linux-kernel - Re: [PATCH 1/1] sched/core: Fix stuck on completion for affine_move

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Message-ID: <20230928151917.GB29651@noisy.programming.kicks-ass.net>
Date:   Thu, 28 Sep 2023 17:19:17 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Kuyo Chang (張建文) <Kuyo.Chang@...iatek.com>
Cc:     "dietmar.eggemann@....com" <dietmar.eggemann@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>,
        wsd_upstream <wsd_upstream@...iatek.com>,
        "vschneid@...hat.com" <vschneid@...hat.com>,
        "bristot@...hat.com" <bristot@...hat.com>,
        "juri.lelli@...hat.com" <juri.lelli@...hat.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "bsegall@...gle.com" <bsegall@...gle.com>,
        "mgorman@...e.de" <mgorman@...e.de>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "vincent.guittot@...aro.org" <vincent.guittot@...aro.org>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>
Subject: Re: [PATCH 1/1] sched/core: Fix stuck on completion for
 affine_move_task() when stopper disable

On Thu, Sep 28, 2023 at 05:16:16PM +0200, Peter Zijlstra wrote:

> AFAICT this is migrate_enable(), which acts on current, so how can the
> CPU that current runs on go away?

> Your patch has at least one very obvious resource leak.

Sorry those are not so, I ended up staring at the wrong
stop_one_cpu_nowait() :-/

Still, the rest is very much the case, if you can't describe the exact
race scenario, you can't be talking about a solution.