Re: Confusing behaviour with /proc/sys/kernel/nmi_watchdog

From: Andrew Jones
Date: Wed Jan 21 2015 - 05:53:16 EST


On Wed, Jan 21, 2015 at 02:39:42PM +1100, Anton Blanchard wrote:
> Hi Andrew,
>
> > On Wed, Nov 05, 2014 at 09:34:20AM +1100, Anton Blanchard wrote:
> > > commit 9919e39a1738 ("kvm: ensure hard lockup detection is disabled
> > > by default") provided a way for the kernel to disable the hard
> > > lockup detector at runtime.
> > >
> > > I'm using it on ppc64 but notice some weird behaviour with the
> > > nmi_watchdog procfs variable. At boot, that the hard lockup
> > > detector appears to be enabled even when we disable it via
> > > watchdog_enable_hardlockup_detector(false):
> > >
> > > # cat /proc/sys/kernel/nmi_watchdog
> > > 1
> > >
> > > I have to echo 0 to it then echo 1 again to enable it.
> > >
> > > Anton
> >
> > Hi Anton,
> >
> > Yes, the nmi watchdog proc variables are currently a bit
> > confusing. Uli has posted a series to clear all that up
> > though. Please see
> >
> > https://lkml.org/lkml/2014/10/17/340
>
> Any progress on this? I'm rebasing our hardware NMI patch for ppc64 and
> notice the strange behaviour is still in mainline.
>

Hi Anton,

I'm not aware of anything blocking this series, but maybe I missed
something. Andrew Morton and Don Zickus are the ones to ask. Andrew?
Don?

Thanks,
drew
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