Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753175Ab2JJU5R (ORCPT ); Wed, 10 Oct 2012 16:57:17 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:63305 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751305Ab2JJU5O (ORCPT ); Wed, 10 Oct 2012 16:57:14 -0400 Date: Wed, 10 Oct 2012 13:57:11 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Andrew Morton cc: Peter Zijlstra , Tang Chen , mingo@redhat.com, miaox@cn.fujitsu.com, wency@cn.fujitsu.com, linux-kernel@vger.kernel.org, linux-numa@vger.kernel.org Subject: Re: [PATCH] Do not use cpu_to_node() to find an offlined cpu's node. In-Reply-To: <20121010133709.7eaefcdb.akpm@linux-foundation.org> Message-ID: References: <1349665183-11718-1-git-send-email-tangchen@cn.fujitsu.com> <1349780256.7880.12.camel@twins> <1349815676.7880.85.camel@twins> <1349860216.7880.105.camel@twins> <20121010133709.7eaefcdb.akpm@linux-foundation.org> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1595 Lines: 34 On Wed, 10 Oct 2012, Andrew Morton wrote: > > > So for now, let me NACK that patch. You cannot go change stuff like > > > that. > > > > > > > Agreed, that makes the nack-count up to 2 now. Andrew, please remove > > cpu_hotplug-unmap-cpu2node-when-the-cpu-is-hotremoved.patch > > cpu_hotplug-unmap-cpu2node-when-the-cpu-is-hotremoved-fix.patch > > from -mm. > > Nope. It fixes a BUG() and so I'll be keeping it around until I see a > better fix. It's one of the ways in which I prevent things from falling > through cracks. > It fixes a BUG() that only affects users who are doing node hot-remove, which is still radically under development, and nobody cares about except those on the cc list, but it also introduces the NULL pointer dereference that is attempting to be addressed in this patch. The "fix" that causes this NULL pointer is clearly not the direction we want to go, I think we have agreement at node hot-remove to iterate all possible cpus are map all offline cpus with cpu_to_node(cpu) == node to NUMA_NO_NODE instead in the generic hotplug code. Regardless, this shouldn't be touching the acpi code which cpu_hotplug-unmap-cpu2node-when-the-cpu-is-hotremoved.patch and cpu_hotplug-unmap-cpu2node-when-the-cpu-is-hotremoved-fix.patch do since it makes the behavior inconsistent across interfaces and architectures. -- 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/