From: Peter Zijlstra <peterz@infradead.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Kevin Shanahan <kevin@shanahan.id.au>,
Siegfried Metz <frame@mailbox.org>,
linux-kernel@vger.kernel.org, rafael.j.wysocki@intel.com,
len.brown@intel.com, rjw@rjwysocki.net, diego.viola@gmail.com,
rui.zhang@intel.com, viktor_jaegerskuepper@freenet.de
Subject: Re: REGRESSION: boot stalls on several old dual core Intel CPUs
Date: Mon, 3 Sep 2018 10:54:23 +0200 [thread overview]
Message-ID: <20180903085423.GU24124@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <alpine.DEB.2.21.1809030937230.1349@nanos.tec.linutronix.de>
On Mon, Sep 03, 2018 at 09:38:15AM +0200, Thomas Gleixner wrote:
> On Mon, 3 Sep 2018, Peter Zijlstra wrote:
> > On Sat, Sep 01, 2018 at 11:51:26AM +0930, Kevin Shanahan wrote:
> > > commit 01548f4d3e8e94caf323a4f664eb347fd34a34ab
> > > Author: Martin Schwidefsky <schwidefsky@de.ibm.com>
> > > Date: Tue Aug 18 17:09:42 2009 +0200
> > >
> > > clocksource: Avoid clocksource watchdog circular locking dependency
> > >
> > > stop_machine from a multithreaded workqueue is not allowed because
> > > of a circular locking dependency between cpu_down and the workqueue
> > > execution. Use a kernel thread to do the clocksource downgrade.
> >
> > I cannot find stop_machine usage there; either it went away or I need to
> > like wake up.
>
> timekeeping_notify() which is involved in switching clock source uses stomp
> machine.
ARGH... OK, lemme see if I can come up with something other than
endlessly spawning that kthread.
A special purpose kthread_worker would make more sense than that.
next prev parent reply other threads:[~2018-09-03 8:54 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-30 10:55 Siegfried Metz
2018-08-30 13:04 ` Peter Zijlstra
2018-08-30 13:48 ` Peter Zijlstra
2018-09-01 2:21 ` Kevin Shanahan
2018-09-03 7:25 ` Peter Zijlstra
2018-09-03 7:38 ` Thomas Gleixner
2018-09-03 8:54 ` Peter Zijlstra [this message]
2018-09-03 9:33 ` Peter Zijlstra
2018-09-03 11:30 ` Viktor Jägersküpper
2018-09-03 12:34 ` Kevin Shanahan
2018-09-03 21:34 ` Siegfried Metz
2018-09-04 13:44 ` Niklas Cassel
2018-09-05 8:41 ` [PATCH] clocksource: Revert "Remove kthread" Peter Zijlstra
2018-09-06 10:46 ` [tip:timers/urgent] " tip-bot for Peter Zijlstra
2018-09-06 21:42 ` tip-bot for Peter Zijlstra
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