From: Kunwu Chan <kunwu.chan@gmail.com>
To: paulmck@kernel.org, corbet@lwn.net, mingo@redhat.com,
frederic@kernel.org, neeraj.upadhyay@kernel.org,
josh@joshtriplett.org, urezki@gmail.com, dave@stgolabs.net,
lianux.mm@gmail.com
Cc: stern@rowland.harvard.edu, parri.andrea@gmail.com,
will@kernel.org, peterz@infradead.org, boqun@kernel.org,
npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk,
luc.maranget@inria.fr, akiyks@gmail.com, dlustig@nvidia.com,
joelagnelf@nvidia.com, skhan@linuxfoundation.org,
rdunlap@infradead.org, longman@redhat.com, rostedt@goodmis.org,
mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com,
qiang.zhang@linux.dev, kunwu.chan@gmail.com,
brads@mainlining.org, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org, lkmm@lists.linux.dev,
linux-doc@vger.kernel.org, rcu@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: [PATCH RFC v2 12/15] hazptrtorture: add slowpath and lockdep scenarios
Date: Sat, 3 Oct 2026 01:08:44 +0800 [thread overview]
Message-ID: <20261002170847.3653663-13-kunwu.chan@gmail.com> (raw)
In-Reply-To: <20261002170847.3653663-1-kunwu.chan@gmail.com>
Add a wq_churn kthread and module parameter to exercise lockdep
dynamic-key handling by repeatedly creating and destroying
workqueues. Each workqueue creation registers a dynamic lock
class key and each destruction unregisters it, exercising both
is_dynamic_key() and lockdep_unregister_key().
Add SLOWPATH and LOCKDEP torture scenarios to exercise the
hazptr acquire slow path, including its use by lockdep under
CONFIG_PROVE_LOCKING.
Add both scenarios to CFLIST so that torture.sh --do-hazptr
includes them.
Signed-off-by: Kunwu Chan <kunwu.chan@gmail.com>
---
kernel/rcu/hazptrtorture.c | 57 +++++++++++++++++--
.../rcutorture/configs/hazptr/CFLIST | 2 +
.../rcutorture/configs/hazptr/LOCKDEP | 17 ++++++
.../rcutorture/configs/hazptr/LOCKDEP.boot | 1 +
.../rcutorture/configs/hazptr/SLOWPATH | 16 ++++++
5 files changed, 89 insertions(+), 4 deletions(-)
create mode 100644 tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP
create mode 100644 tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP.boot
create mode 100644 tools/testing/selftests/rcutorture/configs/hazptr/SLOWPATH
diff --git a/kernel/rcu/hazptrtorture.c b/kernel/rcu/hazptrtorture.c
index 7c8b5899fb01..7c144b9bca6a 100644
--- a/kernel/rcu/hazptrtorture.c
+++ b/kernel/rcu/hazptrtorture.c
@@ -23,6 +23,7 @@
#include <linux/torture.h>
#include <linux/hazptr.h>
#include <linux/rcupdate.h>
+#include <linux/workqueue.h>
#include "rcu.h"
@@ -49,6 +50,8 @@ torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
torture_param(int, stat_interval, 60, "Number of seconds between stats printk()s");
torture_param(int, stutter, 5, "Number of seconds to run/halt test");
torture_param(int, verbose, 1, "Enable verbose debugging printk()s");
+torture_param(bool, wq_churn, false,
+ "Churn workqueues to exercise lockdep dynamic keys");
static char *torture_type = "hazptr";
module_param(torture_type, charp, 0444);
@@ -60,6 +63,7 @@ static struct task_struct *preempt_task;
static struct task_struct **reader_tasks;
static struct task_struct *do_pending_task;
static struct task_struct *stats_task;
+static struct task_struct *wq_churn_task;
#define HAZPTR_TORTURE_PIPE_LEN 10
@@ -87,6 +91,7 @@ static DEFINE_PER_CPU(atomic_long_t, hazptr_torture_acquires_irq);
static DEFINE_PER_CPU(atomic_long_t, hazptr_torture_releases_irq);
static DEFINE_PER_CPU(atomic_long_t, hazptr_torture_releases_defer);
static DEFINE_PER_CPU(atomic_long_t, hazptr_torture_releases_undefer);
+static atomic_t n_hazptr_torture_wq_churn;
static struct list_head hazptr_torture_removed;
// State for a deferred (AKA pending) hazard pointer
@@ -643,13 +648,14 @@ hazptr_torture_stats_print(void)
atomic_read(&n_hazptr_torture_alloc_fail),
