linux-kernel - Re: [PATCH] kernel, add panic_on

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Date:	Mon, 03 Nov 2014 08:32:42 -0500
From:	Prarit Bhargava <prarit@...hat.com>
To:	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
	Jonathan Corbet <corbet@....net>, kexec@...ts.infradead.org,
	Rusty Russell <rusty@...tcorp.com.au>,
	linux-doc@...r.kernel.org, jbaron@...mai.com,
	Fabian Frederick <fabf@...net.be>,
	isimatu.yasuaki@...fujitsu.com, "H. Peter Anvin" <hpa@...or.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-api@...r.kernel.org, vgoyal@...hat.com
Subject: Re: [PATCH] kernel, add panic_on_warn



On 10/30/2014 09:58 PM, Hedi Berriche wrote:
> On Thu, Oct 30, 2014 at 17:06 Prarit Bhargava wrote:
> | There have been several times where I have had to rebuild a kernel to
> | cause a panic when hitting a WARN() in the code in order to get a crash
> | dump from a system.  Sometimes this is easy to do, other times (such as
> | in the case of a remote admin) it is not trivial to send new images to the
> | user.
> | 
> | A much easier method would be a switch to change the WARN() over to a
> | panic.  This makes debugging easier in that I can now test the actual
> | image the WARN() was seen on and I do not have to engage in remote
> | debugging.
> 
> Do we want to leave it to usersspace[1] to ensure panic_on_warn is out
> of the way in when the kdump kernel boots? or would a self-contained
> approach be more preferable i.e. test whether we're a kdump kernel
> before bothering with panic_on_warn?

Hmm ... this is a good point.  Vivek, do you have a preference?  I'm willing to
code it either way.  I should be able to put in a is_kdump_kernel() check
without any problems but I'm not sure if that is the right thing to do here.

P.

> 
> Cheers,
> Hedi.
> 
> [1] kexec-tools in the case of the boot param by filtering it out of the
>     kdump kernel cmdline. In the case of sysctl.conf, it would depend on
>     whether there are distros out there that  include it in the kdump
>     initrd.
> 
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