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cgroup/cpuset: Wake up cpuset_attach_wq tasks in cpuset_cancel_attach()

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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>
This commit is contained in:
Waiman Long 2023-04-11 09:35:57 -04:00 committed by Tejun Heo
parent 57dcd64c7e
commit ba9182a896
1 changed files with 5 additions and 1 deletions
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6
kernel/cgroup/cpuset.c
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@ -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);
}