20 files changed, 368 insertions, 289 deletions

diff --git a/Documentation/RCU/Design/Requirements/Requirements.rst b/Documentation/RCU/Design/Requirements/Requirements.rst
index 49387d823619..f3b605285a87 100644
--- a/Documentation/RCU/Design/Requirements/Requirements.rst
+++ b/Documentation/RCU/Design/Requirements/Requirements.rst
@@ -2071,41 +2071,7 @@ call.
 
 Because RCU avoids interrupting idle CPUs, it is illegal to execute an
 RCU read-side critical section on an idle CPU. (Kernels built with
-``CONFIG_PROVE_RCU=y`` will splat if you try it.) The RCU_NONIDLE()
-macro and ``_rcuidle`` event tracing is provided to work around this
-restriction. In addition, rcu_is_watching() may be used to test
-whether or not it is currently legal to run RCU read-side critical
-sections on this CPU. I learned of the need for diagnostics on the one
-hand and RCU_NONIDLE() on the other while inspecting idle-loop code.
-Steven Rostedt supplied ``_rcuidle`` event tracing, which is used quite
-heavily in the idle loop. However, there are some restrictions on the
-code placed within RCU_NONIDLE():
-
-#. Blocking is prohibited. In practice, this is not a serious
-   restriction given that idle tasks are prohibited from blocking to
-   begin with.
-#. Although nesting RCU_NONIDLE() is permitted, they cannot nest
-   indefinitely deeply. However, given that they can be nested on the
-   order of a million deep, even on 32-bit systems, this should not be a
-   serious restriction. This nesting limit would probably be reached
-   long after the compiler OOMed or the stack overflowed.
-#. Any code path that enters RCU_NONIDLE() must sequence out of that
-   same RCU_NONIDLE(). For example, the following is grossly
-   illegal:
-
-      ::
-
-	  1     RCU_NONIDLE({
-	  2       do_something();
-	  3       goto bad_idea;  /* BUG!!! */
-	  4       do_something_else();});
-	  5   bad_idea:
-
-
-   It is just as illegal to transfer control into the middle of
-   RCU_NONIDLE()'s argument. Yes, in theory, you could transfer in
-   as long as you also transferred out, but in practice you could also
-   expect to get sharply worded review comments.
+``CONFIG_PROVE_RCU=y`` will splat if you try it.)
 
 It is similarly socially unacceptable to interrupt an ``nohz_full`` CPU
 running in userspace. RCU must therefore track ``nohz_full`` userspace
diff --git a/Documentation/RCU/whatisRCU.rst b/Documentation/RCU/whatisRCU.rst
index 8eddef28d3a1..e488c8e557a9 100644
--- a/Documentation/RCU/whatisRCU.rst
+++ b/Documentation/RCU/whatisRCU.rst
@@ -1117,7 +1117,6 @@ All: lockdep-checked RCU utility APIs::
 
 	RCU_LOCKDEP_WARN
 	rcu_sleep_check
-	RCU_NONIDLE
 
 All: Unchecked RCU-protected pointer access::
 
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9e5bab29685f..5b544b3f00fc 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4736,43 +4736,6 @@
 			the propagation of recent CPU-hotplug changes up
 			the rcu_node combining tree.
 
-	rcutree.use_softirq=	[KNL]
-			If set to zero, move all RCU_SOFTIRQ processing to
-			per-CPU rcuc kthreads.  Defaults to a non-zero
-			value, meaning that RCU_SOFTIRQ is used by default.
-			Specify rcutree.use_softirq=0 to use rcuc kthreads.
-
-			But note that CONFIG_PREEMPT_RT=y kernels disable
-			this kernel boot parameter, forcibly setting it
-			to zero.
-
-	rcutree.rcu_fanout_exact= [KNL]
-			Disable autobalancing of the rcu_node combining
-			tree.  This is used by rcutorture, and might
-			possibly be useful for architectures having high
-			cache-to-cache transfer latencies.
-
-	rcutree.rcu_fanout_leaf= [KNL]
-			Change the number of CPUs assigned to each
-			leaf rcu_node structure.  Useful for very
-			large systems, which will choose the value 64,
-			and for NUMA systems with large remote-access
-			latencies, which will choose a value aligned
-			with the appropriate hardware boundaries.
-
-	rcutree.rcu_min_cached_objs= [KNL]
-			Minimum number of objects which are cached and
-			maintained per one CPU. Object size is equal
-			to PAGE_SIZE. The cache allows to reduce the
-			pressure to page allocator, also it makes the
-			whole algorithm to behave better in low memory
-			condition.
-
-	rcutree.rcu_delay_page_cache_fill_msec= [KNL]
-			Set the page-cache refill delay (in milliseconds)
-			in response to low-memory conditions.  The range
-			of permitted values is in the range 0:100000.
-
 	rcutree.jiffies_till_first_fqs= [KNL]
 			Set delay from grace-period initialization to
 			first attempt to force quiescent states.
@@ -4811,21 +4774,6 @@
 			When RCU_NOCB_CPU is set, also adjust the
 			priority of NOCB callback kthreads.
 
