From: Mike Galbraith <efault@gmx.de>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: netdev <netdev@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: net/sched: latent livelock in dev_deactivate_many() due to yield() usage
Date: Thu, 06 Apr 2017 03:28:34 +0200 [thread overview]
Message-ID: <1491442114.4718.35.camel@gmx.de> (raw)
In-Reply-To: <20170405173105.7f41d7fc@plumbers-lap.home.lan>
On Wed, 2017-04-05 at 17:31 -0700, Stephen Hemminger wrote:
> On Sun, 02 Apr 2017 06:28:41 +0200
> Mike Galbraith <efault@gmx.de> wrote:
>
> > Livelock can be triggered by setting kworkers to SCHED_FIFO, then
> > suspend/resume.. you come back from sleepy-land with a spinning
> > kworker. For whatever reason, I can only do that with an enterprise
> > like config, my standard config refuses to play, but no matter, it's
> > "Typical broken usage".
> >
> > (yield() should be rendered dead)
>
> The kernel is not normally built to have kworkers run at SCHED_FIFO.
> The user has do some action to alter the process priorities.
>
> I classify this as user error. We don't support killing kworker threads
> either.
We'll have to agree to disagree on that. I assert that any thread that
must run as SCHED_OTHER in order to be safe is in fact broken.
-Mike
next prev parent reply other threads:[~2017-04-06 1:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-02 4:28 net/sched: latent livelock in dev_deactivate_many() due to yield() usage Mike Galbraith
2017-04-04 22:39 ` Cong Wang
2017-04-05 3:20 ` Mike Galbraith
2017-04-05 5:25 ` Cong Wang
2017-04-05 6:12 ` Mike Galbraith
2017-04-05 23:55 ` Cong Wang
2017-04-06 1:08 ` Mike Galbraith
2017-04-06 10:26 ` Peter Zijlstra
2017-04-06 0:31 ` Stephen Hemminger
2017-04-06 1:28 ` Mike Galbraith [this message]
2017-04-06 10:28 ` Peter Zijlstra
2017-04-06 11:08 ` Peter Zijlstra
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