[PATCH 00/23] RCU/lock torture updates for v6.7

[PATCH 00/23] RCU/lock torture updates for v6.7

[Frederic Weisbecker]

Hello,

Please find below the updates for RCU torture, locktorture and the
generic torture infrastructure.

Arnd Bergmann (1):
  rcu: Include torture_sched_setaffinity() declaration

Dan Carpenter (1):
  locktorture: Check the correct variable for allocation failure

Joel Fernandes (Google) (3):
  rcutorture: Fix stuttering races and other issues
  rcutorture: Copy out ftrace into its own console file
  rcutorture: Replace schedule_timeout*() 1-jiffy waits with HZ/20

Paul E. McKenney (17):
  torture: Share torture_random_state with torture_shuffle_tasks()
  torture: Make kvm-recheck.sh use mktemp
  torture: Make torture_hrtimeout_ns() take an hrtimer mode parameter
  torture: Move rcutorture_sched_setaffinity() out of rcutorture
  locktorture: Add readers_bind and writers_bind module parameters
  rcutorture: Add CONFIG_DEBUG_OBJECTS to RCU Tasks testing
  locktorture: Alphabetize torture_param() entries
  locktorture: Consolidate "if" statements in lock_torture_writer()
  locktorture: Add acq_writer_lim to complain about long acquistion
    times
  torture: Print out torture module parameters
  torture: Make torture.sh refscale testing qualify verbose_batched
  locktorture: Add new module parameters to
    lock_torture_print_module_parms()
  locktorture: Add call_rcu_chains module parameter
  doc: Catch-up update for locktorture module parameters
  locktorture: Rename readers_bind/writers_bind to
    bind_readers/bind_writers
  torture: Add kvm.sh --debug-info argument
  torture: Convert parse-console.sh to mktemp

Zqiang (1):
  rcutorture: Traverse possible cpu to set maxcpu in rcu_nocb_toggle()

Thanks,
        Frederic.

 .../admin-guide/kernel-parameters.txt         |  57 ++++-
 include/linux/torture.h                       |   8 +-
 kernel/locking/locktorture.c                  | 216 +++++++++++++-----
 kernel/rcu/rcu.h                              |   4 -
 kernel/rcu/rcutorture.c                       |  16 +-
 kernel/rcu/update.c                           |   9 +-
 kernel/torture.c                              |  75 +++---
 .../selftests/rcutorture/bin/functions.sh     |  29 +++
 .../selftests/rcutorture/bin/kvm-recheck.sh   |   2 +-
 tools/testing/selftests/rcutorture/bin/kvm.sh |  17 +-
 .../selftests/rcutorture/bin/parse-console.sh |   9 +-
 .../selftests/rcutorture/bin/torture.sh       |   2 +-
 .../selftests/rcutorture/configs/rcu/TRACE02  |   1 +
 13 files changed, 322 insertions(+), 123 deletions(-)
 mode change 100644 => 100755 tools/testing/selftests/rcutorture/bin/functions.sh

-- 
2.34.1

[PATCH 01/23] torture: Share torture_random_state with torture_shuffle_tasks()

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

Both torture_shuffle_tasks() and its caller torture_shuffle()
define a torture_random_state structure.  This is suboptimal given
that torture_shuffle_tasks() runs for a very short period of time.
This commit therefore causes torture_shuffle() to pass a pointer to its
torture_random_state structure down to torture_shuffle_tasks().

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/torture.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/kernel/torture.c b/kernel/torture.c
index b28b05bbef02..68dba4ecab5c 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -520,9 +520,8 @@ static void torture_shuffle_task_unregister_all(void)
  * A special case is when shuffle_idle_cpu = -1, in which case we allow
  * the tasks to run on all CPUs.
  */
-static void torture_shuffle_tasks(void)
+static void torture_shuffle_tasks(struct torture_random_state *trp)
 {
-	DEFINE_TORTURE_RANDOM(rand);
 	struct shuffle_task *stp;
 
 	cpumask_setall(shuffle_tmp_mask);
@@ -543,7 +542,7 @@ static void torture_shuffle_tasks(void)
 
 	mutex_lock(&shuffle_task_mutex);
 	list_for_each_entry(stp, &shuffle_task_list, st_l) {
-		if (!random_shuffle || torture_random(&rand) & 0x1)
+		if (!random_shuffle || torture_random(trp) & 0x1)
 			set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
 	}
 	mutex_unlock(&shuffle_task_mutex);
@@ -562,7 +561,7 @@ static int torture_shuffle(void *arg)
 	VERBOSE_TOROUT_STRING("torture_shuffle task started");
 	do {
 		torture_hrtimeout_jiffies(shuffle_interval, &rand);
-		torture_shuffle_tasks();
+		torture_shuffle_tasks(&rand);
 		torture_shutdown_absorb("torture_shuffle");
 	} while (!torture_must_stop());
 	torture_kthread_stopping("torture_shuffle");
@@ -673,7 +672,7 @@ int torture_shutdown_init(int ssecs, void (*cleanup)(void))
 	if (ssecs > 0) {
 		shutdown_time = ktime_add(ktime_get(), ktime_set(ssecs, 0));
 		return torture_create_kthread(torture_shutdown, NULL,
-					     shutdown_task);
+					      shutdown_task);
 	}
 	return 0;
 }
-- 
2.34.1

[PATCH 02/23] torture: Make kvm-recheck.sh use mktemp

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit switches from the old "/tmp/kvm-recheck.sh.$$" approach to
the newer and now reliable "mktemp" approach.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 tools/testing/selftests/rcutorture/bin/kvm-recheck.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
index 5be670dd4009..de65d77b47ff 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-recheck.sh
@@ -13,7 +13,7 @@
 #
 # Authors: Paul E. McKenney <paulmck@linux.ibm.com>
 
-T=/tmp/kvm-recheck.sh.$$
+T="`mktemp ${TMPDIR-/tmp}/kvm-recheck.sh.XXXXXX`"
 trap 'rm -f $T' 0 2
 
 configerrors=0
-- 
2.34.1

[PATCH 03/23] torture: Make torture_hrtimeout_ns() take an hrtimer mode parameter

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

The current torture-test sleeps are waiting for a duration, but there
are situations where it is better to wait for an absolute time, for
example, when ending a stutter interval.  This commit therefore adds
an hrtimer mode parameter to torture_hrtimeout_ns().  Why not also the
other torture_hrtimeout_*() functions?  The theory is that most absolute
times will be in nanoseconds, especially not (say) jiffies.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 include/linux/torture.h |  3 ++-
 kernel/torture.c        | 13 +++++++------
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/include/linux/torture.h b/include/linux/torture.h
index bb466eec01e4..017f0f710815 100644
--- a/include/linux/torture.h
+++ b/include/linux/torture.h
@@ -81,7 +81,8 @@ static inline void torture_random_init(struct torture_random_state *trsp)
 }
 
 /* Definitions for high-resolution-timer sleeps. */
-int torture_hrtimeout_ns(ktime_t baset_ns, u32 fuzzt_ns, struct torture_random_state *trsp);
+int torture_hrtimeout_ns(ktime_t baset_ns, u32 fuzzt_ns, const enum hrtimer_mode mode,
+			 struct torture_random_state *trsp);
 int torture_hrtimeout_us(u32 baset_us, u32 fuzzt_ns, struct torture_random_state *trsp);
 int torture_hrtimeout_ms(u32 baset_ms, u32 fuzzt_us, struct torture_random_state *trsp);
 int torture_hrtimeout_jiffies(u32 baset_j, struct torture_random_state *trsp);
diff --git a/kernel/torture.c b/kernel/torture.c
index 68dba4ecab5c..6ba62e5993e7 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -87,14 +87,15 @@ EXPORT_SYMBOL_GPL(verbose_torout_sleep);
  * nanosecond random fuzz.  This function and its friends desynchronize
  * testing from the timer wheel.
  */
-int torture_hrtimeout_ns(ktime_t baset_ns, u32 fuzzt_ns, struct torture_random_state *trsp)
+int torture_hrtimeout_ns(ktime_t baset_ns, u32 fuzzt_ns, const enum hrtimer_mode mode,
+			 struct torture_random_state *trsp)
 {
 	ktime_t hto = baset_ns;
 
 	if (trsp)
 		hto += torture_random(trsp) % fuzzt_ns;
 	set_current_state(TASK_IDLE);
-	return schedule_hrtimeout(&hto, HRTIMER_MODE_REL);
+	return schedule_hrtimeout(&hto, mode);
 }
 EXPORT_SYMBOL_GPL(torture_hrtimeout_ns);
 
@@ -106,7 +107,7 @@ int torture_hrtimeout_us(u32 baset_us, u32 fuzzt_ns, struct torture_random_state
 {
 	ktime_t baset_ns = baset_us * NSEC_PER_USEC;
 
-	return torture_hrtimeout_ns(baset_ns, fuzzt_ns, trsp);
+	return torture_hrtimeout_ns(baset_ns, fuzzt_ns, HRTIMER_MODE_REL, trsp);
 }
 EXPORT_SYMBOL_GPL(torture_hrtimeout_us);
 
@@ -123,7 +124,7 @@ int torture_hrtimeout_ms(u32 baset_ms, u32 fuzzt_us, struct torture_random_state
 		fuzzt_ns = (u32)~0U;
 	else
 		fuzzt_ns = fuzzt_us * NSEC_PER_USEC;
-	return torture_hrtimeout_ns(baset_ns, fuzzt_ns, trsp);
+	return torture_hrtimeout_ns(baset_ns, fuzzt_ns, HRTIMER_MODE_REL, trsp);
 }
 EXPORT_SYMBOL_GPL(torture_hrtimeout_ms);
 
