Re: [PATCH] mm/rmap: try_to_unmap_one() do not call mmu_notifier under ptl
From: Kirill A. Shutemov
Date: Wed Aug 09 2017 - 12:34:45 EST
On Wed, Aug 09, 2017 at 12:17:09PM -0400, jglisse@xxxxxxxxxx wrote:
> From: Jérôme Glisse <jglisse@xxxxxxxxxx>
>
> MMU notifiers can sleep, but in try_to_unmap_one() we call
> mmu_notifier_invalidate_page() under page table lock.
>
> Let's instead use mmu_notifier_invalidate_range() outside
> page_vma_mapped_walk() loop.
>
> Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
> Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Fixes: c7ab0d2fdc84 ("mm: convert try_to_unmap_one() to use page_vma_mapped_walk()")
> ---
> mm/rmap.c | 36 +++++++++++++++++++++---------------
> 1 file changed, 21 insertions(+), 15 deletions(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index aff607d5f7d2..d60e887f1cda 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1329,7 +1329,8 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
> };
> pte_t pteval;
> struct page *subpage;
> - bool ret = true;
> + bool ret = true, invalidation_needed = false;
> + unsigned long end = address + PAGE_SIZE;
I think it should be 'address + (1UL << compound_order(page))'.
--
Kirill A. Shutemov