Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index c596c6f..3c9feca 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1,23 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  * Read-Copy Update module-based torture test facility
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, you can access it online at
- * http://www.gnu.org/licenses/gpl-2.0.html.
- *
  * Copyright (C) IBM Corporation, 2005, 2006
  *
- * Authors: Paul E. McKenney <paulmck@us.ibm.com>
+ * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
  *	  Josh Triplett <josh@joshtriplett.org>
  *
  * See also:  Documentation/RCU/torture.txt
@@ -56,39 +43,43 @@
 #include <linux/vmalloc.h>
 #include <linux/sched/debug.h>
 #include <linux/sched/sysctl.h>
+#include <linux/oom.h>
 
 #include "rcu.h"
 
 MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
+MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
 
 
 /* Bits for ->extendables field, extendables param, and related definitions. */
 #define RCUTORTURE_RDR_SHIFT	 8	/* Put SRCU index in upper bits. */
 #define RCUTORTURE_RDR_MASK	 ((1 << RCUTORTURE_RDR_SHIFT) - 1)
-#define RCUTORTURE_RDR_BH	 0x1	/* Extend readers by disabling bh. */
-#define RCUTORTURE_RDR_IRQ	 0x2	/*  ... disabling interrupts. */
-#define RCUTORTURE_RDR_PREEMPT	 0x4	/*  ... disabling preemption. */
-#define RCUTORTURE_RDR_RCU	 0x8	/*  ... entering another RCU reader. */
-#define RCUTORTURE_RDR_NBITS	 4	/* Number of bits defined above. */
-#define RCUTORTURE_MAX_EXTEND	 (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | \
-				  RCUTORTURE_RDR_PREEMPT)
+#define RCUTORTURE_RDR_BH	 0x01	/* Extend readers by disabling bh. */
+#define RCUTORTURE_RDR_IRQ	 0x02	/*  ... disabling interrupts. */
+#define RCUTORTURE_RDR_PREEMPT	 0x04	/*  ... disabling preemption. */
+#define RCUTORTURE_RDR_RBH	 0x08	/*  ... rcu_read_lock_bh(). */
+#define RCUTORTURE_RDR_SCHED	 0x10	/*  ... rcu_read_lock_sched(). */
+#define RCUTORTURE_RDR_RCU	 0x20	/*  ... entering another RCU reader. */
+#define RCUTORTURE_RDR_NBITS	 6	/* Number of bits defined above. */
+#define RCUTORTURE_MAX_EXTEND	 \
+	(RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
+	 RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
 #define RCUTORTURE_RDR_MAX_LOOPS 0x7	/* Maximum reader extensions. */
 					/* Must be power of two minus one. */
+#define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
 
-torture_param(int, cbflood_inter_holdoff, HZ,
-	      "Holdoff between floods (jiffies)");
-torture_param(int, cbflood_intra_holdoff, 1,
-	      "Holdoff between bursts (jiffies)");
-torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
-torture_param(int, cbflood_n_per_burst, 20000,
-	      "# callbacks per burst in flood");
 torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
 	      "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
 torture_param(int, fqs_duration, 0,
 	      "Duration of fqs bursts (us), 0 to disable");
 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
+torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
+torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
+torture_param(int, fwd_progress_holdoff, 60,
+	      "Time between forward-progress tests (s)");
+torture_param(bool, fwd_progress_need_resched, 1,
+	      "Hide cond_resched() behind need_resched()");
 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
 torture_param(bool, gp_normal, false,
@@ -125,18 +116,17 @@
 
 static char *torture_type = "rcu";
 module_param(torture_type, charp, 0444);
-MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
+MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
 
 static int nrealreaders;
-static int ncbflooders;
 static struct task_struct *writer_task;
 static struct task_struct **fakewriter_tasks;
 static struct task_struct **reader_tasks;
 static struct task_struct *stats_task;
-static struct task_struct **cbflood_task;
 static struct task_struct *fqs_task;
 static struct task_struct *boost_tasks[NR_CPUS];
 static struct task_struct *stall_task;
+static struct task_struct *fwd_prog_task;
 static struct task_struct **barrier_cbs_tasks;
 static struct task_struct *barrier_task;
 
@@ -170,8 +160,8 @@
 static atomic_long_t n_rcu_torture_timers;
 static long n_barrier_attempts;
 static long n_barrier_successes; /* did rcu_barrier test succeed? */
-static atomic_long_t n_cbfloods;
 static struct list_head rcu_torture_removed;
+static unsigned long shutdown_jiffies;
 
 static int rcu_torture_writer_state;
 #define RTWS_FIXED_DELAY	0
@@ -197,6 +187,18 @@
 	"RTWS_STOPPING",
 };
 