@@ -136,7 +137,7 @@ int torture_hrtimeout_jiffies(u32 baset_j, struct torture_random_state *trsp)
 {
 	ktime_t baset_ns = jiffies_to_nsecs(baset_j);
 
-	return torture_hrtimeout_ns(baset_ns, jiffies_to_nsecs(1), trsp);
+	return torture_hrtimeout_ns(baset_ns, jiffies_to_nsecs(1), HRTIMER_MODE_REL, trsp);
 }
 EXPORT_SYMBOL_GPL(torture_hrtimeout_jiffies);
 
@@ -153,7 +154,7 @@ int torture_hrtimeout_s(u32 baset_s, u32 fuzzt_ms, struct torture_random_state *
 		fuzzt_ns = (u32)~0U;
 	else
 		fuzzt_ns = fuzzt_ms * NSEC_PER_MSEC;
-	return torture_hrtimeout_ns(baset_ns, fuzzt_ns, trsp);
+	return torture_hrtimeout_ns(baset_ns, fuzzt_ns, HRTIMER_MODE_REL, trsp);
 }
 EXPORT_SYMBOL_GPL(torture_hrtimeout_s);
 
-- 
2.34.1

[PATCH 04/23] rcu: Include torture_sched_setaffinity() declaration

[Frederic Weisbecker]

From: Arnd Bergmann <arnd@arndb.de>

The prototype for torture_sched_setaffinity() will be moved to a
different header, which will need to be included from update.c to avoid
this W=1 warning:

kernel/rcu/update.c:529:6: error: no previous prototype for 'torture_sched_setaffinity' [-Werror=missing-prototypes]
  529 | long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask)

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/rcu/update.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 19bf6fa3ee6a..9d3c2e6ba667 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -25,6 +25,7 @@
 #include <linux/interrupt.h>
 #include <linux/sched/signal.h>
 #include <linux/sched/debug.h>
+#include <linux/torture.h>
 #include <linux/atomic.h>
 #include <linux/bitops.h>
 #include <linux/percpu.h>
-- 
2.34.1

[PATCH 05/23] torture: Move rcutorture_sched_setaffinity() out of rcutorture

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

The rcutorture_sched_setaffinity() function is needed by locktorture,
so move its declaration from rcu.h to torture.h and rename it to the
more generic torture_sched_setaffinity() name.

Please note that use of this function is still restricted to torture
tests, and of those, currently only rcutorture and locktorture.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 include/linux/torture.h | 5 +++++
 kernel/rcu/rcu.h        | 4 ----
 kernel/rcu/rcutorture.c | 2 +-
 kernel/rcu/update.c     | 8 ++++----
 4 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/include/linux/torture.h b/include/linux/torture.h
index 017f0f710815..c98d0c83d117 100644
--- a/include/linux/torture.h
+++ b/include/linux/torture.h
@@ -121,10 +121,15 @@ void _torture_stop_kthread(char *m, struct task_struct **tp);
 #define torture_stop_kthread(n, tp) \
 	_torture_stop_kthread("Stopping " #n " task", &(tp))
 
+/* Scheduler-related definitions. */
 #ifdef CONFIG_PREEMPTION
 #define torture_preempt_schedule() __preempt_schedule()
 #else
 #define torture_preempt_schedule()	do { } while (0)
 #endif
 
+#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) || IS_ENABLED(CONFIG_LOCK_TORTURE_TEST) || IS_MODULE(CONFIG_LOCK_TORTURE_TEST)
+long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask);
+#endif
+
 #endif /* __LINUX_TORTURE_H */
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index 98e13be411af..567bd3d72e39 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -568,10 +568,6 @@ void do_trace_rcu_torture_read(const char *rcutorturename,
 static inline void rcu_gp_set_torture_wait(int duration) { }
 #endif
 
-#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST)
-long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask);
-#endif
-
 #ifdef CONFIG_TINY_SRCU
 
 static inline void srcutorture_get_gp_data(enum rcutorture_type test_type,
diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index ade42d6a9d9b..7e82fb887d09 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -810,7 +810,7 @@ static void synchronize_rcu_trivial(void)
 	int cpu;
 
 	for_each_online_cpu(cpu) {
-		rcutorture_sched_setaffinity(current->pid, cpumask_of(cpu));
+		torture_sched_setaffinity(current->pid, cpumask_of(cpu));
 		WARN_ON_ONCE(raw_smp_processor_id() != cpu);
 	}
 }
diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 9d3c2e6ba667..c534d6806d3d 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -525,17 +525,17 @@ EXPORT_SYMBOL_GPL(do_trace_rcu_torture_read);
 	do { } while (0)
 #endif
 
-#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST)
+#if IS_ENABLED(CONFIG_RCU_TORTURE_TEST) || IS_MODULE(CONFIG_RCU_TORTURE_TEST) || IS_ENABLED(CONFIG_LOCK_TORTURE_TEST) || IS_MODULE(CONFIG_LOCK_TORTURE_TEST)
 /* Get rcutorture access to sched_setaffinity(). */
-long rcutorture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
+long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
 {
 	int ret;
 
 	ret = sched_setaffinity(pid, in_mask);
-	WARN_ONCE(ret, "%s: sched_setaffinity() returned %d\n", __func__, ret);
+	WARN_ONCE(ret, "%s: sched_setaffinity(%d) returned %d\n", __func__, pid, ret);
 	return ret;
 }
-EXPORT_SYMBOL_GPL(rcutorture_sched_setaffinity);
+EXPORT_SYMBOL_GPL(torture_sched_setaffinity);
 #endif
 
 #ifdef CONFIG_RCU_STALL_COMMON
-- 
2.34.1

[PATCH 06/23] locktorture: Add readers_bind and writers_bind module parameters

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit adds readers_bind and writers_bind module parameters to
locktorture in order to skew tests across socket boundaries.  This skewing
is intended to provide additional variable-latency stress on the primitive
under test.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/locking/locktorture.c | 64 ++++++++++++++++++++++++++++++++++--
 1 file changed, 62 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 270c7f80ce84..441866259278 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -56,6 +56,55 @@ module_param(torture_type, charp, 0444);
 MODULE_PARM_DESC(torture_type,
 		 "Type of lock to torture (spin_lock, spin_lock_irq, mutex_lock, ...)");
 
+static cpumask_var_t readers_bind; // Bind the readers to the specified set of CPUs.
+static cpumask_var_t writers_bind; // Bind the writers to the specified set of CPUs.
+
+// Parse a cpumask kernel parameter.  If there are more users later on,
+// this might need to got to a more central location.
+static int param_set_cpumask(const char *val, const struct kernel_param *kp)
+{
+	cpumask_var_t *cm_bind = kp->arg;
+	int ret;
+	char *s;
+
+	if (!alloc_cpumask_var(cm_bind, GFP_KERNEL)) {
+		s = "Out of memory";
+		ret = -ENOMEM;
+		goto out_err;
+	}
+	ret = cpulist_parse(val, *cm_bind);
+	if (!ret)
+		return ret;
+	s = "Bad CPU range";
+out_err:
+	pr_warn("%s: %s, all CPUs set\n", kp->name, s);
+	cpumask_setall(*cm_bind);
+	return ret;
+}
+
+// Output a cpumask kernel parameter.
+static int param_get_cpumask(char *buffer, const struct kernel_param *kp)
+{
+	cpumask_var_t *cm_bind = kp->arg;
+
+	return sprintf(buffer, "%*pbl", cpumask_pr_args(*cm_bind));
+}
+
+static bool cpumask_nonempty(cpumask_var_t mask)
+{
+	return cpumask_available(mask) && !cpumask_empty(mask);
+}
+
+static const struct kernel_param_ops lt_bind_ops = {
+	.set = param_set_cpumask,
+	.get = param_get_cpumask,
+};
+
+module_param_cb(readers_bind, &lt_bind_ops, &readers_bind, 0644);
+module_param_cb(writers_bind, &lt_bind_ops, &writers_bind, 0644);
+
+long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask);
+
 static struct task_struct *stats_task;
 static struct task_struct **writer_tasks;
 static struct task_struct **reader_tasks;
@@ -986,16 +1035,23 @@ static int lock_torture_stats(void *arg)
 	return 0;
 }
 
+
 static inline void
 lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
 				const char *tag)
 {
+	static cpumask_t cpumask_all;
+	cpumask_t *rcmp = cpumask_nonempty(readers_bind) ? readers_bind : &cpumask_all;
+	cpumask_t *wcmp = cpumask_nonempty(writers_bind) ? writers_bind : &cpumask_all;
+
+	cpumask_setall(&cpumask_all);
 	pr_alert("%s" TORTURE_FLAG
-		 "--- %s%s: nwriters_stress=%d nreaders_stress=%d nested_locks=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d\n",
+		 "--- %s%s: nwriters_stress=%d nreaders_stress=%d nested_locks=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d readers_bind=%*pbl writers_bind=%*pbl\n",
 		 torture_type, tag, cxt.debug_lock ? " [debug]": "",
 		 cxt.nrealwriters_stress, cxt.nrealreaders_stress,
 		 nested_locks, stat_interval, verbose, shuffle_interval,
-		 stutter, shutdown_secs, onoff_interval, onoff_holdoff);
+		 stutter, shutdown_secs, onoff_interval, onoff_holdoff,
+		 cpumask_pr_args(rcmp), cpumask_pr_args(wcmp));
 }
 
 static void lock_torture_cleanup(void)
@@ -1250,6 +1306,8 @@ static int __init lock_torture_init(void)
 						     writer_fifo ? sched_set_fifo : NULL);
 		if (torture_init_error(firsterr))
 			goto unwind;
+		if (cpumask_nonempty(writers_bind))
+			torture_sched_setaffinity(writer_tasks[i]->pid, writers_bind);
 
 	create_reader:
 		if (cxt.cur_ops->readlock == NULL || (j >= cxt.nrealreaders_stress))
@@ -1259,6 +1317,8 @@ static int __init lock_torture_init(void)
 						  reader_tasks[j]);
 		if (torture_init_error(firsterr))
 			goto unwind;
+		if (cpumask_nonempty(readers_bind))
+			torture_sched_setaffinity(reader_tasks[j]->pid, readers_bind);
 	}
 	if (stat_interval > 0) {
 		firsterr = torture_create_kthread(lock_torture_stats, NULL,
-- 
2.34.1

