Messages in this thread Patch in this message | | | From | Ben Hutchings <> | Date | Sun, 12 Jun 2016 22:34:42 +0100 | Subject | [PATCH 3.2 33/46] mm/huge_memory: replace VM_NO_THP VM_BUG_ON with actual VMA check |
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3.2.81-rc1 review patch. If anyone has any objections, please let me know.
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From: Konstantin Khlebnikov <koct9i@gmail.com>
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> [bwh: Backported to 3.2: - The assertions use VM_BUG_ON() and also check is_linear_pfn_mapping(); keep that check - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- mm/huge_memory.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-)
--- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1635,14 +1635,14 @@ 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; /* * If is_pfn_mapping() is true is_learn_pfn_mapping() must be * true too, verify it here. */ - VM_BUG_ON(is_linear_pfn_mapping(vma) || vm_flags & VM_NO_THP); + VM_BUG_ON(is_linear_pfn_mapping(vma)); hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; hend = vma->vm_end & HPAGE_PMD_MASK; if (hstart < hend) @@ -1831,8 +1831,8 @@ static bool hugepage_vma_check(struct vm * If is_pfn_mapping() is true is_learn_pfn_mapping() must be * true too, verify it here. */ - VM_BUG_ON(is_linear_pfn_mapping(vma) || vma->vm_flags & VM_NO_THP); - return true; + VM_BUG_ON(is_linear_pfn_mapping(vma)); + return !(vma->vm_flags & VM_NO_THP); } static void collapse_huge_page(struct mm_struct *mm,
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