From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Friesen Subject: Re: [Qemu-devel] kvm bug in __rmap_clear_dirty during live migration Date: Tue, 21 Feb 2017 21:08:04 -0600 Message-ID: <58AD0094.90304@windriver.com> References: <589C7E96.9060905@huawei.com> <589D83CE.1090803@huawei.com> <589DDC05.9010807@windriver.com> <58AA51D6.6020508@huawei.com> <1487565495.3740.27.camel@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Cc: "kvm@vger.kernel.org" , "fangying1@huawei.com" , "herongguang.he@huawei.com" , "xudong.hao@linux.intel.com" , "qemu-devel@nongnu.org" , "pbonzini@redhat.com" , "wangxinxin.wang@huawei.com" , "kai.huang@linux.intel.com" , "rkrcmar@redhat.com" , "guangrong.xiao@linux.intel.com" To: "Han, Huaitong" , "hangaohuai@huawei.com" Return-path: Received: from mail5.windriver.com ([192.103.53.11]:54518 "EHLO mail5.wrs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751271AbdBVDI3 (ORCPT ); Tue, 21 Feb 2017 22:08:29 -0500 In-Reply-To: <1487565495.3740.27.camel@intel.com> Sender: kvm-owner@vger.kernel.org List-ID: On 02/19/2017 10:38 PM, Han, Huaitong wrote: > Hi, Gaohuai > > I tried to debug the problem, and I found the indirect cause may be that > the rmap value is not cleared when KVM mmu page is freed. I have read > code without the root cause. Can you stable reproduce the the issue? > Many guesses need to be verified. In both cases it seems to have been triggered by repeatedly live-migrating a KVM virtual machine between two hypervisors with Broadwell CPUs running the latest CentOS 7. It's a race of some sort, it doesn't happen every time. Chris