[PATCH v2] hardlockup: detect hard lockups without NMIs using secondary cpus

[Frederic Weisbecker]

2013/1/15 Colin Cross <ccross at android.com>:
> On Mon, Jan 14, 2013 at 4:13 PM, Frederic Weisbecker <fweisbec at gmail.com> wrote:
>> I believe this is pretty much what the RCU stall detector does
>> already: checks for other CPUs being responsive. The only difference
>> is on how it checks that. For RCU it's about checking for CPUs
>> reporting quiescent states when requested to do so. In your case it's
>> about ensuring the hrtimer interrupt is well handled.
>>
>> One thing you can do is to enqueue an RCU callback (cal_rcu()) every
>> minute so you can force other CPUs to report quiescent states
>> periodically and thus check for lockups.
>
> That's a good point, I'll take a look at using that.  A minute is too
> long, some SoCs have maximum HW watchdog periods of under 30 seconds,
> but a call_rcu every 10-20 seconds might be sufficient.

Sure. And you can tune CONFIG_RCU_CPU_STALL_TIMEOUT accordingly.