From: Waiman Long <longman@xxxxxxxxxx>
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@xxxxxxxxxx>
Reviewed-by: Michal Koutný <mkoutny@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v3.11+
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/cgroup/cpuset.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -2498,11 +2498,15 @@ 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);
}
