On 05/28/2018 09:12 PM, Waiman Long wrote: > On 05/24/2018 06:28 AM, Juri Lelli wrote: >> On 17/05/18 16:55, Waiman Long wrote: >> >> [...] >> >>> @@ -849,7 +860,12 @@ static void rebuild_sched_domains_locked(void) >>> * passing doms with offlined cpu to partition_sched_domains(). >>> * Anyways, hotplug work item will rebuild sched domains. >>> */ >>> - if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) >>> + if (!top_cpuset.isolation_count && >>> + !cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask)) >>> + goto out; >>> + >>> + if (top_cpuset.isolation_count && >>> + !cpumask_subset(top_cpuset.effective_cpus, cpu_active_mask)) >>> goto out; >> Do we cover the case in which hotplug removed one of the isolated cpus >> from cpu_active_mask? > Yes, you are right. That is the remnant of my original patch that allows > only one isolated_cpus at root. Thanks for spotting that.
I am sorry. I would like to take it back my previous comment. The code above looks for inconsistency in the state of the effective_cpus mask to find out if it is racing with a hotplug event. If it is, we can skip the domain generation as the hotplug event will do that too. The checks are still valid with the current patchset. So I don't think we need to make any change here. Cheers, Longman
