Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754454AbaDXXaS (ORCPT ); Thu, 24 Apr 2014 19:30:18 -0400 Received: from longford.logfs.org ([213.229.74.203]:43208 "EHLO longford.logfs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753430AbaDXXaQ (ORCPT ); Thu, 24 Apr 2014 19:30:16 -0400 Date: Thu, 24 Apr 2014 19:29:16 -0400 From: =?utf-8?B?SsO2cm4=?= Engel To: Jiri Kosina Cc: David Rientjes , Greg Kroah-Hartman , Rik van Riel , linux-kernel@vger.kernel.org, peterz@infradead.org, akpm@linux-foundation.org, cxie@redhat.com, Jiri Slaby Subject: Re: [PATCH] printk: Print cpu number along with time Message-ID: <20140424232916.GD25446@logfs.org> References: <20140423125352.704f9fb2@annuminas.surriel.com> <20140424005247.GA17713@logfs.org> <20140424194024.GA25446@logfs.org> <20140424195821.GA3092@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 25 April 2014 00:21:20 +0200, Jiri Kosina wrote: > On Thu, 24 Apr 2014, David Rientjes wrote: > > > > Well, if you have dmesg dump from panic that happens every other year, and > > > you have to do post-mortem analysis on it, I am pretty sure you would love > > > to be able to figure out how the stack traces would look like without > > > inter-CPU interleaving. And I am pretty sure you wouldn't want to > > > insert/enable a tracepoint and wait another two years for the bug to > > > trigger again. > > > > Sounds like the appropriate fix would be to serialize stack dumping to the > > kernel log. > > That's rather difficult, as it can be done both from NMI and non-NMI > contexts, and those are very hard to synchronize. It is also easy to get wrong and cause a panic() that doesn't reboot but instead gets stuck somewhere. Plus, you might want similar serialization for other multi-line debug messages. Scsi error messages come to mind, but we have many more examples. Jörn -- Any headline which ends in a question mark can be answered by the word 'no'. -- Betteridge's Law -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/