linux-kernel - Re: [PATCH 1/2] sched: topology: Fix topology validation error

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Message-ID: <67c2b6bc-7a05-46a5-a409-a51f28f94c64@amd.com>
Date: Mon, 25 Aug 2025 08:48:29 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Tim Chen <tim.c.chen@...ux.intel.com>, Vinicius Costa Gomes
	<vinicius.gomes@...el.com>, Peter Zijlstra <peterz@...radead.org>
CC: Ingo Molnar <mingo@...hat.com>, Juri Lelli <juri.lelli@...hat.com>,
	Dietmar Eggemann <dietmar.eggemann@....com>, Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>, Valentin Schneider <vschneid@...hat.com>, "Tim
 Chen" <tim.c.chen@...el.com>, Vincent Guittot <vincent.guittot@...aro.org>,
	Libo Chen <libo.chen@...cle.com>, Abel Wu <wuyun.abel@...edance.com>, "Len
 Brown" <len.brown@...el.com>, <linux-kernel@...r.kernel.org>, Chen Yu
	<yu.c.chen@...el.com>, "Gautham R . Shenoy" <gautham.shenoy@....com>, "Zhao
 Liu" <zhao1.liu@...el.com>
Subject: Re: [PATCH 1/2] sched: topology: Fix topology validation error

Hello Tim, Vinicius,

On 8/23/2025 1:44 AM, Tim Chen wrote:
> --- a/kernel/sched/topology.c
> +++ b/kernel/sched/topology.c
> @@ -2394,6 +2394,14 @@ static bool topology_span_sane(const struct cpumask *cpu_map)
>  	for_each_sd_topology(tl) {
>  		int tl_common_flags = 0;
>  
> +#ifdef CONFIG_NUMA
> +		/*
> +		 * sd_numa_mask() (one of the possible values of
> +		 * tl->mask()) depends on the current level to work
> +		 * correctly.
> +		 */
> +		sched_domains_curr_level = tl->numa_level;
> +#endif

A similar solution was proposed in [1] and after a few iterations, we
arrived at [2] as a potential solution to this issue. Now that the merge
window is behind us, Peter would it be possible to pick one of these up?

P.S. Leon has confirmed this solved the splat of their deployments too
on an earlier version [3].

[1] https://lore.kernel.org/lkml/20250624041235.1589-1-kprateek.nayak@amd.com/
[2] https://lore.kernel.org/lkml/20250715040824.893-1-kprateek.nayak@amd.com/
[3] https://lore.kernel.org/lkml/20250720104136.GI402218@unreal/

>  		if (tl->sd_flags)
>  			tl_common_flags = (*tl->sd_flags)();
>  

-- 
Thanks and Regards,
Prateek