-	rcutree.rcu_divisor= [KNL]
-			Set the shift-right count to use to compute
-			the callback-invocation batch limit bl from
-			the number of callbacks queued on this CPU.
-			The result will be bounded below by the value of
-			the rcutree.blimit kernel parameter.  Every bl
-			callbacks, the softirq handler will exit in
-			order to allow the CPU to do other work.
-
-			Please note that this callback-invocation batch
-			limit applies only to non-offloaded callback
-			invocation.  Offloaded callbacks are instead
-			invoked in the context of an rcuoc kthread, which
-			scheduler will preempt as it does any other task.
-
 	rcutree.nocb_nobypass_lim_per_jiffy= [KNL]
 			On callback-offloaded (rcu_nocbs) CPUs,
 			RCU reduces the lock contention that would
@@ -4839,14 +4787,6 @@
 			the ->nocb_bypass queue.  The definition of "too
 			many" is supplied by this kernel boot parameter.
 
-	rcutree.rcu_nocb_gp_stride= [KNL]
-			Set the number of NOCB callback kthreads in
-			each group, which defaults to the square root
-			of the number of CPUs.	Larger numbers reduce
-			the wakeup overhead on the global grace-period
-			kthread, but increases that same overhead on
-			each group's NOCB grace-period kthread.
-
 	rcutree.qhimark= [KNL]
 			Set threshold of queued RCU callbacks beyond which
 			batch limiting is disabled.
@@ -4864,6 +4804,56 @@
 			on rcutree.qhimark at boot time and to zero to
 			disable more aggressive help enlistment.
 
+	rcutree.rcu_delay_page_cache_fill_msec= [KNL]
+			Set the page-cache refill delay (in milliseconds)
+			in response to low-memory conditions.  The range
+			of permitted values is in the range 0:100000.
+
+	rcutree.rcu_divisor= [KNL]
+			Set the shift-right count to use to compute
+			the callback-invocation batch limit bl from
+			the number of callbacks queued on this CPU.
+			The result will be bounded below by the value of
+			the rcutree.blimit kernel parameter.  Every bl
+			callbacks, the softirq handler will exit in
+			order to allow the CPU to do other work.
+
+			Please note that this callback-invocation batch
+			limit applies only to non-offloaded callback
+			invocation.  Offloaded callbacks are instead
+			invoked in the context of an rcuoc kthread, which
+			scheduler will preempt as it does any other task.
+
+	rcutree.rcu_fanout_exact= [KNL]
+			Disable autobalancing of the rcu_node combining
+			tree.  This is used by rcutorture, and might
+			possibly be useful for architectures having high
+			cache-to-cache transfer latencies.
+
+	rcutree.rcu_fanout_leaf= [KNL]
+			Change the number of CPUs assigned to each
+			leaf rcu_node structure.  Useful for very
+			large systems, which will choose the value 64,
+			and for NUMA systems with large remote-access
+			latencies, which will choose a value aligned
+			with the appropriate hardware boundaries.
+
+	rcutree.rcu_min_cached_objs= [KNL]
+			Minimum number of objects which are cached and
+			maintained per one CPU. Object size is equal
+			to PAGE_SIZE. The cache allows to reduce the
+			pressure to page allocator, also it makes the
+			whole algorithm to behave better in low memory
+			condition.
+
+	rcutree.rcu_nocb_gp_stride= [KNL]
+			Set the number of NOCB callback kthreads in
+			each group, which defaults to the square root
+			of the number of CPUs.	Larger numbers reduce
+			the wakeup overhead on the global grace-period
+			kthread, but increases that same overhead on
+			each group's NOCB grace-period kthread.
+
 	rcutree.rcu_kick_kthreads= [KNL]
 			Cause the grace-period kthread to get an extra
 			wake_up() if it sleeps three times longer than
@@ -4871,6 +4861,13 @@
 			This wake_up() will be accompanied by a
 			WARN_ONCE() splat and an ftrace_dump().
 
