[PATCH] cgroups: not to iterate other namespace process inside container

[Sukadev Bhattiprolu]

Dave Hansen [dave at linux.vnet.ibm.com] wrote:
| I could have sworn we had some function like
| task_is_in_current_active_pid_ns(), but I looked and couldn't find it.

It was in one of the many signals patchsets we tried but none of them
got accepted. We do have a variant out for review, ns_of_pid() that
could be used, this patch task_pid_vnr() should be fine.

| Maybe we should add one instead of open-coding this everywhere.

If there are lot of users, we should define the wrapper for
'task_pid_vnr() > 0' but there is no other user at present
(kill_something_info() checks for > 1).