tree ac556b1bfa52f06fe2998371d10edec38d5cf2a9
parent 4b53433468c87794b523e4683fbd4e8e8aca1f63
author KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> 1281488578 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1281542358 -0700

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>