+	rcutree.rcu_resched_ns= [KNL]
+			Limit the time spend invoking a batch of RCU
+			callbacks to the specified number of nanoseconds.
+			By default, this limit is checked only once
+			every 32 callbacks in order to limit the pain
+			inflicted by local_clock() overhead.
+
 	rcutree.rcu_unlock_delay= [KNL]
 			In CONFIG_RCU_STRICT_GRACE_PERIOD=y kernels,
 			this specifies an rcu_read_unlock()-time delay
@@ -4885,6 +4882,16 @@
 			rcu_node tree with an eye towards determining
 			why a new grace period has not yet started.
 
+	rcutree.use_softirq=	[KNL]
+			If set to zero, move all RCU_SOFTIRQ processing to
+			per-CPU rcuc kthreads.  Defaults to a non-zero
+			value, meaning that RCU_SOFTIRQ is used by default.
+			Specify rcutree.use_softirq=0 to use rcuc kthreads.
+
+			But note that CONFIG_PREEMPT_RT=y kernels disable
+			this kernel boot parameter, forcibly setting it
+			to zero.
+
 	rcuscale.gp_async= [KNL]
 			Measure performance of asynchronous
 			grace-period primitives such as call_rcu().
@@ -5087,8 +5094,17 @@
 
 	rcutorture.stall_cpu_block= [KNL]
 			Sleep while stalling if set.  This will result
-			in warnings from preemptible RCU in addition
-			to any other stall-related activity.
+			in warnings from preemptible RCU in addition to
+			any other stall-related activity.  Note that
+			in kernels built with CONFIG_PREEMPTION=n and
+			CONFIG_PREEMPT_COUNT=y, this parameter will
+			cause the CPU to pass through a quiescent state.
+			Given CONFIG_PREEMPTION=n, this will suppress
+			RCU CPU stall warnings, but will instead result
+			in scheduling-while-atomic splats.
+
+			Use of this module parameter results in splats.
+
 
 	rcutorture.stall_cpu_holdoff= [KNL]
 			Time to wait (s) after boot before inducing stall.
diff --git a/Documentation/core-api/kernel-api.rst b/Documentation/core-api/kernel-api.rst
index 9b3f3e5f5a95..712e59ad32fa 100644
--- a/Documentation/core-api/kernel-api.rst
+++ b/Documentation/core-api/kernel-api.rst
@@ -412,3 +412,15 @@ Read-Copy Update (RCU)
 .. kernel-doc:: include/linux/rcu_sync.h
 
 .. kernel-doc:: kernel/rcu/sync.c
+
+.. kernel-doc:: kernel/rcu/tasks.h
+
+.. kernel-doc:: kernel/rcu/tree_stall.h
+
+.. kernel-doc:: include/linux/rcupdate_trace.h
+
+.. kernel-doc:: include/linux/rcupdate_wait.h
+
+.. kernel-doc:: include/linux/rcuref.h
+
+.. kernel-doc:: include/linux/rcutree.h
diff --git a/MAINTAINERS b/MAINTAINERS
index 7e0b87d5aa2e..8af0aabe9bf5 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17778,7 +17778,7 @@ M:	Boqun Feng <boqun.feng@gmail.com>
 R:	Steven Rostedt <rostedt@goodmis.org>
 R:	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 R:	Lai Jiangshan <jiangshanlai@gmail.com>
-R:	Zqiang <qiang1.zhang@intel.com>
+R:	Zqiang <qiang.zhang1211@gmail.com>
 L:	rcu@vger.kernel.org
 S:	Supported
 W:	http://www.rdrop.com/users/paulmck/RCU/
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index 2aba75145144..86544707236a 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -106,12 +106,22 @@ extern void srcu_init_notifier_head(struct srcu_notifier_head *nh);
 #define RAW_NOTIFIER_INIT(name)	{				\
 		.head = NULL }
 
