[RESEND 1/7] mm/gup: Replace get_user_pages_longterm() with FOLL_LONGTERM

ira.weiny
2019-03-17T18:34:32Z

From: Ira Weiny <ira.weiny@intel.com>

Rather than have a separate get_user_pages_longterm() call,
introduce FOLL_LONGTERM and change the longterm callers to use
it.

This patch does not change any functionality.

FOLL_LONGTERM can only be supported with get_user_pages() as it
requires vmas to determine if DAX is in use.

CC: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes from V1:
Rebased on 5.1 merge
Adjusted for changes introduced by CONFIG_CMA
Convert new users of GUP longterm
io_uring.c
xdp_umem.c

arch/powerpc/mm/mmu_context_iommu.c | 3 +-
drivers/infiniband/core/umem.c | 5 +-
drivers/infiniband/hw/qib/qib_user_pages.c | 8 +-
drivers/infiniband/hw/usnic/usnic_uiom.c | 9 +-
drivers/media/v4l2-core/videobuf-dma-sg.c | 6 +-
drivers/vfio/vfio_iommu_type1.c | 3 +-
fs/io_uring.c | 5 +-
include/linux/mm.h | 14 +-
mm/gup.c | 171 ++++++++++++---------
mm/gup_benchmark.c | 5 +-
net/xdp/xdp_umem.c | 4 +-
11 files changed, 129 insertions(+), 104 deletions(-)

diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
index e7a9c4f6bfca..2bd48998765e 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -148,7 +148,8 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
}

down_read(&mm->mmap_sem);
- ret = get_user_pages_longterm(ua, entries, FOLL_WRITE, mem->hpages, NULL);
+ ret = get_user_pages(ua, entries, FOLL_WRITE | FOLL_LONGTERM,
+ mem->hpages, NULL);
up_read(&mm->mmap_sem);
if (ret != entries) {
/* free the reference taken */
diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index fe5551562dbc..31191f098e73 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -189,10 +189,11 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,

while (npages) {
down_read(&mm->mmap_sem);
- ret = get_user_pages_longterm(cur_base,
+ ret = get_user_pages(cur_base,
min_t(unsigned long, npages,
PAGE_SIZE / sizeof (struct page *)),
- gup_flags, page_list, vma_list);
+ gup_flags | FOLL_LONGTERM,
+ page_list, vma_list);
if (ret < 0) {
up_read(&mm->mmap_sem);
goto umem_release;
diff --git a/drivers/infiniband/hw/qib/qib_user_pages.c b/drivers/infiniband/hw/qib/qib_user_pages.c
index 123ca8f64f75..f712fb7fa82f 100644
--- a/drivers/infiniband/hw/qib/qib_user_pages.c
+++ b/drivers/infiniband/hw/qib/qib_user_pages.c
@@ -114,10 +114,10 @@ int qib_get_user_pages(unsigned long start_page, size_t num_pages,

down_read(&current->mm->mmap_sem);
for (got = 0; got < num_pages; got += ret) {
- ret = get_user_pages_longterm(start_page + got * PAGE_SIZE,
- num_pages - got,
- FOLL_WRITE | FOLL_FORCE,
- p + got, NULL);
+ ret = get_user_pages(start_page + got * PAGE_SIZE,
+ num_pages - got,
+ FOLL_LONGTERM | FOLL_WRITE | FOLL_FORCE,
+ p + got, NULL);
if (ret < 0) {
up_read(&current->mm->mmap_sem);
goto bail_release;
diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.c b/drivers/infiniband/hw/usnic/usnic_uiom.c
index 06862a6af185..1d9a182ac163 100644
--- a/drivers/infiniband/hw/usnic/usnic_uiom.c
+++ b/drivers/infiniband/hw/usnic/usnic_uiom.c
@@ -143,10 +143,11 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
ret = 0;

while (npages) {
- ret = get_user_pages_longterm(cur_base,
- min_t(unsigned long, npages,
- PAGE_SIZE / sizeof(struct page *)),
- gup_flags, page_list, NULL);
+ ret = get_user_pages(cur_base,
+ min_t(unsigned long, npages,
+ PAGE_SIZE / sizeof(struct page *)),
+ gup_flags | FOLL_LONGTERM,
+ page_list, NULL);

if (ret < 0)
goto out;
diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c
index 08929c087e27..870a2a526e0b 100644
--- a/drivers/media/v4l2-core/videobuf-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf-dma-sg.c
@@ -186,12 +186,12 @@ static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n",
data, size, dma->nr_pages);