atomic_read(&n_hazptr_torture_free));
torture_onoff_stats();
- pr_cont("acq: %lld rel: %lld acqirq: %lld relirq: %lld reldefer: %lld relundefer %lld\n",
+ pr_cont("acq: %lld rel: %lld acqirq: %lld relirq: %lld reldefer: %lld relundefer %lld wqchurn: %d\n",
torture_sum_pcpu_atomic_long(&hazptr_torture_acquires),
torture_sum_pcpu_atomic_long(&hazptr_torture_releases),
torture_sum_pcpu_atomic_long(&hazptr_torture_acquires_irq),
torture_sum_pcpu_atomic_long(&hazptr_torture_releases_irq),
torture_sum_pcpu_atomic_long(&hazptr_torture_releases_defer),
- torture_sum_pcpu_atomic_long(&hazptr_torture_releases_undefer));
+ torture_sum_pcpu_atomic_long(&hazptr_torture_releases_undefer),
+ atomic_read(&n_hazptr_torture_wq_churn));
pr_alert("%s%s ", torture_type, TORTURE_FLAG);
if (i > 1) {
@@ -720,14 +726,14 @@ hazptr_torture_print_module_parms(struct hazptr_torture_ops *cur_ops, const char
"defer_modulus=%d irq_acquire=%d irq_release=%d kthread_do_pending_ms=%d "
"onoff_interval=%d onoff_holdoff=%d "
"preempt_duration=%d preempt_interval=%d "
- "reader_sleep_us=%d "
+ "reader_sleep_us=%d wq_churn=%d "
"shuffle_interval=%d shutdown_secs=%d stat_interval=%d stutter=%d "
"verbose=%d\n",
torture_type, tag, nrealreaders, nwriters,
defer_modulus, irq_acquire, irq_release, kthread_do_pending_ms,
onoff_interval, onoff_holdoff,
preempt_duration, preempt_interval,
- reader_sleep_us,
+ reader_sleep_us, wq_churn,
shuffle_interval, shutdown_secs, stat_interval, stutter,
verbose);
}
@@ -761,6 +767,42 @@ static int hazptr_torture_preempt(void *unused)
return 0;
}
+static void hazptr_torture_wq_churn_fn(struct work_struct *work)
+{
+}
+
+/*
+ * Repeatedly create and destroy workqueues. Each workqueue creation
+ * registers a lockdep dynamic key and each destruction unregisters it,
+ * which exercises both is_dynamic_key() and lockdep_unregister_key(),
+ * the two lockdep paths that use hazptr. Most useful in kernels with
+ * CONFIG_PROVE_LOCKING=y and CONFIG_HAZPTR_ACQUIRE_FORCE_SLOWPATH=y.
+ */
+static int hazptr_torture_wq_churn(void *unused)
+{
+ DEFINE_TORTURE_RANDOM(rand);
+
+ VERBOSE_TOROUT_STRING("hazptr_torture_wq_churn task started");
+ do {
+ struct workqueue_struct *wq;
+ struct work_struct churn_work;
+
+ wq = alloc_workqueue("hazptr-torture-churn", WQ_PERCPU, 1);
+ if (!wq) {
+ torture_hrtimeout_ms(10, 10, &rand);
+ continue;
+ }
+ INIT_WORK(&churn_work, hazptr_torture_wq_churn_fn);
+ queue_work(wq, &churn_work);
+ flush_work(&churn_work);
+ destroy_workqueue(wq);
+ atomic_inc(&n_hazptr_torture_wq_churn);
+ stutter_wait("hazptr_torture_wq_churn");
+ } while (!torture_must_stop());
+ torture_kthread_stopping("hazptr_torture_wq_churn");
+ return 0;
+}
+
static void
hazptr_torture_cleanup(void)
{
@@ -775,6 +817,7 @@ hazptr_torture_cleanup(void)
torture_stop_kthread(hazptr_torture_do_pending, do_pending_task);
torture_stop_kthread(hazptr_torture_preempt, preempt_task);
+ torture_stop_kthread(hazptr_torture_wq_churn, wq_churn_task);
torture_stop_kthread(hazptr_torture_writer, writer_task);
if (reader_tasks) {
@@ -853,6 +896,7 @@ static int __init hazptr_torture_init(void)
atomic_set(&n_hazptr_torture_alloc_fail, 0);
atomic_set(&n_hazptr_torture_free, 0);
atomic_set(&n_hazptr_torture_error, 0);
+ atomic_set(&n_hazptr_torture_wq_churn, 0);
for (i = 0; i < HAZPTR_TORTURE_PIPE_LEN + 1; i++)
atomic_set(&hazptr_torture_wcount[i], 0);
for_each_possible_cpu(cpu) {
@@ -928,6 +972,11 @@ static int __init hazptr_torture_init(void)
if (torture_init_error(firsterr))
goto unwind;
}
+ if (wq_churn) {
+ firsterr = torture_create_kthread(hazptr_torture_wq_churn, NULL, wq_churn_task);
+ if (torture_init_error(firsterr))
+ goto unwind;
+ }
torture_init_end();
return 0;
diff --git a/tools/testing/selftests/rcutorture/configs/hazptr/CFLIST b/tools/testing/selftests/rcutorture/configs/hazptr/CFLIST
