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Message-ID: <7610638e-9954-a6b2-63b2-e1df334a288f@redhat.com>
Date:   Tue, 18 Jan 2022 15:21:44 -0500
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Subject: Re: [PATCH] cpuset: Fix the bug that subpart_cpus updated wrongly in
 update_cpumask()
Content-Language: en-US
To:     Tianchen Ding <dtcccc@linux.alibaba.com>,
        Zefan Li <lizefan.x@bytedance.com>, Tejun Heo <tj@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc:     cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20220118100518.2381118-1-dtcccc@linux.alibaba.com>
From:   Waiman Long <longman@redhat.com>
In-Reply-To: <20220118100518.2381118-1-dtcccc@linux.alibaba.com>
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On 1/18/22 05:05, Tianchen Ding wrote:
> subparts_cpus should be limited as a subset of cpus_allowed, but it is
> updated wrongly by using cpumask_andnot(). Use cpumask_and() instead to
> fix it.
>
> Fixes: ee8dde0cd2ce ("cpuset: Add new v2 cpuset.sched.partition flag")
> Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
> ---
>   kernel/cgroup/cpuset.c | 3 +--
>   1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index bb3531e7fda7..804ff5738c5f 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -1635,8 +1635,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
>   	 * Make sure that subparts_cpus is a subset of cpus_allowed.
>   	 */
>   	if (cs->nr_subparts_cpus) {
> -		cpumask_andnot(cs->subparts_cpus, cs->subparts_cpus,
> -			       cs->cpus_allowed);
> +		cpumask_and(cs->subparts_cpus, cs->subparts_cpus, cs->cpus_allowed);
>   		cs->nr_subparts_cpus = cpumask_weight(cs->subparts_cpus);
>   	}
>   	spin_unlock_irq(&callback_lock);

Thanks for the fix.

Reviewed-by: Waiman Long <longman@redhat.com>