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

[Thomas Fjellstrom <thomas@fjellstrom.ca>]

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 :)

-- 
Thomas Fjellstrom
thomas@fjellstrom.ca