linux-kernel - Re: [PATCH v7 1/3] sched/fair: Co-locate cfs_rq and sched_entity in cfs_tg

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Message-ID: <814a7bca-c5c7-446f-a67a-c09dab397f9b@amd.com>
Date: Mon, 19 Jan 2026 12:10:57 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Zecheng Li <zli94@...u.edu>, Ingo Molnar <mingo@...hat.com>, Peter
 Zijlstra <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>, Vincent
 Guittot <vincent.guittot@...aro.org>
CC: Dietmar Eggemann <dietmar.eggemann@....com>, Steven Rostedt
	<rostedt@...dmis.org>, Ben Segall <bsegall@...gle.com>, Mel Gorman
	<mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>, Rik van Riel
	<riel@...riel.com>, Chris Mason <clm@...com>, Madadi Vineeth Reddy
	<vineethr@...ux.ibm.com>, Xu Liu <xliuprof@...gle.com>, Blake Jones
	<blakejones@...gle.com>, Josh Don <joshdon@...gle.com>, Nilay Vaish
	<nilayvaish@...gle.com>, <linux-kernel@...r.kernel.org>, Zecheng Li
	<zecheng@...gle.com>
Subject: Re: [PATCH v7 1/3] sched/fair: Co-locate cfs_rq and sched_entity in
 cfs_tg_state

Hello Zecheng,

On 1/18/2026 9:04 AM, Zecheng Li wrote:
> @@ -13617,10 +13617,11 @@ void free_fair_sched_group(struct task_group *tg)
>  	int i;
>  
>  	for_each_possible_cpu(i) {
> -		if (tg->cfs_rq)
> -			kfree(tg->cfs_rq[i]);
> -		if (tg->se)
> -			kfree(tg->se[i]);
> +		if (tg->cfs_rq && tg->cfs_rq[i]) {

nit. Since the cfs_tg_state uses __no_randomize_layout now and, "cfs_rq"
is the first member, you can just do kfree(tg->cfs_rq[i]) since it is
the beginning of cfs_tg_state too.

This is how kfree() on tg->se[i] would have freed the entire
"sched_entity_stats" previously.

I know this is a transient change since later you switch to using
free_percpu() but it would still be nice to have a simplified hunk here.

> +			struct cfs_tg_state *state =
> +				container_of(tg->cfs_rq[i], struct cfs_tg_state, cfs_rq);
> +			kfree(state);
> +		}
>  	}
>  
>  	kfree(tg->cfs_rq);

-- 
Thanks and Regards,
Prateek