[PATCH v3 5/7] io_uring: rsrc: use FOLL_SAME_FILE on pin_user_pages()

[PATCH v3 5/7] io_uring: rsrc: use FOLL_SAME_FILE on pin_user_pages()

[Lorenzo Stoakes]

Commit edd478269640 ("io_uring/rsrc: disallow multi-source reg buffers")
prevents io_pin_pages() from pinning pages spanning multiple VMAs with
permitted characteristics (anon/huge), requiring that all VMAs share the
same vm_file.

The newly introduced FOLL_SAME_FILE flag permits this to be expressed as a
GUP flag rather than having to retrieve VMAs to perform the check.

We then only need to perform a VMA lookup for the first VMA to assert the
anon/hugepage requirement as we know the rest of the VMAs will possess the
same characteristics.

Doing this eliminates the one instance of vmas being used by
pin_user_pages().

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 io_uring/rsrc.c | 40 ++++++++++++++++++----------------------
 1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 7a43aed8e395..56de4d7bfc2b 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1141,9 +1141,8 @@ static int io_buffer_account_pin(struct io_ring_ctx *ctx, struct page **pages,
 struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages)
 {
 	unsigned long start, end, nr_pages;
-	struct vm_area_struct **vmas = NULL;
 	struct page **pages = NULL;
-	int i, pret, ret = -ENOMEM;
+	int pret, ret = -ENOMEM;
 
 	end = (ubuf + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	start = ubuf >> PAGE_SHIFT;
@@ -1153,31 +1152,29 @@ struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages)
 	if (!pages)
 		goto done;
 
-	vmas = kvmalloc_array(nr_pages, sizeof(struct vm_area_struct *),
-			      GFP_KERNEL);
-	if (!vmas)
-		goto done;
-
 	ret = 0;
 	mmap_read_lock(current->mm);
-	pret = pin_user_pages(ubuf, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
-			      pages, vmas);
+	pret = pin_user_pages(ubuf, nr_pages,
+			      FOLL_WRITE | FOLL_LONGTERM | FOLL_SAME_FILE,
+			      pages, NULL);
 	if (pret == nr_pages) {
-		struct file *file = vmas[0]->vm_file;
+		/*
+		 * lookup the first VMA, we require that all VMAs in range
+		 * maintain the same file characteristics, as enforced by
+		 * FOLL_SAME_FILE
+		 */
+		struct vm_area_struct *vma = vma_lookup(current->mm, ubuf);
+		struct file *file;
 
-		/* don't support file backed memory */
-		for (i = 0; i < nr_pages; i++) {
-			if (vmas[i]->vm_file != file) {
-				ret = -EINVAL;
-				break;
-			}
-			if (!file)
-				continue;
-			if (!vma_is_shmem(vmas[i]) && !is_file_hugepages(file)) {
+		if (WARN_ON_ONCE(!vma)) {
+			ret = -EINVAL;
+		} else {
+			/* don't support file backed memory */
+			file = vma->vm_file;
+			if (file && !vma_is_shmem(vma) && !is_file_hugepages(file))
 				ret = -EOPNOTSUPP;
-				break;
-			}
 		}
+
 		*npages = nr_pages;
 	} else {
 		ret = pret < 0 ? pret : -EFAULT;
@@ -1194,7 +1191,6 @@ struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages)
 	}
 	ret = 0;
 done:
-	kvfree(vmas);
 	if (ret < 0) {
 		kvfree(pages);
 		pages = ERR_PTR(ret);
-- 
2.40.0

[PATCH v3 6/7] mm/gup: remove vmas parameter from pin_user_pages()

[Lorenzo Stoakes]

After the introduction of FOLL_SAME_FILE we no longer require vmas for any
invocation of pin_user_pages(), so eliminate this parameter from the
function and all callers.

This clears the way to removing the vmas parameter from GUP altogether.

Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
---
 arch/powerpc/mm/book3s64/iommu_api.c       | 2 +-
 drivers/infiniband/hw/qib/qib_user_pages.c | 2 +-
 drivers/infiniband/hw/usnic/usnic_uiom.c   | 2 +-
 drivers/infiniband/sw/siw/siw_mem.c        | 2 +-
 drivers/media/v4l2-core/videobuf-dma-sg.c  | 2 +-
 drivers/vdpa/vdpa_user/vduse_dev.c         | 2 +-
 drivers/vhost/vdpa.c                       | 2 +-
 include/linux/mm.h                         | 3 +--
 io_uring/rsrc.c                            | 2 +-
 mm/gup.c                                   | 9 +++------
 mm/gup_test.c                              | 9 ++++-----
 net/xdp/xdp_umem.c                         | 2 +-
 12 files changed, 17 insertions(+), 22 deletions(-)

diff --git a/arch/powerpc/mm/book3s64/iommu_api.c b/arch/powerpc/mm/book3s64/iommu_api.c
index 81d7185e2ae8..d19fb1f3007d 100644
--- a/arch/powerpc/mm/book3s64/iommu_api.c
+++ b/arch/powerpc/mm/book3s64/iommu_api.c
@@ -105,7 +105,7 @@ static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
 
 		ret = pin_user_pages(ua + (entry << PAGE_SHIFT), n,
 				FOLL_WRITE | FOLL_LONGTERM,
-				mem->hpages + entry, NULL);
+				mem->hpages + entry);
 		if (ret == n) {
 			pinned += n;
 			continue;
diff --git a/drivers/infiniband/hw/qib/qib_user_pages.c b/drivers/infiniband/hw/qib/qib_user_pages.c
index f693bc753b6b..1bb7507325bc 100644
--- a/drivers/infiniband/hw/qib/qib_user_pages.c
+++ b/drivers/infiniband/hw/qib/qib_user_pages.c
@@ -111,7 +111,7 @@ int qib_get_user_pages(unsigned long start_page, size_t num_pages,
 		ret = pin_user_pages(start_page + got * PAGE_SIZE,
 				     num_pages - got,
 				     FOLL_LONGTERM | FOLL_WRITE,
-				     p + got, NULL);
+				     p + got);
 		if (ret < 0) {
 			mmap_read_unlock(current->mm);
 			goto bail_release;
diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.c b/drivers/infiniband/hw/usnic/usnic_uiom.c
index 2a5cac2658ec..84e0f41e7dfa 100644
--- a/drivers/infiniband/hw/usnic/usnic_uiom.c
+++ b/drivers/infiniband/hw/usnic/usnic_uiom.c
@@ -140,7 +140,7 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
 		ret = pin_user_pages(cur_base,
 				     min_t(unsigned long, npages,
 				     PAGE_SIZE / sizeof(struct page *)),
-				     gup_flags, page_list, NULL);
+				     gup_flags, page_list);
 
 		if (ret < 0)
 			goto out;
diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c
index f51ab2ccf151..e6e25f15567d 100644
--- a/drivers/infiniband/sw/siw/siw_mem.c
+++ b/drivers/infiniband/sw/siw/siw_mem.c
@@ -422,7 +422,7 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable)
 		umem->page_chunk[i].plist = plist;
 		while (nents) {
 			rv = pin_user_pages(first_page_va, nents, foll_flags,
-					    plist, NULL);
+					    plist);
 			if (rv < 0)
 				goto out_sem_up;
 
diff --git a/drivers/media/v4l2-core/videobuf-dma-sg.c b/drivers/media/v4l2-core/videobuf-dma-sg.c
index 53001532e8e3..405b89ea1054 100644
--- a/drivers/media/v4l2-core/videobuf-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf-dma-sg.c
@@ -180,7 +180,7 @@ static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
 		data, size, dma->nr_pages);
 
 	err = pin_user_pages(data & PAGE_MASK, dma->nr_pages, gup_flags,
-			     dma->pages, NULL);
+			     dma->pages);
 
 	if (err != dma->nr_pages) {
 		dma->nr_pages = (err >= 0) ? err : 0;
diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 0c3b48616a9f..1f80254604f0 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -995,7 +995,7 @@ static int vduse_dev_reg_umem(struct vduse_dev *dev,
 		goto out;
 
