slave mounts, private mounts

[Tom H]

On Sat, Jan 25, 2020 at 8:39 PM Volker Wysk <post at volker-wysk.de> wrote:
>
> I'm trying to do a slave mount, or a private mount, but both don't
> work.
>
> The mount manpage says: "A slave mount receives propagation from its
> master, but not vice versa. A private mount carries no propagation
> abilities."
>
> Here's how to try it out:
>
> # cd /tmp
> # mkdir a b
> # touch a/x
> # mount --rbind --make-rslave a b
> # ls a/* b/*
> a/x  b/x
>
> A change in the new mount should not be propagated to the old one, but
> it is:
>
> # touch b/y
> # ls a/* b/*
> a/x  a/y  b/x  b/y
>
> With a private mount it's the same:
> # umount b
> # rm a/y
> # mount --rbind --make-private a b
> # touch b/y
> # ls a/* b/*
> a/x  a/y  b/x  b/y
>
> What have I done wrong? I've studied the manpage and searched the web,
> and it looks like it should work exactly like I've tried...

It's further sub-mounts not anything else that aren't propagated.