diff options
| -rw-r--r-- | kernel/cgroup/cpuset.c | 50 |
1 files changed, 15 insertions, 35 deletions
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 6e6eb09b8db6..fea577b4016a 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -1103,53 +1103,33 @@ void dl_rebuild_rd_accounting(void) */ void rebuild_sched_domains_locked(void) { - struct cgroup_subsys_state *pos_css; struct sched_domain_attr *attr; cpumask_var_t *doms; - struct cpuset *cs; int ndoms; + int i; lockdep_assert_cpus_held(); lockdep_assert_held(&cpuset_mutex); force_sd_rebuild = false; - /* - * If we have raced with CPU hotplug, return early to avoid - * passing doms with offlined cpu to partition_sched_domains(). - * Anyways, cpuset_handle_hotplug() will rebuild sched domains. - * - * With no CPUs in any subpartitions, top_cpuset's effective CPUs - * should be the same as the active CPUs, so checking only top_cpuset - * is enough to detect racing CPU offlines. - */ - if (cpumask_empty(subpartitions_cpus) && - !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) - return; + /* Generate domain masks and attrs */ + ndoms = generate_sched_domains(&doms, &attr); /* - * With subpartition CPUs, however, the effective CPUs of a partition - * root should be only a subset of the active CPUs. Since a CPU in any - * partition root could be offlined, all must be checked. - */ - if (!cpumask_empty(subpartitions_cpus)) { - rcu_read_lock(); - cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) { - if (!is_partition_valid(cs)) { - pos_css = css_rightmost_descendant(pos_css); - continue; - } - if (!cpumask_subset(cs->effective_cpus, - cpu_active_mask)) { - rcu_read_unlock(); - return; - } - } - rcu_read_unlock(); + * cpuset_hotplug_workfn is invoked synchronously now, thus this + * function should not race with CPU hotplug. And the effective CPUs + * must not include any offline CPUs. Passing an offline CPU in the + * doms to partition_sched_domains() will trigger a kernel panic. + * + * We perform a final check here: if the doms contains any + * offline CPUs, a warning is emitted and we return directly to + * prevent the panic. + */ + for (i = 0; i < ndoms; ++i) { + if (WARN_ON_ONCE(!cpumask_subset(doms[i], cpu_active_mask))) + return; } - /* Generate domain masks and attrs */ - ndoms = generate_sched_domains(&doms, &attr); - /* Have scheduler rebuild the domains */ partition_sched_domains(ndoms, doms, attr); } |