+#ifdef CONFIG_TREE_SRCU
 #define SRCU_NOTIFIER_INIT(name, pcpu)				\
 	{							\
 		.mutex = __MUTEX_INITIALIZER(name.mutex),	\
 		.head = NULL,					\
+		.srcuu = __SRCU_USAGE_INIT(name.srcuu),		\
 		.srcu = __SRCU_STRUCT_INIT(name.srcu, name.srcuu, pcpu), \
 	}
+#else
+#define SRCU_NOTIFIER_INIT(name, pcpu)				\
+	{							\
+		.mutex = __MUTEX_INITIALIZER(name.mutex),	\
+		.head = NULL,					\
+		.srcu = __SRCU_STRUCT_INIT(name.srcu, name.srcuu, pcpu), \
+	}
+#endif
 
 #define ATOMIC_NOTIFIER_HEAD(name)				\
 	struct atomic_notifier_head name =			\
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 744869ef930a..7d9c2a63b7cd 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -156,31 +156,6 @@ static inline int rcu_nocb_cpu_deoffload(int cpu) { return 0; }
 static inline void rcu_nocb_flush_deferred_wakeup(void) { }
 #endif /* #else #ifdef CONFIG_RCU_NOCB_CPU */
 
-/**
- * RCU_NONIDLE - Indicate idle-loop code that needs RCU readers
- * @a: Code that RCU needs to pay attention to.
- *
- * RCU read-side critical sections are forbidden in the inner idle loop,
- * that is, between the ct_idle_enter() and the ct_idle_exit() -- RCU
- * will happily ignore any such read-side critical sections.  However,
- * things like powertop need tracepoints in the inner idle loop.
- *
- * This macro provides the way out:  RCU_NONIDLE(do_something_with_RCU())
- * will tell RCU that it needs to pay attention, invoke its argument
- * (in this example, calling the do_something_with_RCU() function),
- * and then tell RCU to go back to ignoring this CPU.  It is permissible
- * to nest RCU_NONIDLE() wrappers, but not indefinitely (but the limit is
- * on the order of a million or so, even on 32-bit systems).  It is
- * not legal to block within RCU_NONIDLE(), nor is it permissible to
- * transfer control either into or out of RCU_NONIDLE()'s statement.
- */
-#define RCU_NONIDLE(a) \
-	do { \
-		ct_irq_enter_irqson(); \
-		do { a; } while (0); \
-		ct_irq_exit_irqson(); \
-	} while (0)
-
 /*
  * Note a quasi-voluntary context switch for RCU-tasks's benefit.
  * This is a macro rather than an inline function to avoid #include hell.
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index 41c4b26fb1c1..eb92a50a4599 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -212,7 +212,7 @@ static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp)
 
 	srcu_check_nmi_safety(ssp, false);
 	retval = __srcu_read_lock(ssp);
-	srcu_lock_acquire(&(ssp)->dep_map);
+	srcu_lock_acquire(&ssp->dep_map);
 	return retval;
 }
 
@@ -229,7 +229,7 @@ static inline int srcu_read_lock_nmisafe(struct srcu_struct *ssp) __acquires(ssp
 
 	srcu_check_nmi_safety(ssp, true);
 	retval = __srcu_read_lock_nmisafe(ssp);
-	rcu_lock_acquire(&(ssp)->dep_map);
+	rcu_lock_acquire(&ssp->dep_map);
 	return retval;
 }
 
@@ -284,7 +284,7 @@ static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx)
 {
 	WARN_ON_ONCE(idx & ~0x1);
 	srcu_check_nmi_safety(ssp, false);
-	srcu_lock_release(&(ssp)->dep_map);
+	srcu_lock_release(&ssp->dep_map);
 	__srcu_read_unlock(ssp, idx);
 }
 
