linux-kernel - Re: Confusing behaviour with /proc/sys/kernel/nmi

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Message-ID: <20150121143028.GD116159@redhat.com>
Date:	Wed, 21 Jan 2015 09:30:28 -0500
From:	Don Zickus <dzickus@...hat.com>
To:	Andrew Jones <drjones@...hat.com>
Cc:	Anton Blanchard <anton@...ba.org>, uobergfe@...hat.com,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Michael Ellerman <mpe@...erman.id.au>
Subject: Re: Confusing behaviour with /proc/sys/kernel/nmi_watchdog

On Wed, Jan 21, 2015 at 11:52:51AM +0100, Andrew Jones wrote:
> 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?

Hi Drew,

I poked Andrew again.  I believe he is the person who usually takes my
patches in.

Cheers,
Don
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