[RFC] [PATCH v2 0/2] cgroups: implement moving a threadgroup's threads atomically with cgroup.procs

[Ben Blum <bblum@andrew.cmu.edu>]

This patch series is a revision of http://lkml.org/lkml/2010/1/3/51 and
http://lkml.org/lkml/2010/1/3/52 .

The rwsem in the fork path has been moved to signal_struct to simplify
the locking code in the cgroup_attach_proc side. This depends on Oleg's
recentish changes to signal_struct's lifetime rules (which don't seem to
appear when I check out mmotm with git clone, so I wasn't able to do any
more than basic testing).

There is still a race with exec in the case where the threadgroup leader
changes. To solve this, this implementation checks if the race occurred
after all previous set-up has been done and all necessary locks are
held, and if so, returns -EAGAIN which is handled by the calling
function by looping until a different value is returned.

-- bblum

---
 Documentation/cgroups/cgroups.txt |    9
 include/linux/cgroup.h            |   15 -
 include/linux/init_task.h         |    9
 include/linux/sched.h             |   10
 kernel/cgroup.c                   |  435 +++++++++++++++++++++++++++++++++-----
 kernel/fork.c                     |   10
 6 files changed, 431 insertions(+), 57 deletions(-)