From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757137AbZEEU1m (ORCPT ); Tue, 5 May 2009 16:27:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753524AbZEEU1d (ORCPT ); Tue, 5 May 2009 16:27:33 -0400 Received: from relay3.sgi.com ([192.48.156.57]:37897 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753187AbZEEU1d (ORCPT ); Tue, 5 May 2009 16:27:33 -0400 Date: Tue, 5 May 2009 15:27:30 -0500 From: Jack Steiner To: David Rientjes Cc: "Zhang, Yanmin" , alex.shi@intel.com, LKML , Ingo Molnar , Andi Kleen Subject: Re: [PATCH] Fix early panic issue on machines with memless node Message-ID: <20090505202730.GA9831@sgi.com> References: <1241493327.27664.17.camel@ymzhang> <20090505163608.GA20385@sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 05, 2009 at 12:52:54PM -0700, David Rientjes wrote: > On Tue, 5 May 2009, Jack Steiner wrote: > > > I was able to duplicate your original problem. Your patch below solves the > > problem. AFAICT, it causes no new reqgressions to the various configurations > > that I'm testing. (I'll add the "mem=2G" to my configs that I test). > > > > Great, it would be helpful to catch these problems before 2.6.30 is > released. I've passed my patch along to Ingo. > > > However, I see a new regression that was not present a couple of weeks ago. > > Configurations that have nodes with cpus and no memory panic during > > boot. This occurs both with and without your patch and is not related to "mem=". > > > > I need to isolate the problem but here is the stack trace. : > > Pid: 0, comm: swapper Not tainted 2.6.30-rc4-next-20090505-medusa #12 > > Call Trace: > > [] early_idt_handler+0x5e/0x71 > > [] ? build_zonelists_node+0x4c/0x8d > > [] __build_all_zonelists+0x1ae/0x55a > > [] build_all_zonelists+0x1b5/0x263 > > [] start_kernel+0x17a/0x3c5 > > [] ? early_idt_handler+0x0/0x71 > > [] x86_64_start_reservations+0xae/0xb2 > > [] x86_64_start_kernel+0x152/0x161 > > > > Please post your .config since it apparently differs from x86_64 defconfig > judging by my debugging symbols and also the full output of the panic. I suspect I mislead you when I mentioned "configurations". I did not mean the .config file. I use a more-or-less standard .config file. I do much of my testing on a system simulator. Using a simulator config file, I specify the system configuration such as number of nodes, sockets per node, cpus per socket, memory per socket, address map, boot options, etc. This makes it easy to quickly test a lot of strange (but real) configurations. The configuration above that is failing is a 2-socket Nehelem blade that has no memory on socket 0. All memory is located on socket 1. The panic is caused by a null dereference of NODE_DATA(0). Still looking.... --- jack