kernel/hung_task.c: change hung_task.c to use for_each_process_thread()

In check_hung_uninterruptible_tasks() avoid the use of deprecated
while_each_thread().

The "max_count" logic will prevent a livelock - see commit 0c740d0a
("introduce for_each_thread() to replace the buggy while_each_thread()").
Having said this let's use for_each_process_thread().

Signed-off-by: Aaron Tomlin <[e-mail]>
Acked-by: Oleg Nesterov <[e-mail]>
Cc: David Rientjes <[e-mail]>
Cc: Dave Wysochanski <[e-mail]>
Cc: Aaron Tomlin <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/hung_task.c

···
 		return;
 
 	rcu_read_lock();
-	do_each_thread(g, t) {
+	for_each_process_thread(g, t) {
 		if (!max_count--)
 			goto unlock;
 		if (!--batch_count) {
···
 		/* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
 		if (t->state == TASK_UNINTERRUPTIBLE)
 			check_hung_task(t, timeout);
-	} while_each_thread(g, t);
+	}
  unlock:
 	rcu_read_unlock();
 }