+/* Record reader segment types and duration for first failing read. */
+struct rt_read_seg {
+	int rt_readstate;
+	unsigned long rt_delay_jiffies;
+	unsigned long rt_delay_ms;
+	unsigned long rt_delay_us;
+	bool rt_preempted;
+};
+static int err_segs_recorded;
+static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
+static int rt_read_nsegs;
+
 static const char *rcu_torture_writer_state_getname(void)
 {
 	unsigned int i = READ_ONCE(rcu_torture_writer_state);
@@ -227,6 +229,15 @@
 }
 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 
+/*
+ * Stop aggressive CPU-hog tests a bit before the end of the test in order
+ * to avoid interfering with test shutdown.
+ */
+static bool shutdown_time_arrived(void)
+{
+	return shutdown_secs && time_after(jiffies, shutdown_jiffies - 30 * HZ);
+}
+
 static unsigned long boost_starttime;	/* jiffies of next boost test start. */
 static DEFINE_MUTEX(boost_mutex);	/* protect setting boost_starttime */
 					/*  and boost task create/destroy. */
@@ -236,6 +247,8 @@
 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 
+static bool rcu_fwd_cb_nodelay;		/* Short rcu_torture_delay() delays. */
+
 /*
  * Allocate an element from the rcu_tortures pool.
  */
@@ -278,7 +291,8 @@
 	void (*init)(void);
 	void (*cleanup)(void);
 	int (*readlock)(void);
-	void (*read_delay)(struct torture_random_state *rrsp);
+	void (*read_delay)(struct torture_random_state *rrsp,
+			   struct rt_read_seg *rtrsp);
 	void (*readunlock)(int idx);
 	unsigned long (*get_gp_seq)(void);
 	unsigned long (*gp_diff)(unsigned long new, unsigned long old);
@@ -291,10 +305,11 @@
 	void (*cb_barrier)(void);
 	void (*fqs)(void);
 	void (*stats)(void);
+	int (*stall_dur)(void);
 	int irq_capable;
 	int can_boost;
 	int extendables;
-	int ext_irq_conflict;
+	int slow_gps;
 	const char *name;
 };
 
@@ -310,31 +325,40 @@
 	return 0;
 }
 
-static void rcu_read_delay(struct torture_random_state *rrsp)
+static void
+rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 {
 	unsigned long started;
 	unsigned long completed;
 	const unsigned long shortdelay_us = 200;
-	const unsigned long longdelay_ms = 50;
+	unsigned long longdelay_ms = 300;
 	unsigned long long ts;
 
 	/* We want a short delay sometimes to make a reader delay the grace
 	 * period, and we want a long delay occasionally to trigger
 	 * force_quiescent_state. */
 
-	if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
+	if (!rcu_fwd_cb_nodelay &&
+	    !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 		started = cur_ops->get_gp_seq();
 		ts = rcu_trace_clock_local();
+		if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
+			longdelay_ms = 5; /* Avoid triggering BH limits. */
 		mdelay(longdelay_ms);
+		rtrsp->rt_delay_ms = longdelay_ms;
 		completed = cur_ops->get_gp_seq();
 		do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 					  started, completed);
 	}
-	if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
+	if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
 		udelay(shortdelay_us);
+		rtrsp->rt_delay_us = shortdelay_us;
+	}
 	if (!preempt_count() &&
-	    !(torture_random(rrsp) % (nrealreaders * 500)))
+	    !(torture_random(rrsp) % (nrealreaders * 500))) {
 		torture_preempt_schedule();  /* QS only if preemptible. */
+		rtrsp->rt_preempted = true;
+	}
 }
 
 static void rcu_torture_read_unlock(int idx) __releases(RCU)
@@ -429,53 +453,14 @@
 	.cb_barrier	= rcu_barrier,
 	.fqs		= rcu_force_quiescent_state,
 	.stats		= NULL,
+	.stall_dur	= rcu_jiffies_till_stall_check,
 	.irq_capable	= 1,
 	.can_boost	= rcu_can_boost(),
+	.extendables	= RCUTORTURE_MAX_EXTEND,
 	.name		= "rcu"
 };
 
 /*
- * Definitions for rcu_bh torture testing.
- */
-
-static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
-{
-	rcu_read_lock_bh();
-	return 0;
-}
-
-static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
-{
-	rcu_read_unlock_bh();
-}
-
-static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
-{
-	call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
-}
-
-static struct rcu_torture_ops rcu_bh_ops = {
-	.ttype		= RCU_BH_FLAVOR,
-	.init		= rcu_sync_torture_init,
-	.readlock	= rcu_bh_torture_read_lock,
-	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
-	.readunlock	= rcu_bh_torture_read_unlock,
-	.get_gp_seq	= rcu_bh_get_gp_seq,
-	.gp_diff	= rcu_seq_diff,
-	.deferred_free	= rcu_bh_torture_deferred_free,
-	.sync		= synchronize_rcu_bh,
-	.exp_sync	= synchronize_rcu_bh_expedited,
-	.call		= call_rcu_bh,
-	.cb_barrier	= rcu_barrier_bh,
-	.fqs		= rcu_bh_force_quiescent_state,
-	.stats		= NULL,
-	.irq_capable	= 1,
-	.extendables	= (RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ),
-	.ext_irq_conflict = RCUTORTURE_RDR_RCU,
-	.name		= "rcu_bh"
-};
-
-/*
  * Don't even think about trying any of these in real life!!!
  * The names includes "busted", and they really means it!
  * The only purpose of these functions is to provide a buggy RCU
@@ -531,7 +516,8 @@
 	return srcu_read_lock(srcu_ctlp);
 }
 
-static void srcu_read_delay(struct torture_random_state *rrsp)
+static void
+srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
 {
 	long delay;
 	const long uspertick = 1000000 / HZ;
@@ -541,10 +527,12 @@
 
 	delay = torture_random(rrsp) %
 		(nrealreaders * 2 * longdelay * uspertick);
-	if (!delay && in_task())
+	if (!delay && in_task()) {
 		schedule_timeout_interruptible(longdelay);
-	else
-		rcu_read_delay(rrsp);
+		rtrsp->rt_delay_jiffies = longdelay;
+	} else {
+		rcu_read_delay(rrsp, rtrsp);
+	}
 }
 
 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
@@ -614,12 +602,7 @@
 
 static void srcu_torture_cleanup(void)
 {
-	static DEFINE_TORTURE_RANDOM(rand);
-
-	if (torture_random(&rand) & 0x800)
-		cleanup_srcu_struct(&srcu_ctld);
-	else
-		cleanup_srcu_struct_quiesced(&srcu_ctld);
+	cleanup_srcu_struct(&srcu_ctld);
 	srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 }
 
