On Thu, Mar 02, 2017 at 03:39:18PM +0900, Minchan Kim wrote: > If the page is mapped and rescue in ttuo, page_mapcount(page) == 0 cannot > be true so page_mapcount check in ttu is enough to return SWAP_SUCCESS. > IOW, SWAP_MLOCK check is redundant so remove it. > > Signed-off-by: Minchan Kim <[email protected]> > --- > mm/rmap.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/rmap.c b/mm/rmap.c > index 3a14013..0a48958 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1523,7 +1523,7 @@ int try_to_unmap(struct page *page, enum ttu_flags > flags) > else > ret = rmap_walk(page, &rwc); > > - if (ret != SWAP_MLOCK && !page_mapcount(page)) > + if (!page_mapcount(page))
Hm. I think there's bug in current code. It should be !total_mapcount(page) otherwise it can be false-positive if there's THP mapped with PTEs. And in this case ret != SWAP_MLOCK is helpful to cut down some cost. Althouth it should be fine to remove it, I guess. -- Kirill A. Shutemov
