Thanks for the information. The key was in the /proc/self/mounts output: you have cgroups mounted in schroots. This is triggering a bug in the way cgroups are handled in lxc.
You should be able to work around it by unmounting the cgroup filesystems from under /var/lib/schroot/mount/rtmpdump-test/sys/fs/cgroup.
Thanks for the information. The key was in the /proc/self/mounts output: you have cgroups mounted in schroots. This is triggering a bug in the way cgroups are handled in lxc.
You should be able to work around it by unmounting the cgroup filesystems from under /var/lib/ schroot/ mount/rtmpdump- test/sys/ fs/cgroup.
I'll work on a fix for lxc.