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From: Peter Zijlstra <peterz@infradead.org>
To: Hao Jia <jiahao.os@bytedance.com>
Cc: Benjamin Segall <bsegall@google.com>,
	Bagas Sanjaya <bagasdotme@gmail.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Igor Raits <igor.raits@gmail.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Regressions <regressions@lists.linux.dev>,
	Linux Stable <stable@vger.kernel.org>
Subject: Re: [External] Re: Fwd: WARNING: CPU: 13 PID: 3837105 at kernel/sched/sched.h:1561 __cfsb_csd_unthrottle+0x149/0x160
Date: Tue, 5 Sep 2023 00:23:51 +0200	[thread overview]
Message-ID: <20230904222351.GC2568@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <55e2861e-9722-08f8-2c49-966035ff4218@bytedance.com>

On Thu, Aug 31, 2023 at 04:48:29PM +0800, Hao Jia wrote:

> If I understand correctly, rq->clock_update_flags may be set to
> RQCF_ACT_SKIP after __schedule() holds the rq lock, and sometimes the rq
> lock may be released briefly in __schedule(), such as newidle_balance(). At
> this time Other CPUs hold this rq lock, and then calling
> rq_clock_start_loop_update() may trigger this warning.
> 
> This warning check might be wrong. We need to add assert_clock_updated() to
> check that the rq clock has been updated before calling
> rq_clock_start_loop_update().
> 
> Maybe some things can be like this?

Urgh, aside from it being white space mangled, I think this is entirely
going in the wrong direction.

Leaking ACT_SKIP is dodgy as heck.. it's entirely too late to think
clearly though, I'll have to try again tomorrow.

  reply	other threads:[~2023-09-04 22:24 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-30  0:37 Bagas Sanjaya
2023-08-30  0:42 ` Bagas Sanjaya
2023-08-30 19:16 ` Benjamin Segall
2023-08-31  8:48   ` [External] " Hao Jia
2023-09-04 22:23     ` Peter Zijlstra [this message]
2023-09-07  8:59       ` Hao Jia
2023-09-07 21:01         ` Tim Chen
2023-09-08  3:28           ` Hao Jia
2023-10-24  8:52 ` [tip: sched/core] sched/core: Fix RQCF_ACT_SKIP leak tip-bot2 for Hao Jia
2023-11-01 10:53 ` Fwd: WARNING: CPU: 13 PID: 3837105 at kernel/sched/sched.h:1561 __cfsb_csd_unthrottle+0x149/0x160 Linux regression tracking #update (Thorsten Leemhuis)

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