On Wed, May 26, 2021 at 1:12 PM Yang Shi <shy828301@xxxxxxxxx> 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@xxxxxxxxxx> > Acked-by: Hugh Dickins <hughd@xxxxxxxxxx> > Signed-off-by: Yang Shi <shy828301@xxxxxxxxx> Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
