From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Date: Wed, 21 Mar 2012 23:34:24 +0000 (-0700)
Subject: memcg: remove PCG_MOVE_LOCK flag from page_cgroup
X-Git-Tag: v3.4-rc1~158^2~9
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=312734c04e2fecc58429aec98194e4ff12d8f7d6;p=pandora-kernel.git

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>
---

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