[Qemu-devel] [Bug 1207686] Re: qemu-1.4.0 and onwards, linux kernel 3.2.x, heavy I/O leads to kernel_hung_tasks_timout_secs message and unresponsive qemu-process

[Thomas Huth]

Closing as "Invalid" since this was not a QEMU bug according to comment
#3.

** Changed in: qemu
       Status: New => Invalid

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Title:
  qemu-1.4.0 and onwards, linux kernel 3.2.x, heavy I/O leads to
  kernel_hung_tasks_timout_secs message and unresponsive qemu-process

Status in QEMU:
  Invalid

Bug description:
  Hi,

  after some testing I tried to narrow down a problem, which was initially 
reported by some users.
  Seen on different distros - debian 7.1, ubuntu 12.04 LTS, IPFire-2.3 as 
reported by now.

  All using some flavour of linux-3.2.x kernel.

  Tried e.g. under Ubuntu an upgrade to "Linux 3.8.0-27-generic x86_64" which 
solves the problem.
  Problem could be triggert with some workload ala:

  spew -v --raw -P -t -i 3 -b 4k -p random -B 4k 1G /tmp/doof.dat
  and in parallel do some apt-get install/remove/whatever.

  That results in a somewhat stuck qemu-session with the bad
  "kernel_hung_task..." messages.

  A typical command-line is as follows:

  /usr/local/qemu-1.6.0/bin/qemu-system-x86_64 -usbdevice tablet
  -enable-kvm -daemonize -pidfile /var/run/qemu-server/760.pid -monitor
  unix:/var/run/qemu-server/760.mon,server,nowait -vnc unix:/var/run
  /qemu-server/760.vnc,password -qmp unix:/var/run/qemu-
  server/760.qmp,server,nowait -nodefaults -serial none -parallel none
  -device virtio-net-pci,mac=00:F1:70:00:2F:80,netdev=vlan0d0 -netdev
  
type=tap,id=vlan0d0,ifname=tap760i0d0,script=/etc/fcms/add_if.sh,downscript=/etc/fcms/downscript.sh
  -name 1155823384-4 -m 512 -vga cirrus -k de -smp sockets=1,cores=1
  -device virtio-blk-pci,drive=virtio0 -drive
  
format=raw,file=rbd:1155823384/vm-760-disk-1.rbd:rbd_cache=false,cache=writeback,if=none,id=virtio0,media=disk,index=0,aio=native
  -drive
  
format=raw,file=rbd:1155823384/vm-760-swap-1.rbd:rbd_cache=false,cache=writeback,if=virtio,media=disk,index=1,aio=native
  -drive if=ide,media=cdrom,id=ide1-cd0,readonly=on -drive
  if=ide,media=cdrom,id=ide1-cd1,readonly=on -boot order=dc

  no "system_reset", "sendkey ctrl-alt-delete" or "q" in monitoring-
  session is accepted, need to hard-kill the process.

  Please give any advice on what to do for tracing/debugging, because
  the number of tickets here are raising, and noone knows, what users
  are doing inside their VM.

  Kind regards,

  Oliver Francke.

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