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Subject: Re: [PATCH v8 4/6] cpuset: Make generate_sched_domains() recognize
 isolated_cpus
To:     Juri Lelli <juri.lelli@redhat.com>
Cc:     Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        kernel-team@fb.com, pjt@google.com, luto@amacapital.net,
        Mike Galbraith <efault@gmx.de>, torvalds@linux-foundation.org,
        Roman Gushchin <guro@fb.com>
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 <20180524102837.GA3948@localhost.localdomain>
From:   Waiman Long <longman@redhat.com>
Organization: Red Hat
Message-ID: <45d70c88-e9f5-716a-ee9a-33dc111159cc@redhat.com>
Date:   Mon, 28 May 2018 21:12:55 -0400
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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.

Cheers,
Longman