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authorJohn Hubbard <jhubbard@nvidia.com>2022-03-23 00:39:40 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-23 01:57:01 +0300
commit65462462ffb28fddf13d46c628c4fc55878ab397 (patch)
tree9e06b88d75518d48222a32687803466aa69fe064 /mm/gup.c
parent7196040e19ad634293acd3eff7083149d7669031 (diff)
downloadlinux-65462462ffb28fddf13d46c628c4fc55878ab397.tar.xz
mm/gup: follow_pfn_pte(): -EEXIST cleanup
Remove a quirky special case from follow_pfn_pte(), and adjust its callers to match. Caller changes include: __get_user_pages(): Regardless of any FOLL_* flags, get_user_pages() and its variants should handle PFN-only entries by stopping early, if the caller expected **pages to be filled in. This makes for a more reliable API, as compared to the previous approach of skipping over such entries (and thus leaving them silently unwritten). move_pages(): squash the -EEXIST error return from follow_page() into -EFAULT, because -EFAULT is listed in the man page, whereas -EEXIST is not. Link: https://lkml.kernel.org/r/20220204020010.68930-3-jhubbard@nvidia.com Signed-off-by: John Hubbard <jhubbard@nvidia.com> Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Peter Xu <peterx@redhat.com> Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Hildenbrand <david@redhat.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c13
1 files changed, 8 insertions, 5 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 41da0bd61bec..43ad2bc6ca51 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -464,10 +464,6 @@ static struct page *no_page_table(struct vm_area_struct *vma,
static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
pte_t *pte, unsigned int flags)
{
- /* No page to get reference */
- if (flags & (FOLL_GET | FOLL_PIN))
- return -EFAULT;
-
if (flags & FOLL_TOUCH) {
pte_t entry = *pte;
@@ -1205,8 +1201,15 @@ retry:
} else if (PTR_ERR(page) == -EEXIST) {
/*
* Proper page table entry exists, but no corresponding
- * struct page.
+ * struct page. If the caller expects **pages to be
+ * filled in, bail out now, because that can't be done
+ * for this page.
*/
+ if (pages) {
+ ret = PTR_ERR(page);
+ goto out;
+ }
+
goto next_page;
} else if (IS_ERR(page)) {
ret = PTR_ERR(page);