Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933570AbZGQA7p (ORCPT ); Thu, 16 Jul 2009 20:59:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933111AbZGQA7o (ORCPT ); Thu, 16 Jul 2009 20:59:44 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:57698 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932936AbZGQA7o (ORCPT ); Thu, 16 Jul 2009 20:59:44 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Fri, 17 Jul 2009 09:57:45 +0900 From: KAMEZAWA Hiroyuki To: KOSAKI Motohiro Cc: David Rientjes , Lee Schermerhorn , Miao Xie , Ingo Molnar , Peter Zijlstra , Christoph Lameter , Paul Menage , Nick Piggin , Yasunori Goto , Pekka Enberg , linux-mm , LKML , Andrew Morton Subject: Re: [BUG] set_mempolicy(MPOL_INTERLEAV) cause kernel panic Message-Id: <20090717095745.1d3039b1.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090717090003.A903.A69D9226@jp.fujitsu.com> References: <1247679064.4089.26.camel@useless.americas.hpqcorp.net> <20090717090003.A903.A69D9226@jp.fujitsu.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1775 Lines: 48 On Fri, 17 Jul 2009 09:04:46 +0900 (JST) KOSAKI Motohiro wrote: > > On Wed, 15 Jul 2009, Lee Schermerhorn wrote: > > > > > Interestingly, on ia64, the top cpuset mems_allowed gets set to all > > > possible nodes, while on x86_64, it gets set to on-line nodes [or nodes > > > with memory]. Maybe this is a to support hot-plug? > > > > > > > numactl --interleave=all simply passes a nodemask with all bits set, so if > > cpuset_current_mems_allowed includes offline nodes from node_possible_map, > > then mpol_set_nodemask() doesn't mask them off. > > > > Seems like we could handle this strictly in mempolicies without worrying > > about top_cpuset like in the following? > > This patch seems band-aid patch. it will change memory-hotplug behavior. > Please imazine following scenario: > > 1. numactl interleave=all process-A > 2. memory hot-add > > before 2.6.30: > -> process-A can use hot-added memory > > your proposal patch: > -> process-A can't use hot-added memory > IMHO, the application itseld should be notifed to change its mempolicy by hot-plug script on the host. While an application uses interleave, a new node hot-added is just a noise. I think "How pages are interleaved" should not be changed implicitly. Then, checking at set_mempolicy() seems sane. If notified, application can do page migration and rebuild his mapping in ideal way. BUT I don't linke init->mem_allowed contains N_POSSIBLE...it should be initialized to N_HIGH_MEMORY, IMHO. Thanks, -Kame -- 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/