Re: [Crash-utility] Problem on getting kernel backtrace with a `virsh dump' dumped kvm dumpfile

Hi Dave, On Fri, Aug 27, 2010 at 08:40:17AM -0400, Dave Anderson wrote: > > ----- hutao(a)cn.fujitsu.com wrote: > > > Hi, > > > > I encountered a problem on getting backtrace with a `virsh dump' dumped > > kvm dumpfile, the bt command did not get kernel backtrace properly. > > > > guest kernel: 2.6.32 > > crash: 5.0.6 patched with qemu_ram_version_4.patch(attached) > > > > steps to get dumpfile: > > > > 1. virsh start vm > > 2. connect to vm, say by vnc > > 3. On guest, build and run the code: > > > > int main(void) > > { > > while (1); > > > > return 0; > > } > > > > 4. On host, run `virsh dump vm > > /mnt/data/kernel-2.6.32.dump3-userspace-endless-loop' > > > > Then run crash: > > > > crash /mnt/data/kernel/linux-2.6.32/System.map > > /mnt/data/kernel/linux-2.6.32/vmlinux > > /mnt/data/kernel-2.6.32.dump3-userspace-endless-loop > > > > got the result: > > > > crash 5.0.6 > > Copyright (C) 2002-2010 Red Hat, Inc. > > Copyright (C) 2004, 2005, 2006 IBM Corporation > > Copyright (C) 1999-2006 Hewlett-Packard Co > > Copyright (C) 2005, 2006 Fujitsu Limited > > Copyright (C) 2006, 2007 VA Linux Systems Japan K.K. > > Copyright (C) 2005 NEC Corporation > > Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc. > > Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc. > > This program is free software, covered by the GNU General Public License, > > and you are welcome to change it and/or distribute copies of it under > > certain conditions. Enter "help copying" to see the conditions. > > This program has absolutely no warranty. Enter "help warranty" for > > details. > > > > GNU gdb (GDB) 7.0 > > Copyright (C) 2009 Free Software Foundation, Inc. > > License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> > > This is free software: you are free to change and redistribute it. > > There is NO WARRANTY, to the extent permitted by law. Type "show copying" > > and "show warranty" for details. > > This GDB was configured as "x86_64-unknown-linux-gnu"... > > > > SYSTEM MAP: /mnt/data/kernel/linux-2.6.32/System.map > > DEBUG KERNEL: /mnt/data/kernel/linux-2.6.32/vmlinux (2.6.32) > > DUMPFILE: /mnt/data/kernel-2.6.32.dump3-userspace-endless-loop > > CPUS: 1 > > DATE: Fri Aug 27 05:18:12 2010 > > UPTIME: 00:00:51 > > LOAD AVERAGE: 0.44, 0.11, 0.03 > > TASKS: 67 > > NODENAME: localhost.localdomain > > RELEASE: 2.6.32 > > VERSION: #2 SMP PREEMPT Wed Aug 25 15:26:48 CST 2010 > > MACHINE: x86_64 (2925 Mhz) > > MEMORY: 511.6 MB > > PANIC: "Oops: 0003 [#1] PREEMPT SMP " (check log for details) > > PID: 0 > > COMMAND: "swapper" > > TASK: ffffffff8158df70 [THREAD_INFO: ffffffff8154e000] > > CPU: 0 > > STATE: TASK_RUNNING > > WARNING: panic task not found > > > > crash> bt > > PID: 0 TASK: ffffffff8158df70 CPU: 0 COMMAND: "swapper" > > #0 [ffffffff8154fe28] schedule at ffffffff8138baa3 > > bt: invalid kernel virtual address: 41 type: "call byte" > > bt: invalid kernel virtual address: 44e6835ad type: "call byte" > > bt: load_memfile_offset: read: Success > > bt: read error: kernel virtual address: fffffffffffffffc type: "call byte" > > bt: invalid kernel virtual address: e7ab type: "call byte" > > bt: invalid kernel virtual address: e273 type: "call byte" > > bt: invalid kernel virtual address: 13a7b type: "call byte" > > bt: invalid kernel virtual address: 935cb type: "call byte" > > bt: load_memfile_offset: read: Success > > bt: read error: kernel virtual address: fffffffffffffffb type: "call byte" > > bt: invalid kernel virtual address: 935cb type: "call byte" > > #1 [ffffffff8154fef0] cpu_idle at ffffffff8100ad1e > > crash> > > > > > > Note the output of `bt' command. Without running that endless-loop > > code then`bt' got: > > > > > > crash> bt > > PID: 0 TASK: ffffffff8158df70 CPU: 0 COMMAND: "swapper" > > #0 [ffffffff8154fe28] schedule at ffffffff8138baa3 > > #1 [ffffffff8154fe48] apic_timer_interrupt at ffffffff8100c65e > > #2 [ffffffff8154fed0] need_resched at ffffffff810125a8 > > #3 [ffffffff8154fee0] default_idle at ffffffff81012e03 > > #4 [ffffffff8154fef0] cpu_idle at ffffffff8100acd6 > > crash> > > > > > > Any suggestions on how to solve the problem? > > Not really. > > If there's no kernel crash, then the selection of the current > context defaults to the cpu 0 swapper task. I don't know > what was happening to the "swapper" task at the time that the > guest was paused. Without using System.map, `bt' indeed got crash> bt PID: 0 TASK: ffffffff8158df70 CPU: 0 COMMAND: "swapper" #0 [ffffffff8154fe28] schedule at ffffffff8138baa3 #1 [ffffffff8154fef0] cpu_idle at ffffffff8100ad1e crash> > > If you want to make the vmlinux/dumpfile available for me > to download, I can take a look. (I don't know why you're > using a System.map). Do you still need vmlinux/dumpfile? If yes I will make them available for you.

Thank you, Dave. > > Dave > > > > > Regards, > > Hu Tao