linux-kernel - Re: [PATCH] sched/schedutil: Fix deadlock between cpuset and cpu hotplug when using schedutil

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YuG2tU1EoQmRqLjK@slm.duckdns.org>
Date:   Wed, 27 Jul 2022 12:05:41 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Qais Yousef <qais.yousef@....com>,
        Xuewen Yan <xuewen.yan@...soc.com>, rafael@...nel.org,
        viresh.kumar@...aro.org, mingo@...hat.com, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, linux-kernel@...r.kernel.org,
        ke.wang@...soc.com, xuewyan@...mail.com, linux-pm@...r.kernel.org,
        Waiman Long <longman@...hat.com>
Subject: Re: [PATCH] sched/schedutil: Fix deadlock between cpuset and cpu
 hotplug when using schedutil

Hello,

On Thu, Jul 28, 2022 at 12:01:35AM +0200, Peter Zijlstra wrote:
> On Tue, Jul 12, 2022 at 06:13:46AM -1000, Tejun Heo wrote:
> 
> > But now we're failing user-initiated operations randomly. I have a hard time
> > seeing that as an acceptable solution. 
> 
> There (sadly) is precedent for that; grep for "cpu_hotplug_disable".

Yeah, there's another one in cpu cgroup controller attach path. We should
get better at not doing these. Low frequency arbitrary failures are really
difficult to handle reliably downstream.

Thanks.

-- 
tejun