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authorHugh Dickins <hughd@google.com>2021-07-07 13:11:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-07-11 15:05:15 -0700
commit023e1a8dd502405ba378a7fbb1ce62beb0616708 (patch)
treea460bbc7478c15f8cea3366785ad91607d0529fc
parentd9770fcc1c0c5b3e77dfac83b47defa3981fa7cd (diff)
mm/rmap: fix new bug: premature return from page_mlock_one()
In the unlikely race case that page_mlock_one() finds VM_LOCKED has been cleared by the time it got page table lock, page_vma_mapped_walk_done() must be called before returning, either explicitly, or by a final call to page_vma_mapped_walk() - otherwise the page table remains locked. Fixes: cd62734ca60d ("mm/rmap: split try_to_munlock from try_to_unmap") Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Alistair Popple <apopple@nvidia.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Reported-by: kernel test robot <oliver.sang@intel.com> Link: https://lore.kernel.org/lkml/20210711151446.GB4070@xsang-OptiPlex-9020/ Link: https://lore.kernel.org/lkml/f71f8523-cba7-3342-40a7-114abc5d1f51@google.com/ Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Yang Shi <shy828301@gmail.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/rmap.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 0e83c3be8568..1235368f0628 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1990,14 +1990,13 @@ static bool page_mlock_one(struct page *page, struct vm_area_struct *vma,
* this function is never called when PageDoubleMap().
*/
mlock_vma_page(page);
+ /*
+ * No need to scan further once the page is marked
+ * as mlocked.
+ */
page_vma_mapped_walk_done(&pvmw);
+ return false;
}
-
- /*
- * no need to continue scanning other vma's if the page has
- * been locked.
- */
- return false;
}
return true;