[PATCH] Enable kdump if 2nd-kernel is loaded.

[Ken'ichi Ohmichi]

Hi Simon,

Thank you so much for your review and comment.

I have one question.
Should I resend the patch to LKML with your "Acked-by:" tag for merging it ?
Or isn't that necessary ?


Thanks
Ken'ichi Ohmichi

Simon Horman wrote:
> On Thu, Jul 09, 2009 at 09:43:19AM +0900, Ken'ichi Ohmichi wrote:
>> Hi Simon,
>>
>> Thank you for the comment.
>>
>> Simon Horman wrote:
>>> On Wed, Jul 08, 2009 at 01:38:59PM +0900, Ken'ichi Ohmichi wrote:
>>>> Hi,
>>>>
>>>> This patch enables a kdump if 2nd-kernel is loaded.
>>>> (The patch is based on linux-2.6.31-rc2.)
>>>>
>>>> Now, a kdump is enabled if a kernel parameter "oops=panic" is specified and
>>>> 2nd-kernel is loaded. I think that a kdump should be enabled regardless of
>>>> "oops=panic" if 2nd-kernel is loaded, because a system administrator loads
>>>> 2nd-kernel for enabling a kdump.
>>> I'm not sure that I like this change. To my mind, panic on oops
>>> should only occur if specifically requested.
>> My patch does not make panic_on_oops effective when 2nd-kernel is loaded,
>> and it makes a kdump effective.
>>
>> kexec_should_crash() is called only by oops_end() for checking whether to
>> call crash_kexec(). crash_kexec() is not panic, and I feel it is better
>> that crash_kexec() is called when 2nd-kernel is loaded.
>>
>>
>> I tried to test a kdump on linux-2.6.31-rc1 *without* a kernel parameter
>> "oops=panic" by `echo c > /proc/sysrq-trigger`, but a kdump did not work
>> because a kdump, which is occurred by `echo c > /proc/sysrq-trigger`, has
>> been changed to a NULL pointer error instead of calling crash_kexec()
>> since linux-2.6.31-rc1. Then I tried to boot linux-2.6.31-rc1 *with* a
>> kernel parameter "oops=panic", the kernel got a panic while kernel booting
>> due to a problem other than a kdump. 
>> So I think a kdump should be enabled when 2nd-kernel is loaded.
> 
> Hi,
> 
> thanks for the more detailed explanation. I've reconsidered my position
> and actually I think that I quite like your idea - it does indeed make
> sense for kdump to occur if a kdump kernel has been loaded.
> 
> Acked-by: Simon Horman <horms at verge.net.au>
> 
>> Thanks
>> Ken'ichi Ohmichi
>>
>>>> Signed-off-by: Ken'ichi Ohmichi <oomichi at mxs.nes.nec.co.jp>
>>>> ---
>>>> --- a/kernel/kexec.c	2009-07-08 12:30:26.000000000 +0900
>>>> +++ b/kernel/kexec.c	2009-07-08 12:38:08.000000000 +0900
>>>> @@ -57,6 +57,8 @@ struct resource crashk_res = {
>>>>  
>>>>  int kexec_should_crash(struct task_struct *p)
>>>>  {
>>>> +	if (kexec_crash_image)
>>>> +		return 1;
>>>>  	if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
>>>>  		return 1;
>>>>  	return 0;
>>>>
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>>
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>