Comment 1 for bug 1789161

I've reproduced this on Ubuntu 4.15 but Jonathan reported being able to use this flaw on a variety of kernels.

Note that fixing this issue, as was fixing the initial mount visibility issue will come at the cost of some userspace breakages where they effectively rely on this bug.

It's my understanding that Jonathan's own software is currently relying on this bug and will need to switch to an alternative/proper way of dealing with this.