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Yang Shi
1fb08ac63b
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. Link: https://lkml.kernel.org/r/[email protected] Suggested-by: Hugh Dickins <[email protected]> Signed-off-by: Yang Shi <[email protected]> Acked-by: Minchan Kim <[email protected]> Reviewed-by: Shakeel Butt <[email protected]> Acked-by: Kirill A. Shutemov <[email protected]> Signed-off-by: Hugh Dickins <[email protected]> Acked-by: Naoya Horiguchi <[email protected]> Cc: Alistair Popple <[email protected]> Cc: Jan Kara <[email protected]> Cc: Jue Wang <[email protected]> Cc: "Matthew Wilcox (Oracle)" <[email protected]> Cc: Miaohe Lin <[email protected]> Cc: Oscar Salvador <[email protected]> Cc: Peter Xu <[email protected]> Cc: Ralph Campbell <[email protected]> Cc: Wang Yugui <[email protected]> Cc: Zi Yan <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>