Messages in this thread | | | Date | Fri, 18 Mar 2011 13:19:32 -0400 | From | Don Zickus <> | Subject | Re: [PATCH 1/2 v2] watchdog, nmi: Allow hardlockup to panic by default |
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On Thu, Mar 17, 2011 at 06:50:13PM -0700, Andrew Morton wrote: > On Mon, 7 Mar 2011 16:37:39 -0500 Don Zickus <dzickus@redhat.com> wrote: > > > Add a Kconfig option to allow users to set the hardlockup to panic > > by default. Also add in a 'nmi_watchdog=nopanic' to override this. > > > > Changelog forgot to tell us "why".
Yeah, sorry about that.
When a cpu is considered stuck, instead of limping along and just printing a warning, it is sometimes preferred to just panic, let kdump capture the vmcore and reboot. This gets the machine back into a stable state quickly while saving the info that got it into a stuck state to begin with.
> > > Format: [state][,regs][,debounce][,die] > > > > nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels > > - Format: [panic,][num] > > + Format: [panic,][nopanic,][num] > > It would be better to support panic=[0|1], if that can be simply done > in a back-compatible fashion.
I am open to the idea, just can't figure the best way to implement that in a backwards compatible way.
Personally I was wondering if there were situations where you would _not_ want it to panic. If the cpu is stuck spinning after 60 seconds, the odds of it freeing itself is low and you are probably stuck rebooting anyway.
> > > static int __init hardlockup_panic_setup(char *str) > > { > > if (!strncmp(str, "panic", 5)) > > hardlockup_panic = 1; > > + else if (!strncmp(str, "nopanic", 5)) > > s/5/7/
doh.
I can send a refreshed patch with the above changes.
Cheers, Don
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