linux-kernel - Re: [GIT PULL] scheduler changes for v4.11

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Message-ID: <20170222205144.GV28416@codeblueprint.co.uk>
Date:   Wed, 22 Feb 2017 20:51:44 +0000
From:   Matt Fleming <matt@...eblueprint.co.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Thomas Gleixner <tglx@...utronix.de>,
        Mike Galbraith <efault@....de>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] scheduler changes for v4.11

On Wed, 22 Feb, at 12:41:01PM, Linus Torvalds wrote:
> Hmm. The scheduler changes seem to show problems with suspend/resume.
> 
> I now get his when suspending:
> 
>   ...
>   Disabling non-boot CPUs ...
>   Cannot set affinity for irq 285
>   smpboot: CPU 1 is now offline
>   ------------[ cut here ]------------
>    WARNING: CPU: 2 PID: 25 at kernel/sched/sched.h:812
> update_load_avg+0x779/0xa70
>   rq->clock_update_flags < RQCF_ACT_SKIP
>   ...
>   Call Trace:
>     update_load_avg+0x779/0xa70
>     set_next_entity+0xd9/0x220
>     pick_next_task_fair+0x88/0x550
>     sched_cpu_dying+0x1cf/0x2a0
>     cpuhp_invoke_callback+0x80/0x3b0
>     take_cpu_down+0x5e/0xa0
>     multi_cpu_stop+0xb6/0xe0
> 
> the issue may have been going on for a while, but the new WARN_ON()
> was added in this merge window.
> 
> (Not sure how consistent this warning is, it definitely doesn't happen
> every time, I've only seen it once)

I think Peter has the fix for this somewhere, but it doesn't look like
it made it to tip/sched/core.

Peter, this is the original patch,

  https://lkml.kernel.org/r/20170202155506.GX6515@twins.programming.kicks-ass.net