From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Tokarev Subject: Re: [Qemu-devel] segmentation fault in qemu-kvm-0.14.0 Date: Wed, 09 Mar 2011 10:39:17 +0300 Message-ID: <4D772EA5.8030809@msgid.tls.msk.ru> References: <2640D58E-2101-47FA-99B6-28815666651E@dlh.net> <4D772BBC.4040603@mail.berlios.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Peter Lieven , qemu-devel , kvm@vger.kernel.org, anthony@codemonkey.ws To: Stefan Weil Return-path: Received: from isrv.corpit.ru ([86.62.121.231]:52206 "EHLO isrv.corpit.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753454Ab1CIHjU (ORCPT ); Wed, 9 Mar 2011 02:39:20 -0500 In-Reply-To: <4D772BBC.4040603@mail.berlios.de> Sender: kvm-owner@vger.kernel.org List-ID: 09.03.2011 10:26, Stefan Weil wrote: > Am 08.03.2011 23:53, schrieb Peter Lieven: >> Hi, >> >> during testing of qemu-kvm-0.14.0 i can reproduce the following >> segfault. i have seen similar crash already in 0.13.0, but had no time >> to debug. >> my guess is that this segfault is related to the threaded vnc server >> which was introduced in qemu 0.13.0. the bug is only triggerable if a vnc >> client is attached. it might also be connected to a resolution change >> in the guest. i have a backtrace attached. the debugger is still >> running if someone >> needs more output >> [] > Hi Peter, > > did you apply this patch which fixes one of the known vnc problems > (but is still missing in qemu git master): > > http://lists.nongnu.org/archive/html/qemu-devel/2011-03/msg00256.html This patch is not suitable for 0.14 since in current qemu/master quite alot of stuff were changed in this area (bitmaps added), there's no similar infrastructure in 0.14. > Then you can read this thread: > > http://lists.nongnu.org/archive/html/qemu-devel/2011-03/msg00313.html > > And finally the following modifications of ui/vnc.c might help to see > whether you experience the same kind of crash as I get here in > my environment. They add assertions for bad memory access > which occurs sometimes when a vnc client-server connection exists and > the screen is refreshed after a resolution change. > The code line with the //~ comment also includes a fix which > works for me. The same is true for this patch, but of a less extent: it can be applied manually (the bitmap_empty context line). I wonder if something similar actually exists in 0.13/0.14 too and needs to be backported to -stable. > Regards, > Stefan W. Thanks! /mjt From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=46425 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PxDzP-0004Gh-MG for qemu-devel@nongnu.org; Wed, 09 Mar 2011 02:39:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PxDzO-0003XU-C7 for qemu-devel@nongnu.org; Wed, 09 Mar 2011 02:39:23 -0500 Received: from isrv.corpit.ru ([86.62.121.231]:37493) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PxDzO-0003Wx-5P for qemu-devel@nongnu.org; Wed, 09 Mar 2011 02:39:22 -0500 Message-ID: <4D772EA5.8030809@msgid.tls.msk.ru> Date: Wed, 09 Mar 2011 10:39:17 +0300 From: Michael Tokarev MIME-Version: 1.0 Subject: Re: [Qemu-devel] segmentation fault in qemu-kvm-0.14.0 References: <2640D58E-2101-47FA-99B6-28815666651E@dlh.net> <4D772BBC.4040603@mail.berlios.de> In-Reply-To: <4D772BBC.4040603@mail.berlios.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Weil Cc: Peter Lieven , qemu-devel , kvm@vger.kernel.org 09.03.2011 10:26, Stefan Weil wrote: > Am 08.03.2011 23:53, schrieb Peter Lieven: >> Hi, >> >> during testing of qemu-kvm-0.14.0 i can reproduce the following >> segfault. i have seen similar crash already in 0.13.0, but had no time >> to debug. >> my guess is that this segfault is related to the threaded vnc server >> which was introduced in qemu 0.13.0. the bug is only triggerable if a vnc >> client is attached. it might also be connected to a resolution change >> in the guest. i have a backtrace attached. the debugger is still >> running if someone >> needs more output >> [] > Hi Peter, > > did you apply this patch which fixes one of the known vnc problems > (but is still missing in qemu git master): > > http://lists.nongnu.org/archive/html/qemu-devel/2011-03/msg00256.html This patch is not suitable for 0.14 since in current qemu/master quite alot of stuff were changed in this area (bitmaps added), there's no similar infrastructure in 0.14. > Then you can read this thread: > > http://lists.nongnu.org/archive/html/qemu-devel/2011-03/msg00313.html > > And finally the following modifications of ui/vnc.c might help to see > whether you experience the same kind of crash as I get here in > my environment. They add assertions for bad memory access > which occurs sometimes when a vnc client-server connection exists and > the screen is refreshed after a resolution change. > The code line with the //~ comment also includes a fix which > works for me. The same is true for this patch, but of a less extent: it can be applied manually (the bitmap_empty context line). I wonder if something similar actually exists in 0.13/0.14 too and needs to be backported to -stable. > Regards, > Stefan W. Thanks! /mjt