Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU changes from Ingo Molnar:
 "The main changes in this cycle were:

   - changes permitting use of call_rcu() and friends very early in
     boot, for example, before rcu_init() is invoked.

   - add in-kernel API to enable and disable expediting of normal RCU
     grace periods.

   - improve RCU's handling of (hotplug-) outgoing CPUs.

   - NO_HZ_FULL_SYSIDLE fixes.

   - tiny-RCU updates to make it more tiny.

   - documentation updates.

   - miscellaneous fixes"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (58 commits)
  cpu: Provide smpboot_thread_init() on !CONFIG_SMP kernels as well
  cpu: Defer smpboot kthread unparking until CPU known to scheduler
  rcu: Associate quiescent-state reports with grace period
  rcu: Yet another fix for preemption and CPU hotplug
  rcu: Add diagnostics to grace-period cleanup
  rcutorture: Default to grace-period-initialization delays
  rcu: Handle outgoing CPUs on exit from idle loop
  cpu: Make CPU-offline idle-loop transition point more precise
  rcu: Eliminate ->onoff_mutex from rcu_node structure
  rcu: Process offlining and onlining only at grace-period start
  rcu: Move rcu_report_unblock_qs_rnp() to common code
  rcu: Rework preemptible expedited bitmask handling
  rcu: Remove event tracing from rcu_cpu_notify(), used by offline CPUs
  rcutorture: Enable slow grace-period initializations
  rcu: Provide diagnostic option to slow down grace-period initialization
  rcu: Detect stalls caused by failure to propagate up rcu_node tree
  rcu: Eliminate empty HOTPLUG_CPU ifdef
  rcu: Simplify sync_rcu_preempt_exp_init()
  rcu: Put all orphan-callback-related code under same comment
  rcu: Consolidate offline-CPU callback initialization
  ...

1 files changed, 15 insertions, 5 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 01aa47d3b6ab..05c36118f8d7 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2969,6 +2969,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			Set maximum number of finished RCU callbacks to
 			process in one batch.
 
+	rcutree.gp_init_delay=	[KNL]
+			Set the number of jiffies to delay each step of
+			RCU grace-period initialization.  This only has
+			effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT is
+			set.
+
 	rcutree.rcu_fanout_leaf= [KNL]
 			Increase the number of CPUs assigned to each
 			leaf rcu_node structure.  Useful for very large
@@ -2992,11 +2998,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			value is one, and maximum value is HZ.
 
 	rcutree.kthread_prio= 	 [KNL,BOOT]
-			Set the SCHED_FIFO priority of the RCU
-			per-CPU kthreads (rcuc/N). This value is also
-			used for the priority of the RCU boost threads
-			(rcub/N). Valid values are 1-99 and the default
-			is 1 (the least-favored priority).
+			Set the SCHED_FIFO priority of the RCU per-CPU
+			kthreads (rcuc/N). This value is also used for
+			the priority of the RCU boost threads (rcub/N)
+			and for the RCU grace-period kthreads (rcu_bh,
+			rcu_preempt, and rcu_sched). If RCU_BOOST is
+			set, valid values are 1-99 and the default is 1
+			(the least-favored priority).  Otherwise, when
+			RCU_BOOST is not set, valid values are 0-99 and
+			the default is zero (non-realtime operation).
 
 	rcutree.rcu_nocb_leader_stride= [KNL]
 			Set the number of NOCB kthread groups, which