I have a 64-bit Ubuntu 12.04 KVM instance which I built from an image I purchsed from stacklet.com and converted to KVM format with Cloudmin.
When I created the VM, I set the root disk to 40GB and swap to 1GB. It created two disk images: 20GB root and 1GB swap. However, the swap image was not mounted. I was able to mount the swap by adding it (/dev/sdb1, as reported by fdisk) to /etc/fstab. I also chaned LABEL=root to /dev/sda1 for the root device.
I then tried to resize the 20GB image to 40GB, which failed. I noticed the device name was listed as /dev/hda for the root disk and /dev/hdb for swap. I tried to change these to /dev/sda1 and /dev/sdb1 with no success -- it says it worked, but remained set to the initial values.
There's other strangness going on too, e.g. I tried to remove the swap disk and re-add it, and it added as the root disk (i.e. "Mounted on / as Linux EXT4 (new)").
I wonder if this will be fixed by http://www.virtualmin.com/node/24175 or if there's another issue here.