* Confusing behaviour with /proc/sys/kernel/nmi_watchdog
@ 2014-11-04 22:34 Anton Blanchard
2014-11-05 10:26 ` Andrew Jones
2014-11-05 14:53 ` Don Zickus
0 siblings, 2 replies; 7+ messages in thread
From: Anton Blanchard @ 2014-11-04 22:34 UTC (permalink / raw)
To: uobergfe, drjones, dzickus, akpm; +Cc: linux-kernel
Hi,
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
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Confusing behaviour with /proc/sys/kernel/nmi_watchdog
2014-11-04 22:34 Confusing behaviour with /proc/sys/kernel/nmi_watchdog Anton Blanchard
@ 2014-11-05 10:26 ` Andrew Jones
2015-01-21 3:39 ` Anton Blanchard
2014-11-05 14:53 ` Don Zickus
1 sibling, 1 reply; 7+ messages in thread
From: Andrew Jones @ 2014-11-05 10:26 UTC (permalink / raw)
To: Anton Blanchard; +Cc: uobergfe, dzickus, akpm, linux-kernel
On Wed, Nov 05, 2014 at 09:34:20AM +1100, Anton Blanchard wrote:
>
> Hi,
>
> 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
drew
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Confusing behaviour with /proc/sys/kernel/nmi_watchdog
2014-11-04 22:34 Confusing behaviour with /proc/sys/kernel/nmi_watchdog Anton Blanchard
2014-11-05 10:26 ` Andrew Jones
@ 2014-11-05 14:53 ` Don Zickus
2014-11-05 18:53 ` Anton Blanchard
1 sibling, 1 reply; 7+ messages in thread
From: Don Zickus @ 2014-11-05 14:53 UTC (permalink / raw)
To: Anton Blanchard; +Cc: uobergfe, drjones, akpm, linux-kernel
On Wed, Nov 05, 2014 at 09:34:20AM +1100, Anton Blanchard wrote:
>
> Hi,
>
> 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.
Hi Anton,
I believe Andrew answered the question for you, it's a WIP and we have
patches to clean that up.
I don't see ppc64 watchdog support in arch/powerpc, is that something you
are working with on implementing?
Cheers,
Don
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Confusing behaviour with /proc/sys/kernel/nmi_watchdog
2014-11-05 14:53 ` Don Zickus
@ 2014-11-05 18:53 ` Anton Blanchard
0 siblings, 0 replies; 7+ messages in thread
From: Anton Blanchard @ 2014-11-05 18:53 UTC (permalink / raw)
To: Don Zickus; +Cc: uobergfe, drjones, akpm, linux-kernel, Michael Ellerman
Hi Don,
> > 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.
>
> I believe Andrew answered the question for you, it's a WIP and we have
> patches to clean that up.
Thanks, yes good to see it being worked on.
> I don't see ppc64 watchdog support in arch/powerpc, is that something
> you are working with on implementing?
I've submitted it over on linuxppc-dev:
http://patchwork.ozlabs.org/patch/406802/
Anton
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Confusing behaviour with /proc/sys/kernel/nmi_watchdog
2014-11-05 10:26 ` Andrew Jones
@ 2015-01-21 3:39 ` Anton Blanchard
2015-01-21 10:52 ` Andrew Jones
0 siblings, 1 reply; 7+ messages in thread
From: Anton Blanchard @ 2015-01-21 3:39 UTC (permalink / raw)
To: Andrew Jones; +Cc: uobergfe, dzickus, akpm, linux-kernel, Michael Ellerman
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.
Anton
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Confusing behaviour with /proc/sys/kernel/nmi_watchdog
2015-01-21 3:39 ` Anton Blanchard
@ 2015-01-21 10:52 ` Andrew Jones
2015-01-21 14:30 ` Don Zickus
0 siblings, 1 reply; 7+ messages in thread
From: Andrew Jones @ 2015-01-21 10:52 UTC (permalink / raw)
To: Anton Blanchard; +Cc: uobergfe, dzickus, akpm, linux-kernel, Michael Ellerman
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
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: Confusing behaviour with /proc/sys/kernel/nmi_watchdog
2015-01-21 10:52 ` Andrew Jones
@ 2015-01-21 14:30 ` Don Zickus
0 siblings, 0 replies; 7+ messages in thread
From: Don Zickus @ 2015-01-21 14:30 UTC (permalink / raw)
To: Andrew Jones
Cc: Anton Blanchard, uobergfe, akpm, linux-kernel, Michael Ellerman
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
^ permalink raw reply [flat|nested] 7+ messages in thread
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2014-11-04 22:34 Confusing behaviour with /proc/sys/kernel/nmi_watchdog Anton Blanchard
2014-11-05 10:26 ` Andrew Jones
2015-01-21 3:39 ` Anton Blanchard
2015-01-21 10:52 ` Andrew Jones
2015-01-21 14:30 ` Don Zickus
2014-11-05 14:53 ` Don Zickus
2014-11-05 18:53 ` Anton Blanchard
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