From 6568d4a9c9ff16d6c4f0b14dfea567806ce579e4 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Fri, 20 Jan 2012 14:34:12 -0800 Subject: [PATCH] mm: memcg: update the correct soft limit tree during migration end_migration() passes the old page instead of the new page to commit the charge. This page descriptor is not used for committing itself, though, since we also pass the (correct) page_cgroup descriptor. But it's used to find the soft limit tree through the page's zone, so the soft limit tree of the old page's zone is updated instead of that of the new page's, which might get slightly out of date until the next charge reaches the ratelimit point. This glitch has been present since 5564e88 ("memcg: condense page_cgroup-to-page lookup points"). This fixes a bug that I introduced in 2.6.38. It's benign enough (to my knowledge) that we probably don't want this for stable. Reported-by: Hugh Dickins Signed-off-by: Johannes Weiner Acked-by: KAMEZAWA Hiroyuki Acked-by: Michal Hocko Acked-by: Kirill A. Shutemov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 3dbff4dcde35..4baddbae94cc 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3247,7 +3247,7 @@ int mem_cgroup_prepare_migration(struct page *page, ctype = MEM_CGROUP_CHARGE_TYPE_CACHE; else ctype = MEM_CGROUP_CHARGE_TYPE_SHMEM; - __mem_cgroup_commit_charge(memcg, page, 1, pc, ctype); + __mem_cgroup_commit_charge(memcg, newpage, 1, pc, ctype); return ret; }