@@ -300,7 +300,7 @@ static inline void srcu_read_unlock_nmisafe(struct srcu_struct *ssp, int idx)
 {
 	WARN_ON_ONCE(idx & ~0x1);
 	srcu_check_nmi_safety(ssp, true);
-	rcu_lock_release(&(ssp)->dep_map);
+	rcu_lock_release(&ssp->dep_map);
 	__srcu_read_unlock_nmisafe(ssp, idx);
 }
 
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 153ddc4c47ef..949d3deae506 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -33,24 +33,19 @@
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
 
-torture_param(int, nwriters_stress, -1,
-	     "Number of write-locking stress-test threads");
-torture_param(int, nreaders_stress, -1,
-	     "Number of read-locking stress-test threads");
+torture_param(int, nwriters_stress, -1, "Number of write-locking stress-test threads");
+torture_param(int, nreaders_stress, -1, "Number of read-locking stress-test threads");
+torture_param(int, long_hold, 100, "Do occasional long hold of lock (ms), 0=disable");
 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
-torture_param(int, onoff_interval, 0,
-	     "Time between CPU hotplugs (s), 0=disable");
-torture_param(int, shuffle_interval, 3,
-	     "Number of jiffies between shuffles, 0=disable");
+torture_param(int, onoff_interval, 0, "Time between CPU hotplugs (s), 0=disable");
+torture_param(int, shuffle_interval, 3, "Number of jiffies between shuffles, 0=disable");
 torture_param(int, shutdown_secs, 0, "Shutdown time (j), <= zero to disable.");
-torture_param(int, stat_interval, 60,
-	     "Number of seconds between stats printk()s");
+torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s");
 torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
 torture_param(int, rt_boost, 2,
-		"Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types.");
+		   "Do periodic rt-boost. 0=Disable, 1=Only for rt_mutex, 2=For all lock types.");
 torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens.");
-torture_param(int, verbose, 1,
-	     "Enable verbose debugging printk()s");
+torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
 torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)");
 /* Going much higher trips "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" errors */
 #define MAX_NESTED_LOCKS 8
@@ -120,7 +115,7 @@ static int torture_lock_busted_write_lock(int tid __maybe_unused)
 
 static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
 {
-	const unsigned long longdelay_ms = 100;
+	const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
 
 	/* We want a long delay occasionally to force massive contention.  */
 	if (!(torture_random(trsp) %
@@ -198,16 +193,18 @@ __acquires(torture_spinlock)
 static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
 {
 	const unsigned long shortdelay_us = 2;
-	const unsigned long longdelay_ms = 100;
+	const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
+	unsigned long j;
 
 	/* We want a short delay mostly to emulate likely code, and
 	 * we want a long delay occasionally to force massive contention.
 	 */
-	if (!(torture_random(trsp) %
-	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
+	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * longdelay_ms))) {
+		j = jiffies;
 		mdelay(longdelay_ms);
-	if (!(torture_random(trsp) %
-	      (cxt.nrealwriters_stress * 2 * shortdelay_us)))
+		pr_alert("%s: delay = %lu jiffies.\n", __func__, jiffies - j);
+	}
+	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 200 * shortdelay_us)))
 		udelay(shortdelay_us);
 	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 		torture_preempt_schedule();  /* Allow test to be preempted. */
@@ -322,7 +319,7 @@ __acquires(torture_rwlock)
 static void torture_rwlock_write_delay(struct torture_random_state *trsp)
 {
 	const unsigned long shortdelay_us = 2;
-	const unsigned long longdelay_ms = 100;
+	const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
 
 	/* We want a short delay mostly to emulate likely code, and
 	 * we want a long delay occasionally to force massive contention.
@@ -455,14 +452,12 @@ __acquires(torture_mutex)
 
 static void torture_mutex_delay(struct torture_random_state *trsp)
 {
-	const unsigned long longdelay_ms = 100;
+	const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
 
 	/* We want a long delay occasionally to force massive contention.  */
 	if (!(torture_random(trsp) %
 	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 		mdelay(longdelay_ms * 5);
-	else
-		mdelay(longdelay_ms / 5);
 	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
@@ -630,7 +625,7 @@ __acquires(torture_rtmutex)
 static void torture_rtmutex_delay(struct torture_random_state *trsp)
 {
 	const unsigned long shortdelay_us = 2;
-	const unsigned long longdelay_ms = 100;
+	const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
 
