Hi,
I am using qemu 2.1.2 and some VMs hang while playing videos. QEMU parameters and stack information is as follows: /usr/bin/qemu-system-x86_64 -name S398_ABC-047 -S -machine pc-i440fx-2.1,accel=kvm,usb=off -m 1024 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid 2f9fa97a-0061-436c-a40c-e7abc3d0cdb1 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/S398_ABC-047.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=localtime -no-shutdown -global PIIX4_PM.disable_s3=1 -global PIIX4_PM.disable_s4=0 -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 -drive file=/opt/cvm/win7_64_S398_ABC-047.inst,if=none,id=drive-ide0-0-0,format=qcow2,cache=writeback,discard=unmap -device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 -drive file=/opt/data/hugedisk/win7_64_S398_ABC-047_share.add,if=none,id=drive-ide0-0-1,format=qcow2,cache=writeback -device ide-hd,bus=ide.0,unit=1,drive=drive-ide0-0-1,id=ide0-0-1 -netdev tap,fd=21,id=hostnet0,vhost=on,vhostfd=23 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:19:a6:93,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev pty,id=charserial1 -device isa-serial,chardev=charserial1,id=serial1 -chardev spicevmc,id=charchannel0,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0 -chardev spiceport,id=charchannel1,name=webcam -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel1,id=channel1,name=com.redhat.spice.webcam -device usb-tablet,id=input0 -spice port=5902,addr=0.0.0.0,disable-ticketing,seamless-migration=on -vnc 0.0.0.0:3 -device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,bus=pci.0,addr=0x2 -device intel-hda,id=sound0,bus=pci.0,addr=0x4 -device hda-micro,id=sound0-codec0,bus=sound0.0,cad=0 -device hda-duplex,id=sound0-codec1,bus=sound0.0,cad=1 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6 -readconfig /etc/qemu/ich9-ehci-uhci.cfg -chardev spicevmc,name=usbredir,id=usbredirchardev1 -device usb-redir,chardev=usbredirchardev1,id=usbredirdev1,bus=ehci.0 -chardev spicevmc,name=usbredir,id=usbredirchardev2 -device usb-redir,chardev=usbredirchardev2,id=usbredirdev2,bus=ehci.0 -chardev spicevmc,name=usbredir,id=usbredirchardev3 -device usb-redir,chardev=usbredirchardev3,id=usbredirdev3,bus=ehci.0 -cpu SandyBridge,host=on,+vmx,model_id=Intel(R) Xeon(R) CPU E5-26xx series,hv-relaxed=on,hv-time=on,hv-spinlocks=0x1fff Thread 4 (Thread 0x7fa09a527700 (LWP 48069)): #0 0x00007fa09ec7b3e7 in ppoll () from /lib64/libc.so.6 #1 0x00007fa0a2f7e27b in qemu_poll_ns (fds=<value optimized out>, nfds=<value optimized out>, timeout=<value optimized out>) #2 0x00007fa0a2f7edf4 in aio_poll (ctx=0x7fa0a5835620, blocking=true) #3 0x00007fa0a2f782e8 in bdrv_drain_all () #4 0x00007fa0a2eb602a in bmdma_cmd_writeb (bm=0x7fa0a5ce8cc8, val=0) #5 0x00007fa0a2d17e68 in access_with_adjusted_size (addr=0, value=0x7fa09a526aa0, size=1, access_size_min=<value optimized out>, access_size_max=<value optimized out>, access=0x7fa0a2d19b10 <memory_region_write_accessor>, mr=0x7fa0a5ce8e30) #6 0x00007fa0a2d1988c in memory_region_dispatch_write (mr=0x7fa0a5ce8e30, addr=0, val=<value optimized out>, size=1) #7 io_mem_write (mr=0x7fa0a5ce8e30, addr=0, val=<value optimized out>, size=1) #8 0x00007fa0a2cdd73a in address_space_rw (as=0x7fa0a3412380, addr=<value optimized out>, buf=<value optimized out>, len=1, is_write=true) #9 0x00007fa0a2d155c4 in kvm_handle_io (cpu=<value optimized out>) #10 kvm_cpu_exec (cpu=<value optimized out>) #11 0x00007fa0a2d0470c in qemu_kvm_cpu_thread_fn (arg=0x7fa0a5ca95c0) #12 0x00007fa0a17ec9d1 in start_thread () from /lib64/libpthread.so.0 #13 0x00007fa09ec849dd in clone () from /lib64/libc.so.6 Thread 3 (Thread 0x7fa0995ff700 (LWP 48071)): #0 0x00007fa09ec7b1b3 in poll () from /lib64/libc.so.6 #1 0x00007fa09fbfb306 in ?? () from /usr/lib64/libspice-server.so.1 #2 0x00007fa0a17ec9d1 in start_thread () from /lib64/libpthread.so.0 #3 0x00007fa09ec849dd in clone () from /lib64/libc.so.6 Thread 2 (Thread 0x7fa098bff700 (LWP 48072)): #0 0x00007fa0a17f05bc in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0 #1 0x00007fa0a2fca499 in qemu_cond_wait (cond=<value optimized out>, mutex=<value optimized out>) #2 0x00007fa0a2f6c9d3 in vnc_worker_thread_loop (queue=0x7fa0a5e62170) #3 0x00007fa0a2f6cf80 in vnc_worker_thread (arg=0x7fa0a5e62170) #4 0x00007fa0a17ec9d1 in start_thread () from /lib64/libpthread.so.0 #5 0x00007fa09ec849dd in clone () from /lib64/libc.so.6 Thread 1 (Thread 0x7fa0a2c1d9c0 (LWP 48065)): #0 0x00007fa0a17f3264 in __lll_lock_wait () from /lib64/libpthread.so.0 #1 0x00007fa0a17ee508 in _L_lock_854 () from /lib64/libpthread.so.0 #2 0x00007fa0a17ee3d7 in pthread_mutex_lock () from /lib64/libpthread.so.0 #3 0x00007fa0a2fca719 in qemu_mutex_lock (mutex=<value optimized out>) #4 0x00007fa0a2f7cedb in os_host_main_loop_wait ( nonblocking=<value optimized out>) #5 main_loop_wait (nonblocking=<value optimized out>) #6 0x00007fa0a2df9aeb in main_loop (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>) #7 main (argc=<value optimized out>, argv=<value optimized out>, envp=<value optimized out>) Did anyone meet this problem before? If I want to fix it, which patches I could apply. Thank you very much! Regards, Qian Peng