Comment 13 for bug 1021471

The following seems pretty reliable to me:
 - gcc reproducer.c -o reproducer (using the paste.ubuntu.com code above)
 - sudo ./reproducer
 - ctrl+c
 - lxc-start -n <some-container>
 - dmesg | grep unregister

It appears that reproducing it that way is very reliable here, though the result is slightly different. Using this reproducer, the container will usually hang at startup for a few minutes, then eventually succeed to boot.
When getting the bug without that reproducer, it'd usually hang indefinitely (where indefinitely > 10 minutes).