Re: [PATCH] kernel/watchdog: fix spurious hard lockups

[Andi Kleen]

On Tue, Jun 20, 2017 at 06:34:23PM -0400, Prarit Bhargava wrote:
> 
> 
> On 06/20/2017 05:33 PM, kan.liang@xxxxxxxxx wrote:
> > From: Kan Liang <Kan.liang@xxxxxxxxx>
> > 
> > Some users reported spurious NMI watchdog timeouts.
> > 
> > We now have more and more systems where the Turbo range is wide enough
> > that the NMI watchdog expires faster than the soft watchdog timer that
> > updates the interrupt tick the NMI watchdog relies on.
> > 
> 
> Hmm ... odd that I haven't seen this.  We're running a pretty wide
> variety of systems here.  Do you have a reproducer?  I'd like to see
> this occur on production HW.

It only happens on a few specific CPU SKUs with a very wide Turbo range.
Reproducer is typically some stress workload that turbos very high.

-Andi