From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932272AbYD1HIq (ORCPT ); Mon, 28 Apr 2008 03:08:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763374AbYD1HIi (ORCPT ); Mon, 28 Apr 2008 03:08:38 -0400 Received: from yw-out-2324.google.com ([74.125.46.29]:20200 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1765375AbYD1HIh (ORCPT ); Mon, 28 Apr 2008 03:08:37 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=r/BmyqtjWBd/LFUapPm4Lzv4mP/YAHGcFXNtcjjtMtB759OF/A5fIdZjsDVMtX31sV344YAAUN1gG/gGhrpW33DgUyyZyTH9viKvIl/zI7nUepD2/LaqHjtqoBSHMjkupwRsE4ZELUNKLeAdT41LrJPjQCgELTKQYqBuL1V81Ps= Message-ID: Date: Mon, 28 Apr 2008 15:08:36 +0800 From: "Dave Young" To: dpn@isomerica.net Subject: Re: NULL dereference OOPS on SysRq-w Cc: "Linux Kernel Mailing List" , mingo@elte.hu In-Reply-To: <48157664.2060302@isomerica.net> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <48141EFA.6080700@isomerica.net> <20080428065736.GA2714@darkstar.te-china.tietoenator.com> <48157664.2060302@isomerica.net> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 28, 2008 at 3:01 PM, Dan Noe wrote: > Dave Young wrote: > > > [snip] > > > > I have a fix for the NULL pointer reference BUG, tested on my pc. > > --- > > > > "m" will be NULL if seq_printf & seq_puts is called from sched_debug_show > > Use SEQ_* macros to fix it > > Signed-off-by: Dave Young > > > > There is actually already a patch out for this which simply hasn't made it > upstream yet - Mike Galbraith emailed me with it and it indeed fixes the > problem. I hadn't realized his email didn't go to lkml.. otherwise I would > have echoed that here to avoid wasting people's time. My apologies. Ok, thanks. While debuging this issue I found another BUG about sysrq, echo w >/proc/sys/kernel/sysrq My system hangs, there's no response from then on. > > Cheers, > Dan > > === > > Here is his message: > > From: efault@gmx.de > > Peter's fix didn't make it up-stream. > > Subject: sched: fix oops > > sched_debug uses SEQ_printf to use printk when the seqfile 'm' is NULL. > Instead of doing that here too; choose to not output the weight tree > to cut back on output. > > Signed-off-by: Peter Zijlstra > --- > diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c > index 89fa32b..353a481 100644 > --- a/kernel/sched_fair.c > +++ b/kernel/sched_fair.c > @@ -1643,8 +1643,10 @@ static void print_cfs_stats(struct seq_file *m, int > cpu) > > for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq) > print_cfs_rq(m, cpu, cfs_rq); > > - seq_printf(m, "\nWeight tree:\n"); > - print_cfs_rq_tasks(m, &cpu_rq(cpu)->cfs, 1); > + if (m) { > + seq_printf(m, "\nWeight tree:\n"); > > + print_cfs_rq_tasks(m, &cpu_rq(cpu)->cfs, 1); > + } > rcu_read_unlock(); > } > #endif > > > > > -- > /--------------- - - - - - - > | Dan Noe > | http://isomerica.net/~dpn/ >