From: Li Zefan <lizf@cn.fujitsu.com>
Date: Fri, 23 Apr 2010 02:35:52 +0000 (+0800)
Subject: cgroup: Check task_lock in task_subsys_state()
X-Git-Tag: v2.6.34-rc7~11^2~2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1ce7e4ff24fe338438bc7837e02780f202bf202b;p=pandora-kernel.git

cgroup: Check task_lock in task_subsys_state()

Expand task_subsys_state()'s rcu_dereference_check() to include the full
locking rule as documented in Documentation/cgroups/cgroups.txt by adding
a check for task->alloc_lock being held.

This fixes an RCU false positive when resuming from suspend. The warning
comes from freezer cgroup in cgroup_freezing_or_frozen().

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Matt Helsley <matthltc@us.ibm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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