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Date: Mon, 13 Feb 2017 12:25:28 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: lkml@pengaru.com
cc: Pavel Machek <pavel@ucw.cz>, Woody Suwalski <terraluna977@gmail.com>,
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        kernel list <linux-kernel@vger.kernel.org>, mingo@redhat.com,
        hpa@zytor.com
Subject: Re: 4.10-rc1: thinkpad x60: who ate my cpu?
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On Mon, 13 Feb 2017, lkml@pengaru.com wrote:

> On Mon, Feb 13, 2017 at 10:42:36AM +0100, Pavel Machek wrote:
> > Hi!
> > 
> > On Mon 2017-02-13 09:48:41, Thomas Gleixner wrote:
> > > On Mon, 13 Feb 2017, Pavel Machek wrote:
> > > > cd /sys/devices/system/cpu/cpu1
> > > > while true; do echo 0 > online; echo 1 > online; done
> > > > 
> > > > ...crashes x60 with 4.10-rc in few minutes. [Which is bad -- it should
> > > > not die, but also good -- this is easier to reproduce then running 100
> > > > suspend cycles.]
> > > 
> > > Can you tell where it crashes?
> > 
> > I did not expect a crash, so I was in X... I have a feeling that this
> > will be reproducible on a lot of hardware, but let me try.
> 
> FYI: Lockup reproduced with 4.10.0-rc7 with an X61s.
> 
> Caught a glimpse of something about an RCU stall timeout before the system shut
> off.  Prior to that, during the loop execution, a bunch of systemd processes
> were experiencing watchdog timeouts, and procps `top` would start but
> never refresh, leaving the CPU column all "nan".

Does the machine use intel_idle by chance?

Thanks,

	tglx