[Unionfs] uniofs in ubuntu 7.04?

[Markku Savela]

Just wondering... is the unionfs in the current Ubuntu in "working
condition"? I'm asking, because I attempted to make simple "jail" with
following the rough plan as follows

  - mount / read-only
  - mount USB stick rw 
  
And then chroot into union directory (idea is to run installation
script and see how it changes the system). However, the following
chroot gets stuck in "D" state

sudo /usr/sbin/chroot /mnt/union /bin/su --shell /bin/bash --login msa

My kernel version says

  2.6.20-16-386 #2 Fri Aug 31 00:51:58 UTC 2007 i686 GNU/Linux

modinfo unionfs
filename:       /lib/modules/2.6.20-16-386/kernel/ubuntu/fs/unionfs/unionfs.ko
license:        GPL
description:    Unionfs 20060916-2203 (http://unionfs.filesystems.org/)
author:         Filesystems and Storage Lab, Stony Brook University (http://www.fsl.cs.sunysb.edu/)
srcversion:     610C6F84F34F921EBB601CF
depends:        
vermagic:       2.6.20-16-386 mod_unload 486 
parm:           debug:Initial Unionfs debug value. (int)