[GIT PULL] cgroup fixes for v4.4-rc4

[Tejun Heo <tj@kernel.org>]

Hello, Linus.

More change than I'd have liked at this stage.  The pids controller
and the changes made to cgroup core to support it introduced and
revealed several important issues.

* Assigning membership to a newly created task and migrating it can
  race leading to incorrect accounting.  Oleg fixed it by widening
  threadgroup synchronization.  It looks like we'll be able to merge
  it with a different percpu rwsem which is used in fork path making
  things simpler and cheaper.

* The recent change to extend cgroup membership to zombies (so that
  pid accounting can extend till the pid is actually released) missed
  pinning the underlying data structures leading to use-after-free.
  Fixed.

* v2 hierarchy was calling subsystem callbacks with the wrong target
  cgroup_subsys_state based on the incorrect assumption that they
  share the same target.  pids is the first controller affected by
  this.  Subsys callbacks updated so that they can deal with
  multi-target migrations.

Thanks.

The following changes since commit 527e9316f8ec44bd53d90fb9f611fa7ffff52bb9:

  Linux 4.4-rc4 (2015-12-06 15:43:12 -0800)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-4.4-fixes

for you to fetch changes up to 0b98f0c04245877ae0b625a7f0aa55b8ff98e0c4:

  Merge branch 'master' into for-4.4-fixes (2015-12-07 10:09:03 -0500)

----------------------------------------------------------------
Oleg Nesterov (2):
      cgroup: pids: fix race between cgroup_post_fork() and cgroup_migrate()
      cgroup: pids: kill pids_fork(), simplify pids_can_fork() and pids_cancel_fork()

Tejun Heo (6):
      cgroup: fix cftype->file_offset handling
      cgroup: make css_set pin its css's to avoid use-afer-free
      cgroup_freezer: simplify propagation of CGROUP_FROZEN clearing in freezer_attach()
      cgroup: fix handling of multi-destination migration from subtree_control enabling
      cgroup_pids: don't account for the root cgroup
      Merge branch 'master' into for-4.4-fixes

 block/blk-cgroup.c           |  6 +--
 include/linux/cgroup-defs.h  | 13 ++----
 include/linux/cgroup.h       | 47 ++++++++++-----------
 kernel/cgroup.c              | 99 ++++++++++++++++++++++++++++++++++----------
 kernel/cgroup_freezer.c      | 23 +++++-----
 kernel/cgroup_pids.c         | 77 +++++++++-------------------------
 kernel/cpuset.c              | 33 +++++++++------
 kernel/events/core.c         |  6 +--
 kernel/fork.c                |  9 ++--
 kernel/sched/core.c          | 12 +++---
 mm/memcontrol.c              | 45 ++++++++++----------
 net/core/netclassid_cgroup.c |  6 ++-
 net/core/netprio_cgroup.c    |  9 ++--
 13 files changed, 202 insertions(+), 183 deletions(-)

-- 
tejun