Re: [PATCHv2] thp: keep huge zero page pinned until tlb flush

[Andrea Arcangeli <aarcange@redhat.com>]

On Tue, Apr 05, 2016 at 01:12:34PM +0300, Kirill A. Shutemov wrote:
> Andrea has found[1] a race condition on MMU-gather based TLB flush vs
> split_huge_page() or shrinker which frees huge zero under us (patch 1/2
> and 2/2 respectively).
> 
> With new THP refcounting, we don't need patch 1/2: mmu_gather keeps the
> page pinned until flush is complete and the pin prevents the page from
> being split under us.
> 
> We still need patch 2/2. This is simplified version of Andrea's patch.
> We don't need fancy encoding.
> 
> [1] http://lkml.kernel.org/r/1447938052-22165-1-git-send-email-aarcange@redhat.com
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reported-by: Andrea Arcangeli <aarcange@redhat.com>
> ---
>  v2:
>    - fix build for !THP;
>    - typos;
> ---
>  include/linux/huge_mm.h | 5 +++++
>  mm/huge_memory.c        | 6 +++---
>  mm/swap.c               | 5 +++++
>  3 files changed, 13 insertions(+), 3 deletions(-)

Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>

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