From: Waiman Long longman@redhat.com
commit ba9182a89626d5f83c2ee4594f55cb9c1e60f0e2 upstream.
After a successful cpuset_can_attach() call which increments the attach_in_progress flag, either cpuset_cancel_attach() or cpuset_attach() will be called later. In cpuset_attach(), tasks in cpuset_attach_wq, if present, will be woken up at the end. That is not the case in cpuset_cancel_attach(). So missed wakeup is possible if the attach operation is somehow cancelled. Fix that by doing the wakeup in cpuset_cancel_attach() as well.
Fixes: e44193d39e8d ("cpuset: let hotplug propagation work wait for task attaching") Signed-off-by: Waiman Long longman@redhat.com Reviewed-by: Michal Koutný mkoutny@suse.com Cc: stable@vger.kernel.org # v3.11+ Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/cgroup/cpuset.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -2502,11 +2502,15 @@ out_unlock: static void cpuset_cancel_attach(struct cgroup_taskset *tset) { struct cgroup_subsys_state *css; + struct cpuset *cs;
cgroup_taskset_first(tset, &css); + cs = css_cs(css);
percpu_down_write(&cpuset_rwsem); - css_cs(css)->attach_in_progress--; + cs->attach_in_progress--; + if (!cs->attach_in_progress) + wake_up(&cpuset_attach_wq); percpu_up_write(&cpuset_rwsem); }