Changes in V3:
* Fixed to put error in retval (thanks Frederic Weisbecker)
  * https://lkml.org/lkml/2011/12/20/255
Changes in V2:
* Updated commit message as per Tejun's feedback:
  * https://lkml.org/lkml/2011/12/19/289

-- >8 -- (snip)

We can now assume that the css_set reference held by the task
will not go away for an exiting task. PF_EXITING state can be
trusted throughout migration by checking it after locking
threadgroup.

While at it, renamed css_set_check_fetched to css_set_fetched.
!css_set_fetched() seems to read better than
!css_set_check_fetched().

Signed-off-by: Mandeep Singh Baines <redacted>
Cc: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <redacted>
Cc: containers@lists.linux-foundation.org
Cc: cgroups@vger.kernel.org
Cc: KAMEZAWA Hiroyuki <redacted>
Cc: Frederic Weisbecker <redacted>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Menage <redacted>
---
 kernel/cgroup.c |   25 ++++++-------------------
 1 files changed, 6 insertions(+), 19 deletions(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index bc3caff..4166066 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c

@@ -1856,7 +1856,6 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
 	 */
 	task_lock(tsk);