*
* Iterate through each task of @cs updating its cpus_allowed to the
* effective cpuset's. As this function is called with cpuset_rwsem held,
- * cpuset membership stays stable.
+ * cpuset membership stays stable. For top_cpuset, task_cpu_possible_mask()
+ * is used instead of effective_cpus to make sure all offline CPUs are also
+ * included as hotplug code won't update cpumasks for tasks in top_cpuset.
*/
static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
{
css_task_iter_start(&cs->css, 0, &it);
while ((task = css_task_iter_next(&it))) {
- /*
- * Percpu kthreads in top_cpuset are ignored
- */
- if (top_cs && (task->flags & PF_KTHREAD) &&
- kthread_is_per_cpu(task))
- continue;
+ const struct cpumask *possible_mask = task_cpu_possible_mask(task);
- cpumask_and(new_cpus, cs->effective_cpus,
- task_cpu_possible_mask(task));
+ if (top_cs) {
+ /*
+ * Percpu kthreads in top_cpuset are ignored
+ */
+ if ((task->flags & PF_KTHREAD) && kthread_is_per_cpu(task))
+ continue;
+ cpumask_andnot(new_cpus, possible_mask, cs->subparts_cpus);
+ } else {
+ cpumask_and(new_cpus, possible_mask, cs->effective_cpus);
+ }
set_cpus_allowed_ptr(task, new_cpus);
}
css_task_iter_end(&it);