From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932356AbWFBPWO (ORCPT ); Fri, 2 Jun 2006 11:22:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932373AbWFBPWO (ORCPT ); Fri, 2 Jun 2006 11:22:14 -0400 Received: from ebiederm.dsl.xmission.com ([166.70.28.69]:41121 "EHLO ebiederm.dsl.xmission.com") by vger.kernel.org with ESMTP id S932356AbWFBPWN (ORCPT ); Fri, 2 Jun 2006 11:22:13 -0400 To: Preben Traerup Cc: "Akiyama, Nobuyuki" , fastboot@lists.osdl.org, linux-kernel@vger.kernel.org, Vivek Goyal Subject: Re: [Fastboot] [RFC][PATCH] Add missing notifier before crashing References: <20060530183359.a8d5d736.akiyama.nobuyuk@jp.fujitsu.com> <20060530145658.GC6536@in.ibm.com> <20060531182045.9db2fac9.akiyama.nobuyuk@jp.fujitsu.com> <20060531154322.GA8475@in.ibm.com> <20060601213730.dc9f1ec4.akiyama.nobuyuk@jp.fujitsu.com> <20060601151605.GA7380@in.ibm.com> <20060602141301.cdecf0e1.akiyama.nobuyuk@jp.fujitsu.com> <44800E1A.1080306@ericsson.com> <44803B1F.8070302@ericsson.com> From: ebiederm@xmission.com (Eric W. Biederman) Date: Fri, 02 Jun 2006 09:20:52 -0600 In-Reply-To: <44803B1F.8070302@ericsson.com> (Preben Traerup's message of "Fri, 02 Jun 2006 15:20:31 +0200") Message-ID: User-Agent: Gnus/5.1007 (Gnus v5.10.7) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Preben Traerup writes: > Something like out of memory and oops-es are enough to deeme the system must > panic > because it is simply not supposed to happen in a Telco server at any time. That is clearly enough to deem that the system must take some sever action and stop running. You don't necessarily have to handle it through a kernel panic. > kdump helps debugging these cases, but more importantly another server > must take over the work, and this has and always will have highest priority. > > I'm happy about what crash_kexec does today, but the timing issue makes it > unusable for > notifications to external systems, if I need to wait until properly running in > next kernel. Nothing says you have to wait until properly running in the next kernel. You can also write a dedicated piece of code that just pushes one packet out the NIC. Then you can start up a kernel for analysis purposes. Although I have a hard time believing you can't tune a kernel to start up quickly enough if you leave out just about everything. And for purposes analysis assume that the oops happened somewhere in the network stack. > That leaves me the choice of doing notification before executing crash_kexec ? Only because you have assumed that you have to start another kernel and starting that other kernel must be an expensive operation. > Since I'm apperantly not the only one left with this choice I rather prefer a > solution > made in public, that is known to be "bad" in some (well known) situations than > each and everybody implements their own solution to the same problem. It is certainly worth discussing. Eric