memcg: bugfix check mem_cgroup_disabled() at split fixup

mem_cgroup_disabled() should be checked at splitting.  If disabled, no
heavy work is necesary.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 1eb1a04..8ab1d42 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2145,6 +2145,8 @@ void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail)
        struct page_cgroup *tail_pc = lookup_page_cgroup(tail);
        unsigned long flags;
 
+       if (mem_cgroup_disabled())
+               return;
        /*
         * We have no races with charge/uncharge but will have races with
         * page state accounting.