- err = get_user_pages_longterm(data & PAGE_MASK, dma->nr_pages,
- flags, dma->pages, NULL);
+ err = get_user_pages(data & PAGE_MASK, dma->nr_pages,
+ flags | FOLL_LONGTERM, dma->pages, NULL);

if (err != dma->nr_pages) {
dma->nr_pages = (err >= 0) ? err : 0;
- dprintk(1, "get_user_pages_longterm: err=%d [%d]\n", err,
+ dprintk(1, "get_user_pages: err=%d [%d]\n", err,
dma->nr_pages);
return err < 0 ? err : -EINVAL;
}
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 73652e21efec..1500bd0bb6da 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -351,7 +351,8 @@ static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,

down_read(&mm->mmap_sem);
if (mm == current->mm) {
- ret = get_user_pages_longterm(vaddr, 1, flags, page, vmas);
+ ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page,
+ vmas);
} else {
ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page,
vmas, NULL);
diff --git a/fs/io_uring.c b/fs/io_uring.c
index e2bd77da5e21..8d61b81373bd 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2450,8 +2450,9 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,

ret = 0;
down_read(&current->mm->mmap_sem);
- pret = get_user_pages_longterm(ubuf, nr_pages, FOLL_WRITE,
- pages, vmas);
+ pret = get_user_pages(ubuf, nr_pages,
+ FOLL_WRITE | FOLL_LONGTERM,
+ pages, vmas);
if (pret == nr_pages) {
/* don't support file backed memory */
for (j = 0; j < nr_pages; j++) {
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2d483dbdffc0..6831077d126c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1531,19 +1531,6 @@ long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags);

-#if defined(CONFIG_FS_DAX) || defined(CONFIG_CMA)
-long get_user_pages_longterm(unsigned long start, unsigned long nr_pages,
- unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas);
-#else
-static inline long get_user_pages_longterm(unsigned long start,
- unsigned long nr_pages, unsigned int gup_flags,
- struct page **pages, struct vm_area_struct **vmas)
-{
- return get_user_pages(start, nr_pages, gup_flags, pages, vmas);
-}
-#endif /* CONFIG_FS_DAX */
-
int get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages);

@@ -2609,6 +2596,7 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
#define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */
#define FOLL_COW 0x4000 /* internal GUP flag */
#define FOLL_ANON 0x8000 /* don't do file mappings */
+#define FOLL_LONGTERM 0x10000 /* mapping is intended for a long term pin */

static inline int vm_fault_to_errno(vm_fault_t vm_fault, int foll_flags)
{
diff --git a/mm/gup.c b/mm/gup.c
index f84e22685aaa..8cb4cff067bc 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1112,26 +1112,7 @@ long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
}
EXPORT_SYMBOL(get_user_pages_remote);

-/*
- * This is the same as get_user_pages_remote(), just with a
- * less-flexible calling convention where we assume that the task
- * and mm being operated on are the current task's and don't allow
- * passing of a locked parameter. We also obviously don't pass
- * FOLL_REMOTE in here.
- */
-long get_user_pages(unsigned long start, unsigned long nr_pages,
- unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas)
-{
- return __get_user_pages_locked(current, current->mm, start, nr_pages,
- pages, vmas, NULL,
- gup_flags | FOLL_TOUCH);
-}
-EXPORT_SYMBOL(get_user_pages);
-
#if defined(CONFIG_FS_DAX) || defined (CONFIG_CMA)
-
-#ifdef CONFIG_FS_DAX
static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
{
long i;
@@ -1150,12 +1131,6 @@ static bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
}
return false;
}
-#else
-static inline bool check_dax_vmas(struct vm_area_struct **vmas, long nr_pages)
-{
- return false;
-}
-#endif

