Bug#841026: Pull: "userns: proc and sysfs mount fix"

[Dato Simó <dato@debian.org>]

Control: tags -1 - moreinfo

> Are you sure you are seening the same bug? AFAICT, the 
> 
> mnt: Fix fs_fully_visible to verify the root directory is visible
> 
> is as well included in the 3.16.7-ckt17-1 upload.

Oh!

That's a very good point indeed, thank you. I hadn't noticed.

I tried 3.16.7-ckt17-1: still get EPERM when trying to mount /proc on a
user namespace.

For reference, I'm seeing the bug when using vagga, a tool to manage
user namespaces.

The bug seems awfully similar to
https://github.com/tailhook/vagga/issues/12.

I'm going to leave a note in that bug pointing to here. I have no idea
what's going on, but the symptoms are the same.

Thanks!

-d