linux-kernel - Re: [PATCH v3 4/8] sched/deadline: Rebuild root domain accounting after every update

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Message-ID: <797146a4-97d6-442e-b2d3-f7c4f438d209@arm.com>
Date: Mon, 10 Mar 2025 19:54:13 +0100
From: Dietmar Eggemann <dietmar.eggemann@....com>
To: Juri Lelli <juri.lelli@...hat.com>, linux-kernel@...r.kernel.org,
 cgroups@...r.kernel.org
Cc: Ingo Molnar <mingo@...hat.com>, Peter Zijlstra <peterz@...radead.org>,
 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>,
 Waiman Long <longman@...hat.com>, Tejun Heo <tj@...nel.org>,
 Johannes Weiner <hannes@...xchg.org>, Michal Koutný
 <mkoutny@...e.com>, Qais Yousef <qyousef@...alina.io>,
 Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 Swapnil Sapkal <swapnil.sapkal@....com>,
 Shrikanth Hegde <sshegde@...ux.ibm.com>, Phil Auld <pauld@...hat.com>,
 luca.abeni@...tannapisa.it, tommaso.cucinotta@...tannapisa.it,
 Jon Hunter <jonathanh@...dia.com>
Subject: Re: [PATCH v3 4/8] sched/deadline: Rebuild root domain accounting
 after every update

On 10/03/2025 10:37, Juri Lelli wrote:
> Rebuilding of root domains accounting information (total_bw) is
> currently broken on some cases, e.g. suspend/resume on aarch64. Problem

Nit: Couldn't spot any arch dependency here. I guess it was just tested
on Arm64 platforms so far.

[...]

> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
> index 44093339761c..363ad268a25b 100644
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -2791,6 +2791,7 @@ void partition_sched_domains_locked(int ndoms_new, cpumask_var_t doms_new[],
>  	ndoms_cur = ndoms_new;
>  
>  	update_sched_domain_debugfs();
> +	dl_rebuild_rd_accounting();

Won't dl_rebuild_rd_accounting()'s lockdep_assert_held(&cpuset_mutex)
barf when called via cpuhp's:

sched_cpu_deactivate()

  cpuset_cpu_inactive()

    partition_sched_domains()

      partition_sched_domains_locked()

        dl_rebuild_rd_accounting()

?

[...]