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Fri, 02 Oct 2026 10:11:22 -0700 (PDT) From: Kunwu Chan 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 Message-ID: <20261002170847.3653663-13-kunwu.chan@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261002170847.3653663-1-kunwu.chan@gmail.com> References: <20261002170847.3653663-1-kunwu.chan@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- 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 #include #include +#include #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