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Subject: Re: [PATCH v2] sched/topology, cpuset: Account for housekeeping CPUs
 to avoid empty cpumasks
From:   Valentin Schneider <valentin.schneider@arm.com>
To:     linux-kernel@vger.kernel.org, cgroups@vger.kernel.org
Cc:     lizefan@huawei.com, tj@kernel.org, hannes@cmpxchg.org,
        mingo@kernel.org, peterz@infradead.org, vincent.guittot@linaro.org,
        Dietmar.Eggemann@arm.com, morten.rasmussen@arm.com,
        qperret@google.com,
        =?UTF-8?Q?Michal_Koutn=c3=bd?= <mkoutny@suse.com>
References: <20191104003906.31476-1-valentin.schneider@arm.com>
Message-ID: <d7ed40aa-1ac1-a42d-51eb-b1bd9f839fb1@arm.com>
Date:   Thu, 14 Nov 2019 16:03:50 +0000
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On 04/11/2019 00:39, Valentin Schneider wrote:
> Michal noted that a cpuset's effective_cpus can be a non-empy mask, but
> because of the masking done with housekeeping_cpumask(HK_FLAG_DOMAIN)
> further down the line, we can still end up with an empty cpumask being
> passed down to partition_sched_domains_locked().
> 
> Do the proper thing and don't just check the mask is non-empty - check
> that its intersection with housekeeping_cpumask(HK_FLAG_DOMAIN) is
> non-empty.
> 
> Fixes: cd1cb3350561 ("sched/topology: Don't try to build empty sched domains")
> Reported-by: Michal Koutný <mkoutny@suse.com>

Michal, could I nag you for a reviewed-by? I'd feel a bit more confident
with any sort of approval from folks who actually do use cpusets.

> Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>