ubuntu-vm-builder error log

gistfile1.txt

user0@ML110:~/vm$ sudo ubuntu-vm-builder kvm oneiric                   --domain newvm                   --dest newvm                   --arch i386                   --hostname hostnameformyvm                   --mem 512                   --user john                   --pass doe                   --ip 192.168.1.101                   --mask 255.255.255.0                   --net 192.168.1.0                   --bcast 192.168.1.255                   --gw 192.168.1.1                   --dns 192.168.1.1                   --mirror http://jp.archive.ubuntu.com/ubuntu                   --components main,universe                   --addpkg acpid \ --debug
2012-01-24 23:09:34,653 INFO    : Calling hook: preflight_check
2012-01-24 23:09:34,657 INFO    : Calling hook: set_defaults
2012-01-24 23:09:34,657 INFO    : Calling hook: bootstrap
2012-01-24 23:13:46,232 INFO    : Calling hook: configure_os
2012-01-24 23:14:03,168 INFO    : invoke-rc.d: policy-rc.d denied execution of start.
2012-01-24 23:14:07,853 INFO    : 
2012-01-24 23:14:07,854 INFO    : Current default time zone: 'Etc/UTC'
2012-01-24 23:14:07,858 INFO    : Local time is now:      Tue Jan 24 14:14:07 UTC 2012.
2012-01-24 23:14:07,858 INFO    : Universal Time is now:  Tue Jan 24 14:14:07 UTC 2012.
2012-01-24 23:14:07,858 INFO    : 
2012-01-24 23:14:23,543 INFO    : 
2012-01-24 23:14:23,543 INFO    : Current default time zone: 'Etc/UTC'
2012-01-24 23:14:23,547 INFO    : Local time is now:      Tue Jan 24 14:14:23 UTC 2012.
2012-01-24 23:14:23,547 INFO    : Universal Time is now:  Tue Jan 24 14:14:23 UTC 2012.
2012-01-24 23:14:23,548 INFO    : Run 'dpkg-reconfigure tzdata' if you wish to change it.
2012-01-24 23:14:23,548 INFO    : 
2012-01-24 23:14:33,983 INFO    : restart: Unknown instance: 
2012-01-24 23:14:46,494 INFO    : umount: /tmp/tmp7qFpez/dev: device is busy.
2012-01-24 23:14:46,494 INFO    :         (In some cases useful info about processes that use
2012-01-24 23:14:46,494 INFO    :          the device is found by lsof(8) or fuser(1))
2012-01-24 23:14:46,495 INFO    : Cleaning up
2012-01-24 23:14:46,495 ERROR   : Process (['umount', '/tmp/tmp7qFpez/dev']) returned 1. stdout: , stderr: umount: /tmp/tmp7qFpez/dev: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))

Traceback (most recent call last):
  File "/usr/bin/ubuntu-vm-builder", line 24, in <module>
    uvb.main()
  File "/usr/lib/python2.7/dist-packages/VMBuilder/contrib/cli.py", line 216, in main
    distro.build_chroot()
  File "/usr/lib/python2.7/dist-packages/VMBuilder/distro.py", line 84, in build_chroot
    self.call_hooks('configure_os')
  File "/usr/lib/python2.7/dist-packages/VMBuilder/distro.py", line 67, in call_hooks
    call_hooks(self, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/VMBuilder/util.py", line 165, in call_hooks
    getattr(context, func, log_no_such_method)(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/VMBuilder/plugins/ubuntu/distro.py", line 155, in configure_os
    self.suite.unmount_dev()
  File "/usr/lib/python2.7/dist-packages/VMBuilder/plugins/ubuntu/dapper.py", line 118, in unmount_dev
    run_cmd('umount', '%s/dev' % self.context.chroot_dir)
  File "/usr/lib/python2.7/dist-packages/VMBuilder/util.py", line 120, in run_cmd
    raise VMBuilderException, "Process (%s) returned %d. stdout: %s, stderr: %s" % (args.__repr__(), status, mystdout.buf, mystderr.buf)
VMBuilder.exception.VMBuilderException: Process (['umount', '/tmp/tmp7qFpez/dev']) returned 1. stdout: , stderr: umount: /tmp/tmp7qFpez/dev: device is busy.
        (In some cases useful info about processes that use
         the device is found by lsof(8) or fuser(1))

user0@ML110:~/vm$