Description of problem:

BUG: Kernel soft lockup and unresponsive when netperf from host to kvm_guest

Version-Release number of selected component (if applicable):
2.6.32-198.el6.x86_64.debug

How reproducible:
4 / 4

Steps to Reproduce:
1.boot a rhel6.2 kvm guest with 4 nics [virtio_blk,virtio_net]
2.setup guest as a netperf netserver , host as netperf client
3.[on host ]
netperf -t TCP_STREAM -H Guest_ip1 -l 60 -- -m 1500
netperf -t TCP_STREAM -H Guest_ip2 -l 60 -- -m 1500
netperf -t TCP_STREAM -H Guest_ip3 -l 60 -- -m 1500
netperf -t TCP_STREAM -H Guest_ip4 -l 60 -- -m 1500
  
Actual results:
host soft lockup and unresponsive,only serial outputting

Expected results:
Both host and guest run healthy

Additional info:
Host_cpu quad_core
processor	: 3
vendor_id	: GenuineIntel
cpu family	: 6
model		: 23
model name	: Intel(R) Core(TM)2 Quad CPU    Q9400  @ 2.66GHz

Host_ram 8G

qemu-kvm-0.12.1.2-2.190.el6.x86_64