[PATCH 07/23] rcutorture: Add CONFIG_DEBUG_OBJECTS to RCU Tasks testing

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit adds CONFIG_DEBUG_OBJECTS=y to the TRACE02 rcutorture scenario
to catch any further RCU Tasks bugs involving this Kconfig option.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 tools/testing/selftests/rcutorture/configs/rcu/TRACE02 | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRACE02 b/tools/testing/selftests/rcutorture/configs/rcu/TRACE02
index 093ea6e8e65c..9003c56cd764 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TRACE02
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TRACE02
@@ -11,3 +11,4 @@ CONFIG_FORCE_TASKS_TRACE_RCU=y
 #CHECK#CONFIG_TASKS_TRACE_RCU=y
 CONFIG_TASKS_TRACE_RCU_READ_MB=n
 CONFIG_RCU_EXPERT=y
+CONFIG_DEBUG_OBJECTS=y
-- 
2.34.1

[PATCH 08/23] rcutorture: Fix stuttering races and other issues

[Frederic Weisbecker]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

The stuttering code isn't functioning as expected. Ideally, it should
pause the torture threads for a designated period before resuming. Yet,
it fails to halt the test for the correct duration. Additionally, a race
condition exists, potentially causing the stuttering code to pause for
an extended period if the 'spt' variable is non-zero due to the stutter
orchestration thread's inadequate CPU time.

Moreover, over-stuttering can hinder RCU's progress on TREE07 kernels.
This happens as the stuttering code may run within a softirq due to RCU
callbacks. Consequently, ksoftirqd keeps a CPU busy for several seconds,
thus obstructing RCU's progress. This situation triggers a warning
message in the logs:

[ 2169.481783] rcu_torture_writer: rtort_pipe_count: 9

This warning suggests that an RCU torture object, although invisible to
RCU readers, couldn't make it past the pipe array and be freed -- a
strong indication that there weren't enough grace periods during the
stutter interval.

To address these issues, this patch sets the "stutter end" time to an
absolute point in the future set by the main stutter thread. This is
then used for waiting in stutter_wait(). While the stutter thread still
defines this absolute time, the waiters' waiting logic doesn't rely on
the stutter thread receiving sufficient CPU time to halt the stuttering
as the halting is now self-controlled.

Cc: stable@vger.kernel.org
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/torture.c | 45 ++++++++++++---------------------------------
 1 file changed, 12 insertions(+), 33 deletions(-)

diff --git a/kernel/torture.c b/kernel/torture.c
index 6ba62e5993e7..fd353f98162f 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -720,7 +720,7 @@ static void torture_shutdown_cleanup(void)
  * suddenly applied to or removed from the system.
  */
 static struct task_struct *stutter_task;
-static int stutter_pause_test;
+static ktime_t stutter_till_abs_time;
 static int stutter;
 static int stutter_gap;
 
@@ -730,30 +730,16 @@ static int stutter_gap;
  */
 bool stutter_wait(const char *title)
 {
-	unsigned int i = 0;
 	bool ret = false;
-	int spt;
+	ktime_t till_ns;
 
 	cond_resched_tasks_rcu_qs();
-	spt = READ_ONCE(stutter_pause_test);
-	for (; spt; spt = READ_ONCE(stutter_pause_test)) {
-		if (!ret && !rt_task(current)) {
-			sched_set_normal(current, MAX_NICE);
-			ret = true;
-		}
-		if (spt == 1) {
-			torture_hrtimeout_jiffies(1, NULL);
-		} else if (spt == 2) {
-			while (READ_ONCE(stutter_pause_test)) {
-				if (!(i++ & 0xffff))
-					torture_hrtimeout_us(10, 0, NULL);
-				cond_resched();
-			}
-		} else {
-			torture_hrtimeout_jiffies(round_jiffies_relative(HZ), NULL);
-		}
-		torture_shutdown_absorb(title);
+	till_ns = READ_ONCE(stutter_till_abs_time);
+	if (till_ns && ktime_before(ktime_get(), till_ns)) {
+		torture_hrtimeout_ns(till_ns, 0, HRTIMER_MODE_ABS, NULL);
+		ret = true;
 	}
+	torture_shutdown_absorb(title);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(stutter_wait);
@@ -764,23 +750,16 @@ EXPORT_SYMBOL_GPL(stutter_wait);
  */
 static int torture_stutter(void *arg)
 {
-	DEFINE_TORTURE_RANDOM(rand);
-	int wtime;
+	ktime_t till_ns;
 
 	VERBOSE_TOROUT_STRING("torture_stutter task started");
 	do {
 		if (!torture_must_stop() && stutter > 1) {
-			wtime = stutter;
-			if (stutter > 2) {
-				WRITE_ONCE(stutter_pause_test, 1);
-				wtime = stutter - 3;
-				torture_hrtimeout_jiffies(wtime, &rand);
-				wtime = 2;
-			}
-			WRITE_ONCE(stutter_pause_test, 2);
-			torture_hrtimeout_jiffies(wtime, NULL);
+			till_ns = ktime_add_ns(ktime_get(),
+					       jiffies_to_nsecs(stutter));
+			WRITE_ONCE(stutter_till_abs_time, till_ns);
+			torture_hrtimeout_jiffies(stutter - 1, NULL);
 		}
-		WRITE_ONCE(stutter_pause_test, 0);
 		if (!torture_must_stop())
 			torture_hrtimeout_jiffies(stutter_gap, NULL);
 		torture_shutdown_absorb("torture_stutter");
-- 
2.34.1

[PATCH 09/23] locktorture: Alphabetize torture_param() entries

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

There are getting to be too many module parameters for a random list to be
comfortable, so this commit alphabetizes the list.  Strictly code motion.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/locking/locktorture.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 441866259278..57ee16cf879d 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -33,21 +33,21 @@
 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, long_hold, 100, "Do occasional long hold of lock (ms), 0=disable");
+torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)");
+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, 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, rt_boost, 2,
+		   "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, 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, 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.");
-torture_param(int, rt_boost_factor, 50, "A factor determining how often rt-boost happens.");
 torture_param(int, writer_fifo, 0, "Run writers at sched_set_fifo() priority");
 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
 
-- 
2.34.1

[PATCH 10/23] locktorture: Consolidate "if" statements in lock_torture_writer()

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

There is a pair of adjacent "if" statements with identical conditions in
the lock_torture_writer() function.  This commit therefore combines them.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/locking/locktorture.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 57ee16cf879d..c8c322e69a90 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -889,11 +889,10 @@ static int lock_torture_writer(void *arg)
 			lock_is_write_held = true;
 			if (WARN_ON_ONCE(atomic_read(&lock_is_read_held)))
 				lwsp->n_lock_fail++; /* rare, but... */
-
 			lwsp->n_lock_acquired++;
-		}
-		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);
-- 
2.34.1

[PATCH 11/23] locktorture: Add acq_writer_lim to complain about long acquistion times

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit adds a locktorture.acq_writer_lim module parameter that
specifies the maximum number of jiffies that is expected to be consumed
by write-side lock acquisition.  If this limit is exceeded, a WARN_ONCE()
causes a splat.  Note that this limit applies to the main lock acquisition
only, not to any nested acquisitions.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/locking/locktorture.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index c8c322e69a90..296815ef67ae 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -33,6 +33,7 @@
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
 
+torture_param(int, acq_writer_lim, 0, "Write_acquisition time limit (jiffies).");
 torture_param(int, long_hold, 100, "Do occasional long hold of lock (ms), 0=disable");
 torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)");
 torture_param(int, nreaders_stress, -1, "Number of read-locking stress-test threads");
@@ -852,11 +853,13 @@ static struct lock_torture_ops percpu_rwsem_lock_ops = {
  */
 static int lock_torture_writer(void *arg)
 {
-	struct lock_stress_stats *lwsp = arg;
-	int tid = lwsp - cxt.lwsa;
-	DEFINE_TORTURE_RANDOM(rand);
+	unsigned long j;
+	unsigned long j1;
 	u32 lockset_mask;
+	struct lock_stress_stats *lwsp = arg;
+	DEFINE_TORTURE_RANDOM(rand);
 	bool skip_main_lock;
+	int tid = lwsp - cxt.lwsa;
 
 	VERBOSE_TOROUT_STRING("lock_torture_writer task started");
 	if (!rt_task(current))
@@ -883,12 +886,20 @@ static int lock_torture_writer(void *arg)
 			cxt.cur_ops->nested_lock(tid, lockset_mask);
 
 		if (!skip_main_lock) {
+			if (acq_writer_lim > 0)
+				j = jiffies;
 			cxt.cur_ops->writelock(tid);
 			if (WARN_ON_ONCE(lock_is_write_held))
 				lwsp->n_lock_fail++;
 			lock_is_write_held = true;
 			if (WARN_ON_ONCE(atomic_read(&lock_is_read_held)))
 				lwsp->n_lock_fail++; /* rare, but... */
+			if (acq_writer_lim > 0) {
+				j1 = jiffies;
+				WARN_ONCE(time_after(j1, j + acq_writer_lim),
+					  "%s: Lock acquisition took %lu jiffies.\n",
+					  __func__, j1 - j);
+			}
 			lwsp->n_lock_acquired++;
 
 			cxt.cur_ops->write_delay(&rand);
-- 
2.34.1

[PATCH 12/23] rcutorture: Copy out ftrace into its own console file

[Frederic Weisbecker]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

When debugging, it can be difficult to quickly find the ftrace dump
within the console log, which in turn makes it difficult to process it
independent of the rest of the console output.  This commit therefore
copies the contents of the buffers into its own file to make it easier
to locate and process the ftrace dump. The original ftrace dump is still
available in the console log in cases because it can be more convenient
to process it in situ, for example, for scripts that process console
output as well as ftrace-dump data.

