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Message-ID: <7f8a14be-762b-7ab8-4cef-1de6799d2dce@linux.alibaba.com>
Date:   Wed, 26 Jan 2022 10:17:54 +0800
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Subject: Re: [PATCH] cpuset: Fix the bug that subpart_cpus updated wrongly in
 update_cpumask()
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From:   Tianchen Ding <dtcccc@linux.alibaba.com>
To:     Zefan Li <lizefan.x@bytedance.com>, Tejun Heo <tj@kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Waiman Long <longman@redhat.com>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc:     cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20220118100518.2381118-1-dtcccc@linux.alibaba.com>
In-Reply-To: <20220118100518.2381118-1-dtcccc@linux.alibaba.com>
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Ping~
Any maintainer take a look?

On 2022/1/18 18:05, 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);