Re: [PATCH] mm/huge_memory: replace VM_NO_THP VM_BUG_ON with actual VMA check

[Vlastimil Babka]

On 04/02/2016 05:37 PM, Konstantin Khlebnikov wrote:
> 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.
>
> Signed-off-by: Konstantin Khlebnikov <koct9i@xxxxxxxxx>
> Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Link: http://lkml.kernel.org/r/CACT4Y+ZmuZMV5CjSFOeXviwQdABAgT7T+StKfTqan9YDtgEi5g@xxxxxxxxxxxxxx
> Fixes: 78f11a255749 ("mm: thp: fix /dev/zero MAP_PRIVATE and vm_flags cleanups")
> Cc: stable <stable@xxxxxxxxxxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>