From: Waiman Long <longman@xxxxxxxxxx>
Commit 6667439f51c446fead5d991ff49b842a811a6195 upstream.
Similar to commit 3fb906e7fabb ("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@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Luiz Capitulino <luizcap@xxxxxxxxxx>
---
kernel/cgroup/cpuset.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 8664b9c1edc8..91c4256a3da4 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -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);
--
2.40.1
