From d6430968d8f323f4f97b6b7d07cca6454db793bd Mon Sep 17 00:00:00 2001 From: Jia He Date: Fri, 29 May 2026 08:58:55 +0000 Subject: [PATCH] lib/tests: test_ratelimit: fix stress test thread lifecycle and leak The stress test's WARN_ON_ONCE(!sktp->tp) check in the child thread is racy and unnecessary: since kthread_run() wakes the thread before returning, the child can run before sktp[i].tp has been assigned. Moreover, sktp->tp is never actually used in the child function, so the check serves no purpose. Remove it and keep the original kthread_run() Also add a common cleanup path for thread creation failures. If creating one of the later threads fails, stop all threads that were already started and free the allocated array instead of leaving orphan kthreads and leaked memory behind. Finally, replace the module-static doneflag with kthread_should_stop(). With the doneflag, child threads may exit before the parent calls kthread_stop(), so the task lifetime is no longer guaranteed when the parent later tries to stop them. Using kthread_should_stop() keeps each child alive until kthread_stop() synchronously terminates it. Suggested-by: Petr Mladek Signed-off-by: Jia He Reviewed-by: Petr Mladek Tested-by: Petr Mladek Acked-by: Paul E. McKenney Link: https://patch.msgid.link/20260529085855.1810870-1-justin.he@arm.com Signed-off-by: Petr Mladek --- lib/tests/test_ratelimit.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-) diff --git a/lib/tests/test_ratelimit.c b/lib/tests/test_ratelimit.c index 33cea5f3d28b..e244f8cd47d7 100644 --- a/lib/tests/test_ratelimit.c +++ b/lib/tests/test_ratelimit.c @@ -68,7 +68,6 @@ static void test_ratelimit_smoke(struct kunit *test) static struct ratelimit_state stressrl = RATELIMIT_STATE_INIT_FLAGS("stressrl", HZ / 10, 3, RATELIMIT_MSG_ON_RELEASE); -static int doneflag; static const int stress_duration = 2 * HZ; struct stress_kthread { @@ -84,9 +83,8 @@ static int test_ratelimit_stress_child(void *arg) struct stress_kthread *sktp = arg; set_user_nice(current, MAX_NICE); - WARN_ON_ONCE(!sktp->tp); - while (!READ_ONCE(doneflag)) { + while (!kthread_should_stop()) { sktp->nattempts++; if (___ratelimit(&stressrl, __func__)) sktp->nunlimited++; @@ -105,26 +103,37 @@ static void test_ratelimit_stress(struct kunit *test) const int n_stress_kthread = cpumask_weight(cpu_online_mask); struct stress_kthread skt = { 0 }; struct stress_kthread *sktp = kzalloc_objs(*sktp, n_stress_kthread); + int n_started = 0; - KUNIT_EXPECT_NOT_NULL_MSG(test, sktp, "Memory allocation failure"); + KUNIT_ASSERT_NOT_NULL_MSG(test, sktp, "Memory allocation failure"); for (i = 0; i < n_stress_kthread; i++) { sktp[i].tp = kthread_run(test_ratelimit_stress_child, &sktp[i], "%s/%i", "test_ratelimit_stress_child", i); - KUNIT_EXPECT_NOT_NULL_MSG(test, sktp, "kthread creation failure"); + if (IS_ERR(sktp[i].tp)) { + KUNIT_FAIL(test, "kthread_run failed: %ld", PTR_ERR(sktp[i].tp)); + goto out_stop; + } + n_started++; pr_alert("Spawned test_ratelimit_stress_child %d\n", i); } schedule_timeout_idle(stress_duration); - WRITE_ONCE(doneflag, 1); - for (i = 0; i < n_stress_kthread; i++) { + +out_stop: + for (i = 0; i < n_started; i++) { kthread_stop(sktp[i].tp); skt.nattempts += sktp[i].nattempts; skt.nunlimited += sktp[i].nunlimited; skt.nlimited += sktp[i].nlimited; skt.nmissed += sktp[i].nmissed; } - KUNIT_ASSERT_EQ_MSG(test, skt.nunlimited + skt.nlimited, skt.nattempts, - "Outcomes not equal to attempts"); - KUNIT_ASSERT_EQ_MSG(test, skt.nlimited, skt.nmissed, "Misses not equal to limits"); + if (n_started == n_stress_kthread) { + KUNIT_ASSERT_EQ_MSG(test, skt.nunlimited + skt.nlimited, skt.nattempts, + "Outcomes not equal to attempts"); + KUNIT_ASSERT_EQ_MSG(test, skt.nlimited, skt.nmissed, + "Misses not equal to limits"); + } + + kfree(sktp); } static struct kunit_case ratelimit_test_cases[] = {