[Devel] Re: [PATCH 0/13] Pid namespaces (OpenVZ view)

[Eric W. Biederman]

Pavel Emelianov <xemul at openvz.org> writes:

> That's how OpenVZ sees the pid namespaces.
>
> The main idea is that kernel keeps operating with tasks pid
> as it did before, but each task obtains one more pid for each
> pid type - the virtual pid. When putting the pid to user or
> getting the pid from it kernel operates with the virtual ones.

Just a quick reaction. 

- I would very much like to see a minimum of 3 levels of pids,
  being supported.  Otherwise it is easy to overlook some of the
  cases that are required to properly support nesting, which long
  terms seems important.

- Semantically fork is easier then unshare.  Unshare can mean
  a lot of things, and it is easy to pick a meaning that has weird
  side effects.  Your implementation has a serious problem in that you
  change the value of getpid() at runtime.  Glibc does not know how to
  cope with the value of getpid() changing.

Eric