diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup/cpuset.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 98af44a7f399..d2ec7b128960 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -518,10 +518,26 @@ static void guarantee_active_cpus(struct task_struct *tsk, rcu_read_lock(); cs = task_cs(tsk); - while (!cpumask_intersects(cs->effective_cpus, pmask)) + while (!cpumask_intersects(cs->effective_cpus, pmask)) { cs = parent_cs(cs); - + if (unlikely(!cs)) { + /* + * The top cpuset doesn't have any active cpu as a + * consequence of a race between its caller and the cpu + * hotplug operation where cpu_active_mask is updated + * asynchronously before cpuset_handle_hotplug() is + * being called to adjust the effective_cpus of the + * affected cpusets. But we know the top cpuset's + * effective_cpus is on its way to be identical to + * cpu_active_mask minus the exclusive CPUs dedicated + * to other valid cpuset partitions. Just pass back + * the filtered cpu_active_mask in this case. + */ + goto out_unlock; + } + } cpumask_and(pmask, pmask, cs->effective_cpus); +out_unlock: rcu_read_unlock(); } |