From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 92C6F6B009C for ; Sat, 25 Jul 2009 09:21:23 -0400 (EDT) Received: by yxe35 with SMTP id 35so3910644yxe.12 for ; Sat, 25 Jul 2009 06:21:29 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <9443f91bd4648e6214b32acff4512b97.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> <9443f91bd4648e6214b32acff4512b97.squirrel@webmail-b.css.fujitsu.com> Date: Sat, 25 Jul 2009 22:21:29 +0900 Message-ID: <2f11576a0907250621w3696fdc0pe61638c8c935c981@mail.gmail.com> Subject: Re: [BUG] set_mempolicy(MPOL_INTERLEAV) cause kernel panic From: KOSAKI Motohiro Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Andrew Morton , David Rientjes , lee.schermerhorn@hp.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 List-ID: 2009/07/25 12:15 に KAMEZAWA Hiroyuki さんは書きました: > 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. Umm.. I don't think this is optimal behavior. but if hotplug guys agree this, I agree this too. Thanks. -- 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