Also handle the case of multiple ftrace dumps potentially showing up in the
log. Example for a file like [1], it will extract as [2].

[1]:
foo
foo
Dumping ftrace buffer:
---------------------------------
blah
blah
---------------------------------
more
bar
baz
Dumping ftrace buffer:
---------------------------------
blah2
blah2
---------------------------------
bleh
bleh

[2]:

Ftrace dump 1:
blah
blah

Ftrace dump 2:
blah2
blah2

[ paulmck: Fixed awk indentation, input up front. ]

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 .../selftests/rcutorture/bin/functions.sh     | 29 +++++++++++++++++++
 .../selftests/rcutorture/bin/parse-console.sh |  7 +++++
 2 files changed, 36 insertions(+)
 mode change 100644 => 100755 tools/testing/selftests/rcutorture/bin/functions.sh

diff --git a/tools/testing/selftests/rcutorture/bin/functions.sh b/tools/testing/selftests/rcutorture/bin/functions.sh
old mode 100644
new mode 100755
index b8e2ea23cb3f..6e415ddb206f
--- a/tools/testing/selftests/rcutorture/bin/functions.sh
+++ b/tools/testing/selftests/rcutorture/bin/functions.sh
@@ -331,3 +331,32 @@ specify_qemu_net () {
 		echo $1 -net none
 	fi
 }
+
+# Extract the ftrace output from the console log output
+# The ftrace output in the original logs look like:
+# Dumping ftrace buffer:
+# ---------------------------------
+# [...]
+# ---------------------------------
+extract_ftrace_from_console() {
+	awk < "$1" '
+
+	/Dumping ftrace buffer:/ {
+		buffer_count++
+		print "Ftrace dump " buffer_count ":"
+		capture = 1
+		next
+	}
+
+	/---------------------------------/ {
+		if(capture == 1) {
+			capture = 2
+			next
+		} else if(capture == 2) {
+			capture = 0
+			print ""
+		}
+	}
+
+	capture == 2'
+}
diff --git a/tools/testing/selftests/rcutorture/bin/parse-console.sh b/tools/testing/selftests/rcutorture/bin/parse-console.sh
index 9ab0f6bc172c..e3d2f69ec0fb 100755
--- a/tools/testing/selftests/rcutorture/bin/parse-console.sh
+++ b/tools/testing/selftests/rcutorture/bin/parse-console.sh
@@ -182,3 +182,10 @@ if ! test -s $file.diags
 then
 	rm -f $file.diags
 fi
+
+# Call extract_ftrace_from_console function, if the output is empty,
+# don't create $file.ftrace. Otherwise output the results to $file.ftrace
+extract_ftrace_from_console $file > $file.ftrace
+if [ ! -s $file.ftrace ]; then
+	rm -f $file.ftrace
+fi
-- 
2.34.1

[PATCH 13/23] torture: Print out torture module parameters

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

The kernel/torture.c module now has several module parameters, so this
commit causes them to be printed out.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/torture.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/torture.c b/kernel/torture.c
index fd353f98162f..c72ab2d251f4 100644
--- a/kernel/torture.c
+++ b/kernel/torture.c
@@ -791,6 +791,13 @@ static void torture_stutter_cleanup(void)
 	stutter_task = NULL;
 }
 
+static void
+torture_print_module_parms(void)
+{
+	pr_alert("torture module --- %s:  disable_onoff_at_boot=%d ftrace_dump_at_shutdown=%d verbose_sleep_frequency=%d verbose_sleep_duration=%d random_shuffle=%d\n",
+		 torture_type, disable_onoff_at_boot, ftrace_dump_at_shutdown, verbose_sleep_frequency, verbose_sleep_duration, random_shuffle);
+}
+
 /*
  * Initialize torture module.  Please note that this is -not- invoked via
  * the usual module_init() mechanism, but rather by an explicit call from
@@ -813,6 +820,7 @@ bool torture_init_begin(char *ttype, int v)
 	torture_type = ttype;
 	verbose = v;
 	fullstop = FULLSTOP_DONTSTOP;
+	torture_print_module_parms();
 	return true;
 }
 EXPORT_SYMBOL_GPL(torture_init_begin);
-- 
2.34.1

[PATCH 14/23] torture: Make torture.sh refscale testing qualify verbose_batched

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

In torture.sh, the testing of refscale incorrectly used verbose_batched
as a kernel boot parameter, which causes this parameter to be passed
to the init process.  This commit therefore prefixes it with refscale,
so that refscale.verbose_batched is passed to the kernel.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 tools/testing/selftests/rcutorture/bin/torture.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/rcutorture/bin/torture.sh b/tools/testing/selftests/rcutorture/bin/torture.sh
index 12b50a4a881a..d5a0d8a33c27 100755
--- a/tools/testing/selftests/rcutorture/bin/torture.sh
+++ b/tools/testing/selftests/rcutorture/bin/torture.sh
@@ -472,7 +472,7 @@ do
 	if test -n "$firsttime"
 	then
 		torture_bootargs="refscale.scale_type="$prim" refscale.nreaders=$HALF_ALLOTED_CPUS refscale.loops=10000 refscale.holdoff=20 torture.disable_onoff_at_boot"
-		torture_set "refscale-$prim" tools/testing/selftests/rcutorture/bin/kvm.sh --torture refscale --allcpus --duration 5 --kconfig "CONFIG_TASKS_TRACE_RCU=y CONFIG_NR_CPUS=$HALF_ALLOTED_CPUS" --bootargs "verbose_batched=$VERBOSE_BATCH_CPUS torture.verbose_sleep_frequency=8 torture.verbose_sleep_duration=$VERBOSE_BATCH_CPUS" --trust-make
+		torture_set "refscale-$prim" tools/testing/selftests/rcutorture/bin/kvm.sh --torture refscale --allcpus --duration 5 --kconfig "CONFIG_TASKS_TRACE_RCU=y CONFIG_NR_CPUS=$HALF_ALLOTED_CPUS" --bootargs "refscale.verbose_batched=$VERBOSE_BATCH_CPUS torture.verbose_sleep_frequency=8 torture.verbose_sleep_duration=$VERBOSE_BATCH_CPUS" --trust-make
 		mv $T/last-resdir-nodebug $T/first-resdir-nodebug || :
 		if test -f "$T/last-resdir-kasan"
 		then
-- 
2.34.1

[PATCH 15/23] locktorture: Add new module parameters to lock_torture_print_module_parms()

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit adds new module parameters to lock_torture_print_module_parms,
and alphabetizes things while in the area.  This change makes locktorture
test results more useful and self-contained.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/locking/locktorture.c | 64 +++++++++++++-----------------------
 1 file changed, 23 insertions(+), 41 deletions(-)

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 296815ef67ae..d2a3a8cc1902 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -47,8 +47,8 @@ torture_param(int, shuffle_interval, 3, "Number of jiffies between shuffles, 0=d
 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, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
-torture_param(int, writer_fifo, 0, "Run writers at sched_set_fifo() priority");
 torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
+torture_param(int, writer_fifo, 0, "Run writers at sched_set_fifo() priority");
 /* Going much higher trips "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!" errors */
 #define MAX_NESTED_LOCKS 8
 
@@ -166,12 +166,9 @@ 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 = 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);
+	if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold)))
+		mdelay(long_hold);
 	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
@@ -244,15 +241,14 @@ __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 = 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 (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold))) {
 		j = jiffies;
-		mdelay(longdelay_ms);
+		mdelay(long_hold);
 		pr_alert("%s: delay = %lu jiffies.\n", __func__, jiffies - j);
 	}
 	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 200 * shortdelay_us)))
@@ -370,14 +366,12 @@ __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 = 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.
 	 */
-	if (!(torture_random(trsp) %
-	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
-		mdelay(longdelay_ms);
+	if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold)))
+		mdelay(long_hold);
 	else
 		udelay(shortdelay_us);
 }
@@ -398,14 +392,12 @@ __acquires(torture_rwlock)
 static void torture_rwlock_read_delay(struct torture_random_state *trsp)
 {
 	const unsigned long shortdelay_us = 10;
-	const unsigned long longdelay_ms = 100;
 
