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cgroup/cpuset: Include offline CPUs when tasks' cpumasks in top_cpuset are updated

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Similar to commit 3fb906e7fa ("group/cpuset: Don't filter offline
CPUs in cpuset_cpus_allowed() for top cpuset tasks"), the whole set of
possible CPUs including offline ones should be used for setting cpumasks
for tasks in the top cpuset when a cpuset partition is modified as the
hotplug code won't update cpumasks for tasks in the top cpuset when
CPUs become online or offline.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long 2023-03-17 11:15:07 -04:00 committed by Tejun Heo
parent df59b72cd8
commit 6667439f51
1 changed files with 14 additions and 9 deletions
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23
kernel/cgroup/cpuset.c
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@ -1209,7 +1209,9 @@ void rebuild_sched_domains(void)
*
* 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)
{
@ -1219,15 +1221,18 @@ 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);