 	/*
 	 * We want a short delay mostly to emulate likely code, and
@@ -640,7 +635,7 @@ static void torture_rtmutex_delay(struct torture_random_state *trsp)
 	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 		mdelay(longdelay_ms);
 	if (!(torture_random(trsp) %
-	      (cxt.nrealwriters_stress * 2 * shortdelay_us)))
+	      (cxt.nrealwriters_stress * 200 * shortdelay_us)))
 		udelay(shortdelay_us);
 	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 		torture_preempt_schedule();  /* Allow test to be preempted. */
@@ -695,14 +690,12 @@ __acquires(torture_rwsem)
 
 static void torture_rwsem_write_delay(struct torture_random_state *trsp)
 {
-	const unsigned long longdelay_ms = 100;
+	const unsigned long longdelay_ms = long_hold ? long_hold : ULONG_MAX;
 
 	/* We want a long delay occasionally to force massive contention.  */
 	if (!(torture_random(trsp) %
 	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
 		mdelay(longdelay_ms * 10);
-	else
-		mdelay(longdelay_ms / 10);
 	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
@@ -848,8 +841,8 @@ static int lock_torture_writer(void *arg)
 
 			lwsp->n_lock_acquired++;
 		}
-		cxt.cur_ops->write_delay(&rand);
 		if (!skip_main_lock) {
+			cxt.cur_ops->write_delay(&rand);
 			lock_is_write_held = false;
 			WRITE_ONCE(last_lock_release, jiffies);
 			cxt.cur_ops->writeunlock(tid);
diff --git a/kernel/rcu/Kconfig b/kernel/rcu/Kconfig
index 9071182b1284..bdd7eadb33d8 100644
--- a/kernel/rcu/Kconfig
+++ b/kernel/rcu/Kconfig
@@ -314,4 +314,22 @@ config RCU_LAZY
 	  To save power, batch RCU callbacks and flush after delay, memory
 	  pressure, or callback list growing too big.
 
+config RCU_DOUBLE_CHECK_CB_TIME
+	bool "RCU callback-batch backup time check"
+	depends on RCU_EXPERT
+	default n
+	help
+	  Use this option to provide more precise enforcement of the
+	  rcutree.rcu_resched_ns module parameter in situations where
+	  a single RCU callback might run for hundreds of microseconds,
+	  thus defeating the 32-callback batching used to amortize the
+	  cost of the fine-grained but expensive local_clock() function.
+
+	  This option rounds rcutree.rcu_resched_ns up to the next
+	  jiffy, and overrides the 32-callback batching if this limit
+	  is exceeded.
+
+	  Say Y here if you need tighter callback-limit enforcement.
+	  Say N here if you are unsure.
+
 endmenu # "RCU Subsystem"
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 4a1b9622598b..98c1544cf572 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -642,4 +642,10 @@ void show_rcu_tasks_trace_gp_kthread(void);
 static inline void show_rcu_tasks_trace_gp_kthread(void) {}
 #endif
 
+#ifdef CONFIG_TINY_RCU
+static inline bool rcu_cpu_beenfullyonline(int cpu) { return true; }
+#else
+bool rcu_cpu_beenfullyonline(int cpu);
+#endif
+
 #endif /* __LINUX_RCU_H */
diff --git a/kernel/rcu/rcuscale.c b/kernel/rcu/rcuscale.c
index e82ec9f9a5d8..d1221731c7cf 100644
--- a/kernel/rcu/rcuscale.c
+++ b/kernel/rcu/rcuscale.c
@@ -522,89 +522,6 @@ rcu_scale_print_module_parms(struct rcu_scale_ops *cur_ops, const char *tag)
 		 scale_type, tag, nrealreaders, nrealwriters, verbose, shutdown);
 }
 
