cpuset: initialize effective masks when clone_children is enabled

If clone_children is enabled, effective masks won't be initialized
due to the bug:

  # mount -t cgroup -o cpuset xxx /mnt
  # echo 1 > cgroup.clone_children
  # mkdir /mnt/tmp
  # cat /mnt/tmp/
  # cat cpuset.effective_cpus

  # cat cpuset.cpus
  0-15

And then this cpuset won't constrain the tasks in it.

Either the bug or the fix has no effect on unified hierarchy, as
there's no clone_chidren flag there any more.

Reported-by: Christian Brauner <[email protected]>
Reported-by: Serge Hallyn <[email protected]>
Cc: <[email protected]> # 3.17+
Signed-off-by: Zefan Li <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
Tested-by: Serge Hallyn <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 1d1fe9361d29..89d4ed08afba 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1979,7 +1979,9 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
 
 	spin_lock_irq(&callback_lock);
 	cs->mems_allowed = parent->mems_allowed;
+	cs->effective_mems = parent->mems_allowed;
 	cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
+	cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
 	spin_unlock_irq(&callback_lock);
 out_unlock:
 	mutex_unlock(&cpuset_mutex);