[ kvm-Bugs-2351676 ] Guests hang periodically on Ubuntu-8.10

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Bugs item #2351676, was opened at 2008-11-26 19:59
Message generated for change (Comment added) made by technologov
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Chris Jones (c_jones)
Assigned to: Nobody/Anonymous (nobody)
Summary: Guests hang periodically on Ubuntu-8.10

Initial Comment:
I'm seeing periodic hangs on my guests.  I've been unable so far to find a trigger - they always boot fine, but after anywhere from 10 minutes to 24 hours they eventually hang completely.

My setup:
  * AMD Athlon X2 4850e (2500 MHz dual core)
  * 4Gig memory
  * Ubuntu 8.10 server, 64-bit
  * KVMs tried:
    : kvm-72 (shipped with ubuntu)
    : kvm-79 (built myself, --patched-kernel option)
  * Kernels tried:
    : 2.6.27.7 (kernel.org, self built)
    : 2.6.27-7-server from Ubuntu 8.10 distribution

  In guests
  * Ubuntu 8.10 server, 64-bit (virtual machine install)
  * kernel 2.6.27-7-server from Ubuntu 8.10

I'm running the guests like:
  sudo /usr/local/bin/qemu-system-x86_64        \
     -daemonize                                 \
     -no-kvm-irqchip                            \
     -hda Imgs/ndev_root.img                    \
     -m 1024                                    \
     -cdrom ISOs/ubuntu-8.10-server-amd64.iso   \
     -vnc :4                                    \
     -net nic,macaddr=DE:AD:BE:EF:04:04,model=e1000 \
     -net tap,ifname=tap4,script=/home/chris/kvm/qemu-ifup.sh 

The problem does not happen if I use -no-kvm.

I've tried some other options that have no effect:
  -no-kvm-pit
  -no-acpi

The disk images are raw format.

When the guests hang, I cannot ping them, and the vnc console us hung.  The qemu monitor is still accessible, and the guests recover if I issue a system_reset command from the monitor.  However, often, the console will not take keyboard after doing so.

When the guest is hung, kvm_stat shows all 0s for the counters:

efer_relo      exits  fpu_reloa  halt_exit  halt_wake  host_stat  hypercall
+insn_emul  insn_emul     invlpg   io_exits  irq_exits  irq_windo  largepage
+mmio_exit  mmu_cache  mmu_flood  mmu_pde_z  mmu_pte_u  mmu_pte_w  mmu_recyc
+mmu_shado  nmi_windo   pf_fixed   pf_guest  remote_tl  request_i  signal_ex
+tlb_flush
>          0          0          0          0          0          0          0
+0          0          0          0          0          0          0          0
+0          0          0          0          0          0          0          0
+0          0          0          0          0          0

gdb shows two threads - both waiting:

c(gdb) info threads
  2 Thread 0x414f1950 (LWP 422)  0x00007f36f07a03e1 in sigtimedwait ()
   from /lib/libc.so.6
  1 Thread 0x7f36f1f306e0 (LWP 414)  0x00007f36f084b482 in select ()
   from /lib/libc.so.6
(gdb) thread 1
[Switching to thread 1 (Thread 0x7f36f1f306e0 (LWP 414))]#0  0x00007f36f084b482
+in select () from /lib/libc.so.6
(gdb) bt
#0  0x00007f36f084b482 in select () from /lib/libc.so.6
#1  0x00000000004094cb in main_loop_wait (timeout=0)
    at /home/chris/pkgs/kvm/kvm-79/qemu/vl.c:4719
#2  0x000000000050a7ea in kvm_main_loop ()
    at /home/chris/pkgs/kvm/kvm-79/qemu/qemu-kvm.c:619
#3  0x000000000040fafc in main (argc=<value optimized out>,
    argv=0x7ffff9f41948) at /home/chris/pkgs/kvm/kvm-79/qemu/vl.c:4871
(gdb) thread 2
[Switching to thread 2 (Thread 0x414f1950 (LWP 422))]#0  0x00007f36f07a03e1 in
+sigtimedwait () from /lib/libc.so.6
(gdb) bt
#0  0x00007f36f07a03e1 in sigtimedwait () from /lib/libc.so.6
#1  0x000000000050a560 in kvm_main_loop_wait (env=0xc319e0, timeout=0)
    at /home/chris/pkgs/kvm/kvm-79/qemu/qemu-kvm.c:284
#2  0x000000000050aaf7 in ap_main_loop (_env=<value optimized out>)
    at /home/chris/pkgs/kvm/kvm-79/qemu/qemu-kvm.c:425
#3  0x00007f36f11ba3ea in start_thread () from /lib/libpthread.so.0
#4  0x00007f36f0852c6d in clone () from /lib/libc.so.6
#5  0x0000000000000000 in ?? ()


Any clues to help me resolve this would be much appreciated.


----------------------------------------------------------------------

Comment By: Technologov (technologov)
Date: 2008-11-27 14:54

Message:
In my opinion it is not the Ubuntu host that is problematic - but the guest
on KVM.

I mean that Ubuntu 8.10 guest is unstable on KVM. I have not found out
why.

If you try some better tested guest (Fedora 7/8 or Windows XP guest it
should be lots more stable).

And if you try some other host (i.e. Fedora host and run Ubuntu 8.10 guest
it will be unstable).

In short - in my opinion - the problem is not host OS, but either KVM or
it's connection with guest OS.

-Alexey E. "Technologov", 27.11.2008.

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=893831&aid=2351676&group_id=180599