-static void
-rcu_scale_cleanup(void)
-{
-	int i;
-	int j;
-	int ngps = 0;
-	u64 *wdp;
-	u64 *wdpp;
-
-	/*
-	 * Would like warning at start, but everything is expedited
-	 * during the mid-boot phase, so have to wait till the end.
-	 */
-	if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
-		SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
-	if (rcu_gp_is_normal() && gp_exp)
-		SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
-	if (gp_exp && gp_async)
-		SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
-
-	if (torture_cleanup_begin())
-		return;
-	if (!cur_ops) {
-		torture_cleanup_end();
-		return;
-	}
-
-	if (reader_tasks) {
-		for (i = 0; i < nrealreaders; i++)
-			torture_stop_kthread(rcu_scale_reader,
-					     reader_tasks[i]);
-		kfree(reader_tasks);
-	}
-
-	if (writer_tasks) {
-		for (i = 0; i < nrealwriters; i++) {
-			torture_stop_kthread(rcu_scale_writer,
-					     writer_tasks[i]);
-			if (!writer_n_durations)
-				continue;
-			j = writer_n_durations[i];
-			pr_alert("%s%s writer %d gps: %d\n",
-				 scale_type, SCALE_FLAG, i, j);
-			ngps += j;
-		}
-		pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
-			 scale_type, SCALE_FLAG,
-			 t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
-			 t_rcu_scale_writer_finished -
-			 t_rcu_scale_writer_started,
-			 ngps,
-			 rcuscale_seq_diff(b_rcu_gp_test_finished,
-					   b_rcu_gp_test_started));
-		for (i = 0; i < nrealwriters; i++) {
-			if (!writer_durations)
-				break;
-			if (!writer_n_durations)
-				continue;
-			wdpp = writer_durations[i];
-			if (!wdpp)
-				continue;
-			for (j = 0; j < writer_n_durations[i]; j++) {
-				wdp = &wdpp[j];
-				pr_alert("%s%s %4d writer-duration: %5d %llu\n",
-					scale_type, SCALE_FLAG,
-					i, j, *wdp);
-				if (j % 100 == 0)
-					schedule_timeout_uninterruptible(1);
-			}
-			kfree(writer_durations[i]);
-		}
-		kfree(writer_tasks);
-		kfree(writer_durations);
-		kfree(writer_n_durations);
-	}
-
-	/* Do torture-type-specific cleanup operations.  */
-	if (cur_ops->cleanup != NULL)
-		cur_ops->cleanup();
-
-	torture_cleanup_end();
-}
-
 /*
  * Return the number if non-negative.  If -1, the number of CPUs.
  * If less than -1, that much less than the number of CPUs, but
@@ -625,20 +542,6 @@ static int compute_real(int n)
 }
 
 /*
- * RCU scalability shutdown kthread.  Just waits to be awakened, then shuts
- * down system.
- */
-static int
-rcu_scale_shutdown(void *arg)
-{
-	wait_event_idle(shutdown_wq, atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
-	smp_mb(); /* Wake before output. */
-	rcu_scale_cleanup();
-	kernel_power_off();
-	return -EINVAL;
-}
-
-/*
  * kfree_rcu() scalability tests: Start a kfree_rcu() loop on all CPUs for number
  * of iterations and measure total time and number of GP for all iterations to complete.
  */
@@ -874,6 +777,108 @@ unwind:
 	return firsterr;
 }
 
