linux-kernel - Re: Re: [PATCH] kernel/panic: Add "late_kdump" option for kdump in unstable condition

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Date:	Mon, 21 Apr 2014 09:59:07 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	Satoru MORIYA <satoru.moriya.br@...achi.com>,
	Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@...achi.com>,
	Takenori Nagano <t-nagano@...jp.nec.com>,
	Eric Biederman <ebiederm@...ssion.com>,
	Motohiro Kosaki <Motohiro.Kosaki@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: Re: [PATCH] kernel/panic: Add "late_kdump" option for kdump
 in unstable condition

(2014/04/18 12:09), Masami Hiramatsu wrote:
> (2014/04/17 22:43), Vivek Goyal wrote:
>> On Thu, Apr 17, 2014 at 10:59:14AM +0900, Masami Hiramatsu wrote:
>>
>> [..]
>>>>> @@ -112,9 +113,14 @@ void panic(const char *fmt, ...)
>>>>>  	/*
>>>>>  	 * If we have crashed and we have a crash kernel loaded let it handle
>>>>>  	 * everything else.
>>>>> -	 * Do we want to call this before we try to display a message?
>>>>> +	 * If we want to call this after we try to display a message, pass
>>>>> +	 * the "late_kdump" option to the kernel.
>>>>>  	 */
>>>>> -	crash_kexec(NULL);
>>>>> +	if (!late_kdump)
>>>>> +		crash_kexec(NULL);
>>>>> +	else
>>>>> +		pr_emerg("Warning: late_kdump option is set. Please DO NOT "
>>>>> +			"report bugs about kdump failure with this option.\n");
>>>>
>>>> I think above message about DO NOT report bugs seems unnecessary. 
>>>
>>> OK, so I just notify the option is set as below.
>>> "Warning: crash_kexec_post_notifiers is set.\n"
>>
>> I would say for the time being don't put any extra message. User will
>> think what this warning is supposed to mean. We can introduce one if
>> we run into many issues.
> 
> Ah, I see.
> 
>> For the time being we can just look at kernel logs and look at command
>> line options and see whether crash_kexec_post_notifiers was set or not.
> 
> Yeah, I know. However since the kernel command line is shown in very early
> part of kernel logs, I worried about the case that it is pushed out from
> kmsg buffer. And usually users will send a bug report with the very last
> of the kernel logs because it becomes too long.

Anyway, I'll send v3 soon to remove that message completely :)

Thank you!

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com


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