Alan Jenkins [off-list ref] wrote:

I can see that this covers copy_mnt_ns().  It should also cover what will
happen in future, if you pass an OPEN_TREE_CLONE fd to a process with a
different mnt_ns and mnt_ns->user_ns, and that process mounts the fd using
move_mount().  However, I can't work out how this covers mount propagation
across namespaces.

The comment "Notice when we are propagating across user namespaces" is moved
to attach_recursive_mnt().  I can't find any call to attach_recursive_mount()
inside the mount propagation code.  Am I overlooking something?

You've spelt the function name two different ways?

Further, attach_recursive_mnt() calls propagation, not the other way round.

David (& Al)