- * Wait for tasks that are in the process of exiting. This
- * does only part of the job, ensuring that all tasks that were
- * previously exiting reach the point where they have disabled
- * preemption, allowing the later synchronize_rcu() to finish
- * the job.
+ * Exiting tasks may escape the tasklist scan. Those are vulnerable
+ * until their final schedule() with TASK_DEAD state. To cope with
+ * this, divide the fragile exit path part in two intersecting
+ * read side critical sections:
+ *
+ * 1) An _SRCU_ read side starting before calling exit_notify(),
+ * which may remove the task from the tasklist, and ending after
+ * the final preempt_disable() call in do_exit().
+ *
+ * 2) An _RCU_ read side starting with the final preempt_disable()
+ * call in do_exit() and ending with the final call to schedule()
+ * with TASK_DEAD state.
+ *
+ * This handles the part 1). And postgp will handle part 2) with a
+ * call to synchronize_rcu().