How to diagnose memory leak in kvm-qemu-0.14.0?

[Steve Kemp <steve@bytemark.co.uk>]

  I'm running the most recent release of KVM, version 0.14.0
 on a host kernel 2.6.32.15, and seem to be able to trigger
 a leak of memory pretty easily.

  Inside a guest the following one-liner will cause the KVM
 process on the host to gradually increase its memory
 consumption:

    while true; do
      wget http://mirror.bytemark.co.uk/misc/test-files/500M; cp 500M new; rm 500M new; sleep 10 ;
    done

  The guest is launched using loopback files:

  "/opt/kvm/bin/qemu-system-x86_64 -m 500 -drive
  file=/machines/kvm6/jail/root_fs,if=virtio,cache=off -drive
  file=/machines/kvm6/jail/swap_file,if=virtio,boot=off -net
  nic,macaddr=fe:ff:00:00:5a:cb,model=virtio -net
  tap,ifname=tap_kvm6,script=no -pidfile /var/kvm/kvm6.pid -name kvm6
  -serial /dev/tty -no-reboot -monitor
   unix:/var/kvm/kvm6.mon,server,nowait -kernel
   /machines/kvm6/jail/linux -append root=/dev/vda  clocksource=acpi_pm
   notsc console=tty0 console=ttyS0,115200n8 -nographic -boot c
   "

  So we're using an external code, and the virtio for both block
 and NIC.  Using e1000, rtl8139, or virtio for the NIC results in the
 same leak.

  top shows this:


    23074 kvm6      20   0  656m 515m 1060 S  0.0  0.8  13:10.79 qemu-system-x86

  So 656Mb virt, 515Mb resident, and over time the virtual memory
 increases significantly.

  Should I be blaming KVM for this leak?  Or is it possible it is either
 the host or the guest kernels?  Any assistance in tracking down the
 leak is most welcome - even vague hints.

  If helpful I'd be happy to share logins to either a host or a leaky
 guest, or both.


Steve Kemp
--
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