From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753901AbZBWJSU (ORCPT ); Mon, 23 Feb 2009 04:18:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752190AbZBWJSM (ORCPT ); Mon, 23 Feb 2009 04:18:12 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:49329 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752042AbZBWJSM (ORCPT ); Mon, 23 Feb 2009 04:18:12 -0500 Date: Mon, 23 Feb 2009 01:17:12 -0800 From: Andrew Morton To: Ingo Molnar Cc: "Paul E. McKenney" , Vegard Nossum , stable@kernel.org, Nick Piggin , Pekka Enberg , linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: fix lazy vmap purging (use-after-free error) Message-Id: <20090223011712.853aa94d.akpm@linux-foundation.org> In-Reply-To: <20090223090735.GH9582@elte.hu> References: <19f34abd0902200651k7e86aebay5398ef5ac0578561@mail.gmail.com> <20090220154619.GC6960@linux.vnet.ibm.com> <19f34abd0902201551o65a3650egf29d81e8b6823d67@mail.gmail.com> <20090221014056.GU6960@linux.vnet.ibm.com> <19f34abd0902210130p62fba6d0n906b321949409578@mail.gmail.com> <20090221174703.GA6860@linux.vnet.ibm.com> <19f34abd0902211008k39afd449k604aaf34f693c9a6@mail.gmail.com> <19f34abd0902211037w2293af16t561444d11cc834b8@mail.gmail.com> <20090222030030.GD6860@linux.vnet.ibm.com> <20090223051709.GA5990@linux.vnet.ibm.com> <20090223090735.GH9582@elte.hu> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 23 Feb 2009 10:07:35 +0100 Ingo Molnar wrote: > > --- > > > > init/main.c | 3 +++ > > kernel/rcuclassic.c | 4 +++- > > kernel/rcutree.c | 4 +++- > > 3 files changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/init/main.c b/init/main.c > > index 8442094..51f4b71 100644 > > --- a/init/main.c > > +++ b/init/main.c > > @@ -121,6 +121,8 @@ static char *static_command_line; > > static char *execute_command; > > static char *ramdisk_execute_command; > > > > +int idle_task_is_really_idle; /* set to 1 late in boot. */ > > + > > #ifdef CONFIG_SMP > > /* Setup configured maximum number of CPUs to activate */ > > unsigned int __initdata setup_max_cpus = NR_CPUS; > > @@ -463,6 +465,7 @@ static noinline void __init_refok rest_init(void) > > * at least once to get things moving: > > */ > > init_idle_bootup_task(current); > > + idle_task_is_really_idle = 1; > > preempt_enable_no_resched(); > > schedule(); > > preempt_disable(); > > Could you please use system_state instead? We could insert a new > stage - or just use SYSTEM_RUNNING as the trigger. I think the standalone flag is better (once those extern-decls-in-C get fixed). system_state's semantics have, err, evolved over time. If this happens again (and the patch sneaks past my attention) then there's a risk that code which depends upon system_state will break - this has happened in the past. Plus piling more dependencies on system_state of course makes any evolution of its semantics harder to do... It seems safer/saner/more-robust to create the additional application-specific global as Paul has done. One more word of bss won't kill us. It adds a few more words of .text, but it's in __init.