After using lxd-p2c several times on old Ubuntu Trusty machines, the resulting containers end up with /sbin/init spinning at 100% CPU usage.
Studying strace -p $init-pid, then looking at a tight loop of ps fauxww for several minutes suggests the problem relates to tty being continually strobed for some sort of i/o which causes getty to continually start (respawn) + crash repeatedly.
Fix seems to be editing /etc/init/tty*.conf files + commenting out last two lines of each file…
# respawn # exec /sbin/getty -8 38400 ttyX
This seems to stop /sbin/init spinning at 100% CPU for each migrated container.
Hopefully this scrape of information will save someone hours of head scratching I went through.