Description of problem:
Migrate a guest with xbzrle enabled, running the following command (copy cdrom data) inside guest during migration, guest sometimes core dumped after migration on dst host side.

Guest running:
#while true; do cp -r /media/RHEL7\ X86_64  /home/test; sleep 1; rm -rf /home/test; done

Version-Release number of selected component (if applicable):
kernel-3.10.0-63.el7.x86_64
qemu-kvm-1.5.3-30.el7.x86_64


How reproducible:
1/10

Steps to Reproduce:
1.Boot up a guest with a cdrom attached. eg:
/usr/libexec/qemu-kvm -cpu SandyBridge -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -enable-kvm -name t2-rhel6.4-32 -uuid 61b6c504-5a8b-4fe1-8347-6c929b750dde -k en-us -rtc base=localtime,clock=host,driftfix=slew -no-kvm-pit-reinjection -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device usb-tablet,id=input0 -drive file=/mnt/RHEL-Server-6.4-64-virtio.qcow2,if=none,id=disk0,format=qcow2,werror=stop,rerror=stop,aio=native -device ide-drive,bus=ide.0,unit=1,drive=disk0,id=disk0,bootindex=1 -drive file=/mnt/boot.iso,if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device ide-drive,drive=drive-ide0-1-0,bus=ide.1,unit=0,id=cdrom -netdev tap,id=hostnet0 -device rtl8139,netdev=hostnet0,id=net0,mac=44:37:E6:5E:91:85,bus=pci.0,addr=0x5 -monitor stdio -qmp tcp:0:6666,server,nowait -chardev socket,path=/tmp/isa-serial,server,nowait,id=isa1 -device isa-serial,chardev=isa1,id=isa-serial1 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x8 -chardev socket,id=charchannel0,path=/tmp/serial-socket,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.rhevm.vdsm -chardev socket,path=/tmp/foo,server,nowait,id=foo -device virtconsole,chardev=foo,id=console0 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x9 -vnc :10 -k en-us -boot dc -chardev socket,path=/tmp/qga.sock,server,nowait,id=qga0 -device virtserialport,bus=virtio-serial0.0,chardev=qga0,name=org.qemu.guest_agent.0 -global PIIX4_PM.disable_s3=0 -global PIIX4_PM.disable_s4=0

2. Boot the guest on dst host with "-incoming tcp:0:5800"

3. On src host:
(qemu) migrate_set_capability xbzrle on 
(qemu) migrate_set_cache_size 512M

4. Inside guest:
#while true; do cp -r /media/RHEL7\ X86_64  /home/test; sleep 1; rm -rf /home/test; done

5. Migrate guest
(qemu) migrate -d tcp:t2:5800

6. Change the cache size during migration (I'm not sure whether this is relevant with the issue, but this is what I did when I encountered the bug).
(qemu) migrate_set_cache_size 1G
(qemu) migrate_set_cache_size 512M
(qemu) migrate_set_cache_size 1G

Actual results:
Migration finished but guest core dumped and then restart automatically on dst host side.

Expected results:
Guest should not core dumped. 

Additional info:
Core dumped file will be attached.