From patchwork Fri Aug 2 00:37:49 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 13750976 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 330F226AC2; Fri, 2 Aug 2024 00:37:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722559073; cv=none; b=qEALoHYVf2xVZ8NC7hOKffAPMJLDTWpLQhqmuciViWRgcRu5cZFUAgOEhv3iHvmsBwnV5IMEkQGGV4ZEIGceGW0YSySoHVpYp9UlrhVBP25eHtimek49tTCL7KjBEDBINNjqyrDF7OThl6YUPn8qKCb+BhjjZmbD0bLnKfTPMM0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722559073; c=relaxed/simple; bh=rG1LYuhBJekOp6wqHDJn7PtOPxnpbi4tnOcI0lklMZ8=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=JN8/8S81nwnntVxZuEcQx5ghBsb2nxZl7t58hVmDQaXnfe1ec9vYNg2gcSSRtHLsxOFEqcWmKTvaoHwsrQBvxkqx0amlEnhU3OjeGW25zI9bflFfOXzu/X+UY0O7VkAJPDLeJ6SPz9nDJ3TA6u8GCyp2GEkRIoC1UJTKuK1FGYA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bePHb2Tc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bePHb2Tc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0BE4C32786; Fri, 2 Aug 2024 00:37:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722559072; bh=rG1LYuhBJekOp6wqHDJn7PtOPxnpbi4tnOcI0lklMZ8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bePHb2Tc9TIE3FOnqgMyNXpOV3/HEnXWahJexwER97fWsxgCKSXVheYQeN9BlgsPx LzQZsaqipxMJl9T+iW1X+uvmR8ibpuAIt6dg/KdBe9Basq+gEKhwxzgPEUql6wXqYc jMif/a+OsxC1Ja+/rLy9S+2cow8fcYDxkRKBtz0LxaY1ys926cqfhmSC0AcOY4FftU ax3UII4FtI9q6cQCX+tytSMw/YpvJ03zP60OT3dXWfPpcF4zUlzZ05owTMKawjRFj2 gPtD04/gMlstlI5DVWp3OpZVMIQn+QPoXI8O8Oj52hhDGRAT/2S/IZW4hjUuxOk2sZ laAvzcaAwFfvg== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 690D9CE0A01; Thu, 1 Aug 2024 17:37:52 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, "Paul E. McKenney" , Rik van Riel Subject: [PATCH rcu 2/3] rcutorture: Add a stall_cpu_repeat module parameter Date: Thu, 1 Aug 2024 17:37:49 -0700 Message-Id: <20240802003750.4134451-2-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <22c4b040-7b7b-45ff-8fa5-41b741c7cd7e@paulmck-laptop> References: <22c4b040-7b7b-45ff-8fa5-41b741c7cd7e@paulmck-laptop> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 This commit adds an stall_cpu_repeat kernel, which is also the rcutorture.stall_cpu_repeat boot parameter, to test repeated CPU stalls. Note that only the first stall will pay attention to the stall_cpu_irqsoff module parameter. For the second and subsequent stalls, interrupts will be enabled. This is helpful when testing the interaction between RCU CPU stall warnings and CSD-lock stall warnings. Reported-by: Rik van Riel Signed-off-by: Paul E. McKenney --- .../admin-guide/kernel-parameters.txt | 8 ++- kernel/rcu/rcutorture.c | 56 +++++++++++++------ 2 files changed, 47 insertions(+), 17 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 35dd1e69b14d0..d30b81e693f9c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5388,7 +5388,13 @@ Time to wait (s) after boot before inducing stall. rcutorture.stall_cpu_irqsoff= [KNL] - Disable interrupts while stalling if set. + Disable interrupts while stalling if set, but only + on the first stall in the set. + + rcutorture.stall_cpu_repeat= [KNL] + Number of times to repeat the stall sequence, + so that rcutorture.stall_cpu_repeat=3 will result + in four stall sequences. rcutorture.stall_gp_kthread= [KNL] Duration (s) of forced sleep within RCU diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 3dc7ef4af0eca..9dd6764e25f3d 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -115,6 +115,7 @@ torture_param(int, stall_cpu_holdoff, 10, "Time to wait before starting stall (s torture_param(bool, stall_no_softlockup, false, "Avoid softlockup warning during cpu stall."); torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling."); torture_param(int, stall_cpu_block, 0, "Sleep while stalling."); +torture_param(int, stall_cpu_repeat, 0, "Number of additional stalls after the first one."); torture_param(int, stall_gp_kthread, 0, "Grace-period kthread stall duration (s)."); 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"); @@ -1385,7 +1386,8 @@ rcu_torture_writer(void *arg) // If a new stall test is added, this must be adjusted. if (stall_cpu_holdoff + stall_gp_kthread + stall_cpu) - stallsdone += (stall_cpu_holdoff + stall_gp_kthread + stall_cpu + 60) * HZ; + stallsdone += (stall_cpu_holdoff + stall_gp_kthread + stall_cpu + 60) * + HZ * (stall_cpu_repeat + 1); VERBOSE_TOROUT_STRING("rcu_torture_writer task started"); if (!can_expedite) pr_alert("%s" TORTURE_FLAG @@ -2383,7 +2385,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag) "test_boost=%d/%d test_boost_interval=%d " "test_boost_duration=%d shutdown_secs=%d " "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d " - "stall_cpu_block=%d " + "stall_cpu_block=%d stall_cpu_repeat=%d " "n_barrier_cbs=%d " "onoff_interval=%d onoff_holdoff=%d " "read_exit_delay=%d read_exit_burst=%d " @@ -2395,7 +2397,7 @@ rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag) test_boost, cur_ops->can_boost, test_boost_interval, test_boost_duration, shutdown_secs, stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff, - stall_cpu_block, + stall_cpu_block, stall_cpu_repeat, n_barrier_cbs, onoff_interval, onoff_holdoff, read_exit_delay, read_exit_burst, @@ -2473,19 +2475,11 @@ static struct notifier_block rcu_torture_stall_block = { * induces a CPU stall for the time specified by stall_cpu. If a new * stall test is added, stallsdone in rcu_torture_writer() must be adjusted. */ -static int rcu_torture_stall(void *args) +static void rcu_torture_stall_one(int rep, int irqsoff) { int idx; - int ret; unsigned long stop_at; - VERBOSE_TOROUT_STRING("rcu_torture_stall task started"); - if (rcu_cpu_stall_notifiers) { - ret = rcu_stall_chain_notifier_register(&rcu_torture_stall_block); - if (ret) - pr_info("%s: rcu_stall_chain_notifier_register() returned %d, %sexpected.\n", - __func__, ret, !IS_ENABLED(CONFIG_RCU_STALL_COMMON) ? "un" : ""); - } if (stall_cpu_holdoff > 0) { VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff"); schedule_timeout_interruptible(stall_cpu_holdoff * HZ); @@ -2505,12 +2499,12 @@ static int rcu_torture_stall(void *args) stop_at = ktime_get_seconds() + stall_cpu; /* RCU CPU stall is expected behavior in following code. */ idx = cur_ops->readlock(); - if (stall_cpu_irqsoff) + if (irqsoff) local_irq_disable(); else if (!stall_cpu_block) preempt_disable(); - pr_alert("%s start on CPU %d.\n", - __func__, raw_smp_processor_id()); + pr_alert("%s start stall episode %d on CPU %d.\n", + __func__, rep + 1, raw_smp_processor_id()); while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(), stop_at) && !kthread_should_stop()) if (stall_cpu_block) { @@ -2522,12 +2516,42 @@ static int rcu_torture_stall(void *args) } else if (stall_no_softlockup) { touch_softlockup_watchdog(); } - if (stall_cpu_irqsoff) + if (irqsoff) local_irq_enable(); else if (!stall_cpu_block) preempt_enable(); cur_ops->readunlock(idx); } +} + +/* + * CPU-stall kthread. Invokes rcu_torture_stall() once, and then as many + * additional times as specified by the stall_cpu_repeat module parameter. + * Note that stall_cpu_irqsoff is ignored on the second and subsequent + * stall. + */ +static int rcu_torture_stall(void *args) +{ + int i; + int repeat = stall_cpu_repeat; + int ret; + + VERBOSE_TOROUT_STRING("rcu_torture_stall task started"); + if (repeat < 0) { + repeat = 0; + WARN_ON_ONCE(IS_BUILTIN(CONFIG_RCU_TORTURE_TEST)); + } + if (rcu_cpu_stall_notifiers) { + ret = rcu_stall_chain_notifier_register(&rcu_torture_stall_block); + if (ret) + pr_info("%s: rcu_stall_chain_notifier_register() returned %d, %sexpected.\n", + __func__, ret, !IS_ENABLED(CONFIG_RCU_STALL_COMMON) ? "un" : ""); + } + for (i = 0; i <= repeat; i++) { + if (kthread_should_stop()) + break; + rcu_torture_stall_one(i, i == 0 ? stall_cpu_irqsoff : 0); + } pr_alert("%s end.\n", __func__); if (rcu_cpu_stall_notifiers && !ret) { ret = rcu_stall_chain_notifier_unregister(&rcu_torture_stall_block);