tree c1195cd46733b6a3909c11b2b5abcdee4412b99b
parent 619d094b5872a5af153f1af77a8b7f7326faf0d0
author KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> 1332372864 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1332377701 -0700

memcg: remove PCG_MOVE_LOCK flag from page_cgroup

PCG_MOVE_LOCK is used for bit spinlock to avoid race between overwriting
pc->mem_cgroup and page statistics accounting per memcg.  This lock helps
to avoid the race but the race is very rare because moving tasks between
cgroup is not a usual job.  So, it seems using 1bit per page is too
costly.

This patch changes this lock as per-memcg spinlock and removes
PCG_MOVE_LOCK.

If smaller lock is required, we'll be able to add some hashes but I'd like
to start from this.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>