cgroup/cpuset: Fix a partition bug with hotplug

In cpuset_hotplug_workfn(), the detection of whether the cpu list
has been changed is done by comparing the effective cpus of the top
cpuset with the cpu_active_mask. However, in the rare case that just
all the CPUs in the subparts_cpus are offlined, the detection fails
and the partition states are not updated correctly. Fix it by forcing
the cpus_updated flag to true in this particular case.

Fixes: 4b842da276 ("cpuset: Make CPU hotplug work with partition")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long 2021-07-20 10:18:27 -04:00 committed by Tejun Heo
parent 0f3adb8a1e
commit 15d428e6fe

View File

@ -3166,6 +3166,13 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
/*
* In the rare case that hotplug removes all the cpus in subparts_cpus,
* we assumed that cpus are updated.
*/
if (!cpus_updated && top_cpuset.nr_subparts_cpus)
cpus_updated = true;
/* synchronize cpus_allowed to cpu_active_mask */
if (cpus_updated) {
spin_lock_irq(&callback_lock);