() can reap them.
+ * For each buffer_head on @folio, if the buffer has a journal_head but
+ * is not attached to a running or committing transaction, try to remove
+ * it from the checkpoint list. This is needed for data=journal mode
+ * where data buffers are journaled: once they are checkpointed, the
+ * journal_head can be detached and the buffer freed. If any buffer is
+ * still attached to a transaction, the folio cannot be released and we
+ * bail out. Otherwise we call try_to_free_buffers() to detach all
+ * buffer_heads from the folio.
*
- * This function returns non-zero if we wish try_to_free_buffers()
- * to be called. We do this if the page is releasable by try_to_free_buffers().
- * We also do it if the page has locked or dirty buffers and the caller wants
- * us to perform sync or async writeout.
+ * For data=ordered and writeback modes, data buffers never have
+ * journal_heads, so this degenerates to a plain try_to_free_buffers().
*
- * This complicates JBD locking somewhat. We aren't protected by the
- * BKL here. We wish to remove the buffer from its committing or
- * running transaction's ->t_datalist via __jbd2_journal_unfile_buffer.
- *
- * This may *change* the value of transaction_t->t_datalist, so anyone
- * who looks at t_datalist needs to lock against this function.
- *
- * Even worse, someone may be doing a jbd2_journal_dirty_data on this
- * buffer. So we need to lock against that. jbd2_journal_dirty_data()
- * will come out of the lock with the buffer dirty, which makes it
- * ineligible for release here.
- *
- * Who else is affected by this? hmm... Really the only contender
- * is do_get_write_access() - it could be looking at the buffer while
- * journal_try_to_free_buffer() is changing its state. But that
- * cannot happen because we never reallocate freed data as metadata
- * while the data is part of a transaction. Yes?
- *
- * Return false on failure, true on success
+ * Return: true if the folio's buffers were freed, false otherwise
*/
bool jbd2_journal_try_to_free_buffers(journal_t *journal, struct folio *folio)
{
--
2.52.0
^ permalink raw reply related
* Re: [PATCH v10 00/22] fs-verity support for XFS with post EOF merkle tree
From: Eric Biggers @ 2026-05-22 2:06 UTC (permalink / raw)
To: Carlos Maiolino
Cc: Andrey Albershteyn, Christoph Hellwig, Andrey Albershteyn,
linux-xfs, fsverity, linux-fsdevel, linux-ext4, linux-f2fs-devel,
linux-btrfs, linux-unionfs, djwong, david, brauner, amir73il,
miklos
In-Reply-To: <ag7vc9gaHo3XtsBJ@nidhogg.toxiclabs.cc>
On Thu, May 21, 2026 at 01:42:42PM +0200, Carlos Maiolino wrote:
> On Thu, May 21, 2026 at 01:38:45PM +0200, Carlos Maiolino wrote:
> > On Thu, May 21, 2026 at 11:42:13AM +0200, Andrey Albershteyn wrote:
> > > On 2026-05-21 11:07:05, Christoph Hellwig wrote:
> > > > On Wed, May 20, 2026 at 02:36:58PM +0200, Andrey Albershteyn wrote:
> > > > > This series based on v7.1-rc4.
> > > >
> > > > How are we going to merge this? It touches at three subsystem trees
> > > > (fsverity, vfs/iomap, xfs) so some coordination will be needed.
> > >
> > > As most of the patches are xfs, it's probably make sense to go
> > > through xfs tree
> > >
> > > Carlos, what do you think?
> >
> > I was expecting this to come through xfs tree too if Eric and Christian
> > agree.
> > FWIW I'm adding Christian to the Cc
>
> Woops... Also Adding Amir and Miklos to the Cc list due the overlayfs
> patch:
Please go ahead and take it through the XFS tree for 7.2 if you think
it's ready.
- Eric
^ permalink raw reply
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