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authorKonstantin Khlebnikov <koct9i@gmail.com>2016-04-28 16:18:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-04-28 19:34:04 -0700
commit3486b85a29c1741db99d0c522211c82d2b7a56d0 (patch)
tree4f4cae93c4107744a09445f880fc39a14f85ebec
parent314e9b75b3f673a61ecbf0bba401830bc7dfe121 (diff)
downloadlinux-3486b85a29c1741db99d0c522211c82d2b7a56d0.tar.bz2
mm/huge_memory: replace VM_NO_THP VM_BUG_ON with actual VMA check
Khugepaged detects own VMAs by checking vm_file and vm_ops but this way it cannot distinguish private /dev/zero mappings from other special mappings like /dev/hpet which has no vm_ops and popultes PTEs in mmap. This fixes false-positive VM_BUG_ON and prevents installing THP where they are not expected. Link: http://lkml.kernel.org/r/CACT4Y+ZmuZMV5CjSFOeXviwQdABAgT7T+StKfTqan9YDtgEi5g@mail.gmail.com Fixes: 78f11a255749 ("mm: thp: fix /dev/zero MAP_PRIVATE and vm_flags cleanups") Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/huge_memory.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 5346de05f471..df67b53ae3c5 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1960,10 +1960,9 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
* page fault if needed.
*/
return 0;
- if (vma->vm_ops)
+ if (vma->vm_ops || (vm_flags & VM_NO_THP))
/* khugepaged not yet working on file or special mappings */
return 0;
- VM_BUG_ON_VMA(vm_flags & VM_NO_THP, vma);
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
hend = vma->vm_end & HPAGE_PMD_MASK;
if (hstart < hend)
@@ -2352,8 +2351,7 @@ static bool hugepage_vma_check(struct vm_area_struct *vma)
return false;
if (is_vma_temporary_stack(vma))
return false;
- VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma);
- return true;
+ return !(vma->vm_flags & VM_NO_THP);
}
static void collapse_huge_page(struct mm_struct *mm,