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

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

Acked-by: Paul Menage <redacted>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Li Zefan <redacted>
---
 kernel/cpuset.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 3f93e5a..1ca786a 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c

@@ -1836,8 +1836,10 @@ 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

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