* Don Zickus <dzic...@redhat.com> wrote:
> On Mon, Aug 18, 2014 at 11:16:44AM +0200, Ingo Molnar wrote:
> >
> > * Don Zickus <dzic...@redhat.com> wrote:
> >
> > > The running kernel still has the ability to enable/disable at any
> > > time with /proc/sys/kernel/nmi_watchdog us usual. However even
> > > when the default has been overridden /proc/sys/kernel/nmi_watchdog
> > > will initially show '1'. To truly turn it on one must disable/enable
> > > it, i.e.
> > > echo 0 > /proc/sys/kernel/nmi_watchdog
> > > echo 1 > /proc/sys/kernel/nmi_watchdog
> >
> > This looks like a bug, why is this so?
>
> It is, but it always has been there in the case of the PMU
> not being able to provide a resource for the hardlockup.
> This change just exposes it more.
There seems to be two issues:
1)
When it's impossible to enable the hardlockup detector, it
should default to -1 or so, and attempts to set it should
return a -EINVAL or so.
Bootup messages should also indicate when it's not possible to
enable it but a user requests it.
2)
The softlockup and hardlockup detection control variables
should be in separate flags, inside and outside the kernel -
they (should) not relate to each other.
Thanks,
Ingo
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