Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752293AbZGYBdp (ORCPT ); Fri, 24 Jul 2009 21:33:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752127AbZGYBdo (ORCPT ); Fri, 24 Jul 2009 21:33:44 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:55104 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751324AbZGYBdo (ORCPT ); Fri, 24 Jul 2009 21:33:44 -0400 Message-ID: <337c5d83954b38b14a17f0adf4d357d8.squirrel@webmail-b.css.fujitsu.com> In-Reply-To: <20090724160936.a3b8ad29.akpm@linux-foundation.org> References: <20090715182320.39B5.A69D9226@jp.fujitsu.com> <1247679064.4089.26.camel@useless.americas.hpqcorp.net> <20090724160936.a3b8ad29.akpm@linux-foundation.org> Date: Sat, 25 Jul 2009 10:33:41 +0900 (JST) Subject: Re: [BUG] set_mempolicy(MPOL_INTERLEAV) cause kernel panic From: "KAMEZAWA Hiroyuki" To: "Andrew Morton" Cc: "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: 3547 Lines: 104 Andrew Morton wrote: > On Fri, 24 Jul 2009 15:51:51 -0700 (PDT) > David Rientjes wrote: > afaik we don't have a final patch for this. I asked Motohiro-san about > this and he's proposing that we revert the offending change (which one > was it?) if nothing gets fixed soon - the original author is on a > lengthy vacation. > > > If we _do_ have a patch then can we start again? Someone send out the > patch > and let's take a look at it. Hmm, like this ? (cleaned up David's one because we shouldn't have extra nodemask_t on stack.) Problems are - rebind() is maybe broken but no good idea. (but it seems to be broken in old kernels - Who can test this is only a user who has possible node on SRAT. == From: KAMEZAWA Hiroyuki At setting mempolicy's nodemask (or node id), we need to guarantee node-id is online. But cpuset's nodemask may contain not-online(possible) nodes and it can cause an access to NODE_DATA(nid) of not-online nodes. This patch fiexs mempolicy's nodemask to be subset of valid nodes. (N_HIGH_MEMORY). But, there are 2 caes for setting policy's mask - new - rebind A difficult case is rebind. In this patch, if relationship of new cpuset's nodemask & policy's mask is invalid, just use cpuset's mask. Based on David Rientjes's patch. Signed-off-by: KAMEZAWA Hiroyuki --- mm/mempolicy.c | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) Index: mmotm-2.6.31-Jul16/mm/mempolicy.c =================================================================== --- mmotm-2.6.31-Jul16.orig/mm/mempolicy.c +++ mmotm-2.6.31-Jul16/mm/mempolicy.c @@ -204,12 +204,22 @@ static int mpol_set_nodemask(struct memp if (pol->mode == MPOL_PREFERRED && nodes_empty(*nodes)) nodes = NULL; /* explicit local allocation */ else { + /* + * Here, we mask this new nodemask with N_HIGH_MEMORY. + * An issue is memory hotplug. Now, at hot-add, we don't + * update, this. This should be fixed. At hot-remove, we don't + * remove pgdat itself, then, we should update this but + * we'll never see terrible bugs. Leaving it as it is, now. + */ + nodes_and(cpuset_context_mask, &cpuset_current_mems_allowed, + node_states[N_HIGH_MEMORY]); + /* should we call is_valid_nodemask() here ?*/ if (pol->flags & MPOL_F_RELATIVE_NODES) mpol_relative_nodemask(&cpuset_context_nmask, nodes, - &cpuset_current_mems_allowed); + &cpuset_context_nmask); else nodes_and(cpuset_context_nmask, *nodes, - cpuset_current_mems_allowed); + cpuset_context_nmask); if (mpol_store_user_nodemask(pol)) pol->w.user_nodemask = *nodes; else @@ -290,7 +300,16 @@ static void mpol_rebind_nodemask(struct *nodes); pol->w.cpuset_mems_allowed = *nodes; } - + /* + * At rebind, passed *nodes is guaranteed to online, but..calculated + * nodemask can be empty or invalid. print WARNING and use cpuset's + * mask + */ + if (nodes_empty(tmp) || + (pol->mode == MPOL_BIND && !is_valid_nodemask(tmp))) { + tmp = *nodes; + printk("relation amoung cpuset/mempolicy goes bad.\n"); + } pol->v.nodes = tmp; if (!node_isset(current->il_next, tmp)) { current->il_next = next_node(current->il_next, tmp); -- 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/