 	/* 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.nrealreaders_stress * 2000 * longdelay_ms)))
-		mdelay(longdelay_ms);
+	if (long_hold && !(torture_random(trsp) % (cxt.nrealreaders_stress * 2000 * long_hold)))
+		mdelay(long_hold);
 	else
 		udelay(shortdelay_us);
 }
@@ -503,12 +495,9 @@ __acquires(torture_mutex)
 
 static void torture_mutex_delay(struct torture_random_state *trsp)
 {
-	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);
+	if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold)))
+		mdelay(long_hold * 5);
 	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
@@ -676,15 +665,13 @@ __acquires(torture_rtmutex)
 static void torture_rtmutex_delay(struct torture_random_state *trsp)
 {
 	const unsigned long shortdelay_us = 2;
-	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.
 	 */
-	if (!(torture_random(trsp) %
-	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
-		mdelay(longdelay_ms);
+	if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold)))
+		mdelay(long_hold);
 	if (!(torture_random(trsp) %
 	      (cxt.nrealwriters_stress * 200 * shortdelay_us)))
 		udelay(shortdelay_us);
@@ -741,12 +728,9 @@ __acquires(torture_rwsem)
 
 static void torture_rwsem_write_delay(struct torture_random_state *trsp)
 {
-	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);
+	if (long_hold && !(torture_random(trsp) % (cxt.nrealwriters_stress * 2000 * long_hold)))
+		mdelay(long_hold * 10);
 	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
@@ -766,14 +750,11 @@ __acquires(torture_rwsem)
 
 static void torture_rwsem_read_delay(struct torture_random_state *trsp)
 {
-	const unsigned long longdelay_ms = 100;
-
 	/* We want a long delay occasionally to force massive contention.  */
-	if (!(torture_random(trsp) %
-	      (cxt.nrealreaders_stress * 2000 * longdelay_ms)))
-		mdelay(longdelay_ms * 2);
+	if (long_hold && !(torture_random(trsp) % (cxt.nrealreaders_stress * 2000 * long_hold)))
+		mdelay(long_hold * 2);
 	else
-		mdelay(longdelay_ms / 2);
+		mdelay(long_hold / 2);
 	if (!(torture_random(trsp) % (cxt.nrealreaders_stress * 20000)))
 		torture_preempt_schedule();  /* Allow test to be preempted. */
 }
@@ -1056,11 +1037,12 @@ lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
 
 	cpumask_setall(&cpumask_all);
 	pr_alert("%s" TORTURE_FLAG
-		 "--- %s%s: nwriters_stress=%d nreaders_stress=%d nested_locks=%d stat_interval=%d verbose=%d shuffle_interval=%d stutter=%d shutdown_secs=%d onoff_interval=%d onoff_holdoff=%d readers_bind=%*pbl writers_bind=%*pbl\n",
+		 "--- %s%s: acq_writer_lim=%d long_hold=%d nested_locks=%d nreaders_stress=%d nwriters_stress=%d onoff_holdoff=%d onoff_interval=%d rt_boost=%d rt_boost_factor=%d shuffle_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d verbose=%d writer_fifo=%d readers_bind=%*pbl writers_bind=%*pbl\n",
 		 torture_type, tag, cxt.debug_lock ? " [debug]": "",
-		 cxt.nrealwriters_stress, cxt.nrealreaders_stress,
-		 nested_locks, stat_interval, verbose, shuffle_interval,
-		 stutter, shutdown_secs, onoff_interval, onoff_holdoff,
+		 acq_writer_lim, long_hold, nested_locks, cxt.nrealreaders_stress,
+		 cxt.nrealwriters_stress, onoff_holdoff, onoff_interval, rt_boost,
+		 rt_boost_factor, shuffle_interval, shutdown_secs, stat_interval, stutter,
+		 verbose, writer_fifo,
 		 cpumask_pr_args(rcmp), cpumask_pr_args(wcmp));
 }
 
-- 
2.34.1

[PATCH 16/23] locktorture: Add call_rcu_chains module parameter

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

When running locktorture on large systems, there will normally be
enough RCU activity to ensure that there is a grace period in flight
at all times.  However, on smaller systems, RCU might well be idle the
majority of the time.  This situation can be inconvenient in cases where
the RCU CPU stall warning is part of the debugging process.

This commit therefore adds an call_rcu_chains module parameter to
locktorture, allowing the user to specify the desired number of
self-propagating call_rcu() chains.  For good measure, immediately
before invoking call_rcu(), the self-propagating RCU callback invokes
start_poll_synchronize_rcu() to force the immediate start of a grace
period, with the call_rcu() forcing another to start shortly thereafter.

Booting with locktorture.call_rcu_chains=2 increases the probability
of a stuck locking primitive resulting in an RCU CPU stall warning from
about 25% to nearly 100%.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 .../admin-guide/kernel-parameters.txt         |  7 +++
 kernel/locking/locktorture.c                  | 62 ++++++++++++++++++-
 2 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 0a1731a0f0ef..300e2c30986c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2913,6 +2913,13 @@
 			to extract confidential information from the kernel
 			are also disabled.
 
+	locktorture.call_rcu_chains= [KNL]
+			Specify the number of self-propagating call_rcu()
+			chains to set up.  These are used to ensure that
+			there is a high probability of an RCU grace period
+			in progress at any given time.	Defaults to 0,
+			which disables these call_rcu() chains.
+
 	locktorture.nreaders_stress= [KNL]
 			Set the number of locking read-acquisition kthreads.
 			Defaults to being automatically set based on the
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index d2a3a8cc1902..01d56e6c44d7 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -34,6 +34,7 @@ MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
 
 torture_param(int, acq_writer_lim, 0, "Write_acquisition time limit (jiffies).");
+torture_param(int, call_rcu_chains, 0, "Self-propagate call_rcu() chains during test (0=disable).");
 torture_param(int, long_hold, 100, "Do occasional long hold of lock (ms), 0=disable");
 torture_param(int, nested_locks, 0, "Number of nested locks (max = 8)");
 torture_param(int, nreaders_stress, -1, "Number of read-locking stress-test threads");
@@ -119,6 +120,12 @@ struct lock_stress_stats {
 	long n_lock_acquired;
 };
 
+struct call_rcu_chain {
+	struct rcu_head crc_rh;
+	bool crc_stop;
+};
+struct call_rcu_chain *call_rcu_chain;
+
 /* Forward reference. */
 static void lock_torture_cleanup(void);
 
@@ -1037,15 +1044,60 @@ lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
 
 	cpumask_setall(&cpumask_all);
 	pr_alert("%s" TORTURE_FLAG
-		 "--- %s%s: acq_writer_lim=%d long_hold=%d nested_locks=%d nreaders_stress=%d nwriters_stress=%d onoff_holdoff=%d onoff_interval=%d rt_boost=%d rt_boost_factor=%d shuffle_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d verbose=%d writer_fifo=%d readers_bind=%*pbl writers_bind=%*pbl\n",
+		 "--- %s%s: acq_writer_lim=%d call_rcu_chains=%d long_hold=%d nested_locks=%d nreaders_stress=%d nwriters_stress=%d onoff_holdoff=%d onoff_interval=%d rt_boost=%d rt_boost_factor=%d shuffle_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d verbose=%d writer_fifo=%d readers_bind=%*pbl writers_bind=%*pbl\n",
 		 torture_type, tag, cxt.debug_lock ? " [debug]": "",
-		 acq_writer_lim, long_hold, nested_locks, cxt.nrealreaders_stress,
+		 acq_writer_lim, call_rcu_chains, long_hold, nested_locks, cxt.nrealreaders_stress,
 		 cxt.nrealwriters_stress, onoff_holdoff, onoff_interval, rt_boost,
 		 rt_boost_factor, shuffle_interval, shutdown_secs, stat_interval, stutter,
 		 verbose, writer_fifo,
 		 cpumask_pr_args(rcmp), cpumask_pr_args(wcmp));
 }
 
+// If requested, maintain call_rcu() chains to keep a grace period always
+// in flight.  These increase the probability of getting an RCU CPU stall
+// warning and associated diagnostics when a locking primitive stalls.
+
+static void call_rcu_chain_cb(struct rcu_head *rhp)
+{
+	struct call_rcu_chain *crcp = container_of(rhp, struct call_rcu_chain, crc_rh);
+
+	if (!smp_load_acquire(&crcp->crc_stop)) {
+		(void)start_poll_synchronize_rcu(); // Start one grace period...
+		call_rcu(&crcp->crc_rh, call_rcu_chain_cb); // ... and later start another.
+	}
+}
+
+// Start the requested number of call_rcu() chains.
+static int call_rcu_chain_init(void)
+{
+	int i;
+
+	if (call_rcu_chains <= 0)
+		return 0;
+	call_rcu_chain = kcalloc(call_rcu_chains, sizeof(*call_rcu_chain), GFP_KERNEL);
+	if (!call_rcu_chains)
+		return -ENOMEM;
+	for (i = 0; i < call_rcu_chains; i++) {
+		call_rcu_chain[i].crc_stop = false;
+		call_rcu(&call_rcu_chain[i].crc_rh, call_rcu_chain_cb);
+	}
+	return 0;
+}
+
+// Stop all of the call_rcu() chains.
+static void call_rcu_chain_cleanup(void)
+{
+	int i;
+
+	if (!call_rcu_chain)
+		return;
+	for (i = 0; i < call_rcu_chains; i++)
+		smp_store_release(&call_rcu_chain[i].crc_stop, true);
+	rcu_barrier();
+	kfree(call_rcu_chain);
+	call_rcu_chain = NULL;
+}
+
 static void lock_torture_cleanup(void)
 {
 	int i;
@@ -1096,6 +1148,8 @@ static void lock_torture_cleanup(void)
 	kfree(cxt.lrsa);
 	cxt.lrsa = NULL;
 
+	call_rcu_chain_cleanup();
+
 end:
 	if (cxt.init_called) {
 		if (cxt.cur_ops->exit)
@@ -1225,6 +1279,10 @@ static int __init lock_torture_init(void)
 		}
 	}
 
+	firsterr = call_rcu_chain_init();
+	if (torture_init_error(firsterr))
+		goto unwind;
+
 	lock_torture_print_module_parms(cxt.cur_ops, "Start of test");
 
 	/* Prepare torture context. */
-- 
2.34.1

[PATCH 17/23] doc: Catch-up update for locktorture module parameters

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit documents recently added locktorture module parameters.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 .../admin-guide/kernel-parameters.txt         | 50 +++++++++++++++++--
 1 file changed, 47 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 300e2c30986c..47f8b1cef4fd 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2913,6 +2913,11 @@
 			to extract confidential information from the kernel
 			are also disabled.
 
