linux-kernel - Re: [PATCH] sched/core: Avoid WARN_DOUBLE_CLOCK warning when CONFIG_SCHED

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Message-ID: <Y8UyqnVRNTcBD/V7@hirez.programming.kicks-ass.net>
Date:   Mon, 16 Jan 2023 12:19:06 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Hao Jia <jiahao.os@...edance.com>
Cc:     mingo@...hat.com, mingo@...nel.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com,
        mgorman@...hsingularity.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sched/core: Avoid WARN_DOUBLE_CLOCK warning when
 CONFIG_SCHED_CORE

On Tue, Dec 06, 2022 at 03:05:50PM +0800, Hao Jia wrote:
> When we need to call update_rq_clock() to update the rq clock of
> other CPUs on the same core, before that we need to clear RQCF_UPDATED
> of rq->clock_update_flags to avoid the WARN_DOUBLE_CLOCK warning.
> Because at this time the rq->clock_update_flags of other CPUs
> may be RQCF_UPDATED.

So you've found that the WARN_DOUBLE_CLOCK machinery doesn't work for
core-sched -- but then instead of fixing that machinery, you put
band-aids on it :/