Re: one out of four existing kvm guest's not starting after system upgrade

Jan Kiszka
2012-02-18T08:56:07Z

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On 2012-02-18 09:50, Thomas Fjellstrom wrote:
> On Sat Feb 18, 2012, Jan Kiszka wrote:
>> On 2012-02-18 05:49, Thomas Fjellstrom wrote:
>>> I just updated my kvm host, kernel upgraded from 2.6.38 up to 3.2, and
>>> qemu+qemu-kvm updated (not sure from what to what). But after the
>>> upgrade, one of my guests will not start up. It gets stuck with 60-80%
>>> cpu use, almost no memory is allocated by qemu/kvm, and no output of any
>>> kind is seen (in the host console, or a bunch of the guest output
>>> options like curses display, stdio output, virsh console, vnc or sdl
>>> output). I normally use libvirt to manage the guests, but I've attempted
>>> to run qemu manually, and have the same problems.
>>>
>>> What can cause this?
>>>
>>> Just tested booting back into the old kernel, the one guest still won't
>>> start, while the rest do. I'm thoroughly confused.
>>
>> You mean if you only update qemu-kvm, the problem persists, just with
>> lower probability? In that case, we definitely need the version of your
>> current qemu-kvm installation. Also, it would be nice to attach gdb to
>> the stuck qemu-kvm process, issuing a "thread apply all backtrace" in
>> that state.
>>
>> Jan
>
> Sorry I wasn't clear. If I just update qemu-kvm (And qemu with it, and not the
> kernel), it always just hangs on load.
>
> current version:
> QEMU emulator version 1.0 (qemu-kvm-1.0 Debian 1.0+dfsg-8), Copyright (c)
> 2003-2008 Fabrice Bellard
>
> gdb thread apply all bt:
> Thread 2 (Thread 0x7fe7b810c700 (LWP 14650)):
> #0 0x00007fe7c0a11957 in ioctl () from /lib/x86_64-linux-gnu/libc.so.6
> #1 0x00007fe7c53155e9 in kvm_vcpu_ioctl (env=<optimized out>, type=<optimized
> out>) at /build/buildd-qemu-kvm_1.0+dfsg-8-amd64-ppNMqm/qemu-kvm-1.0+dfsg/kvm-
> all.c:1101
> #2 0x00007fe7c5315731 in kvm_cpu_exec (env=0x7fe7c61cb350) at /build/buildd-
> qemu-kvm_1.0+dfsg-8-amd64-ppNMqm/qemu-kvm-1.0+dfsg/kvm-all.c:987
> #3 0x00007fe7c52ecf31 in qemu_kvm_cpu_thread_fn (arg=0x7fe7c61cb350) at
> /build/buildd-qemu-kvm_1.0+dfsg-8-amd64-ppNMqm/qemu-kvm-1.0+dfsg/cpus.c:740
> #4 0x00007fe7c0ccdb50 in start_thread () from /lib/x86_64-linux-
> gnu/libpthread.so.0
> #5 0x00007fe7c0a1890d in clone () from /lib/x86_64-linux-gnu/libc.so.6
> #6 0x0000000000000000 in ?? ()
>
> Thread 1 (Thread 0x7fe7c5101900 (LWP 14648)):
> #0 0x00007fe7c0a12403 in select () from /lib/x86_64-linux-gnu/libc.so.6
> #1 0x00007fe7c525b56c in main_loop_wait (nonblocking=<optimized out>) at
> /build/buildd-qemu-kvm_1.0+dfsg-8-amd64-ppNMqm/qemu-kvm-1.0+dfsg/main-
> loop.c:456
> #2 0x00007fe7c51a372f in main_loop () at /build/buildd-qemu-kvm_1.0+dfsg-8-
> amd64-ppNMqm/qemu-kvm-1.0+dfsg/vl.c:1482
> #3 main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at
> /build/buildd-qemu-kvm_1.0+dfsg-8-amd64-ppNMqm/qemu-kvm-1.0+dfsg/vl.c:3523
>
> Thanks :)
>

OK, then we need a kernel view on this. Can you try

http://www.linux-kvm.org/page/Tracing

?

Thanks,
Jan

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