From: Peter Zijlstra Date: Fri, 15 Jan 2021 18:08:36 +0000 (+0100) Subject: workqueue: Restrict affinity change to rescuer X-Git-Tag: accepted/tizen/unified/20230118.172025~8026^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=640f17c82460e9724fd256f0a1f5d99e7ff0bda4;p=platform%2Fkernel%2Flinux-rpi.git workqueue: Restrict affinity change to rescuer create_worker() will already set the right affinity using kthread_bind_mask(), this means only the rescuer will need to change it's affinity. Howveer, while in cpu-hot-unplug a regular task is not allowed to run on online&&!active as it would be pushed away quite agressively. We need KTHREAD_IS_PER_CPU to survive in that environment. Therefore set the affinity after getting that magic flag. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Valentin Schneider Tested-by: Valentin Schneider Link: https://lkml.kernel.org/r/20210121103506.826629830@infradead.org --- diff --git a/kernel/workqueue.c b/kernel/workqueue.c index cce3433..894bb88 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1849,12 +1849,6 @@ static void worker_attach_to_pool(struct worker *worker, mutex_lock(&wq_pool_attach_mutex); /* - * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any - * online CPUs. It'll be re-applied when any of the CPUs come up. - */ - set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); - - /* * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains * stable across this function. See the comments above the flag * definition for details. @@ -1864,6 +1858,9 @@ static void worker_attach_to_pool(struct worker *worker, else kthread_set_per_cpu(worker->task, pool->cpu); + if (worker->rescue_wq) + set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); + list_add_tail(&worker->node, &pool->workers); worker->pool = pool;