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>
* page fault if needed.
*/
return 0;
* page fault if needed.
*/
return 0;
+ 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.
*/
/* 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)
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
hend = vma->vm_end & HPAGE_PMD_MASK;
if (hstart < hend)
* If is_pfn_mapping() is true is_learn_pfn_mapping() must be
* true too, verify it here.
*/
* 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,
}
static void collapse_huge_page(struct mm_struct *mm,