Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752683Ab1DUCm5 (ORCPT ); Wed, 20 Apr 2011 22:42:57 -0400 Received: from smtp.wow.synacor.com ([64.8.70.55]:56175 "EHLO smtp.mail.wowway.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751567Ab1DUCm4 (ORCPT ); Wed, 20 Apr 2011 22:42:56 -0400 X-Greylist: delayed 481 seconds by postgrey-1.27 at vger.kernel.org; Wed, 20 Apr 2011 22:42:56 EDT X-Spam-Rating: None X_CMAE_Category: 0,0 Undefined,Undefined X-CNFS-Analysis: v=1.1 cv=eKQ+N4rqOQiji9ijAFGVZbvuh9RsgY7ivWxzmg3MFRI= c=1 sm=0 a=EnAg6b0JcI4A:10 a=FKkrIqjQGGEA:10 a=M1VNycxITrcA:10 a=AhRLOILGsKkA:10 a=IkcTkHD0fZMA:10 a=0xuUpNzuAqVGyKJjr2AA:9 a=QEXdDO2ut3YA:10 a=QLvOlBIuGJjmAZ5IHHaCwQ==:117 X-CM-Score: 0 Date: Wed, 20 Apr 2011 22:34:54 -0400 (EDT) From: Stephen Powell To: Heiko Carstens Cc: Jan Glauber , Jonathan Nieder , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, 622570@bugs.debian.org Message-ID: <248142179.74791.1303353294865.JavaMail.root@md01.wow.synacor.com> In-Reply-To: <20110418115141.GA3157@osiris.boeblingen.de.ibm.com> Subject: Re: [OOPS s390] Unable to handle kernel pointer dereference at virtual kernel address (null) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [75.118.95.22] X-Mailer: Zimbra 6.0.5_GA_2328.RHEL5_64 (zclient/6.0.5_GA_2328.RHEL5_64) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1672 Lines: 42 On Mon, 18 Apr 2011 07:51:41 -0400 (EDT), Heiko Carstens wrote: > > That's a bug in the pfault interrupt code. After a cleanup patch which > simplified lowcore accesses we are left with a dereference which shouldn't > be there. The patch below should fix it. > The bug was introduced with 2.6.37-rc1. > > diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c > index 9217e33..4cf85fe 100644 > --- a/arch/s390/mm/fault.c > +++ b/arch/s390/mm/fault.c > @@ -558,9 +558,9 @@ static void pfault_interrupt(unsigned int ext_int_code, > * Get the token (= address of the task structure of the affected task). > */ > #ifdef CONFIG_64BIT > - tsk = *(struct task_struct **) param64; > + tsk = (struct task_struct *) param64; > #else > - tsk = *(struct task_struct **) param32; > + tsk = (struct task_struct *) param32; > #endif > > if (subcode & 0x0080) { I applied the above patch and re-built the kernel. I did not apply Jan Glauber's suggested patch, since Heiko's suggested patch seemed to be a "direct hit". I have had the server up for more than 24 hours now, which is definitely a good sign. Without this patch, I've not been able to keep a 2.6.38 s390x kernel up for more than a few hours. Unfortunately, since I can't reproduce the problem on demand, I cannot say with 100% certainty that the problem is fixed, but it looks good and makes sense. -- .''`. Stephen Powell : :' : `. `'` `- -- 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/