linux-kernel - Re: [PATCH] sched/fair: Prevent cfs_rq from being unthrottled with zero runtime

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Message-ID: <20251015025154.GA35@bytedance>
Date: Wed, 15 Oct 2025 10:51:54 +0800
From: Aaron Lu <ziqianlu@...edance.com>
To: Hao Jia <jiahao.kernel@...il.com>
Cc: Valentin Schneider <vschneid@...hat.com>,
	Ben Segall <bsegall@...gle.com>,
	K Prateek Nayak <kprateek.nayak@....com>,
	Peter Zijlstra <peterz@...radead.org>,
	Chengming Zhou <chengming.zhou@...ux.dev>,
	Josh Don <joshdon@...gle.com>, Ingo Molnar <mingo@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Xi Wang <xii@...gle.com>, linux-kernel@...r.kernel.org,
	Juri Lelli <juri.lelli@...hat.com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>, Mel Gorman <mgorman@...e.de>,
	Chuyi Zhou <zhouchuyi@...edance.com>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	Florian Bezdeka <florian.bezdeka@...mens.com>,
	Songtang Liu <liusongtang@...edance.com>,
	Chen Yu <yu.c.chen@...el.com>,
	Matteo Martelli <matteo.martelli@...ethink.co.uk>,
	Michal Koutný <mkoutny@...e.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: Re: [PATCH] sched/fair: Prevent cfs_rq from being unthrottled with
 zero runtime_remaining

On Wed, Oct 15, 2025 at 09:43:20AM +0800, Hao Jia wrote:
... ...
> Yes, I've already hit the cfs_rq->runtime_remaining < 0 condition in
> tg_unthrottle_up().
> 
> This morning, after applying your patch, I still get the same issue.
> However, As before, because cfs_rq->curr isn't NULL,
> check_enqueue_throttle() returns prematurely, preventing the triggering of
> throttle_cfs_rq().
> 
> 
> Some information to share with you.

Can you also share your cgroup setup and related quota setting etc. and
how to trigger it? Thanks.