As per the Debian bug, run the tool with -vvvv, look for the line similar to this one:
Adding target: 0 8388608 linear 252:2 384
Take the '252:2' there as major:minor and investigate the state of that device. Report all its attributes - use 'blockdev', find it in /sys/block etc. Check if anything has it open. Check its size etc. etc.
Also test with udev disabled in case that's interfering.
As per the Debian bug, run the tool with -vvvv, look for the line similar to this one:
Adding target: 0 8388608 linear 252:2 384
Take the '252:2' there as major:minor and investigate the state of that device. Report all its attributes - use 'blockdev', find it in /sys/block etc. Check if anything has it open. Check its size etc. etc.
Also test with udev disabled in case that's interfering.