[RFC][PATCH 0/7] Resource controllers based on process containers

[Pavel Emelianov]

This patchset adds RSS, accounting and control and
limiting the number of tasks and files within container.

Based on top of Paul Menage's container subsystem v7

RSS controller includes per-container RSS accounter,
reclamation and OOM killer. It behaves like standalone
machine - when container runs out of resources it tries
to reclaim some pages and if it doesn't succeed in it
kills some task which mm_struct belongs to container in
question.

Num tasks and files containers are very simple and
self-descriptive from code.

As discussed before when a task moves from one container
to another no resources follow it - they keep holding the
container they were allocated in.

The difficulties met during using of Pauls' containers were:

1. Container fork hook is placed before new task
   changes. This makes impossible of handling fork
   properly. I.e. new mm_struct should have pointer
   to RSS container, but we don't have one at that
   early time.

2. Extended containers may register themselves too late.
   Kernel threads/helpers start forking, opening files
   and touching pages much earlier. This patchset
   workarounds this in not-so-cute manner and I'm waiting
   for Paul's comments on this issue.