#ifdef CONFIG_CMA
static struct page *new_non_cma_page(struct page *page, unsigned long private)
@@ -1209,10 +1184,13 @@ static struct page *new_non_cma_page(struct page *page, unsigned long private)
return __alloc_pages_node(nid, gfp_mask, 0);
}

-static long check_and_migrate_cma_pages(unsigned long start, long nr_pages,
- unsigned int gup_flags,
+static long check_and_migrate_cma_pages(struct task_struct *tsk,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long nr_pages,
struct page **pages,
- struct vm_area_struct **vmas)
+ struct vm_area_struct **vmas,
+ unsigned int gup_flags)
{
long i;
bool drain_allow = true;
@@ -1268,10 +1246,14 @@ static long check_and_migrate_cma_pages(unsigned long start, long nr_pages,
putback_movable_pages(&cma_page_list);
}
/*
- * We did migrate all the pages, Try to get the page references again
- * migrating any new CMA pages which we failed to isolate earlier.
+ * We did migrate all the pages, Try to get the page references
+ * again migrating any new CMA pages which we failed to isolate
+ * earlier.
*/
- nr_pages = get_user_pages(start, nr_pages, gup_flags, pages, vmas);
+ nr_pages = __get_user_pages_locked(tsk, mm, start, nr_pages,
+ pages, vmas, NULL,
+ gup_flags);
+
if ((nr_pages > 0) && migrate_allow) {
drain_allow = true;
goto check_again;
@@ -1281,66 +1263,115 @@ static long check_and_migrate_cma_pages(unsigned long start, long nr_pages,
return nr_pages;
}
#else
-static inline long check_and_migrate_cma_pages(unsigned long start, long nr_pages,
- unsigned int gup_flags,
- struct page **pages,
- struct vm_area_struct **vmas)
+static long check_and_migrate_cma_pages(struct task_struct *tsk,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long nr_pages,
+ struct page **pages,
+ struct vm_area_struct **vmas,
+ unsigned int gup_flags)
{
return nr_pages;
}
#endif

/*
- * This is the same as get_user_pages() in that it assumes we are
- * operating on the current task's mm, but it goes further to validate
- * that the vmas associated with the address range are suitable for
- * longterm elevated page reference counts. For example, filesystem-dax
- * mappings are subject to the lifetime enforced by the filesystem and
- * we need guarantees that longterm users like RDMA and V4L2 only
- * establish mappings that have a kernel enforced revocation mechanism.
+ * __gup_longterm_locked() is a wrapper for __get_uer_pages_locked which
+ * allows us to process the FOLL_LONGTERM flag if present.
+ *
+ * FOLL_LONGTERM Checks for either DAX VMAs or PPC CMA regions and either fails
+ * the pin or attempts to migrate the page as appropriate.
+ *
+ * In the filesystem-dax case mappings are subject to the lifetime enforced by
+ * the filesystem and we need guarantees that longterm users like RDMA and V4L2
+ * only establish mappings that have a kernel enforced revocation mechanism.
+ *
+ * In the CMA case pages can't be pinned in a CMA region as this would
+ * unnecessarily fragment that region. So CMA attempts to migrate the page
+ * before pinning.
*
* "longterm" == userspace controlled elevated page count lifetime.
* Contrast this to iov_iter_get_pages() usages which are transient.
*/
-long get_user_pages_longterm(unsigned long start, unsigned long nr_pages,
- unsigned int gup_flags, struct page **pages,
- struct vm_area_struct **vmas_arg)
+static __always_inline long __gup_longterm_locked(struct task_struct *tsk,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long nr_pages,
+ struct page **pages,
+ struct vm_area_struct **vmas,
+ unsigned int gup_flags)
{
- struct vm_area_struct **vmas = vmas_arg;
- unsigned long flags;
+ struct vm_area_struct **vmas_tmp = vmas;
+ unsigned long flags = 0;
long rc, i;

- if (!pages)
- return -EINVAL;
-
- if (!vmas) {
- vmas = kcalloc(nr_pages, sizeof(struct vm_area_struct *),
- GFP_KERNEL);
- if (!vmas)
- return -ENOMEM;
+ if (gup_flags & FOLL_LONGTERM) {
+ if (!pages)
+ return -EINVAL;
+
+ if (!vmas_tmp) {
+ vmas_tmp = kcalloc(nr_pages,
+ sizeof(struct vm_area_struct *),
+ GFP_KERNEL);
+ if (!vmas_tmp)
+ return -ENOMEM;
+ }
+ flags = memalloc_nocma_save();
}

