Merge branch 'for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup updates from Tejun Heo:

 - Oleg's pids controller accounting update which gets rid of rcu delay
   in pids accounting updates

 - rstat (cgroup hierarchical stat collection mechanism) optimization

 - Doc updates

* 'for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cpuset: remove unused task_has_mempolicy()
  cgroup, rstat: Don't flush subtree root unless necessary
  cgroup: add documentation for pids.events file
  Documentation: cgroup-v2: eliminate markup warnings
  MAINTAINERS: Update cgroup entry
  cgroup/pids: turn cgroup_subsys->free() into cgroup_subsys->release() to fix the accounting

kernel/exit.c

@@ -219,6 +219,7 @@ repeat:
 	}
 
 	write_unlock_irq(&tasklist_lock);
+	cgroup_release(p);
 	release_thread(p);
 	call_rcu(&p->rcu, delayed_put_task_struct);