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Merge "cpuset: handle race between CPU hotplug and cpuset_hotplug_work"

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Linux Build Service Account 2016-09-19 23:27:57 -07:00 • committed by Gerrit - the friendly Code Review server
commit 646ce8a905
1 changed files with 14 additions and 3 deletions
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17
kernel/cpuset.c
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@ -326,8 +326,7 @@ static struct file_system_type cpuset_fs_type = {
/* /*
* Return in pmask the portion of a cpusets's cpus_allowed that * Return in pmask the portion of a cpusets's cpus_allowed that
* are online. If none are online, walk up the cpuset hierarchy * are online. If none are online, walk up the cpuset hierarchy
* until we find one that does have some online cpus. The top * until we find one that does have some online cpus.
* cpuset always has some cpus online.
* *
* One way or another, we guarantee to return some non-empty subset * One way or another, we guarantee to return some non-empty subset
* of cpu_online_mask. * of cpu_online_mask.
@ -336,8 +335,20 @@ static struct file_system_type cpuset_fs_type = {
*/ */
static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask) static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
{ {
while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) {
cs = parent_cs(cs); cs = parent_cs(cs);
if (unlikely(!cs)) {
/*
* The top cpuset doesn't have any online cpu as a
* consequence of a race between cpuset_hotplug_work
* and cpu hotplug notifier. But we know the top
* cpuset's effective_cpus is on its way to to be
* identical to cpu_online_mask.
*/
cpumask_copy(pmask, cpu_online_mask);
return;
}
}
cpumask_and(pmask, cs->effective_cpus, cpu_online_mask); cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);
} }