+static void
+rcu_scale_cleanup(void)
+{
+	int i;
+	int j;
+	int ngps = 0;
+	u64 *wdp;
+	u64 *wdpp;
+
+	/*
+	 * Would like warning at start, but everything is expedited
+	 * during the mid-boot phase, so have to wait till the end.
+	 */
+	if (rcu_gp_is_expedited() && !rcu_gp_is_normal() && !gp_exp)
+		SCALEOUT_ERRSTRING("All grace periods expedited, no normal ones to measure!");
+	if (rcu_gp_is_normal() && gp_exp)
+		SCALEOUT_ERRSTRING("All grace periods normal, no expedited ones to measure!");
+	if (gp_exp && gp_async)
+		SCALEOUT_ERRSTRING("No expedited async GPs, so went with async!");
+
+	if (kfree_rcu_test) {
+		kfree_scale_cleanup();
+		return;
+	}
+
+	if (torture_cleanup_begin())
+		return;
+	if (!cur_ops) {
+		torture_cleanup_end();
+		return;
+	}
+
+	if (reader_tasks) {
+		for (i = 0; i < nrealreaders; i++)
+			torture_stop_kthread(rcu_scale_reader,
+					     reader_tasks[i]);
+		kfree(reader_tasks);
+	}
+
+	if (writer_tasks) {
+		for (i = 0; i < nrealwriters; i++) {
+			torture_stop_kthread(rcu_scale_writer,
+					     writer_tasks[i]);
+			if (!writer_n_durations)
+				continue;
+			j = writer_n_durations[i];
+			pr_alert("%s%s writer %d gps: %d\n",
+				 scale_type, SCALE_FLAG, i, j);
+			ngps += j;
+		}
+		pr_alert("%s%s start: %llu end: %llu duration: %llu gps: %d batches: %ld\n",
+			 scale_type, SCALE_FLAG,
+			 t_rcu_scale_writer_started, t_rcu_scale_writer_finished,
+			 t_rcu_scale_writer_finished -
+			 t_rcu_scale_writer_started,
+			 ngps,
+			 rcuscale_seq_diff(b_rcu_gp_test_finished,
+					   b_rcu_gp_test_started));
+		for (i = 0; i < nrealwriters; i++) {
+			if (!writer_durations)
+				break;
+			if (!writer_n_durations)
+				continue;
+			wdpp = writer_durations[i];
+			if (!wdpp)
+				continue;
+			for (j = 0; j < writer_n_durations[i]; j++) {
+				wdp = &wdpp[j];
+				pr_alert("%s%s %4d writer-duration: %5d %llu\n",
+					scale_type, SCALE_FLAG,
+					i, j, *wdp);
+				if (j % 100 == 0)
+					schedule_timeout_uninterruptible(1);
+			}
+			kfree(writer_durations[i]);
+		}
+		kfree(writer_tasks);
+		kfree(writer_durations);
+		kfree(writer_n_durations);
+	}
+
+	/* Do torture-type-specific cleanup operations.  */
+	if (cur_ops->cleanup != NULL)
+		cur_ops->cleanup();
+
+	torture_cleanup_end();
+}
+
+/*
+ * RCU scalability shutdown kthread.  Just waits to be awakened, then shuts
+ * down system.
+ */
+static int
+rcu_scale_shutdown(void *arg)
+{
+	wait_event_idle(shutdown_wq, atomic_read(&n_rcu_scale_writer_finished) >= nrealwriters);
+	smp_mb(); /* Wake before output. */
+	rcu_scale_cleanup();
+	kernel_power_off();
+	return -EINVAL;
+}
+
 static int __init
 rcu_scale_init(void)
 {
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 5f4fc8184dd0..b770add3f843 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -241,7 +241,6 @@ static void cblist_init_generic(struct rcu_tasks *rtp)
 	if (rcu_task_enqueue_lim < 0) {
 		rcu_task_enqueue_lim = 1;
 		rcu_task_cb_adjust = true;
-		pr_info("%s: Setting adjustable number of callback queues.\n", __func__);
 	} else if (rcu_task_enqueue_lim == 0) {
 		rcu_task_enqueue_lim = 1;
 	}
@@ -272,7 +271,9 @@ static void cblist_init_generic(struct rcu_tasks *rtp)
 		raw_spin_unlock_rcu_node(rtpcp); // irqs remain disabled.
 	}
 	raw_spin_unlock_irqrestore(&rtp->cbs_gbl_lock, flags);
-	pr_info("%s: Setting shift to %d and lim to %d.\n", __func__, data_race(rtp->percpu_enqueue_shift), data_race(rtp->percpu_enqueue_lim));
+
+	pr_info("%s: Setting shift to %d and lim to %d rcu_task_cb_adjust=%d.\n", rtp->name,
+			data_race(rtp->percpu_enqueue_shift), data_race(rtp->percpu_enqueue_lim), rcu_task_cb_adjust);
 }
 
 // IRQ-work handler that does deferred wakeup for call_rcu_tasks_generic().
@@ -463,6 +464,7 @@ static void rcu_tasks_invoke_cbs(struct rcu_tasks *rtp, struct rcu_tasks_percpu
 {
 	int cpu;
 	int cpunext;
+	int cpuwq;
 	unsigned long flags;
 	int len;
 	struct rcu_head *rhp;