From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from terminus.zytor.com ([2001:1868:205::10] helo=mail.zytor.com) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1XjtT6-0005Rd-FU for kexec@lists.infradead.org; Thu, 30 Oct 2014 17:25:06 +0000 Message-ID: <54527443.6030007@zytor.com> Date: Thu, 30 Oct 2014 10:24:19 -0700 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [PATCH] kernel, add panic_on_warn References: <1414688627-5298-1-git-send-email-prarit@redhat.com> In-Reply-To: <1414688627-5298-1-git-send-email-prarit@redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Prarit Bhargava , linux-kernel@vger.kernel.org Cc: Andi Kleen , Jonathan Corbet , kexec@lists.infradead.org, Rusty Russell , linux-doc@vger.kernel.org, jbaron@akamai.com, Fabian Frederick , isimatu.yasuaki@jp.fujitsu.com, linux-api@vger.kernel.org, Masami Hiramatsu , Andrew Morton , vgoyal@redhat.com On 10/30/2014 10:03 AM, 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. > > This patch adds a panic_on_warn kernel parameter and > /proc/sys/kernel/panic_on_warn calls panic() in the warn_slowpath_common() > path. The function will still print out the location of the warning. > > An example of the panic_on_warn output: > > The first line below is from the WARN_ON() to output the WARN_ON()'s location. > After that the panic() output is displayed. > There is another very valid use for this: many operators would rather a machine shuts down than being potentially compromised either functionally or security-wise. -hpa _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH] kernel, add panic_on_warn Date: Thu, 30 Oct 2014 10:24:19 -0700 Message-ID: <54527443.6030007@zytor.com> References: <1414688627-5298-1-git-send-email-prarit@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1414688627-5298-1-git-send-email-prarit-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+glkk-kexec=m.gmane.org-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org To: Prarit Bhargava , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: Andi Kleen , Jonathan Corbet , kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Rusty Russell , linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, jbaron-JqFfY2XvxFXQT0dZR+AlfA@public.gmane.org, Fabian Frederick , isimatu.yasuaki-+CUm20s59erQFUHtdCDX3A@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Masami Hiramatsu , Andrew Morton , vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org List-Id: linux-api@vger.kernel.org On 10/30/2014 10:03 AM, 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. > > This patch adds a panic_on_warn kernel parameter and > /proc/sys/kernel/panic_on_warn calls panic() in the warn_slowpath_common() > path. The function will still print out the location of the warning. > > An example of the panic_on_warn output: > > The first line below is from the WARN_ON() to output the WARN_ON()'s location. > After that the panic() output is displayed. > There is another very valid use for this: many operators would rather a machine shuts down than being potentially compromised either functionally or security-wise. -hpa From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760601AbaJ3RZa (ORCPT ); Thu, 30 Oct 2014 13:25:30 -0400 Received: from terminus.zytor.com ([198.137.202.10]:42374 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758469AbaJ3RZ2 (ORCPT ); Thu, 30 Oct 2014 13:25:28 -0400 Message-ID: <54527443.6030007@zytor.com> Date: Thu, 30 Oct 2014 10:24:19 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Prarit Bhargava , linux-kernel@vger.kernel.org CC: Jonathan Corbet , Andrew Morton , Rusty Russell , Andi Kleen , Masami Hiramatsu , Fabian Frederick , vgoyal@redhat.com, isimatu.yasuaki@jp.fujitsu.com, jbaron@akamai.com, linux-doc@vger.kernel.org, kexec@lists.infradead.org, linux-api@vger.kernel.org Subject: Re: [PATCH] kernel, add panic_on_warn References: <1414688627-5298-1-git-send-email-prarit@redhat.com> In-Reply-To: <1414688627-5298-1-git-send-email-prarit@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/30/2014 10:03 AM, 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. > > This patch adds a panic_on_warn kernel parameter and > /proc/sys/kernel/panic_on_warn calls panic() in the warn_slowpath_common() > path. The function will still print out the location of the warning. > > An example of the panic_on_warn output: > > The first line below is from the WARN_ON() to output the WARN_ON()'s location. > After that the panic() output is displayed. > There is another very valid use for this: many operators would rather a machine shuts down than being potentially compromised either functionally or security-wise. -hpa