 	pinned = pin_user_pages(uaddr, npages, FOLL_LONGTERM | FOLL_WRITE,
-				page_list, NULL);
+				page_list);
 	if (pinned != npages) {
 		ret = pinned < 0 ? pinned : -ENOMEM;
 		goto out;
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 7be9d9d8f01c..4317128c1c62 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -952,7 +952,7 @@ static int vhost_vdpa_pa_map(struct vhost_vdpa *v,
 	while (npages) {
 		sz2pin = min_t(unsigned long, npages, list_size);
 		pinned = pin_user_pages(cur_base, sz2pin,
-					gup_flags, page_list, NULL);
+					gup_flags, page_list);
 		if (sz2pin != pinned) {
 			if (pinned < 0) {
 				ret = pinned;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 1bfe73a2b6d3..363e3d0d46f4 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2382,8 +2382,7 @@ long pin_user_pages_remote(struct mm_struct *mm,
 long get_user_pages(unsigned long start, unsigned long nr_pages,
 		    unsigned int gup_flags, struct page **pages);
 long pin_user_pages(unsigned long start, unsigned long nr_pages,
-		    unsigned int gup_flags, struct page **pages,
-		    struct vm_area_struct **vmas);
+		    unsigned int gup_flags, struct page **pages);
 long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
 		    struct page **pages, unsigned int gup_flags);
 long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index 56de4d7bfc2b..bd45681de660 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -1156,7 +1156,7 @@ struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages)
 	mmap_read_lock(current->mm);
 	pret = pin_user_pages(ubuf, nr_pages,
 			      FOLL_WRITE | FOLL_LONGTERM | FOLL_SAME_FILE,
-			      pages, NULL);
+			      pages);
 	if (pret == nr_pages) {
 		/*
 		 * lookup the first VMA, we require that all VMAs in range
diff --git a/mm/gup.c b/mm/gup.c
index 3954ce499a4a..714970ef3b30 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -3132,8 +3132,6 @@ EXPORT_SYMBOL(pin_user_pages_remote);
  * @gup_flags:	flags modifying lookup behaviour
  * @pages:	array that receives pointers to the pages pinned.
  *		Should be at least nr_pages long.
- * @vmas:	array of pointers to vmas corresponding to each page.
- *		Or NULL if the caller does not require them.
  *
  * Nearly the same as get_user_pages(), except that FOLL_TOUCH is not set, and
  * FOLL_PIN is set.
@@ -3142,15 +3140,14 @@ EXPORT_SYMBOL(pin_user_pages_remote);
  * see Documentation/core-api/pin_user_pages.rst for details.
  */
 long pin_user_pages(unsigned long start, unsigned long nr_pages,
-		    unsigned int gup_flags, struct page **pages,
-		    struct vm_area_struct **vmas)
+		    unsigned int gup_flags, struct page **pages)
 {
 	int locked = 1;
 
-	if (!is_valid_gup_args(pages, vmas, NULL, &gup_flags, FOLL_PIN))
+	if (!is_valid_gup_args(pages, NULL, NULL, &gup_flags, FOLL_PIN))
 		return 0;
 	return __gup_longterm_locked(current->mm, start, nr_pages,
-				     pages, vmas, &locked, gup_flags);
+				     pages, NULL, &locked, gup_flags);
 }
 EXPORT_SYMBOL(pin_user_pages);
 
