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SubjectRe: [v4 PATCH 2/2] mm: rmap: make try_to_unmap() void function
On Wed, May 26, 2021 at 1:12 PM Yang Shi <shy828301@gmail.com> wrote:
>
> Currently try_to_unmap() return bool value by checking page_mapcount(),
> however this may return false positive since page_mapcount() doesn't
> check all subpages of compound page. The total_mapcount() could be used
> instead, but its cost is higher since it traverses all subpages.
>
> Actually the most callers of try_to_unmap() don't care about the
> return value at all. So just need check if page is still mapped by
> page_mapped() when necessary. And page_mapped() does bail out early
> when it finds mapped subpage.
>
> Suggested-by: Hugh Dickins <hughd@google.com>
> Acked-by: Hugh Dickins <hughd@google.com>
> Signed-off-by: Yang Shi <shy828301@gmail.com>

Reviewed-by: Shakeel Butt <shakeelb@google.com>

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