Question about current->namespace and check_mnt()

[Jamie Lokier <jamie@shareable.org>]

Hi Al,

I have a specific namespace.c question:

I really like to know what the purpose of check_mnt() is in
namespace.c.  In standard kernels you can't enter another process'
namespace so I don't see how check_mnt() can _ever_ fail.  Can it
fail, or in other words, what is the purpose of that check?

And if it can't fail, is there really a need for current->namespace, or
can it just be removed?

Also, I would think the current process' rootmnt->mnt_namespace would
adequately define the "current process namespace", so making
current->namespace redundant in that way.  Is that right?

Thanks,
-- Jamie