Merge branch 'for-3.5' of ../cgroup into block/for-3.5/core-merged

cgroup/for-3.5 contains the following changes which blk-cgroup needs
to proceed with the on-going cleanup.

* Dynamic addition and removal of cftypes to make config/stat file
  handling modular for policies.

* cgroup removal update to not wait for css references to drain to fix
  blkcg removal hang caused by cfq caching cfqgs.

Pull in cgroup/for-3.5 into block/for-3.5/core.  This causes the
following conflicts in block/blk-cgroup.c.

* 761b3ef50e "cgroup: remove cgroup_subsys argument from callbacks"
  conflicts with blkiocg_pre_destroy() addition and blkiocg_attach()
  removal.  Resolved by removing @subsys from all subsys methods.

* 676f7c8f84 "cgroup: relocate cftype and cgroup_subsys definitions in
  controllers" conflicts with ->pre_destroy() and ->attach() updates
  and removal of modular config.  Resolved by dropping forward
  declarations of the methods and applying updates to the relocated
  blkio_subsys.

* 4baf6e3325 "cgroup: convert all non-memcg controllers to the new
  cftype interface" builds upon the previous item.  Resolved by adding
  ->base_cftypes to the relocated blkio_subsys.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 2e48ec0c2e91..c21449f85a2a 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -119,15 +119,20 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
  * For preemptible RCU it is sufficient to call rcu_read_unlock in order
  * to exit the grace period. For classic RCU, a reschedule is required.
  */
-static void rcu_lock_break(struct task_struct *g, struct task_struct *t)
+static bool rcu_lock_break(struct task_struct *g, struct task_struct *t)
 {
+        bool can_cont;
+
         get_task_struct(g);
         get_task_struct(t);
         rcu_read_unlock();
         cond_resched();
         rcu_read_lock();
+        can_cont = pid_alive(g) && pid_alive(t);
         put_task_struct(t);
         put_task_struct(g);
+
+        return can_cont;
 }
 
 /*
@@ -154,9 +159,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
                         goto unlock;
                 if (!--batch_count) {
                         batch_count = HUNG_TASK_BATCHING;
-                        rcu_lock_break(g, t);
-                        /* Exit if t or g was unhashed during refresh. */
-                        if (t->state == TASK_DEAD || g->state == TASK_DEAD)
+                        if (!rcu_lock_break(g, t))
                                 goto unlock;
                 }
                 /* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */