Description of problem:
When try to guest-reboot through guest-agent command during the moment that the screen is adjusting the resolution ,qemu-kvm core dumpd.

Version-Release number of selected component (if applicable):
Host machine :AMD
Host kernel:kernel-3.10.0-187.el7.x86_64
Qemu-kvm-rhev:qemu-kvm-rhev-2.1.2-3.el7.x86_64
spice-glib-0.22-2.el7.x86_64
spice-server-0.12.4-7.el7.x86_64


How reproducible:
<10%

Steps to Reproduce:
1.Install rhel6.6 guest with following command.
/bin/qemu-kvm \
    -S  \
    -name 'virt-tests-vm1'  \
    -sandbox off  \
    -M pc  \
    -nodefaults  \
    -vga qxl  \
    -global qxl-vga.vram_size=33554432  \
    -chardev socket,id=qmp_id_qmpmonitor1,path=/tmp/monitor-qmpmonitor1-20141015-171359-5DnBKPzm,server,nowait \
    -mon chardev=qmp_id_qmpmonitor1,mode=control  \
    -chardev socket,id=serial_id_serial0,path=/tmp/serial-serial0-20141015-171359-5DnBKPzm,server,nowait \
    -device isa-serial,chardev=serial_id_serial0  \
    -chardev socket,id=serial_id_org.qemu.guest_agent.0,path=/tmp/serial-org.qemu.guest_agent.0-20141015-171359-5DnBKPzm,server,nowait \
    -device isa-serial,chardev=serial_id_org.qemu.guest_agent.0  \
    -chardev socket,id=seabioslog_id_20141015-171359-5DnBKPzm,path=/tmp/seabios-20141015-171359-5DnBKPzm,server,nowait \
    -device isa-debugcon,chardev=seabioslog_id_20141015-171359-5DnBKPzm,iobase=0x402 \
    -device ich9-usb-uhci1,id=usb1,bus=pci.0,addr=03 \
    -drive id=drive_image1,if=none,cache=none,snapshot=off,aio=native,file=/dev/sdb \
    -device virtio-blk-pci,id=image1,drive=drive_image1,bootindex=0,bus=pci.0,addr=04 \
    -device virtio-net-pci,mac=9a:a7:a8:a9:aa:ab,id=idFKpPah,vectors=4,netdev=idZAZMUM,bus=pci.0,addr=05  \
    -netdev tap,id=idZAZMUM,vhost=on,vhostfd=25,fd=21  \
    -m 16384  \
    -smp 8,cores=4,threads=1,sockets=2  \
    -cpu 'Opteron_G3',+kvm_pv_unhalt \
    -device usb-tablet,id=usb-tablet1,bus=usb1.0,port=1  \
    -spice port=3000,password=123456,addr=0,image-compression=auto_glz,zlib-glz-wan-compression=auto,streaming-video=all,agent-mouse=on,playback-compression=on,ipv4  \
    -rtc base=utc,clock=host,driftfix=slew  \
    -boot order=cdn,once=c,menu=off  \
    -no-kvm-pit-reinjection \
    -enable-kvm
2.(guest) login guest and install 'qemu-guest-agent' package
  rpm -q qemu-guest-agent || yum install -y qemu-guest-agent
3.(guest)Try to start 'qemu-guest-agent'
  pgrep qemu-ga || qemu-ga -d -m isa-serial -p /dev/ttyS1
4.Reboot guest with guest-agent command
  (host)  nc  -U /tmp/serial-org.qemu.guest_agent.0-20141015-171359-5DnBKPzm
   {"execute": "guest-sync", "arguments": {"id": 8891}}
   {"execute": "guest-info"}
   {"execute": "guest-ping"}
   {"execute": "guest-info"}
   {"execute": "guest-shutdown", "arguments": {"mode": "reboot"}}
   

Actual results:
qemu-kvm coredumped after execute  guest-agent command  '{"execute":
"guest-shutdown", "arguments": {"mode": "reboot"}'

Expected results:
guest reboot suceessful and qemu-kvm not codedump.

Additional info:
(gdb) bt
#0  0x00007f30d7b65028 in __memcmp_sse2 () from /usr/lib64/libc.so.6
#1  0x00007f30de3a8019 in qemu_spice_create_update (ssd=0x7f30df67efb8) at ui/spice-display.c:228
#2  qemu_spice_display_refresh (ssd=0x7f30df67efb8) at ui/spice-display.c:464
#3  0x00007f30de3a0012 in dpy_refresh (s=0x7f30df6696f0) at ui/console.c:1454
#4  gui_update (opaque=0x7f30df6696f0) at ui/console.c:195
#5  0x00007f30de3ccdd9 in timerlist_run_timers (timer_list=0x7f30df566b10) at qemu-timer.c:491
#6  0x00007f30de3ccf50 in qemu_clock_run_timers (type=<optimized out>) at qemu-timer.c:502
#7  qemu_clock_run_all_timers () at qemu-timer.c:608
#8  0x00007f30de3cbe7c in main_loop_wait (nonblocking=<optimized out>) at main-loop.c:490
#9  0x00007f30de1af77e in main_loop () at vl.c:2010
#10 main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at vl.c:4552

see more infos in attachment (include cpuinfo and serial port log. full
backtrace)