Can't get mount namespaces to behave as expected [LWN.net]

Can't get mount namespaces to behave as expected

Posted Mar 7, 2015 10:04 UTC (Sat) by mkerrisk (subscriber, #1978)
In reply to: Can't get mount namespaces to behave as expected by apollock
Parent article: Namespaces in operation, part 4: more on PID namespaces

So, going back to your earlier comment:

> It looks like I have to do the same thing to /proc prior to mounting it

Yes, you're right. I was getting confused with another case, where if we mount a procfs at a location other than the usual /proc, then we need to make / a private or slave mount in order not to have that mount appear in the initial mount namespace.

So, in fact all that's needed if we're mounting at /proc inside the simple_init program is

# ./ns_child_exec -p -m ./simple_init
init$ mount --make-slave /proc            # <== NEW
init$ mount -t proc proc /proc
init$ ps a

Nothing needs to be done to /, as far as I can tell.