Commit 1f52e67e authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

khugepaged: recheck pmd after mmap_sem re-acquired 

Vlastimil noted[1] that pmd can be no longer valid after we drop
mmap_sem.  We need recheck it once mmap_sem taken again.

[1] http://lkml.kernel.org/r/12918dcd-a695-c6f4-e06f-69141c5f357f@suse.cz

Link: http://lkml.kernel.org/r/1466021202-61880-6-git-send-email-kirill.shutemov@linux.intel.com


Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8024ee2a

mm/huge_memory.c

+6 −0
Original line number Diff line number Diff line
@@ -2433,6 +2433,9 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, 
			/* vma is no longer available, don't continue to swapin */

			if (hugepage_vma_revalidate(mm, address))

				return false;

			/* check if the pmd is still valid */

			if (mm_find_pmd(mm, address) != pmd)

				return false;

		}

		if (ret & VM_FAULT_ERROR) {

			trace_mm_collapse_huge_page_swapin(mm, swapped_in, 0);
@@ -2518,6 +2521,9 @@ static void collapse_huge_page(struct mm_struct *mm, 
	result = hugepage_vma_revalidate(mm, address);

	if (result)

		goto out;

	/* check if the pmd is still valid */

	if (mm_find_pmd(mm, address) != pmd)

		goto out;



	anon_vma_lock_write(vma->anon_vma);

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