Commit 8b46f880 authored Apr 21, 2010 by Paul E. McKenney Committed by Ingo Molnar Apr 30, 2010

rcu: Fix RCU lockdep splat on freezer_fork path

Add an RCU read-side critical section to suppress this false
positive.

Located-by: Eric Paris <eparis@parisplace.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: eric.dumazet@gmail.com
LKML-Reference: <1271880131-3951-2-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 8b08ca52

kernel/cgroup_freezer.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -205,9 +205,12 @@ static void freezer_fork(struct cgroup_subsys ss, struct task_struct task)
		* No lock is needed, since the task isn't on tasklist yet,
		* so it can't be moved to another cgroup, which means the
		* freezer won't be removed and will be valid during this
		* function call.
		* function call. Nevertheless, apply RCU read-side critical
		* section to suppress RCU lockdep false positives.
		*/
		rcu_read_lock();
		freezer = task_freezer(task);
		rcu_read_unlock();

		/*
		* The root cgroup is non-freezable, so we can skip the

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