The following commit has been merged into the sched/urgent branch of tip: Commit-ID: 640f17c82460e9724fd256f0a1f5d99e7ff0bda4 Gitweb: https://git.kernel.org/tip/640f17c82460e9724fd256f0a1f5d99e7ff0bda4 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Fri, 15 Jan 2021 19:08:36 +01:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Fri, 22 Jan 2021 15:09:43 +01:00 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) <peterz@xxxxxxxxxxxxx> Reviewed-by: Valentin Schneider <valentin.schneider@xxxxxxx> Tested-by: Valentin Schneider <valentin.schneider@xxxxxxx> Link: https://lkml.kernel.org/r/20210121103506.826629830@xxxxxxxxxxxxx --- kernel/workqueue.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) 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;
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