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

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Date:	Tue, 10 May 2011 09:28:00 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	"prasad@...ux.vnet.ibm.com" <prasad@...ux.vnet.ibm.com>
CC:	Andi Kleen <andi@...stfloor.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"Luck, Tony" <tony.luck@...el.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>
Subject: Re: [Bug] Kdump does not work when panic triggered due to MCE

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
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