Description of problem:
guest kernel panic when savevm/loadvm several times, and send system_reset to reboot guest. 

Version-Release number of selected component (if applicable):

qemu-kvm-0.12.1.2-2.156.el6.x86_64
How reproducible:
sometimes

Steps to Reproduce:
1. cmd
/usr/libexec/qemu-kvm -monitor stdio -chardev socket,id=serial_id_20110411-172643-3ln9,path=/tmp/serial-20110411-172643-3ln9,server,nowait -device isa-serial,chardev=serial_id_20110411-172643-3ln9 -drive file='/home/images/RHEL-Server-6.0-64-virtio.qcow2',index=0,if=none,id=drive-virtio-disk1,media=disk,cache=none,format=qcow2,aio=native -device virtio-blk-pci,bus=pci.0,addr=0x4,drive=drive-virtio-disk1,id=virtio-disk1 -device virtio-net-pci,netdev=idxfABTU,mac=9a:5e:79:58:5e:2f,id=ndev00idxfABTU,bus=pci.0,addr=0x3 -netdev tap,id=idxfABTU,vhost=on,script='/home/scripts/qemu-ifup-switch',downscript='no' -m 4096 -smp 4,cores=2,threads=1,sockets=2 -cpu Westmere -vnc :0 -rtc base=utc,clock=host,driftfix=none -M rhel6.1.0 -boot order=cdn,once=c,menu=off   -usbdevice tablet -no-kvm-pit-reinjection -enable-kvm
2. savevm/loadvm
3. (qemu) info snapshots 
Snapshot devices: drive-virtio-disk1
Snapshot list (from drive-virtio-disk1):
ID        TAG                 VM SIZE                DATE       VM CLOCK
1         nothing                358M 2011-04-12 10:11:55   00:02:32.633
2         dd                     400M 2011-04-12 10:14:38   00:04:25.416
3         3                      400M 2011-04-12 10:20:06   00:05:04.813
4         --help                 400M 2011-04-12 10:25:23   00:05:21.979
5         file                   401M 2011-04-12 10:30:58   00:05:38.479
6         6                      401M 2011-04-12 10:37:22   00:06:53.989
7         test                   367M 2011-04-12 10:44:46   00:01:04.203
8         dd2                    394M 2011-04-12 10:55:35   00:01:32.699
9         9                      392M 2011-04-12 11:09:56   00:01:53.124


4. send system_reset to reboot guest

Actual results:
guest kernel panic

Expected results:

Additional info:
1. host
kernel: 2.6.32-130.el6.x86_64

cpuinfo:
processor	: 15
vendor_id	: GenuineIntel
cpu family	: 6
model		: 44
model name	: Intel(R) Xeon(R) CPU           E5620  @ 2.40GHz
stepping	: 2
cpu MHz		: 2394.004
cache size	: 12288 KB
physical id	: 0
siblings	: 8
core id		: 10
cpu cores	: 4
apicid		: 21
initial apicid	: 21
fpu		: yes
fpu_exception	: yes
cpuid level	: 11
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2 popcnt aes lahf_lm ida arat tpr_shadow vnmi flexpriority ept vpid
bogomips	: 4787.84
clflush size	: 64
cache_alignment	: 64
address sizes	: 40 bits physical, 48 bits virtual

2. guest
rhel6.0z-64 (2.6.32-71.24.1.el6.x86_64)

3. call trace info (attached)