From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757999Ab3K0WTA (ORCPT ); Wed, 27 Nov 2013 17:19:00 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:41924 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753959Ab3K0WS5 (ORCPT ); Wed, 27 Nov 2013 17:18:57 -0500 Message-ID: <52966FA1.3020606@oracle.com> Date: Wed, 27 Nov 2013 15:18:09 -0700 From: Khalid Aziz Organization: Oracle Corp User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.1 MIME-Version: 1.0 To: Matthew Garrett , Greg KH CC: "Eric W. Biederman" , bhelgaas@google.com, cl91tp@gmail.com, tianyu.lan@intel.com, khlebnikov@openvz.org, gnomes@lxorguk.ukuu.org.uk, indou.takao@jp.fujitsu.com, jility09@gmail.com, f.otti@gmx.at, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, stable@vger.kernel.org Subject: Re: [PATCH] PCI: Clear Bus Master bit only on kexec reboot References: <1385579908-24608-1-git-send-email-khalid.aziz@oracle.com> <87ob55my8z.fsf@xmission.com> <52964F2C.1020803@oracle.com> <20131127212227.GA31237@kroah.com> <20131127215309.GA15320@srcf.ucam.org> <20131127220106.GA21887@kroah.com> <20131127220704.GA15609@srcf.ucam.org> In-Reply-To: <20131127220704.GA15609@srcf.ucam.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/27/2013 03:07 PM, Matthew Garrett wrote: > On Wed, Nov 27, 2013 at 02:01:06PM -0800, Greg KH wrote: >> Anyway, I really don't care either way, but this seems like something >> that the drivers should be doing. What suddenly changed that caused >> this problem to occur that hasn't happened in the years prior to now >> that drives this to be a stable-kernel issue? > > We started clearing the busmaster bit on all devices on shutdown in > 3.something in order to ensure that DMA wasn't occuring while we were > in the process of performing a kexec. Some machines freeze on shutdown > as a result. This patch reverts back to the original behaviour on real > shutdown, while still avoiding the "This PCI device scribbled over my > new kernel" kexec case. > Thanks for explaining this, Matthew. That was my reasoning exactly for why this patch should apply to stable. It fixes a real problem some users are experiencing. Commit log contains the URL to bugzilla entry for the problem. -- Khalid