From: Waiman Long Date: Tue, 20 Jul 2021 14:18:27 +0000 (-0400) Subject: cgroup/cpuset: Fix a partition bug with hotplug X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=15d428e6fe77fffc3f4fff923336036f5496ef17;p=linux.git 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: 4b842da276a8 ("cpuset: Make CPU hotplug work with partition") Signed-off-by: Waiman Long Signed-off-by: Tejun Heo --- diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index f5fef5516d99b..28a784bf64b1d 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -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);