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From: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>,
	Simon Horman <horms@verge.net.au>,
	kexec-ml <kexec@lists.infradead.org>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH-v2] kdump: Enable kdump if 2nd-kernel is loaded.
Date: Tue, 14 Jul 2009 11:04:37 +0900	[thread overview]
Message-ID: <4A5BE7B5.7080500@jp.fujitsu.com> (raw)
In-Reply-To: <m14otga4xa.fsf@fess.ebiederm.org>

Eric W. Biederman wrote:
> The Documentation for sysrq-c certainly needs to be updated.

No doubt about it.

> If I am doing development on a system I like oops's.  All of the
> information and nothing goes down.  I can get at /proc/kcore etc.
> 
> In a setting where I can't be Johnny on the spot and look at
> things a core dump is probably the best I can get.  In that scenario
> panic_on_oops sounds good.
> 
> As I read the current check it reads:
> If we are going to panic and not oops || panic_on_oops
> 	kexec_should_crash = true;
> 
> Which seems a very reasonable implementation of policy.

If I understand it,

a) panic
b) oops
c) SysRq (from keyboard interrupt)
d) echo c > /proc/sysrq-trigger

   a      b      c      d
common, w/o CONFIG_KEXEC:
 panic  oops   panic   oops  :
 panic  panic  panic   panic : w/ panic_on_oops

A) 2.6.30 + CONFIG_KEXEC:
 panic  oops   -       -     : w/o kdump-image
 panic  panic  -       -     : w/o kdump-image w/ panic_on_oops
 kdump  oops   kdump   kdump : w/ kdump-image
 kdump  kdump  kdump   kdump : w/ kdump-image w/ panic_on_oops

B) 2.6.31-rc1 + CONFIG_KEXEC:
 panic  oops   panic   oops  : w/o kdump-image
 panic  panic  panic   panic : w/o kdump-image w/ panic_on_oops
 kdump  oops   kdump   oops  : w/ kdump-image
 kdump  kdump  kdump   kdump : w/ kdump-image w/ panic_on_oops

C) After this patch + CONFIG_KEXEC:
 panic  oops   panic   oops  : w/o kdump-image
 panic  panic  panic   panic : w/o kdump-image w/ panic_on_oops
 kdump  kdump  kdump   kdump : w/ kdump-image
 kdump  kdump  kdump   kdump : w/ kdump-image w/ panic_on_oops

Ohmichi-san pointed "oops on d) with kdump-image" in B) and suggested
it should be "kdump."
And Eric pointed "kdump on b) without panic_on_oops" in C) and requested
it should be "oops."
(Plus, IMHO, "oops on d) without panic_on_oops" should be "panic.") 

... Right?

Then as I mentioned, use panic in sysrq would be one of solutions.
Are there any better fix?


Thanks,
H.Seto


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WARNING: multiple messages have this Message-ID (diff)
From: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Ken'ichi Ohmichi" <oomichi@mxs.nes.nec.co.jp>,
	kexec-ml <kexec@lists.infradead.org>,
	lkml <linux-kernel@vger.kernel.org>,
	Simon Horman <horms@verge.net.au>
Subject: Re: [PATCH-v2] kdump: Enable kdump if 2nd-kernel is loaded.
Date: Tue, 14 Jul 2009 11:04:37 +0900	[thread overview]
Message-ID: <4A5BE7B5.7080500@jp.fujitsu.com> (raw)
In-Reply-To: <m14otga4xa.fsf@fess.ebiederm.org>

Eric W. Biederman wrote:
> The Documentation for sysrq-c certainly needs to be updated.

No doubt about it.

> If I am doing development on a system I like oops's.  All of the
> information and nothing goes down.  I can get at /proc/kcore etc.
> 
> In a setting where I can't be Johnny on the spot and look at
> things a core dump is probably the best I can get.  In that scenario
> panic_on_oops sounds good.
> 
> As I read the current check it reads:
> If we are going to panic and not oops || panic_on_oops
> 	kexec_should_crash = true;
> 
> Which seems a very reasonable implementation of policy.

If I understand it,

a) panic
b) oops
c) SysRq (from keyboard interrupt)
d) echo c > /proc/sysrq-trigger

   a      b      c      d
common, w/o CONFIG_KEXEC:
 panic  oops   panic   oops  :
 panic  panic  panic   panic : w/ panic_on_oops

A) 2.6.30 + CONFIG_KEXEC:
 panic  oops   -       -     : w/o kdump-image
 panic  panic  -       -     : w/o kdump-image w/ panic_on_oops
 kdump  oops   kdump   kdump : w/ kdump-image
 kdump  kdump  kdump   kdump : w/ kdump-image w/ panic_on_oops

B) 2.6.31-rc1 + CONFIG_KEXEC:
 panic  oops   panic   oops  : w/o kdump-image
 panic  panic  panic   panic : w/o kdump-image w/ panic_on_oops
 kdump  oops   kdump   oops  : w/ kdump-image
 kdump  kdump  kdump   kdump : w/ kdump-image w/ panic_on_oops

C) After this patch + CONFIG_KEXEC:
 panic  oops   panic   oops  : w/o kdump-image
 panic  panic  panic   panic : w/o kdump-image w/ panic_on_oops
 kdump  kdump  kdump   kdump : w/ kdump-image
 kdump  kdump  kdump   kdump : w/ kdump-image w/ panic_on_oops

Ohmichi-san pointed "oops on d) with kdump-image" in B) and suggested
it should be "kdump."
And Eric pointed "kdump on b) without panic_on_oops" in C) and requested
it should be "oops."
(Plus, IMHO, "oops on d) without panic_on_oops" should be "panic.") 

... Right?

Then as I mentioned, use panic in sysrq would be one of solutions.
Are there any better fix?


Thanks,
H.Seto


  reply	other threads:[~2009-07-14  2:05 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-09  8:05 [PATCH] kdump: Enable kdump if 2nd-kernel is loaded Ken'ichi Ohmichi
2009-07-09  8:05 ` Ken'ichi Ohmichi
2009-07-10  6:32 ` Hidetoshi Seto
2009-07-10  6:32   ` Hidetoshi Seto
2009-07-10  7:05   ` Ken'ichi Ohmichi
2009-07-10  7:05     ` Ken'ichi Ohmichi
2009-07-10  7:52     ` Hidetoshi Seto
2009-07-10  7:52       ` Hidetoshi Seto
2009-07-13  4:33   ` [PATCH-v2] " Ken'ichi Ohmichi
2009-07-13  4:33     ` Ken'ichi Ohmichi
2009-07-13  7:48     ` Hidetoshi Seto
2009-07-13  7:48       ` Hidetoshi Seto
2009-07-13 17:06     ` Eric W. Biederman
2009-07-13 17:06       ` Eric W. Biederman
2009-07-14  2:04       ` Hidetoshi Seto [this message]
2009-07-14  2:04         ` Hidetoshi Seto

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