Re: [PATCH] watchdog: Add sysctl knob hardlockup_panic

From: Jiri Kosina
Date: Thu Oct 15 2015 - 17:02:45 EST


On Wed, 14 Oct 2015, Don Zickus wrote:

> The only way to enable a hardlockup to panic the machine is to set
> 'nmi_watchdog=panic' on the kernel command line.
>
> This makes it awkward for end users and folks who want to run automate tests
> (like myself).
>
> Mimic the softlockup_panic knob and create a /proc/sys/kernel/hardlockup_panic
> knob.
>
> Signed-off-by: Don Zickus <dzickus@xxxxxxxxxx>

Seems like with my previous stack-dumping patch + this one, we are finally
covering all the possible combinations. Hence in principle

Acked-by: Jiri Kosina <jkosina@xxxxxxx>

The build failure reported by Fengguang's bot of course needs to be fixed,
but I think it's there for soft lockup detector as well, but Fengguang's
.config has soft lockup detector enable, so that failure is invisible.

I guess the most straightfoward fix is to ...

[ ... snip ... ]
> index b7b9501..5e65b14 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -384,6 +384,7 @@ extern int proc_dowatchdog_thresh(struct ctl_table *table, int write,
> void __user *buffer,
> size_t *lenp, loff_t *ppos);
> extern unsigned int softlockup_panic;
> +extern unsigned int hardlockup_panic;

... those two be there only if appropriate config options are set.

Thanks,

--
Jiri Kosina
SUSE Labs

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