@@ -663,48 +646,6 @@
 };
 
 /*
- * Definitions for sched torture testing.
- */
-
-static int sched_torture_read_lock(void)
-{
-	preempt_disable();
-	return 0;
-}
-
-static void sched_torture_read_unlock(int idx)
-{
-	preempt_enable();
-}
-
-static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
-{
-	call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
-}
-
-static struct rcu_torture_ops sched_ops = {
-	.ttype		= RCU_SCHED_FLAVOR,
-	.init		= rcu_sync_torture_init,
-	.readlock	= sched_torture_read_lock,
-	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
-	.readunlock	= sched_torture_read_unlock,
-	.get_gp_seq	= rcu_sched_get_gp_seq,
-	.gp_diff	= rcu_seq_diff,
-	.deferred_free	= rcu_sched_torture_deferred_free,
-	.sync		= synchronize_sched,
-	.exp_sync	= synchronize_sched_expedited,
-	.get_state	= get_state_synchronize_sched,
-	.cond_sync	= cond_synchronize_sched,
-	.call		= call_rcu_sched,
-	.cb_barrier	= rcu_barrier_sched,
-	.fqs		= rcu_sched_force_quiescent_state,
-	.stats		= NULL,
-	.irq_capable	= 1,
-	.extendables	= RCUTORTURE_MAX_EXTEND,
-	.name		= "sched"
-};
-
-/*
  * Definitions for RCU-tasks torture testing.
  */
 
@@ -737,9 +678,51 @@
 	.fqs		= NULL,
 	.stats		= NULL,
 	.irq_capable	= 1,
+	.slow_gps	= 1,
 	.name		= "tasks"
 };
 
+/*
+ * Definitions for trivial CONFIG_PREEMPT=n-only torture testing.
+ * This implementation does not necessarily work well with CPU hotplug.
+ */
+
+static void synchronize_rcu_trivial(void)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu) {
+		rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
+		WARN_ON_ONCE(raw_smp_processor_id() != cpu);
+	}
+}
+
+static int rcu_torture_read_lock_trivial(void) __acquires(RCU)
+{
+	preempt_disable();
+	return 0;
+}
+
+static void rcu_torture_read_unlock_trivial(int idx) __releases(RCU)
+{
+	preempt_enable();
+}
+
+static struct rcu_torture_ops trivial_ops = {
+	.ttype		= RCU_TRIVIAL_FLAVOR,
+	.init		= rcu_sync_torture_init,
+	.readlock	= rcu_torture_read_lock_trivial,
+	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
+	.readunlock	= rcu_torture_read_unlock_trivial,
+	.get_gp_seq	= rcu_no_completed,
+	.sync		= synchronize_rcu_trivial,
+	.exp_sync	= synchronize_rcu_trivial,
+	.fqs		= NULL,
+	.stats		= NULL,
+	.irq_capable	= 1,
+	.name		= "trivial"
+};
+
 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
 {
 	if (!cur_ops->gp_diff)
@@ -915,59 +898,6 @@
 	return 0;
 }
 
-static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
-{
-}
-
-/*
- * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
- * to call_rcu() or analogous, increasing the probability of occurrence
- * of callback-overflow corner cases.
- */
-static int
-rcu_torture_cbflood(void *arg)
-{
-	int err = 1;
-	int i;
-	int j;
-	struct rcu_head *rhp;
-
-	if (cbflood_n_per_burst > 0 &&
-	    cbflood_inter_holdoff > 0 &&
-	    cbflood_intra_holdoff > 0 &&
-	    cur_ops->call &&
-	    cur_ops->cb_barrier) {
-		rhp = vmalloc(array3_size(cbflood_n_burst,
-					  cbflood_n_per_burst,
-					  sizeof(*rhp)));
-		err = !rhp;
-	}
-	if (err) {
-		VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
-		goto wait_for_stop;
-	}
-	VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
-	do {
-		schedule_timeout_interruptible(cbflood_inter_holdoff);
-		atomic_long_inc(&n_cbfloods);
-		WARN_ON(signal_pending(current));
-		for (i = 0; i < cbflood_n_burst; i++) {
-			for (j = 0; j < cbflood_n_per_burst; j++) {
-				cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
-					      rcu_torture_cbflood_cb);
-			}
-			schedule_timeout_interruptible(cbflood_intra_holdoff);
-			WARN_ON(signal_pending(current));
-		}
-		cur_ops->cb_barrier();
-		stutter_wait("rcu_torture_cbflood");
-	} while (!torture_must_stop());
-	vfree(rhp);
-wait_for_stop:
-	torture_kthread_stopping("rcu_torture_cbflood");
-	return 0;
-}
-
 /*
  * RCU torture force-quiescent-state kthread.  Repeatedly induces
  * bursts of calls to force_quiescent_state(), increasing the probability
@@ -1116,7 +1046,8 @@
 				break;
 			}
 		}
-		rcu_torture_current_version++;
+		WRITE_ONCE(rcu_torture_current_version,
+			   rcu_torture_current_version + 1);
 		/* Cycle through nesting levels of rcu_expedite_gp() calls. */
 		if (can_expedite &&
 		    !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
@@ -1132,7 +1063,17 @@
 				       !rcu_gp_is_normal();
 		}
 		rcu_torture_writer_state = RTWS_STUTTER;
-		stutter_wait("rcu_torture_writer");
+		if (stutter_wait("rcu_torture_writer") &&
+		    !READ_ONCE(rcu_fwd_cb_nodelay) &&
+		    !cur_ops->slow_gps &&
+		    !torture_must_stop())
+			for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
+				if (list_empty(&rcu_tortures[i].rtort_free) &&
+				    rcu_access_pointer(rcu_torture_current) !=
+				    &rcu_tortures[i]) {
+					rcu_ftrace_dump(DUMP_ALL);
+					WARN(1, "%s: rtort_pipe_count: %d\n", __func__, rcu_tortures[i].rtort_pipe_count);
+				}
 	} while (!torture_must_stop());
 	/* Reset expediting back to unexpedited. */
 	if (expediting > 0)
@@ -1199,7 +1140,8 @@
  * change, do a ->read_delay().
  */
 static void rcutorture_one_extend(int *readstate, int newstate,
-				  struct torture_random_state *trsp)
+				  struct torture_random_state *trsp,
+				  struct rt_read_seg *rtrsp)
 {
 	int idxnew = -1;
 	int idxold = *readstate;
@@ -1208,6 +1150,7 @@
 