diff --git a/mm/gup_test.c b/mm/gup_test.c
index 9ba8ea23f84e..1668ce0e0783 100644
--- a/mm/gup_test.c
+++ b/mm/gup_test.c
@@ -146,18 +146,17 @@ static int __gup_test_ioctl(unsigned int cmd,
 						 pages + i);
 			break;
 		case PIN_BASIC_TEST:
-			nr = pin_user_pages(addr, nr, gup->gup_flags, pages + i,
-					    NULL);
+			nr = pin_user_pages(addr, nr, gup->gup_flags, pages + i);
 			break;
 		case PIN_LONGTERM_BENCHMARK:
 			nr = pin_user_pages(addr, nr,
 					    gup->gup_flags | FOLL_LONGTERM,
-					    pages + i, NULL);
+					    pages + i);
 			break;
 		case DUMP_USER_PAGES_TEST:
 			if (gup->test_flags & GUP_TEST_FLAG_DUMP_PAGES_USE_PIN)
 				nr = pin_user_pages(addr, nr, gup->gup_flags,
-						    pages + i, NULL);
+						    pages + i);
 			else
 				nr = get_user_pages(addr, nr, gup->gup_flags,
 						    pages + i);
@@ -270,7 +269,7 @@ static inline int pin_longterm_test_start(unsigned long arg)
 							gup_flags, pages);
 		else
 			cur_pages = pin_user_pages(addr, remaining_pages,
-						   gup_flags, pages, NULL);
+						   gup_flags, pages);
 		if (cur_pages < 0) {
 			pin_longterm_test_stop();
 			ret = cur_pages;
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 02207e852d79..06cead2b8e34 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -103,7 +103,7 @@ static int xdp_umem_pin_pages(struct xdp_umem *umem, unsigned long address)
 
 	mmap_read_lock(current->mm);
 	npgs = pin_user_pages(address, umem->npgs,
-			      gup_flags | FOLL_LONGTERM, &umem->pgs[0], NULL);
+			      gup_flags | FOLL_LONGTERM, &umem->pgs[0]);
 	mmap_read_unlock(current->mm);
 
 	if (npgs != umem->npgs) {
-- 
2.40.0

Re: [PATCH v3 6/7] mm/gup: remove vmas parameter from pin_user_pages()

[David Hildenbrand]

On 15.04.23 14:09, Lorenzo Stoakes wrote:
> After the introduction of FOLL_SAME_FILE we no longer require vmas for any
> invocation of pin_user_pages(), so eliminate this parameter from the
> function and all callers.
> 
> This clears the way to removing the vmas parameter from GUP altogether.
> 
> Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
> ---

Ideally, we'd avoid FOLL_SAME_FILE as well

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb

Re: [PATCH v3 6/7] mm/gup: remove vmas parameter from pin_user_pages()

[Dennis Dalessandro]

On 4/15/23 8:09 AM, Lorenzo Stoakes wrote:
> After the introduction of FOLL_SAME_FILE we no longer require vmas for any
> invocation of pin_user_pages(), so eliminate this parameter from the
> function and all callers.
> 
> This clears the way to removing the vmas parameter from GUP altogether.
> 
> Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com>
> ---
>  arch/powerpc/mm/book3s64/iommu_api.c       | 2 +-
>  drivers/infiniband/hw/qib/qib_user_pages.c | 2 +-
>  drivers/infiniband/hw/usnic/usnic_uiom.c   | 2 +-
>  drivers/infiniband/sw/siw/siw_mem.c        | 2 +-
>  drivers/media/v4l2-core/videobuf-dma-sg.c  | 2 +-
>  drivers/vdpa/vdpa_user/vduse_dev.c         | 2 +-
>  drivers/vhost/vdpa.c                       | 2 +-
>  include/linux/mm.h                         | 3 +--
>  io_uring/rsrc.c                            | 2 +-
>  mm/gup.c                                   | 9 +++------
>  mm/gup_test.c                              | 9 ++++-----
>  net/xdp/xdp_umem.c                         | 2 +-
>  12 files changed, 17 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/qib/qib_user_pages.c b/drivers/infiniband/hw/qib/qib_user_pages.c
> index f693bc753b6b..1bb7507325bc 100644
> --- a/drivers/infiniband/hw/qib/qib_user_pages.c
> +++ b/drivers/infiniband/hw/qib/qib_user_pages.c
> @@ -111,7 +111,7 @@ int qib_get_user_pages(unsigned long start_page, size_t num_pages,
>  		ret = pin_user_pages(start_page + got * PAGE_SIZE,
>  				     num_pages - got,
>  				     FOLL_LONGTERM | FOLL_WRITE,
> -				     p + got, NULL);
> +				     p + got);
>  		if (ret < 0) {
>  			mmap_read_unlock(current->mm);
>  			goto bail_release;

For Qib...

Acked-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>