From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 77A236B0055 for ; Thu, 16 Jul 2009 20:59:47 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n6H0xhSa012159 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Fri, 17 Jul 2009 09:59:43 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 4C73A45DE50 for ; Fri, 17 Jul 2009 09:59:43 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 2346345DE5A for ; Fri, 17 Jul 2009 09:59:43 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id CDD401DB8038 for ; Fri, 17 Jul 2009 09:59:42 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 50B64E38004 for ; Fri, 17 Jul 2009 09:59:42 +0900 (JST) Date: Fri, 17 Jul 2009 09:57:45 +0900 From: KAMEZAWA Hiroyuki 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> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org 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 List-ID: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org