Comment 17 for bug 1551854

I'm getting something kind of similar without juju. If I remount debugfs ro in the host then start the container I get this in /var/log/upstart/mountall.log:

mount: cannot remount block device debugfs read-write, is write-protected
mountall: mount /sys/kernel/debug [143] terminated with status 32
mountall: Event failed

and services don't start in the container. If I completely unmount debugfs in the host though everything is happy, though debugfs is not mounted in the container.

Casey/Adam: Can one of you confirm that debugfs is not mounted in the host when you get the failures? If it is mounted can you paste the output of 'mount | grep debugfs' in the host?

@hallyn: I didn't find that line you were referring to in /usr/share/lxc/config/ubuntu.common.conf, in fact I didn't find any reference to debugfs in any of the template files. And debugfs is not a ns-mountable filesystem, so I guess it must be a bind mount? So getting EACCES makes sense if the container tries to mount debugfs, I'm just not sure why their containers are trying to mount debugfs if not mounted in the host and mine does not, which is what I assume must be going on.

Maybe it has something to do with that juju-lxd profile. Can someone paste in its contents (lxc profile show juju-lxd) or point me to where I can find it?

At this point I don't really think this is a kernel bug. debugfs is _not_ namespace mountable, nor should it be.