Re: 4.10-rc1: thinkpad x60: who ate my cpu?

[lkml]

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".

Regards,
Vito Caputo