+	locktorture.acq_writer_lim= [KNL]
+			Set the time limit in jiffies for a lock
+			acquisition.  Acquisitions exceeding this limit
+			will result in a splat once they do complete.
+
 	locktorture.call_rcu_chains= [KNL]
 			Specify the number of self-propagating call_rcu()
 			chains to set up.  These are used to ensure that
@@ -2920,6 +2925,18 @@
 			in progress at any given time.	Defaults to 0,
 			which disables these call_rcu() chains.
 
+	locktorture.long_hold= [KNL]
+			Specify the duration in milliseconds for the
+			occasional long-duration lock hold time.  Defaults
+			to 100 milliseconds.  Select 0 to disable.
+
+	locktorture.nested_locks= [KNL]
+			Specify the maximum lock nesting depth that
+			locktorture is to exercise, up to a limit of 8
+			(MAX_NESTED_LOCKS).  Specify zero to disable.
+			Note that this parameter is ineffective on types
+			of locks that do not support nested acquisition.
+
 	locktorture.nreaders_stress= [KNL]
 			Set the number of locking read-acquisition kthreads.
 			Defaults to being automatically set based on the
@@ -2935,6 +2952,29 @@
 			Set time (s) between CPU-hotplug operations, or
 			zero to disable CPU-hotplug testing.
 
+	locktorture.readers_bind= [KNL]
+			Specify the list of CPUs to which the readers are
+			to be bound.
+
+	locktorture.rt_boost= [KNL]
+			Do periodic testing of real-time lock priority
+			boosting.  Select 0 to disable, 1 to boost
+			only rt_mutex, and 2 to boost unconditionally.
+			Defaults to 2, which might seem to be an
+			odd choice, but which should be harmless for
+			non-real-time spinlocks, due to their disabling
+			of preemption.	Note that non-realtime mutexes
+			disable boosting.
+
+	locktorture.rt_boost_factor= [KNL]
+			Number that determines how often and for how
+			long priority boosting is exercised.  This is
+			scaled down by the number of writers, so that the
+			number of boosts per unit time remains roughly
+			constant as the number of writers increases.
+			On the other hand, the duration of each boost
+			increases with the number of writers.
+
 	locktorture.shuffle_interval= [KNL]
 			Set task-shuffle interval (jiffies).  Shuffling
 			tasks allows some CPUs to go into dyntick-idle
@@ -2957,13 +2997,17 @@
 	locktorture.torture_type= [KNL]
 			Specify the locking implementation to test.
 
+	locktorture.verbose= [KNL]
+			Enable additional printk() statements.
+
+	locktorture.writers_bind= [KNL]
+			Specify the list of CPUs to which the writers are
+			to be bound.
+
 	locktorture.writer_fifo= [KNL]
 			Run the write-side locktorture kthreads at
 			sched_set_fifo() real-time priority.
 
-	locktorture.verbose= [KNL]
-			Enable additional printk() statements.
-
 	logibm.irq=	[HW,MOUSE] Logitech Bus Mouse Driver
 			Format: <irq>
 
-- 
2.34.1

[PATCH 18/23] locktorture: Rename readers_bind/writers_bind to bind_readers/bind_writers

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit renames the readers_bind and writers_bind module parameters
to bind_readers and bind_writers, respectively.  This provides added
clarity via the imperative mode and better organizes the documentation.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 .../admin-guide/kernel-parameters.txt         | 16 +++++------
 kernel/locking/locktorture.c                  | 28 +++++++++----------
 2 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 47f8b1cef4fd..1d539c6d9d1c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2918,6 +2918,14 @@
 			acquisition.  Acquisitions exceeding this limit
 			will result in a splat once they do complete.
 
+	locktorture.bind_readers= [KNL]
+			Specify the list of CPUs to which the readers are
+			to be bound.
+
+	locktorture.bind_writers= [KNL]
+			Specify the list of CPUs to which the writers are
+			to be bound.
+
 	locktorture.call_rcu_chains= [KNL]
 			Specify the number of self-propagating call_rcu()
 			chains to set up.  These are used to ensure that
@@ -2952,10 +2960,6 @@
 			Set time (s) between CPU-hotplug operations, or
 			zero to disable CPU-hotplug testing.
 
-	locktorture.readers_bind= [KNL]
-			Specify the list of CPUs to which the readers are
-			to be bound.
-
 	locktorture.rt_boost= [KNL]
 			Do periodic testing of real-time lock priority
 			boosting.  Select 0 to disable, 1 to boost
@@ -3000,10 +3004,6 @@
 	locktorture.verbose= [KNL]
 			Enable additional printk() statements.
 
-	locktorture.writers_bind= [KNL]
-			Specify the list of CPUs to which the writers are
-			to be bound.
-
 	locktorture.writer_fifo= [KNL]
 			Run the write-side locktorture kthreads at
 			sched_set_fifo() real-time priority.
diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 01d56e6c44d7..a3abcd136f56 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -58,8 +58,8 @@ module_param(torture_type, charp, 0444);
 MODULE_PARM_DESC(torture_type,
 		 "Type of lock to torture (spin_lock, spin_lock_irq, mutex_lock, ...)");
 
-static cpumask_var_t readers_bind; // Bind the readers to the specified set of CPUs.
-static cpumask_var_t writers_bind; // Bind the writers to the specified set of CPUs.
+static cpumask_var_t bind_readers; // Bind the readers to the specified set of CPUs.
+static cpumask_var_t bind_writers; // Bind the writers to the specified set of CPUs.
 
 // Parse a cpumask kernel parameter.  If there are more users later on,
 // this might need to got to a more central location.
@@ -102,8 +102,8 @@ static const struct kernel_param_ops lt_bind_ops = {
 	.get = param_get_cpumask,
 };
 
-module_param_cb(readers_bind, &lt_bind_ops, &readers_bind, 0644);
-module_param_cb(writers_bind, &lt_bind_ops, &writers_bind, 0644);
+module_param_cb(bind_readers, &lt_bind_ops, &bind_readers, 0644);
+module_param_cb(bind_writers, &lt_bind_ops, &bind_writers, 0644);
 
 long torture_sched_setaffinity(pid_t pid, const struct cpumask *in_mask);
 
@@ -1039,18 +1039,18 @@ lock_torture_print_module_parms(struct lock_torture_ops *cur_ops,
 				const char *tag)
 {
 	static cpumask_t cpumask_all;
-	cpumask_t *rcmp = cpumask_nonempty(readers_bind) ? readers_bind : &cpumask_all;
-	cpumask_t *wcmp = cpumask_nonempty(writers_bind) ? writers_bind : &cpumask_all;
+	cpumask_t *rcmp = cpumask_nonempty(bind_readers) ? bind_readers : &cpumask_all;
+	cpumask_t *wcmp = cpumask_nonempty(bind_writers) ? bind_writers : &cpumask_all;
 
 	cpumask_setall(&cpumask_all);
 	pr_alert("%s" TORTURE_FLAG
-		 "--- %s%s: acq_writer_lim=%d call_rcu_chains=%d long_hold=%d nested_locks=%d nreaders_stress=%d nwriters_stress=%d onoff_holdoff=%d onoff_interval=%d rt_boost=%d rt_boost_factor=%d shuffle_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d verbose=%d writer_fifo=%d readers_bind=%*pbl writers_bind=%*pbl\n",
+		 "--- %s%s: acq_writer_lim=%d bind_readers=%*pbl bind_writers=%*pbl call_rcu_chains=%d long_hold=%d nested_locks=%d nreaders_stress=%d nwriters_stress=%d onoff_holdoff=%d onoff_interval=%d rt_boost=%d rt_boost_factor=%d shuffle_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d verbose=%d writer_fifo=%d\n",
 		 torture_type, tag, cxt.debug_lock ? " [debug]": "",
-		 acq_writer_lim, call_rcu_chains, long_hold, nested_locks, cxt.nrealreaders_stress,
+		 acq_writer_lim, cpumask_pr_args(rcmp), cpumask_pr_args(wcmp),
+		 call_rcu_chains, long_hold, nested_locks, cxt.nrealreaders_stress,
 		 cxt.nrealwriters_stress, onoff_holdoff, onoff_interval, rt_boost,
 		 rt_boost_factor, shuffle_interval, shutdown_secs, stat_interval, stutter,
-		 verbose, writer_fifo,
-		 cpumask_pr_args(rcmp), cpumask_pr_args(wcmp));
+		 verbose, writer_fifo);
 }
 
