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authorKonstantin Khlebnikov <koct9i@gmail.com>2016-04-28 16:18:32 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-05-04 14:48:49 -0700
commitbe591a683e3b4cc58466e08cd6b5e4a71c02b19a (patch)
tree72bf04eecd0f4bbf6cf920fada9be443ce831833
parent52526076a5a686906a0acc22d27530ecb9364d84 (diff)
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mm/huge_memory: replace VM_NO_THP VM_BUG_ON with actual VMA check
commit 3486b85a29c1741db99d0c522211c82d2b7a56d0 upstream. 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> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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 62fe06bb7d04..530e6427f823 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2134,10 +2134,9 @@ 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)
@@ -2498,8 +2497,7 @@ 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,