workqueue: respect isolated cpus when queueing an unbound work

Initialize wq_unbound_cpumask to exclude cpus that were isolated by
the cmdline's isolcpus parameter.

Signed-off-by: Tal Shorer <tal.shorer@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

kernel/workqueue.c

@@ -4980,6 +4980,10 @@ int workqueue_set_unbound_cpumask(cpumask_var_t cpumask)
 	if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL))
 		return -ENOMEM;
 
+	/*
+	 * Not excluding isolated cpus on purpose.
+	 * If the user wishes to include them, we allow that.
+	 */
 	cpumask_and(cpumask, cpumask, cpu_possible_mask);
 	if (!cpumask_empty(cpumask)) {
 		apply_wqattrs_lock();
@@ -5579,7 +5583,7 @@ int __init workqueue_init_early(void)
 	WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
 
 	BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL));
-	cpumask_copy(wq_unbound_cpumask, cpu_possible_mask);
+	cpumask_andnot(wq_unbound_cpumask, cpu_possible_mask, cpu_isolated_map);
 
 	pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);