[PATCH 4/4] cpuset: Hold callback_mutex in cpuset_clone()

[Li Zefan <lizf@cn.fujitsu.com>]

Chaning cpuset->mems/cpuset->cpus should be protected under
callback_mutex.

cpuset_clone() doesn't follow this rule. It's ok because it's
called when creating and initializing a cgroup, but we'd better
hold the lock to avoid subtil break in the future.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
 kernel/cpuset.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 1e18d26..445573b 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1840,8 +1840,10 @@ static void cpuset_post_clone(struct cgroup_subsys *ss,
 	cs = cgroup_cs(cgroup);
 	parent_cs = cgroup_cs(parent);
 
+	mutex_lock(&callback_mutex);
 	cs->mems_allowed = parent_cs->mems_allowed;
 	cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed);
+	mutex_unlock(&callback_mutex);
 	return;
 }
 
-- 
1.7.3.1