 	WARN_ON_ONCE(idxold < 0);
 	WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
+	rtrsp->rt_readstate = newstate;
 
 	/* First, put new protection in place to avoid critical-section gap. */
 	if (statesnew & RCUTORTURE_RDR_BH)
@@ -1216,6 +1159,10 @@
 		local_irq_disable();
 	if (statesnew & RCUTORTURE_RDR_PREEMPT)
 		preempt_disable();
+	if (statesnew & RCUTORTURE_RDR_RBH)
+		rcu_read_lock_bh();
+	if (statesnew & RCUTORTURE_RDR_SCHED)
+		rcu_read_lock_sched();
 	if (statesnew & RCUTORTURE_RDR_RCU)
 		idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
 
@@ -1226,12 +1173,16 @@
 		local_bh_enable();
 	if (statesold & RCUTORTURE_RDR_PREEMPT)
 		preempt_enable();
+	if (statesold & RCUTORTURE_RDR_RBH)
+		rcu_read_unlock_bh();
+	if (statesold & RCUTORTURE_RDR_SCHED)
+		rcu_read_unlock_sched();
 	if (statesold & RCUTORTURE_RDR_RCU)
 		cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
 
 	/* Delay if neither beginning nor end and there was a change. */
 	if ((statesnew || statesold) && *readstate && newstate)
-		cur_ops->read_delay(trsp);
+		cur_ops->read_delay(trsp, rtrsp);
 
 	/* Update the reader state. */
 	if (idxnew == -1)
@@ -1260,22 +1211,19 @@
 {
 	int mask = rcutorture_extend_mask_max();
 	unsigned long randmask1 = torture_random(trsp) >> 8;
-	unsigned long randmask2 = randmask1 >> 1;
+	unsigned long randmask2 = randmask1 >> 3;
 
 	WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
-	/* Half the time lots of bits, half the time only one bit. */
-	if (randmask1 & 0x1)
+	/* Mostly only one bit (need preemption!), sometimes lots of bits. */
+	if (!(randmask1 & 0x7))
 		mask = mask & randmask2;
 	else
 		mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
+	/* Can't enable bh w/irq disabled. */
 	if ((mask & RCUTORTURE_RDR_IRQ) &&
-	    !(mask & RCUTORTURE_RDR_BH) &&
-	    (oldmask & RCUTORTURE_RDR_BH))
-		mask |= RCUTORTURE_RDR_BH; /* Can't enable bh w/irq disabled. */
-	if ((mask & RCUTORTURE_RDR_IRQ) &&
-	    !(mask & cur_ops->ext_irq_conflict) &&
-	    (oldmask & cur_ops->ext_irq_conflict))
-		mask |= cur_ops->ext_irq_conflict; /* Or if readers object. */
+	    ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
+	     (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
+		mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
 	return mask ?: RCUTORTURE_RDR_RCU;
 }
 
@@ -1283,20 +1231,25 @@
  * Do a randomly selected number of extensions of an existing RCU read-side
  * critical section.
  */
-static void rcutorture_loop_extend(int *readstate,
-				   struct torture_random_state *trsp)
+static struct rt_read_seg *
+rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
+		       struct rt_read_seg *rtrsp)
 {
 	int i;
+	int j;
 	int mask = rcutorture_extend_mask_max();
 
 	WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
 	if (!((mask - 1) & mask))
-		return;  /* Current RCU flavor not extendable. */
-	i = (torture_random(trsp) >> 3) & RCUTORTURE_RDR_MAX_LOOPS;
-	while (i--) {
+		return rtrsp;  /* Current RCU reader not extendable. */
+	/* Bias towards larger numbers of loops. */
+	i = (torture_random(trsp) >> 3);
+	i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
+	for (j = 0; j < i; j++) {
 		mask = rcutorture_extend_mask(*readstate, trsp);
-		rcutorture_one_extend(readstate, mask, trsp);
+		rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
 	}
+	return &rtrsp[j];
 }
 
