Re: [Bug] Kdump does not work when panic triggered due to MCE

Huang Ying
2011-05-10T01:28:05Z

Hi, Prasad,

On 05/10/2011 12:35 AM, K.Prasad wrote:
> On Fri, May 06, 2011 at 07:38:25PM +0200, Andi Kleen wrote:
>>> Has anybody tested this before? Or have found kdump working when fatal
>>> MCEs have actually occurred?
>>
>> Ying did some testing. mce-test has test cases for kdump.
>>
>
> We'd be glad to hear about any successful testcases with recent kernels.
> My manual testing was quite similar to what the LTP kdump testcase would
> do i.e. configure kdump service, trigger crash through
> /proc/sysrq-trigger and watchout for kdump....but as you could see in
> the logs, that did not happen.
>
>> My guess is you injected the error into some area used by the kexec
>> code or boot up path of the kexec kernel.
>>
>> -Andi
>
> The logs did not suggest that the second kernel was booted into. The
> "Rebooting in ... seconds" message appeared from the first kernel. I
> tried the kdump testcase in atleast two dissimilar machines but with
> the same results, so it is not clear if the kexec code was affected by
> the MCE injection in both the cases.

From your panic logs, it seems that panic is triggered for MCE on one
CPU, when crash_kexec is executing, another panic is triggered on
another CPU for timeout mechanism in MCE. We have seen something like
that in mce-test developing. Please try following command line for mce
injecting.

mce-inject --no-random
/home/prasadkr/mce/mce-test/cases/soft-inj/panic_ucr/data/srar_over

Which is used by kdump test driver of mce-test too.

Best Regards,
Huang Ying