The patch titled
From: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
has been added to the -mm tree. Its filename is
mm-huge_memory-replace-vm_no_thp-vm_bug_on-with-actual-vma-check.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-huge_memory-replace-vm_no_thp-vm_bug_on-with-actual-vma-check.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-huge_memory-replace-vm_no_thp-vm_bug_on-with-actual-vma-check.patch
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From: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Subject: 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@xxxxxxxxxxxxxx
Fixes: 78f11a255749 ("mm: thp: fix /dev/zero MAP_PRIVATE and vm_flags cleanups")
Signed-off-by: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff -puN mm/huge_memory.c~mm-huge_memory-replace-vm_no_thp-vm_bug_on-with-actual-vma-check mm/huge_memory.c
--- a/mm/huge_memory.c~mm-huge_memory-replace-vm_no_thp-vm_bug_on-with-actual-vma-check
+++ a/mm/huge_memory.c
@@ -1960,10 +1960,9 @@ int khugepaged_enter_vma_merge(struct vm
* 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
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,
_
Patches currently in -mm which might be from koct9i@xxxxxxxxx are
mm-huge_memory-replace-vm_no_thp-vm_bug_on-with-actual-vma-check.patch
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