linux-kernel - Re: [PATCH v10 2/5] sched: CGroup tagging interface for core scheduling

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Message-ID: <CABk29NuGDmRADRjcOKN7zbYYsd8yV-KkMwvgokz9-bX2G3YYpQ@mail.gmail.com>
Date:   Mon, 1 Mar 2021 13:01:57 -0800
From:   Josh Don <joshdon@...gle.com>
To:     Chris Hyser <chris.hyser@...cle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        Nishanth Aravamudan <naravamudan@...italocean.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Vineeth Pillai <viremana@...ux.microsoft.com>,
        Aaron Lu <aaron.lwe@...il.com>,
        Aubrey Li <aubrey.intel@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>, mingo@...nel.org,
        torvalds@...ux-foundation.org, fweisbec@...il.com,
        Kees Cook <keescook@...omium.org>,
        Greg Kerr <kerrnel@...gle.com>, Phil Auld <pauld@...hat.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>, vineeth@...byteword.org,
        Chen Yu <yu.c.chen@...el.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Agata Gruza <agata.gruza@...el.com>,
        Antonio Gomez Iglesias <antonio.gomez.iglesias@...el.com>,
        graf@...zon.com, konrad.wilk@...cle.com, dfaggioli@...e.com,
        Paul Turner <pjt@...gle.com>,
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        Alexandre Chartre <alexandre.chartre@...cle.com>,
        James.Bottomley@...senpartnership.com, OWeisse@...ch.edu,
        Dhaval Giani <dhaval.giani@...cle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Jesse Barnes <jsbarnes@...gle.com>,
        Ben Segall <bsegall@...gle.com>, Hao Luo <haoluo@...gle.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [PATCH v10 2/5] sched: CGroup tagging interface for core scheduling

On Fri, Feb 26, 2021 at 12:08 PM Chris Hyser <chris.hyser@...cle.com> wrote:
>
> Update:
>
> The clone syscall stress test I have is causing a deadlock with this patchset when
> compiled with CONFIG_PROVE_RAW_LOCK_NESTING=y. I am able to get stacktraces with
> nmi_watchdog and am looking through those. Josh was not able to duplicate the
> deadlock, instead getting an actual warning about kmalloc w/GFP_ATOMIC while
> under a raw spinlock in the function __sched_core_update_cookie(). When I retry
> the test with a patch Josh sent, removing the kmalloc() and thus the trigger of
> the warning, no more deadlock. So some combination of CONFIGs, timing and
> function calls seems to have found something in this LOCK proving code.
>
> -chrish

I have a patch to remove the dynamic allocation and overall simplify
the logic here. Will squash that along with the rest of the
modifications suggested by Peter in the next version.