linux-kernel - Re: [PATCH/for-next v3 3/3] cgroup/cpuset: Call housekeeping_update() without holding cpus_read

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Message-ID: <1fff6bd2-b62a-48d9-9408-af3b5552815e@huaweicloud.com>
Date: Wed, 4 Feb 2026 10:51:45 +0800
From: Chen Ridong <chenridong@...weicloud.com>
To: Waiman Long <longman@...hat.com>, Tejun Heo <tj@...nel.org>,
 Johannes Weiner <hannes@...xchg.org>, Michal Koutný
 <mkoutny@...e.com>, Ingo Molnar <mingo@...hat.com>,
 Peter Zijlstra <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>,
 Vincent Guittot <vincent.guittot@...aro.org>,
 Steven Rostedt <rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>,
 Mel Gorman <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>,
 Anna-Maria Behnsen <anna-maria@...utronix.de>,
 Frederic Weisbecker <frederic@...nel.org>,
 Thomas Gleixner <tglx@...utronix.de>, Shuah Khan <shuah@...nel.org>
Cc: cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-kselftest@...r.kernel.org
Subject: Re: [PATCH/for-next v3 3/3] cgroup/cpuset: Call housekeeping_update()
 without holding cpus_read_lock



On 2026/2/3 4:11, Waiman Long wrote:
> --- a/kernel/time/timer_migration.c
> +++ b/kernel/time/timer_migration.c
> @@ -1559,8 +1559,6 @@ int tmigr_isolated_exclude_cpumask(struct cpumask *exclude_cpumask)
>  	cpumask_var_t cpumask __free(free_cpumask_var) = CPUMASK_VAR_NULL;
>  	int cpu;
>  
> -	lockdep_assert_cpus_held();
> -
>  	if (!works)
>  		return -ENOMEM;
>  	if (!alloc_cpumask_var(&cpumask, GFP_KERNEL))
> @@ -1570,6 +1568,7 @@ int tmigr_isolated_exclude_cpumask(struct cpumask *exclude_cpumask)
>  	 * First set previously isolated CPUs as available (unisolate).
>  	 * This cpumask contains only CPUs that switched to available now.
>  	 */
> +	guard(cpus_read_lock)();
>  	cpumask_andnot(cpumask, cpu_online_mask, exclude_cpumask);
>  	cpumask_andnot(cpumask, cpumask, tmigr_available_cpumask);
>  

It may lead to lockdep issue.

tmigr_init_isolation
	guard(cpus_read_lock)()
	tmigr_isolated_exclude_cpumask(cpumask)
		guard(cpus_read_lock)()

-- 
Best regards,
Ridong