Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu

Pull RCU changes from Paul E. McKenney:

 - Expedited grace-period changes, most notably avoiding having
   user threads drive expedited grace periods, using a workqueue
   instead.

 - Miscellaneous fixes, including a performance fix for lists
   that was sent with the lists modifications (second URL below).

 - CPU hotplug updates, most notably providing exact CPU-online
   tracking for RCU.  This will in turn allow removal of the
   checks supporting RCU's prior heuristic that was based on the
   assumption that CPUs would take no longer than one jiffy to
   come online.

 - Torture-test updates.

 - Documentation updates.

Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/core.c

@@ -581,6 +581,8 @@ static bool wake_up_full_nohz_cpu(int cpu)
 	 * If needed we can still optimize that later with an
 	 * empty IRQ.
 	 */
+	if (cpu_is_offline(cpu))
+		return true;  /* Don't try to wake offline CPUs. */
 	if (tick_nohz_full_cpu(cpu)) {
 		if (cpu != smp_processor_id() ||
 		    tick_nohz_tick_stopped())
@@ -591,6 +593,11 @@ static bool wake_up_full_nohz_cpu(int cpu)
 	return false;
 }
 
+/*
+ * Wake up the specified CPU.  If the CPU is going offline, it is the
+ * caller's responsibility to deal with the lost wakeup, for example,
+ * by hooking into the CPU_DEAD notifier like timers and hrtimers do.
+ */
 void wake_up_nohz_cpu(int cpu)
 {
 	if (!wake_up_full_nohz_cpu(cpu))