- flags = memalloc_nocma_save();
- rc = get_user_pages(start, nr_pages, gup_flags, pages, vmas);
- memalloc_nocma_restore(flags);
- if (rc < 0)
- goto out;
+ rc = __get_user_pages_locked(tsk, mm, start, nr_pages, pages,
+ vmas_tmp, NULL, gup_flags);

- if (check_dax_vmas(vmas, rc)) {
- for (i = 0; i < rc; i++)
- put_page(pages[i]);
- rc = -EOPNOTSUPP;
- goto out;
+ if (gup_flags & FOLL_LONGTERM) {
+ memalloc_nocma_restore(flags);
+ if (rc < 0)
+ goto out;
+
+ if (check_dax_vmas(vmas_tmp, rc)) {
+ for (i = 0; i < rc; i++)
+ put_page(pages[i]);
+ rc = -EOPNOTSUPP;
+ goto out;
+ }
+
+ rc = check_and_migrate_cma_pages(tsk, mm, start, rc, pages,
+ vmas_tmp, gup_flags);
}

- rc = check_and_migrate_cma_pages(start, rc, gup_flags, pages, vmas);
out:
- if (vmas != vmas_arg)
- kfree(vmas);
+ if (vmas_tmp != vmas)
+ kfree(vmas_tmp);
return rc;
}
-EXPORT_SYMBOL(get_user_pages_longterm);
-#endif /* CONFIG_FS_DAX */
+#else /* !CONFIG_FS_DAX && !CONFIG_CMA */
+static __always_inline long __gup_longterm_locked(struct task_struct *tsk,
+ struct mm_struct *mm,
+ unsigned long start,
+ unsigned long nr_pages,
+ struct page **pages,
+ struct vm_area_struct **vmas,
+ unsigned int flags)
+{
+ return __get_user_pages_locked(tsk, mm, start, nr_pages, pages, vmas,
+ NULL, flags);
+}
+#endif /* CONFIG_FS_DAX || CONFIG_CMA */
+
+/*
+ * This is the same as get_user_pages_remote(), just with a
+ * less-flexible calling convention where we assume that the task
+ * and mm being operated on are the current task's and don't allow
+ * passing of a locked parameter. We also obviously don't pass
+ * FOLL_REMOTE in here.
+ */
+long get_user_pages(unsigned long start, unsigned long nr_pages,
+ unsigned int gup_flags, struct page **pages,
+ struct vm_area_struct **vmas)
+{
+ return __gup_longterm_locked(current, current->mm, start, nr_pages,
+ pages, vmas, gup_flags | FOLL_TOUCH);
+}
+EXPORT_SYMBOL(get_user_pages);

/**
* populate_vma_page_range() - populate a range of pages in the vma.
diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
index 6c0279e70cc4..7dd602d7f8db 100644
--- a/mm/gup_benchmark.c
+++ b/mm/gup_benchmark.c
@@ -54,8 +54,9 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
pages + i);
break;
case GUP_LONGTERM_BENCHMARK:
- nr = get_user_pages_longterm(addr, nr, gup->flags & 1,
- pages + i, NULL);
+ nr = get_user_pages(addr, nr,
+ (gup->flags & 1) | FOLL_LONGTERM,
+ pages + i, NULL);
break;
case GUP_BENCHMARK:
nr = get_user_pages(addr, nr, gup->flags & 1, pages + i,
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 77520eacee8f..ab489454a63e 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -267,8 +267,8 @@ static int xdp_umem_pin_pages(struct xdp_umem *umem)
return -ENOMEM;

down_read(&current->mm->mmap_sem);
- npgs = get_user_pages_longterm(umem->address, umem->npgs,
- gup_flags, &umem->pgs[0], NULL);
+ npgs = get_user_pages(umem->address, umem->npgs,
+ gup_flags | FOLL_LONGTERM, &umem->pgs[0], NULL);
up_read(&current->mm->mmap_sem);

if (npgs != umem->npgs) {
--
2.20.1