From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Date: Wed, 11 Aug 2010 01:02:58 +0000 (-0700)
Subject: memcg: clean up waiting move acct
X-Git-Tag: v2.6.36-rc1~150
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2bd9bb206b338888b226e70139a25a67d10007f0;p=pandora-kernel.git

memcg: clean up waiting move acct

Now, for checking a memcg is under task-account-moving, we do css_tryget()
against mc.to and mc.from.  But this is just complicating things.  This
patch makes the check easier.

This patch adds a spinlock to move_charge_struct and guard modification of
mc.to and mc.from.  By this, we don't have to think about complicated
races arount this not-critical path.

[balbir@linux.vnet.ibm.com: don't crash on a null memcg being passed]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
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>
---

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