From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Xn65c-0004gC-B6 for kexec@lists.infradead.org; Sat, 08 Nov 2014 13:30:05 +0000 Message-ID: <545E1AB1.9030001@redhat.com> Date: Sat, 08 Nov 2014 08:29:21 -0500 From: Prarit Bhargava MIME-Version: 1.0 Subject: Re: [PATCH v8] kernel, add panic_on_warn References: <1415187736-16242-1-git-send-email-prarit@redhat.com> <545B733C.6080903@redhat.com> <20141106220731.GA13590@redhat.com> <545CA765.8010403@redhat.com> In-Reply-To: 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: David Rientjes Cc: Andi Kleen , Jonathan Corbet , jbaron@akamai.com, kexec@lists.infradead.org, Rusty Russell , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Fabian Frederick , isimatu.yasuaki@jp.fujitsu.com, "H. Peter Anvin" , Masami Hiramatsu , Andrew Morton , linux-api@vger.kernel.org, Vivek Goyal On 11/07/2014 04:09 PM, David Rientjes wrote: > On Fri, 7 Nov 2014, Prarit Bhargava wrote: > >> There very much is. Consider a thread that hits a WARN() and then panics. Then >> somewhere in the panic code the thread hits another WARN() ... and then panics >> again. Previously this would have caused the system to "finish" panick'ing. >> Now it makes the system hang. >> > > Then we're back to square one which is what is obviously the intent of > your patch and the comment that goes along with it: My original reply pointed out that the comment was wrong. we want to clear > panic_on_warn once and not allow multiple panic(). On _this_ thread. The multiple panic across threads cannot occur. So why not just add > the necessary synchronization to make sure that happens when WARN() > happens on two cpus simultaneously? See above. P. > _______________________________________________ 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: Prarit Bhargava Subject: Re: [PATCH v8] kernel, add panic_on_warn Date: Sat, 08 Nov 2014 08:29:21 -0500 Message-ID: <545E1AB1.9030001@redhat.com> References: <1415187736-16242-1-git-send-email-prarit@redhat.com> <545B733C.6080903@redhat.com> <20141106220731.GA13590@redhat.com> <545CA765.8010403@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: 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: David Rientjes Cc: Andi Kleen , Jonathan Corbet , jbaron-JqFfY2XvxFXQT0dZR+AlfA@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Rusty Russell , linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Fabian Frederick , isimatu.yasuaki-+CUm20s59erQFUHtdCDX3A@public.gmane.org, "H. Peter Anvin" , Masami Hiramatsu , Andrew Morton , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Vivek Goyal List-Id: linux-api@vger.kernel.org On 11/07/2014 04:09 PM, David Rientjes wrote: > On Fri, 7 Nov 2014, Prarit Bhargava wrote: > >> There very much is. Consider a thread that hits a WARN() and then panics. Then >> somewhere in the panic code the thread hits another WARN() ... and then panics >> again. Previously this would have caused the system to "finish" panick'ing. >> Now it makes the system hang. >> > > Then we're back to square one which is what is obviously the intent of > your patch and the comment that goes along with it: My original reply pointed out that the comment was wrong. we want to clear > panic_on_warn once and not allow multiple panic(). On _this_ thread. The multiple panic across threads cannot occur. So why not just add > the necessary synchronization to make sure that happens when WARN() > happens on two cpus simultaneously? See above. P. > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753860AbaKHNaQ (ORCPT ); Sat, 8 Nov 2014 08:30:16 -0500 Received: from mx1.redhat.com ([209.132.183.28]:34715 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753744AbaKHNaL (ORCPT ); Sat, 8 Nov 2014 08:30:11 -0500 Message-ID: <545E1AB1.9030001@redhat.com> Date: Sat, 08 Nov 2014 08:29:21 -0500 From: Prarit Bhargava User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131028 Thunderbird/17.0.10 MIME-Version: 1.0 To: David Rientjes CC: Vivek Goyal , linux-kernel@vger.kernel.org, Jonathan Corbet , Andrew Morton , Rusty Russell , "H. Peter Anvin" , Andi Kleen , Masami Hiramatsu , Fabian Frederick , 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 v8] kernel, add panic_on_warn References: <1415187736-16242-1-git-send-email-prarit@redhat.com> <545B733C.6080903@redhat.com> <20141106220731.GA13590@redhat.com> <545CA765.8010403@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/07/2014 04:09 PM, David Rientjes wrote: > On Fri, 7 Nov 2014, Prarit Bhargava wrote: > >> There very much is. Consider a thread that hits a WARN() and then panics. Then >> somewhere in the panic code the thread hits another WARN() ... and then panics >> again. Previously this would have caused the system to "finish" panick'ing. >> Now it makes the system hang. >> > > Then we're back to square one which is what is obviously the intent of > your patch and the comment that goes along with it: My original reply pointed out that the comment was wrong. we want to clear > panic_on_warn once and not allow multiple panic(). On _this_ thread. The multiple panic across threads cannot occur. So why not just add > the necessary synchronization to make sure that happens when WARN() > happens on two cpus simultaneously? See above. P. >