index 4d62eb4a39f9..380b8402ccc9 100644
--- a/tools/testing/selftests/rcutorture/configs/hazptr/CFLIST
+++ b/tools/testing/selftests/rcutorture/configs/hazptr/CFLIST
@@ -1,2 +1,4 @@
NOPREEMPT
PREEMPT
+SLOWPATH
+LOCKDEP
diff --git a/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP b/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP
new file mode 100644
index 000000000000..129769e2e32e
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP
@@ -0,0 +1,17 @@
+CONFIG_SMP=y
+CONFIG_NR_CPUS=16
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
+CONFIG_HZ_PERIODIC=n
+CONFIG_NO_HZ_IDLE=y
+CONFIG_NO_HZ_FULL=n
+CONFIG_HOTPLUG_CPU=y
+CONFIG_SUSPEND=n
+CONFIG_HIBERNATION=n
+CONFIG_DEBUG_LOCK_ALLOC=y
+CONFIG_PROVE_LOCKING=y
+CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
+CONFIG_DEBUG_KERNEL=y
+CONFIG_HAZPTR_DEBUG=y
+CONFIG_HAZPTR_ACQUIRE_FORCE_SLOWPATH=y
diff --git a/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP.boot b/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP.boot
new file mode 100644
index 000000000000..7b16720214bd
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/hazptr/LOCKDEP.boot
@@ -0,0 +1 @@
+hazptrtorture.wq_churn=1
diff --git a/tools/testing/selftests/rcutorture/configs/hazptr/SLOWPATH b/tools/testing/selftests/rcutorture/configs/hazptr/SLOWPATH
new file mode 100644
index 000000000000..4d13028ca84c
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/hazptr/SLOWPATH
@@ -0,0 +1,16 @@
+CONFIG_SMP=y
+CONFIG_NR_CPUS=16
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
+CONFIG_HZ_PERIODIC=n
+CONFIG_NO_HZ_IDLE=y
+CONFIG_NO_HZ_FULL=n
+CONFIG_HOTPLUG_CPU=y
+CONFIG_SUSPEND=n
+CONFIG_HIBERNATION=n
+CONFIG_PROVE_LOCKING=n
+CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
+CONFIG_DEBUG_KERNEL=y
+CONFIG_HAZPTR_DEBUG=y
+CONFIG_HAZPTR_ACQUIRE_FORCE_SLOWPATH=y
--
2.43.0
next prev parent reply other threads:[~2026-10-02 17:11 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-02 17:08 [PATCH RFC v2 00/15] hazptr: batch synchronize operations through a shared scan Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 01/15] hazptr: add shared scan kthread Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 02/15] hazptr: use Bloom filter for shared scan waiters Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 03/15] hazptr: scan all per-CPU slots before overflow lists Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 04/15] hazptr: add scoped_guard() support Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 05/15] hazptr: add debug option to force the acquire slow path Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 06/15] hazptr: elide redundant first drain pass Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 07/15] Documentation/litmus-tests: add hazptr wildcard-flip escape test Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 08/15] locking/lockdep: use hazptr to wait for dynamic key lookups Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 09/15] rcuscale: add hazptr scale type Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 10/15] hazptr: fix kernel-doc of hazptr_release() Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 11/15] Documentation/litmus-tests: add hazptr acquire-before-scan test Kunwu Chan
2026-10-02 17:08 ` Kunwu Chan [this message]
2026-10-02 17:08 ` [PATCH RFC v2 13/15] hazptrtorture: add READERS4 and READERS0 torture configs Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 14/15] hazptrtorture: add 128- and 256-CPU configs Kunwu Chan
2026-10-02 17:08 ` [PATCH RFC v2 15/15] selftests/rcutorture: add hazptr torture test script Kunwu Chan
2026-10-02 17:12 ` [PATCH RFC v2 00/15] hazptr: batch synchronize operations through a shared scan Bradley Morgan
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