From a978d6f521063514812a7094dbe5036e056e4de3 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Sat, 18 Oct 2008 20:26:58 -0700 Subject: [PATCH] mm: unlockless reclaim unlock_page is fairly expensive. It can be avoided in page reclaim success path. By definition if we have any other references to the page it would be a bug anyway. Signed-off-by: Nick Piggin Reviewed-by: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmscan.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 412d7872fc7..3b5860294bb 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -732,7 +732,14 @@ static unsigned long shrink_page_list(struct list_head *page_list, if (!mapping || !__remove_mapping(mapping, page)) goto keep_locked; - unlock_page(page); + /* + * At this point, we have no other references and there is + * no way to pick any more up (removed from LRU, removed + * from pagecache). Can use non-atomic bitops now (and + * we obviously don't have to worry about waking up a process + * waiting on the page lock, because there are no references. + */ + __clear_page_locked(page); free_it: nr_reclaimed++; if (!pagevec_add(&freed_pvec, page)) { -- 2.41.1