From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id BF1AC6B004D for ; Mon, 27 Jul 2009 20:56:47 -0400 (EDT) Received: from m5.gw.fujitsu.co.jp ([10.0.50.75]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n6S0uq4u010667 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Tue, 28 Jul 2009 09:56:52 +0900 Received: from smail (m5 [127.0.0.1]) by outgoing.m5.gw.fujitsu.co.jp (Postfix) with ESMTP id 8E6F02AEA81 for ; Tue, 28 Jul 2009 09:56:51 +0900 (JST) Received: from s5.gw.fujitsu.co.jp (s5.gw.fujitsu.co.jp [10.0.50.95]) by m5.gw.fujitsu.co.jp (Postfix) with ESMTP id 1F7D21EF082 for ; Tue, 28 Jul 2009 09:56:51 +0900 (JST) Received: from s5.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s5.gw.fujitsu.co.jp (Postfix) with ESMTP id AD3F61DB805A for ; Tue, 28 Jul 2009 09:56:50 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s5.gw.fujitsu.co.jp (Postfix) with ESMTP id 1547E1DB8040 for ; Tue, 28 Jul 2009 09:56:49 +0900 (JST) Date: Tue, 28 Jul 2009 09:54:53 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [BUG] set_mempolicy(MPOL_INTERLEAV) cause kernel panic Message-Id: <20090728095453.1fe79de1.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: References: <20090715182320.39B5.A69D9226@jp.fujitsu.com> <1247679064.4089.26.camel@useless.americas.hpqcorp.net> <20090724160936.a3b8ad29.akpm@linux-foundation.org> <337c5d83954b38b14a17f0adf4d357d8.squirrel@webmail-b.css.fujitsu.com> <5bb65c0e4c6828b1331d33745f34d9ee.squirrel@webmail-b.css.fujitsu.com> <9443f91bd4648e6214b32acff4512b97.squirrel@webmail-b.css.fujitsu.com> <20090728085810.f7ae678a.kamezawa.hiroyu@jp.fujitsu.com> <20090728092529.bb0d7e9c.kamezawa.hiroyu@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: David Rientjes Cc: Andrew Morton , Lee Schermerhorn , KOSAKI Motohiro , miaox@cn.fujitsu.com, Ingo Molnar , Peter Zijlstra , Christoph Lameter , Paul Menage , Nick Piggin , y-goto@jp.fujitsu.com, Pekka Enberg , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Mon, 27 Jul 2009 17:38:30 -0700 (PDT) David Rientjes wrote: > On Tue, 28 Jul 2009, KAMEZAWA Hiroyuki wrote: > > > Because we dont' update, task->mems_allowed need to be initilaized as > > N_POSSIBLE_NODES. At usual thinking, it should be N_HIGH_MEMORY or > > N_ONLINE_NODES, as my patch does. > > > > On MEM_OFFLINE, cpusets calls scan_for_empty_cpusets() which will > intersect each system cpuset's mems_allowed with N_HIGH_MEMORY. It then > calls update_tasks_nodemask() which will update task->mems_allowed for > each task assigned to those cpusets. This has a callback into the > mempolicy code to rebind the policy with the new mems. > > So there's no apparent issue with memory hotplug in dealing with cpuset > mems, although I suggested that this be done for MEM_GOING_OFFLINE instead > of waiting until the mem is actually offline. > I _wrote_ this is just a side story to bug. online/offline isn't related to this bug. > The problem originally reported here doesn't appear to have anything to do > with hotplug, it looks like it is the result of Lee's observation that > ia64 defaults top_cpuset's mems to N_POSSIBLE, which _should_ have been > updated by cpuset_init_smp(). cpuset_init_smp() just updates cpuset's mask. init's task->mems_allowed is intizialized independently from cpuset's mask. Could you teach me a pointer for Lee's observation ? > So it makes me believe that N_HIGH_MEMORY > isn't actually ready by the time do_basic_setup() is called to be useful. > N_HIGH_MEMORY should be ready when zonelist is built. If not, it's bug. 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