From 46a4d679ef88285ea17c3e1e4fed330be2044f21 Mon Sep 17 00:00:00 2001 From: Lai Jiangshan Date: Fri, 29 Jul 2022 17:44:38 +0800 Subject: [PATCH] workqueue: Avoid a false warning in unbind_workers() Doing set_cpus_allowed_ptr() with wq_unbound_cpumask can be possible fails and trigger the false warning. Use cpu_possible_mask instead when wq_unbound_cpumask has no active CPUs. It is very easy to trigger the warning: Set wq_unbound_cpumask to a small set of CPUs. Offline all the CPUs of wq_unbound_cpumask. Offline an extra CPU and trigger the warning. Fixes: 10a5a651e3af ("workqueue: Restrict kworker in the offline CPU pool running on housekeeping CPUs") Signed-off-by: Lai Jiangshan Signed-off-by: Tejun Heo --- kernel/workqueue.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 1ea50f6..aa8a82b 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5001,7 +5001,10 @@ static void unbind_workers(int cpu) for_each_pool_worker(worker, pool) { kthread_set_per_cpu(worker->task, -1); - WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0); + if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask)) + WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0); + else + WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); } mutex_unlock(&wq_pool_attach_mutex); -- 2.7.4