 // If requested, maintain call_rcu() chains to keep a grace period always
@@ -1356,8 +1356,8 @@ static int __init lock_torture_init(void)
 						     writer_fifo ? sched_set_fifo : NULL);
 		if (torture_init_error(firsterr))
 			goto unwind;
-		if (cpumask_nonempty(writers_bind))
-			torture_sched_setaffinity(writer_tasks[i]->pid, writers_bind);
+		if (cpumask_nonempty(bind_writers))
+			torture_sched_setaffinity(writer_tasks[i]->pid, bind_writers);
 
 	create_reader:
 		if (cxt.cur_ops->readlock == NULL || (j >= cxt.nrealreaders_stress))
@@ -1367,8 +1367,8 @@ static int __init lock_torture_init(void)
 						  reader_tasks[j]);
 		if (torture_init_error(firsterr))
 			goto unwind;
-		if (cpumask_nonempty(readers_bind))
-			torture_sched_setaffinity(reader_tasks[j]->pid, readers_bind);
+		if (cpumask_nonempty(bind_readers))
+			torture_sched_setaffinity(reader_tasks[j]->pid, bind_readers);
 	}
 	if (stat_interval > 0) {
 		firsterr = torture_create_kthread(lock_torture_stats, NULL,
-- 
2.34.1

[PATCH 19/23] torture: Add kvm.sh --debug-info argument

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit adds a --debug-info argument to kvm.sh in order to ease
interpretation of addresses printed on the console and the like.
This argument also disables KASLR.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 tools/testing/selftests/rcutorture/bin/kvm.sh | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh
index b0f36a638a69..7af73ddc148d 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm.sh
@@ -49,6 +49,7 @@ TORTURE_SHUTDOWN_GRACE=180
 TORTURE_SUITE=rcu
 TORTURE_MOD=rcutorture
 TORTURE_TRUST_MAKE=""
+debuginfo="CONFIG_DEBUG_INFO_NONE=n CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y"
 resdir=""
 configs=""
 cpus=0
@@ -68,6 +69,7 @@ usage () {
 	echo "       --cpus N"
 	echo "       --datestamp string"
 	echo "       --defconfig string"
+	echo "       --debug-info"
 	echo "       --dryrun batches|scenarios|sched|script"
 	echo "       --duration minutes | <seconds>s | <hours>h | <days>d"
 	echo "       --gdb"
@@ -135,6 +137,15 @@ do
 		ds=$2
 		shift
 		;;
+	--debug-info|--debuginfo)
+		if test -z "$TORTURE_KCONFIG_KCSAN_ARG" && test -z "$TORTURE_BOOT_GDB_ARG"
+		then
+			TORTURE_KCONFIG_KCSAN_ARG="$debuginfo"; export TORTURE_KCONFIG_KCSAN_ARG
+			TORTURE_BOOT_GDB_ARG="nokaslr"; export TORTURE_BOOT_GDB_ARG
+		else
+			echo "Ignored redundant --debug-info (implied by --kcsan &c)"
+		fi
+		;;
 	--defconfig)
 		checkarg --defconfig "defconfigtype" "$#" "$2" '^[^/][^/]*$' '^--'
 		TORTURE_DEFCONFIG=$2
@@ -163,7 +174,7 @@ do
 		shift
 		;;
 	--gdb)
-		TORTURE_KCONFIG_GDB_ARG="CONFIG_DEBUG_INFO_NONE=n CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y"; export TORTURE_KCONFIG_GDB_ARG
+		TORTURE_KCONFIG_GDB_ARG="$debuginfo"; export TORTURE_KCONFIG_GDB_ARG
 		TORTURE_BOOT_GDB_ARG="nokaslr"; export TORTURE_BOOT_GDB_ARG
 		TORTURE_QEMU_GDB_ARG="-s -S"; export TORTURE_QEMU_GDB_ARG
 		;;
@@ -179,7 +190,7 @@ do
 		shift
 		;;
 	--kasan)
-		TORTURE_KCONFIG_KASAN_ARG="CONFIG_DEBUG_INFO_NONE=n CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y CONFIG_KASAN=y"; export TORTURE_KCONFIG_KASAN_ARG
+		TORTURE_KCONFIG_KASAN_ARG="$debuginfo CONFIG_KASAN=y"; export TORTURE_KCONFIG_KASAN_ARG
 		if test -n "$torture_qemu_mem_default"
 		then
 			TORTURE_QEMU_MEM=2G
@@ -191,7 +202,7 @@ do
 		shift
 		;;
 	--kcsan)
-		TORTURE_KCONFIG_KCSAN_ARG="CONFIG_DEBUG_INFO_NONE=n CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y CONFIG_KCSAN=y CONFIG_KCSAN_STRICT=y CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000 CONFIG_KCSAN_VERBOSE=y CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y"; export TORTURE_KCONFIG_KCSAN_ARG
+		TORTURE_KCONFIG_KCSAN_ARG="$debuginfo CONFIG_KCSAN=y CONFIG_KCSAN_STRICT=y CONFIG_KCSAN_REPORT_ONCE_IN_MS=100000 CONFIG_KCSAN_VERBOSE=y CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y"; export TORTURE_KCONFIG_KCSAN_ARG
 		;;
 	--kmake-arg|--kmake-args)
 		checkarg --kmake-arg "(kernel make arguments)" $# "$2" '.*' '^error$'
-- 
2.34.1

[PATCH 20/23] rcutorture: Replace schedule_timeout*() 1-jiffy waits with HZ/20

[Frederic Weisbecker]

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>

In the past, spinning on schedule_timeout* with a wait of 1 jiffy has
hung the kernel. See for example d52d3a2bf408 ("torture: Fix hang during
kthread shutdown phase").

This issue recently recurred in torture's stutter code.  The result is
that the function instantly returns and never goes to sleep, preempting
whatever might otherwise make useful forward progress.

To prevent future issues, apply the commit-d52d3a2bf408 fix throughout
rcutorture, moving from a 1-jiffy wait to a 50-millisecond wait.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/rcu/rcutorture.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 7e82fb887d09..8136fec0310b 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1149,7 +1149,7 @@ static int rcu_torture_boost(void *arg)
 				mutex_unlock(&boost_mutex);
 				break;
 			}
-			schedule_timeout_uninterruptible(1);
+			schedule_timeout_uninterruptible(HZ / 20);
 		}
 
 		/* Go do the stutter. */
@@ -1160,7 +1160,7 @@ checkwait:	if (stutter_wait("rcu_torture_boost"))
 	/* Clean up and exit. */
 	while (!kthread_should_stop()) {
 		torture_shutdown_absorb("rcu_torture_boost");
-		schedule_timeout_uninterruptible(1);
+		schedule_timeout_uninterruptible(HZ / 20);
 	}
 	torture_kthread_stopping("rcu_torture_boost");
 	return 0;
@@ -1183,7 +1183,7 @@ rcu_torture_fqs(void *arg)
 		fqs_resume_time = jiffies + fqs_stutter * HZ;
 		while (time_before(jiffies, fqs_resume_time) &&
 		       !kthread_should_stop()) {
-			schedule_timeout_interruptible(1);
+			schedule_timeout_interruptible(HZ / 20);
 		}
 		fqs_burst_remaining = fqs_duration;
 		while (fqs_burst_remaining > 0 &&
@@ -2899,7 +2899,7 @@ static int rcu_torture_fwd_prog(void *args)
 			WRITE_ONCE(rcu_fwd_seq, rcu_fwd_seq + 1);
 		} else {
 			while (READ_ONCE(rcu_fwd_seq) == oldseq && !torture_must_stop())
-				schedule_timeout_interruptible(1);
+				schedule_timeout_interruptible(HZ / 20);
 			oldseq = READ_ONCE(rcu_fwd_seq);
 		}
 		pr_alert("%s: Starting forward-progress test %d\n", __func__, rfp->rcu_fwd_id);
@@ -3200,7 +3200,7 @@ static int rcu_torture_read_exit_child(void *trsp_in)
 	set_user_nice(current, MAX_NICE);
 	// Minimize time between reading and exiting.
 	while (!kthread_should_stop())
-		schedule_timeout_uninterruptible(1);
+		schedule_timeout_uninterruptible(HZ / 20);
 	(void)rcu_torture_one_read(trsp, -1);
 	return 0;
 }
@@ -3248,7 +3248,7 @@ static int rcu_torture_read_exit(void *unused)
 	smp_mb(); // Store before wakeup.
 	wake_up(&read_exit_wq);
 	while (!torture_must_stop())
-		schedule_timeout_uninterruptible(1);
+		schedule_timeout_uninterruptible(HZ / 20);
 	torture_kthread_stopping("rcu_torture_read_exit");
 	return 0;
 }
-- 
2.34.1

[PATCH 21/23] rcutorture: Traverse possible cpu to set maxcpu in rcu_nocb_toggle()

[Frederic Weisbecker]

From: Zqiang <qiang.zhang1211@gmail.com>

Currently, the maxcpu is set by traversing online CPUs, however, if the
rcutorture.onoff_holdoff is set zero and onoff_interval is set non-zero,
and the some CPUs with larger cpuid has been offline before setting
maxcpu, for these CPUs, even if they are online again, also cannot
be offload or deoffload.  This can result in rcutorture attempting to
(de-)offload CPUs that have never been online, but the (de-)offload code
handles this.

This commit therefore use for_each_possible_cpu() instead of
for_each_online_cpu() in rcu_nocb_toggle().

