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workqueue: Init rescuer's affinities as wq_unbound_cpumask

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The affinity to set to the rescuers should be consistent in all paths
when a rescuer is in detached state. The affinity could be either
wq_unbound_cpumask or unbound_effective_cpumask(wq).

Related paths:
       rescuer's worker_detach_from_pool()
       update wq_unbound_cpumask
       update wq's cpumask
       init_rescuer()

Both affinities are Ok as long as they are consistent in all paths.

In the commit 449b31ad29 ("workqueue: Init rescuer's affinities as
the wq's effective cpumask") makes init_rescuer use
unbound_effective_cpumask(wq) which is consistent with then
apply_wqattrs_commit().

But using unbound_effective_cpumask(wq) requres much more code to
maintain the consistency, and it doesn't make much sense since the
affinity is only effective when the rescuer is not processing works.
wq_unbound_cpumask is more favorable.

So apply_wqattrs_commit() and the path of "updating wq's cpumask" had
been changed to not update the rescuer's affinity, and both the paths
of "updating wq_unbound_cpumask" and "rescuer's
worker_detach_from_pool()" had been changed to use wq_unbound_cpumask.

Now, make init_rescuer() use wq_unbound_cpumask for rescuer's affinity
and make all the paths consistent.

Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Lai Jiangshan
2025-11-17 11:09:13 +08:00
committed by Tejun Heo
parent 8ac4dbe7dd
commit c9c19e8bbc
1 changed files with 5 additions and 2 deletions
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7
kernel/workqueue.c
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@@ -5603,10 +5603,13 @@ static int init_rescuer(struct workqueue_struct *wq)
}
wq->rescuer = rescuer;
if (wq->flags & WQ_UNBOUND)
kthread_bind_mask(rescuer->task, unbound_effective_cpumask(wq));
/* initial cpumask is consistent with the detached rescuer and unbind_worker() */
if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask))
kthread_bind_mask(rescuer->task, wq_unbound_cpumask);
else
kthread_bind_mask(rescuer->task, cpu_possible_mask);
wake_up_process(rescuer->task);
return 0;