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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2016-07-26 15:25:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-26 16:19:19 -0700
commit1f52e67e5e7f48424059f8168e3a65bddc80ad97 (patch)
tree2719a0782dd6af0708d27564392a8beb9e4e3f8e /mm/huge_memory.c
parent8024ee2a09c6135102505bab4105e1410c279832 (diff)
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Vlastimil noted[1] that pmd can be no longer valid after we drop mmap_sem.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: 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/huge_memory.c')
-rw-r--r--mm/huge_memory.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1841e0ceac23..1a90f55d930f 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -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);