 /*
@@ -1306,16 +1259,20 @@
  */
 static bool rcu_torture_one_read(struct torture_random_state *trsp)
 {
+	int i;
 	unsigned long started;
 	unsigned long completed;
 	int newstate;
 	struct rcu_torture *p;
 	int pipe_count;
 	int readstate = 0;
+	struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
+	struct rt_read_seg *rtrsp = &rtseg[0];
+	struct rt_read_seg *rtrsp1;
 	unsigned long long ts;
 
 	newstate = rcutorture_extend_mask(readstate, trsp);
-	rcutorture_one_extend(&readstate, newstate, trsp);
+	rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
 	started = cur_ops->get_gp_seq();
 	ts = rcu_trace_clock_local();
 	p = rcu_dereference_check(rcu_torture_current,
@@ -1325,12 +1282,12 @@
 				  torturing_tasks());
 	if (p == NULL) {
 		/* Wait for rcu_torture_writer to get underway */
-		rcutorture_one_extend(&readstate, 0, trsp);
+		rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
 		return false;
 	}
 	if (p->rtort_mbtest == 0)
 		atomic_inc(&n_rcu_torture_mberror);
-	rcutorture_loop_extend(&readstate, trsp);
+	rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
 	preempt_disable();
 	pipe_count = p->rtort_pipe_count;
 	if (pipe_count > RCU_TORTURE_PIPE_LEN) {
@@ -1351,8 +1308,17 @@
 	}
 	__this_cpu_inc(rcu_torture_batch[completed]);
 	preempt_enable();
-	rcutorture_one_extend(&readstate, 0, trsp);
+	rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
 	WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
+
+	/* If error or close call, record the sequence of reader protections. */
+	if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
+		i = 0;
+		for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
+			err_segs[i++] = *rtrsp1;
+		rt_read_nsegs = i;
+	}
+
 	return true;
 }
 
@@ -1387,6 +1353,9 @@
 static int
 rcu_torture_reader(void *arg)
 {
+	unsigned long lastsleep = jiffies;
+	long myid = (long)arg;
+	int mynumonline = myid;
 	DEFINE_TORTURE_RANDOM(rand);
 	struct timer_list t;
 
@@ -1402,6 +1371,12 @@
 		}
 		if (!rcu_torture_one_read(&rand))
 			schedule_timeout_interruptible(HZ);
+		if (time_after(jiffies, lastsleep)) {
+			schedule_timeout_interruptible(1);
+			lastsleep = jiffies + 10;
+		}
+		while (num_online_cpus() < mynumonline && !torture_must_stop())
+			schedule_timeout_interruptible(HZ / 5);
 		stutter_wait("rcu_torture_reader");
 	} while (!torture_must_stop());
 	if (irqreader && cur_ops->irq_capable) {
@@ -1443,8 +1418,9 @@
 	}
 
 	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
-	pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
+	pr_cont("rtc: %p %s: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
 		rcu_torture_current,
+		rcu_torture_current ? "ver" : "VER",
 		rcu_torture_current_version,
 		list_empty(&rcu_torture_freelist),
 		atomic_read(&n_rcu_torture_alloc),
@@ -1460,11 +1436,10 @@
 		n_rcu_torture_boosts,
 		atomic_long_read(&n_rcu_torture_timers));
 	torture_onoff_stats();
-	pr_cont("barrier: %ld/%ld:%ld ",
+	pr_cont("barrier: %ld/%ld:%ld\n",
 		n_barrier_successes,
 		n_barrier_attempts,
 		n_rcu_torture_barrier_error);
-	pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
 
 	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
 	if (atomic_read(&n_rcu_torture_mberror) != 0 ||
@@ -1655,6 +1630,375 @@
 	return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
 }
 
