Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: [RFC PATCH v3 1/3] workqueue: Hold wq_pool_mutex while affining tasks to wq_unbound_cpumask | Date | Thu, 04 Aug 2022 12:40:21 +0100 |
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On 03/08/22 11:40, Lai Jiangshan wrote: > On 2022/8/2 16:41, Valentin Schneider wrote: >> When unbind_workers() reads wq_unbound_cpumask to set the affinity of >> freshly-unbound kworkers, it only holds wq_pool_attach_mutex. This isn't >> sufficient as wq_unbound_cpumask is only protected by wq_pool_mutex. >> >> This is made more obvious as of recent commit >> >> 46a4d679ef88 ("workqueue: Avoid a false warning in unbind_workers()") >> >> e.g. >> >> unbind_workers() workqueue_set_unbound_cpumask() >> kthread_set_per_cpu(p, -1); >> if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask)) >> cpumask_copy(wq_unbound_cpumask, cpumask); >> WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0); >> >> Make workqueue_offline_cpu() invoke unbind_workers() with wq_pool_mutex >> held. > > I would prefer to protect wq_unbound_cpumask with wq_pool_attach_mutex.
That looks alright to me, do you want to push that separately as it's a standalone patch, or should I carry it with this series?
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