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 449b31ad2937 ("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.
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| @@ -5603,10 +5603,13 @@ static int init_rescuer(struct workqueue_struct *wq) · 5602 unmodified lines | ||
| 5603 | 5603 | } |
| 5604 | 5604 | |
| 5605 | 5605 | wq->rescuer = rescuer; |
| 5606 | − if (wq->flags & WQ_UNBOUND) | |
| 5607 | − kthread_bind_mask(rescuer->task, unbound_effective_cpumask(wq)); | |
| 5606 | + | |
| 5607 | + /* initial cpumask is consistent with the detached rescuer and unbind_worker() */ | |
| 5608 | + if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask)) | |
| 5609 | + kthread_bind_mask(rescuer->task, wq_unbound_cpumask); | |
| 5608 | 5610 | else |
| 5609 | 5611 | kthread_bind_mask(rescuer->task, cpu_possible_mask); |
| 5612 | + | |
| 5610 | 5613 | wake_up_process(rescuer->task); |
| 5611 | 5614 | |
| 5612 | 5615 | return 0; |