+/* State structure for forward-progress self-propagating RCU callback. */
+struct fwd_cb_state {
+	struct rcu_head rh;
+	int stop;
+};
+
+/*
+ * Forward-progress self-propagating RCU callback function.  Because
+ * callbacks run from softirq, this function is an implicit RCU read-side
+ * critical section.
+ */
+static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
+{
+	struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
+
+	if (READ_ONCE(fcsp->stop)) {
+		WRITE_ONCE(fcsp->stop, 2);
+		return;
+	}
+	cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
+}
+
+/* State for continuous-flood RCU callbacks. */
+struct rcu_fwd_cb {
+	struct rcu_head rh;
+	struct rcu_fwd_cb *rfc_next;
+	int rfc_gps;
+};
+static DEFINE_SPINLOCK(rcu_fwd_lock);
+static struct rcu_fwd_cb *rcu_fwd_cb_head;
+static struct rcu_fwd_cb **rcu_fwd_cb_tail = &rcu_fwd_cb_head;
+static long n_launders_cb;
+static unsigned long rcu_fwd_startat;
+static bool rcu_fwd_emergency_stop;
+#define MAX_FWD_CB_JIFFIES	(8 * HZ) /* Maximum CB test duration. */
+#define MIN_FWD_CB_LAUNDERS	3	/* This many CB invocations to count. */
+#define MIN_FWD_CBS_LAUNDERED	100	/* Number of counted CBs. */
+#define FWD_CBS_HIST_DIV	10	/* Histogram buckets/second. */
+struct rcu_launder_hist {
+	long n_launders;
+	unsigned long launder_gp_seq;
+};
+#define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
+static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
+static unsigned long rcu_launder_gp_seq_start;
+
+static void rcu_torture_fwd_cb_hist(void)
+{
+	unsigned long gps;
+	unsigned long gps_old;
+	int i;
+	int j;
+
+	for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
+		if (n_launders_hist[i].n_launders > 0)
+			break;
+	pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
+		 __func__, jiffies - rcu_fwd_startat);
+	gps_old = rcu_launder_gp_seq_start;
+	for (j = 0; j <= i; j++) {
+		gps = n_launders_hist[j].launder_gp_seq;
+		pr_cont(" %ds/%d: %ld:%ld",
+			j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders,
+			rcutorture_seq_diff(gps, gps_old));
+		gps_old = gps;
+	}
+	pr_cont("\n");
+}
+
+/* Callback function for continuous-flood RCU callbacks. */
+static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
+{
+	unsigned long flags;
+	int i;
+	struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
+	struct rcu_fwd_cb **rfcpp;
+
+	rfcp->rfc_next = NULL;
+	rfcp->rfc_gps++;
+	spin_lock_irqsave(&rcu_fwd_lock, flags);
+	rfcpp = rcu_fwd_cb_tail;
+	rcu_fwd_cb_tail = &rfcp->rfc_next;
+	WRITE_ONCE(*rfcpp, rfcp);
+	WRITE_ONCE(n_launders_cb, n_launders_cb + 1);
+	i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
+	if (i >= ARRAY_SIZE(n_launders_hist))
+		i = ARRAY_SIZE(n_launders_hist) - 1;
+	n_launders_hist[i].n_launders++;
+	n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
+	spin_unlock_irqrestore(&rcu_fwd_lock, flags);
+}
+
+// Give the scheduler a chance, even on nohz_full CPUs.
+static void rcu_torture_fwd_prog_cond_resched(unsigned long iter)
+{
+	if (IS_ENABLED(CONFIG_PREEMPT) && IS_ENABLED(CONFIG_NO_HZ_FULL)) {
+		// Real call_rcu() floods hit userspace, so emulate that.
+		if (need_resched() || (iter & 0xfff))
+			schedule();
+	} else {
+		// No userspace emulation: CB invocation throttles call_rcu()
+		cond_resched();
+	}
+}
+
+/*
+ * Free all callbacks on the rcu_fwd_cb_head list, either because the
+ * test is over or because we hit an OOM event.
+ */
+static unsigned long rcu_torture_fwd_prog_cbfree(void)
+{
+	unsigned long flags;
+	unsigned long freed = 0;
+	struct rcu_fwd_cb *rfcp;
+
+	for (;;) {
+		spin_lock_irqsave(&rcu_fwd_lock, flags);
+		rfcp = rcu_fwd_cb_head;
+		if (!rfcp) {
+			spin_unlock_irqrestore(&rcu_fwd_lock, flags);
+			break;
+		}
+		rcu_fwd_cb_head = rfcp->rfc_next;
+		if (!rcu_fwd_cb_head)
+			rcu_fwd_cb_tail = &rcu_fwd_cb_head;
+		spin_unlock_irqrestore(&rcu_fwd_lock, flags);
+		kfree(rfcp);
+		freed++;
+		rcu_torture_fwd_prog_cond_resched(freed);
+	}
+	return freed;
+}
+
+/* Carry out need_resched()/cond_resched() forward-progress testing. */
+static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
+{
+	unsigned long cver;
+	unsigned long dur;
+	struct fwd_cb_state fcs;
+	unsigned long gps;
+	int idx;
+	int sd;
+	int sd4;
+	bool selfpropcb = false;
+	unsigned long stopat;
+	static DEFINE_TORTURE_RANDOM(trs);
+
+	if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
+		init_rcu_head_on_stack(&fcs.rh);
+		selfpropcb = true;
+	}
+
+	/* Tight loop containing cond_resched(). */
+	WRITE_ONCE(rcu_fwd_cb_nodelay, true);
+	cur_ops->sync(); /* Later readers see above write. */
+	if  (selfpropcb) {
+		WRITE_ONCE(fcs.stop, 0);
+		cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
+	}
+	cver = READ_ONCE(rcu_torture_current_version);
+	gps = cur_ops->get_gp_seq();
+	sd = cur_ops->stall_dur() + 1;
+	sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
+	dur = sd4 + torture_random(&trs) % (sd - sd4);
+	WRITE_ONCE(rcu_fwd_startat, jiffies);
+	stopat = rcu_fwd_startat + dur;
+	while (time_before(jiffies, stopat) &&
+	       !shutdown_time_arrived() &&
+	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
+		idx = cur_ops->readlock();
+		udelay(10);
+		cur_ops->readunlock(idx);
+		if (!fwd_progress_need_resched || need_resched())
+			rcu_torture_fwd_prog_cond_resched(1);
+	}
+	(*tested_tries)++;
+	if (!time_before(jiffies, stopat) &&
+	    !shutdown_time_arrived() &&
+	    !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
+		(*tested)++;
+		cver = READ_ONCE(rcu_torture_current_version) - cver;
+		gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
+		WARN_ON(!cver && gps < 2);
+		pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
+	}
+	if (selfpropcb) {
+		WRITE_ONCE(fcs.stop, 1);
+		cur_ops->sync(); /* Wait for running CB to complete. */
+		cur_ops->cb_barrier(); /* Wait for queued callbacks. */
+	}
+
+	if (selfpropcb) {
+		WARN_ON(READ_ONCE(fcs.stop) != 2);
+		destroy_rcu_head_on_stack(&fcs.rh);
+	}
+	schedule_timeout_uninterruptible(HZ / 10); /* Let kthreads recover. */
+	WRITE_ONCE(rcu_fwd_cb_nodelay, false);
+}
+