Signed-off-by: Zqiang <qiang.zhang1211@gmail.com>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/rcu/rcutorture.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 8136fec0310b..b17ad45cd67e 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2126,7 +2126,7 @@ static int rcu_nocb_toggle(void *arg)
 	VERBOSE_TOROUT_STRING("rcu_nocb_toggle task started");
 	while (!rcu_inkernel_boot_has_ended())
 		schedule_timeout_interruptible(HZ / 10);
-	for_each_online_cpu(cpu)
+	for_each_possible_cpu(cpu)
 		maxcpu = cpu;
 	WARN_ON(maxcpu < 0);
 	if (toggle_interval > ULONG_MAX)
-- 
2.34.1

[PATCH 22/23] torture: Convert parse-console.sh to mktemp

[Frederic Weisbecker]

From: "Paul E. McKenney" <paulmck@kernel.org>

This commit does the long-overdue conversion of the parse-console.sh
file to use mktemp to create its temporary directory.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 tools/testing/selftests/rcutorture/bin/parse-console.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/rcutorture/bin/parse-console.sh b/tools/testing/selftests/rcutorture/bin/parse-console.sh
index e3d2f69ec0fb..b07c11cf6929 100755
--- a/tools/testing/selftests/rcutorture/bin/parse-console.sh
+++ b/tools/testing/selftests/rcutorture/bin/parse-console.sh
@@ -11,7 +11,7 @@
 #
 # Authors: Paul E. McKenney <paulmck@linux.ibm.com>
 
-T=${TMPDIR-/tmp}/parse-console.sh.$$
+T="`mktemp -d ${TMPDIR-/tmp}/parse-console.sh.XXXXXX`"
 file="$1"
 title="$2"
 
-- 
2.34.1

[PATCH 23/23] locktorture: Check the correct variable for allocation failure

[Frederic Weisbecker]

From: Dan Carpenter <dan.carpenter@linaro.org>

There is a typo so this checks the wrong variable.  "chains" plural vs
"chain" singular.  We already know that "chains" is non-zero.

Fixes: 7f993623e9eb ("locktorture: Add call_rcu_chains module parameter")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/locking/locktorture.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index a3abcd136f56..69d3cd2cfc3b 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -1075,7 +1075,7 @@ static int call_rcu_chain_init(void)
 	if (call_rcu_chains <= 0)
 		return 0;
 	call_rcu_chain = kcalloc(call_rcu_chains, sizeof(*call_rcu_chain), GFP_KERNEL);
-	if (!call_rcu_chains)
+	if (!call_rcu_chain)
 		return -ENOMEM;
 	for (i = 0; i < call_rcu_chains; i++) {
 		call_rcu_chain[i].crc_stop = false;
-- 
2.34.1

Re: [PATCH 23/23] locktorture: Check the correct variable for allocation failure

[Paul E. McKenney]

On Tue, Oct 10, 2023 at 01:59:21PM +0200, Frederic Weisbecker wrote:
> From: Dan Carpenter <dan.carpenter@linaro.org>
> 
> There is a typo so this checks the wrong variable.  "chains" plural vs
> "chain" singular.  We already know that "chains" is non-zero.
> 
> Fixes: 7f993623e9eb ("locktorture: Add call_rcu_chains module parameter")
> Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>

Reviewed-by: Paul E. McKenney <paulmck@kernel.org>

A name change to increase the Hamming distance would of course also be
good, though less urgent.  ;-)

> ---
>  kernel/locking/locktorture.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
> index a3abcd136f56..69d3cd2cfc3b 100644
> --- a/kernel/locking/locktorture.c
> +++ b/kernel/locking/locktorture.c
> @@ -1075,7 +1075,7 @@ static int call_rcu_chain_init(void)
>  	if (call_rcu_chains <= 0)
>  		return 0;
>  	call_rcu_chain = kcalloc(call_rcu_chains, sizeof(*call_rcu_chain), GFP_KERNEL);
> -	if (!call_rcu_chains)
> +	if (!call_rcu_chain)
>  		return -ENOMEM;
>  	for (i = 0; i < call_rcu_chains; i++) {
>  		call_rcu_chain[i].crc_stop = false;
> -- 
> 2.34.1
> 

Re: [PATCH 23/23] locktorture: Check the correct variable for allocation failure

[Dan Carpenter]

On Tue, Oct 10, 2023 at 06:55:40AM -0700, Paul E. McKenney wrote:
> On Tue, Oct 10, 2023 at 01:59:21PM +0200, Frederic Weisbecker wrote:
> > From: Dan Carpenter <dan.carpenter@linaro.org>
> > 
> > There is a typo so this checks the wrong variable.  "chains" plural vs
> > "chain" singular.  We already know that "chains" is non-zero.
> > 
> > Fixes: 7f993623e9eb ("locktorture: Add call_rcu_chains module parameter")
> > Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> > Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> 
> Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
> 
> A name change to increase the Hamming distance would of course also be
> good, though less urgent.  ;-)

"Hamming distance" is such a great phrase.  I'm going to use that every
time I complain about confusingly similar variable names going forward.

regards,
dan carpenter

Re: [PATCH 23/23] locktorture: Check the correct variable for allocation failure

[Paul E. McKenney]

On Tue, Oct 10, 2023 at 05:07:00PM +0300, Dan Carpenter wrote:
> On Tue, Oct 10, 2023 at 06:55:40AM -0700, Paul E. McKenney wrote:
> > On Tue, Oct 10, 2023 at 01:59:21PM +0200, Frederic Weisbecker wrote:
> > > From: Dan Carpenter <dan.carpenter@linaro.org>
> > > 
> > > There is a typo so this checks the wrong variable.  "chains" plural vs
> > > "chain" singular.  We already know that "chains" is non-zero.
> > > 
> > > Fixes: 7f993623e9eb ("locktorture: Add call_rcu_chains module parameter")
> > > Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> > 
> > Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
> > 
> > A name change to increase the Hamming distance would of course also be
> > good, though less urgent.  ;-)
> 
> "Hamming distance" is such a great phrase.  I'm going to use that every
> time I complain about confusingly similar variable names going forward.

Glad you like it!

But the horrible thing is that I first heard that phrase back in
the 1970s, and I am the guilty party who created these particular
too-similar variable names.  (Why has the phrase fallen out of favor?
No idea, really, but one guess has to do with the fact that current
error-correcting codes must deal with different probabilities of different
bits flipping in different directions, so you would instead needs a
weirdly weighted variant of Hamming distance to accomplish anything with
modern error-correcting codes.)

But how about something like the following?

							Thanx, paul

------------------------------------------------------------------------

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index 991496afc0d9..48fd4562a754 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -126,7 +126,7 @@ struct call_rcu_chain {
 	struct rcu_head crc_rh;
 	bool crc_stop;
 };
-struct call_rcu_chain *call_rcu_chain;
+struct call_rcu_chain *call_rcu_chain_list;
 
 /* Forward reference. */
 static void lock_torture_cleanup(void);
@@ -1106,12 +1106,12 @@ static int call_rcu_chain_init(void)
 
 	if (call_rcu_chains <= 0)
 		return 0;
-	call_rcu_chain = kcalloc(call_rcu_chains, sizeof(*call_rcu_chain), GFP_KERNEL);
-	if (!call_rcu_chain)
+	call_rcu_chain_list = kcalloc(call_rcu_chains, sizeof(*call_rcu_chain_list), GFP_KERNEL);
+	if (!call_rcu_chain_list)
 		return -ENOMEM;
 	for (i = 0; i < call_rcu_chains; i++) {
-		call_rcu_chain[i].crc_stop = false;
-		call_rcu(&call_rcu_chain[i].crc_rh, call_rcu_chain_cb);
+		call_rcu_chain_list[i].crc_stop = false;
+		call_rcu(&call_rcu_chain_list[i].crc_rh, call_rcu_chain_cb);
 	}
 	return 0;
 }
@@ -1121,13 +1121,13 @@ static void call_rcu_chain_cleanup(void)
 {
 	int i;
 
-	if (!call_rcu_chain)
+	if (!call_rcu_chain_list)
 		return;
 	for (i = 0; i < call_rcu_chains; i++)
-		smp_store_release(&call_rcu_chain[i].crc_stop, true);
+		smp_store_release(&call_rcu_chain_list[i].crc_stop, true);
 	rcu_barrier();
-	kfree(call_rcu_chain);
-	call_rcu_chain = NULL;
+	kfree(call_rcu_chain_list);
+	call_rcu_chain_list = NULL;
 }
 
 static struct notifier_block lock_torture_stall_block;

Re: [PATCH 23/23] locktorture: Check the correct variable for allocation failure

[Dan Carpenter]

On Tue, Oct 10, 2023 at 08:53:36AM -0700, Paul E. McKenney wrote:
> On Tue, Oct 10, 2023 at 05:07:00PM +0300, Dan Carpenter wrote:
> > On Tue, Oct 10, 2023 at 06:55:40AM -0700, Paul E. McKenney wrote:
> > > On Tue, Oct 10, 2023 at 01:59:21PM +0200, Frederic Weisbecker wrote:
> > > > From: Dan Carpenter <dan.carpenter@linaro.org>
> > > > 
> > > > There is a typo so this checks the wrong variable.  "chains" plural vs
> > > > "chain" singular.  We already know that "chains" is non-zero.
> > > > 
> > > > Fixes: 7f993623e9eb ("locktorture: Add call_rcu_chains module parameter")
> > > > Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> > > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
> > > 
> > > Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
> > > 
> > > A name change to increase the Hamming distance would of course also be
> > > good, though less urgent.  ;-)
> > 
> > "Hamming distance" is such a great phrase.  I'm going to use that every
> > time I complain about confusingly similar variable names going forward.
> 
> Glad you like it!
> 
> But the horrible thing is that I first heard that phrase back in
> the 1970s, and I am the guilty party who created these particular
> too-similar variable names.  (Why has the phrase fallen out of favor?
> No idea, really, but one guess has to do with the fact that current
> error-correcting codes must deal with different probabilities of different
> bits flipping in different directions, so you would instead needs a
> weirdly weighted variant of Hamming distance to accomplish anything with
> modern error-correcting codes.)
> 
> But how about something like the following?
> 

Looks good!

regards,
dan carpenter