Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755308AbZGYDPO (ORCPT ); Fri, 24 Jul 2009 23:15:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751733AbZGYDPO (ORCPT ); Fri, 24 Jul 2009 23:15:14 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:38476 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751630AbZGYDPM (ORCPT ); Fri, 24 Jul 2009 23:15:12 -0400 Message-ID: <9443f91bd4648e6214b32acff4512b97.squirrel@webmail-b.css.fujitsu.com> In-Reply-To: <5bb65c0e4c6828b1331d33745f34d9ee.squirrel@webmail-b.css.fujitsu.com> 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> Date: Sat, 25 Jul 2009 12:15:10 +0900 (JST) Subject: Re: [BUG] set_mempolicy(MPOL_INTERLEAV) cause kernel panic From: "KAMEZAWA Hiroyuki" To: "KAMEZAWA Hiroyuki" Cc: "KAMEZAWA Hiroyuki" , "Andrew Morton" , "David Rientjes" , lee.schermerhorn@hp.com, kosaki.motohiro@jp.fujitsu.com, miaox@cn.fujitsu.com, mingo@elte.hu, a.p.zijlstra@chello.nl, cl@linux-foundation.org, menage@google.com, nickpiggin@yahoo.com.au, y-goto@jp.fujitsu.com, penberg@cs.helsinki.fi, linux-mm@kvack.org, linux-kernel@vger.kernel.org User-Agent: SquirrelMail/1.4.16 MIME-Version: 1.0 Content-Type: text/plain;charset=iso-2022-jp Content-Transfer-Encoding: 8bit X-Priority: 3 (Normal) Importance: Normal Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1064 Lines: 30 KAMEZAWA Hiroyuki wrote: > KAMEZAWA Hiroyuki wrote: > Then, here is a much easier fix. for trusting cpuset more. > just a memo about memory hotplug _Direct_ use of task->mems_allowed is only in cpuset and mempolicy. If no policy is used, it's not checked. (See alloc_pages_current()) memory hotplug's notifier just updates top_cpuset's mems_allowed. But it doesn't update each task's ones. Then, task's bahavior is - tasks which don't use mempolicy will use all nodes, N_HIGH_MEMORY. - tasks under cpuset will be controlled under their own cpuset. - tasks under mempolicy will use their own policy. but no new policy is re-calculated and, then, no new mask. Now, even if all memory on nodes a removed, pgdat just remains. Then, cpuset/mempolicy will never access NODE_DATA(nid) which is NULL. 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/