+/* Carry out call_rcu() forward-progress testing. */
+static void rcu_torture_fwd_prog_cr(void)
+{
+	unsigned long cver;
+	unsigned long gps;
+	int i;
+	long n_launders;
+	long n_launders_cb_snap;
+	long n_launders_sa;
+	long n_max_cbs;
+	long n_max_gps;
+	struct rcu_fwd_cb *rfcp;
+	struct rcu_fwd_cb *rfcpn;
+	unsigned long stopat;
+	unsigned long stoppedat;
+
+	if (READ_ONCE(rcu_fwd_emergency_stop))
+		return; /* Get out of the way quickly, no GP wait! */
+	if (!cur_ops->call)
+		return; /* Can't do call_rcu() fwd prog without ->call. */
+
+	/* Loop continuously posting RCU callbacks. */
+	WRITE_ONCE(rcu_fwd_cb_nodelay, true);
+	cur_ops->sync(); /* Later readers see above write. */
+	WRITE_ONCE(rcu_fwd_startat, jiffies);
+	stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
+	n_launders = 0;
+	n_launders_cb = 0;
+	n_launders_sa = 0;
+	n_max_cbs = 0;
+	n_max_gps = 0;
+	for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
+		n_launders_hist[i].n_launders = 0;
+	cver = READ_ONCE(rcu_torture_current_version);
+	gps = cur_ops->get_gp_seq();
+	rcu_launder_gp_seq_start = gps;
+	while (time_before(jiffies, stopat) &&
+	       !shutdown_time_arrived() &&
+	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
+		rfcp = READ_ONCE(rcu_fwd_cb_head);
+		rfcpn = NULL;
+		if (rfcp)
+			rfcpn = READ_ONCE(rfcp->rfc_next);
+		if (rfcpn) {
+			if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
+			    ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
+				break;
+			rcu_fwd_cb_head = rfcpn;
+			n_launders++;
+			n_launders_sa++;
+		} else {
+			rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
+			if (WARN_ON_ONCE(!rfcp)) {
+				schedule_timeout_interruptible(1);
+				continue;
+			}
+			n_max_cbs++;
+			n_launders_sa = 0;
+			rfcp->rfc_gps = 0;
+		}
+		cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
+		rcu_torture_fwd_prog_cond_resched(n_launders + n_max_cbs);
+	}
+	stoppedat = jiffies;
+	n_launders_cb_snap = READ_ONCE(n_launders_cb);
+	cver = READ_ONCE(rcu_torture_current_version) - cver;
+	gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
+	cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
+	(void)rcu_torture_fwd_prog_cbfree();
+
+	if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop) &&
+	    !shutdown_time_arrived()) {
+		WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
+		pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
+			 __func__,
+			 stoppedat - rcu_fwd_startat, jiffies - stoppedat,
+			 n_launders + n_max_cbs - n_launders_cb_snap,
+			 n_launders, n_launders_sa,
+			 n_max_gps, n_max_cbs, cver, gps);
+		rcu_torture_fwd_cb_hist();
+	}
+	schedule_timeout_uninterruptible(HZ); /* Let CBs drain. */
+	WRITE_ONCE(rcu_fwd_cb_nodelay, false);
+}
+
+
+/*
+ * OOM notifier, but this only prints diagnostic information for the
+ * current forward-progress test.
+ */
+static int rcutorture_oom_notify(struct notifier_block *self,
+				 unsigned long notused, void *nfreed)
+{
+	WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
+	     __func__);
+	rcu_torture_fwd_cb_hist();
+	rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat)) / 2);
+	WRITE_ONCE(rcu_fwd_emergency_stop, true);
+	smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
+	pr_info("%s: Freed %lu RCU callbacks.\n",
+		__func__, rcu_torture_fwd_prog_cbfree());
+	rcu_barrier();
+	pr_info("%s: Freed %lu RCU callbacks.\n",
+		__func__, rcu_torture_fwd_prog_cbfree());
+	rcu_barrier();
+	pr_info("%s: Freed %lu RCU callbacks.\n",
+		__func__, rcu_torture_fwd_prog_cbfree());
+	smp_mb(); /* Frees before return to avoid redoing OOM. */
+	(*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
+	pr_info("%s returning after OOM processing.\n", __func__);
+	return NOTIFY_OK;
+}
+
+static struct notifier_block rcutorture_oom_nb = {
+	.notifier_call = rcutorture_oom_notify
+};
+
+/* Carry out grace-period forward-progress testing. */
+static int rcu_torture_fwd_prog(void *args)
+{
+	int tested = 0;
+	int tested_tries = 0;
+
+	VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
+	rcu_bind_current_to_nocb();
+	if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
+		set_user_nice(current, MAX_NICE);
+	do {
+		schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
+		WRITE_ONCE(rcu_fwd_emergency_stop, false);
+		register_oom_notifier(&rcutorture_oom_nb);
+		rcu_torture_fwd_prog_nr(&tested, &tested_tries);
+		rcu_torture_fwd_prog_cr();
+		unregister_oom_notifier(&rcutorture_oom_nb);
+
+		/* Avoid slow periods, better to test when busy. */
+		stutter_wait("rcu_torture_fwd_prog");
+	} while (!torture_must_stop());
+	/* Short runs might not contain a valid forward-progress attempt. */
+	WARN_ON(!tested && tested_tries >= 5);
+	pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
+	torture_kthread_stopping("rcu_torture_fwd_prog");
+	return 0;
+}
+
+/* If forward-progress checking is requested and feasible, spawn the thread. */
+static int __init rcu_torture_fwd_prog_init(void)
+{
+	if (!fwd_progress)
+		return 0; /* Not requested, so don't do it. */
+	if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
+	    cur_ops == &rcu_busted_ops) {
+		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
+		return 0;
+	}
+	if (stall_cpu > 0) {
+		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
+		if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
+			return -EINVAL; /* In module, can fail back to user. */
+		WARN_ON(1); /* Make sure rcutorture notices conflict. */
+		return 0;
+	}
+	if (fwd_progress_holdoff <= 0)
+		fwd_progress_holdoff = 1;
+	if (fwd_progress_div <= 0)
+		fwd_progress_div = 4;
+	return torture_create_kthread(rcu_torture_fwd_prog,
+				      NULL, fwd_prog_task);
+}
+
 /* Callback function for RCU barrier testing. */
 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
 {
@@ -1817,6 +2161,7 @@
 static void
 rcu_torture_cleanup(void)
 {
+	int firsttime;
 	int flags = 0;
 	unsigned long gp_seq = 0;
 	int i;
@@ -1826,8 +2171,14 @@
 			cur_ops->cb_barrier();
 		return;
 	}
+	if (!cur_ops) {
+		torture_cleanup_end();
+		return;
+	}
 
