Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932257AbWIVDnL (ORCPT ); Thu, 21 Sep 2006 23:43:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932258AbWIVDnL (ORCPT ); Thu, 21 Sep 2006 23:43:11 -0400 Received: from smtp.osdl.org ([65.172.181.4]:24193 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S932257AbWIVDnK (ORCPT ); Thu, 21 Sep 2006 23:43:10 -0400 Date: Thu, 21 Sep 2006 20:42:42 -0700 From: Andrew Morton To: KAMEZAWA Hiroyuki Cc: kmannth@us.ibm.com, linux-kernel@vger.kernel.org, clameter@engr.sgi.com Subject: Re: [BUG] i386 2.6.18 cpu_up: attempt to bring up CPU 4 failed : kernel BUG at mm/slab.c:2698! Message-Id: <20060921204242.53a88487.akpm@osdl.org> In-Reply-To: <20060922123045.d7258e13.kamezawa.hiroyu@jp.fujitsu.com> References: <1158884252.5657.38.camel@keithlap> <20060921174134.4e0d30f2.akpm@osdl.org> <1158888843.5657.44.camel@keithlap> <20060922112427.d5f3aef6.kamezawa.hiroyu@jp.fujitsu.com> <20060921200806.523ce0b2.akpm@osdl.org> <20060922123045.d7258e13.kamezawa.hiroyu@jp.fujitsu.com> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2112 Lines: 60 On Fri, 22 Sep 2006 12:30:45 +0900 KAMEZAWA Hiroyuki wrote: > On Thu, 21 Sep 2006 20:08:06 -0700 > Andrew Morton wrote: > > > But why did the kmalloc() fail? > > > > > from this: > > == > #define NOTIFY_DONE 0x0000 /* Don't care */ > #define NOTIFY_OK 0x0001 /* Suits me */ > #define NOTIFY_STOP_MASK 0x8000 /* Don't call further */ > #define NOTIFY_BAD (NOTIFY_STOP_MASK|0x0002) > == > > I gues someone returns NOTIFY_BAD before pageset_cpuup_callback() is called. > When CPU_UP_CANCELED comes, pageset_cpuup_callback() can't know zone_pcp() > is kmalloced or not. Is this ugly ? > > -Kame > > Before kfree(), we should check zone_pcp() is not boot_pageset[]. > > Signed-Off-By KAMEZAWA Hiroyuki > > Index: linux-2.6.18/mm/page_alloc.c > =================================================================== > --- linux-2.6.18.orig/mm/page_alloc.c 2006-09-20 12:42:06.000000000 +0900 > +++ linux-2.6.18/mm/page_alloc.c 2006-09-22 12:22:03.000000000 +0900 > @@ -1844,9 +1844,11 @@ > > for_each_zone(zone) { > struct per_cpu_pageset *pset = zone_pcp(zone, cpu); > - > - zone_pcp(zone, cpu) = NULL; > - kfree(pset); > + /* When canceled, zone_pcp still points to boot_pageset[] */ > + if (zone_pcp(zone, cpu) != &boot_pageset[cpu]) { > + zone_pcp(zone, cpu) = NULL; > + kfree(pset); > + } > } > } > No, that's OK as it is now. The above code is numa-only, in which case zone_pcp(zone, cpu) is known to be kmalloced. These functions won't even compile on !NUMA because in that case, zone_pcp() isn't an lvalue. OBCodingStyleNit: could we pleeeeeze not go and use macros as lvalues like this? It looks just too weird. Simply do zone_pcp(zone, cpu) and set_zone_pcp(zone, cpu, val). - 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/