linux-kernel - Re: [PATCH v2] sched/topology, cpuset: Account for housekeeping CPUs to avoid empty cpumasks

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Message-ID: <d7ed40aa-1ac1-a42d-51eb-b1bd9f839fb1@arm.com>
Date:   Thu, 14 Nov 2019 16:03:50 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     linux-kernel@...r.kernel.org, cgroups@...r.kernel.org
Cc:     lizefan@...wei.com, tj@...nel.org, hannes@...xchg.org,
        mingo@...nel.org, peterz@...radead.org, vincent.guittot@...aro.org,
        Dietmar.Eggemann@....com, morten.rasmussen@....com,
        qperret@...gle.com,
        Michal Koutný <mkoutny@...e.com>
Subject: Re: [PATCH v2] sched/topology, cpuset: Account for housekeeping CPUs
 to avoid empty cpumasks

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@...e.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@....com>