+	show_rcu_gp_kthreads();
 	rcu_torture_barrier_cleanup();
+	torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
 	torture_stop_kthread(rcu_torture_stall, stall_task);
 	torture_stop_kthread(rcu_torture_writer, writer_task);
 
@@ -1854,13 +2205,11 @@
 		 cur_ops->name, gp_seq, flags);
 	torture_stop_kthread(rcu_torture_stats, stats_task);
 	torture_stop_kthread(rcu_torture_fqs, fqs_task);
-	for (i = 0; i < ncbflooders; i++)
-		torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
 	if (rcu_torture_can_boost())
 		cpuhp_remove_state(rcutor_hp);
 
 	/*
-	 * Wait for all RCU callbacks to fire, then do flavor-specific
+	 * Wait for all RCU callbacks to fire, then do torture-type-specific
 	 * cleanup operations.
 	 */
 	if (cur_ops->cb_barrier != NULL)
@@ -1870,6 +2219,33 @@
 
 	rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
 
+	if (err_segs_recorded) {
+		pr_alert("Failure/close-call rcutorture reader segments:\n");
+		if (rt_read_nsegs == 0)
+			pr_alert("\t: No segments recorded!!!\n");
+		firsttime = 1;
+		for (i = 0; i < rt_read_nsegs; i++) {
+			pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
+			if (err_segs[i].rt_delay_jiffies != 0) {
+				pr_cont("%s%ldjiffies", firsttime ? "" : "+",
+					err_segs[i].rt_delay_jiffies);
+				firsttime = 0;
+			}
+			if (err_segs[i].rt_delay_ms != 0) {
+				pr_cont("%s%ldms", firsttime ? "" : "+",
+					err_segs[i].rt_delay_ms);
+				firsttime = 0;
+			}
+			if (err_segs[i].rt_delay_us != 0) {
+				pr_cont("%s%ldus", firsttime ? "" : "+",
+					err_segs[i].rt_delay_us);
+				firsttime = 0;
+			}
+			pr_cont("%s\n",
+				err_segs[i].rt_preempted ? "preempted" : "");
+
+		}
+	}
 	if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
 		rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
 	else if (torture_onoff_failures())
@@ -1936,15 +2312,23 @@
 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
 }
 
+static void rcutorture_sync(void)
+{
+	static unsigned long n;
+
+	if (cur_ops->sync && !(++n & 0xfff))
+		cur_ops->sync();
+}
+
 static int __init
 rcu_torture_init(void)
 {
-	int i;
+	long i;
 	int cpu;
 	int firsterr = 0;
 	static struct rcu_torture_ops *torture_ops[] = {
-		&rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
-		&busted_srcud_ops, &sched_ops, &tasks_ops,
+		&rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
+		&busted_srcud_ops, &tasks_ops, &trivial_ops,
 	};
 
 	if (!torture_init_begin(torture_type, verbose))
@@ -1963,7 +2347,9 @@
 		for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
 			pr_cont(" %s", torture_ops[i]->name);
 		pr_cont("\n");
+		WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
 		firsterr = -EINVAL;
+		cur_ops = NULL;
 		goto unwind;
 	}
 	if (cur_ops->fqs == NULL && fqs_duration != 0) {
@@ -2013,6 +2399,8 @@
 			per_cpu(rcu_torture_batch, cpu)[i] = 0;
 		}
 	}
+	err_segs_recorded = 0;
+	rt_read_nsegs = 0;
 
 	/* Start up the kthreads. */
 
@@ -2044,7 +2432,7 @@
 		goto unwind;
 	}
 	for (i = 0; i < nrealreaders; i++) {
-		firsterr = torture_create_kthread(rcu_torture_reader, NULL,
+		firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
 						  reader_tasks[i]);
 		if (firsterr)
 			goto unwind;
@@ -2063,7 +2451,10 @@
 	if (stutter < 0)
 		stutter = 0;
 	if (stutter) {
-		firsterr = torture_stutter_init(stutter * HZ);
+		int t;
+
+		t = cur_ops->stall_dur ? cur_ops->stall_dur() : stutter * HZ;
+		firsterr = torture_stutter_init(stutter * HZ, t);
 		if (firsterr)
 			goto unwind;
 	}
@@ -2091,38 +2482,25 @@
 			goto unwind;
 		rcutor_hp = firsterr;
 	}
+	shutdown_jiffies = jiffies + shutdown_secs * HZ;
 	firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
 	if (firsterr)
 		goto unwind;
-	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval);
+	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
+				      rcutorture_sync);
 	if (firsterr)
 		goto unwind;
 	firsterr = rcu_torture_stall_init();
 	if (firsterr)
 		goto unwind;
+	firsterr = rcu_torture_fwd_prog_init();
+	if (firsterr)
+		goto unwind;
 	firsterr = rcu_torture_barrier_init();
 	if (firsterr)
 		goto unwind;
 	if (object_debug)
 		rcu_test_debug_objects();
-	if (cbflood_n_burst > 0) {
-		/* Create the cbflood threads */
-		ncbflooders = (num_online_cpus() + 3) / 4;
-		cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
-				       GFP_KERNEL);
-		if (!cbflood_task) {
-			VERBOSE_TOROUT_ERRSTRING("out of memory");
-			firsterr = -ENOMEM;
-			goto unwind;
-		}
-		for (i = 0; i < ncbflooders; i++) {
-			firsterr = torture_create_kthread(rcu_torture_cbflood,
-							  NULL,
-							  cbflood_task[i]);
-			if (firsterr)
-				goto unwind;
-		}
-	}
 	torture_init_end();
 	return 0;