From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF068C2BB1D for ; Thu, 12 Mar 2020 18:17:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A79B206B1 for ; Thu, 12 Mar 2020 18:17:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584037076; bh=8csvVhRW3l5KCsMDr6QYUn3YY8DNKrig/Br59Zsgyso=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=xYccds3EvlE51cc50ZfAtcHXUaqUAaLbU957w09H8uHjhsmsDeNWPNJoty1eFnb+U fFGuz4a5WRebFhubih6EjXu0IT1M+EH4NORZAUxfDJv8Rq0SkE7gibU94tq052jwcg vBoYxaeKQ4EHXghWdd9OIAkHuWQdJAJAKS15HwWI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726988AbgCLSRz (ORCPT ); Thu, 12 Mar 2020 14:17:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:51958 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726599AbgCLSRG (ORCPT ); Thu, 12 Mar 2020 14:17:06 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 09AF92073B; Thu, 12 Mar 2020 18:17:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584037025; bh=8csvVhRW3l5KCsMDr6QYUn3YY8DNKrig/Br59Zsgyso=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zUOWK6m2oCPce5Zcj5hEAhQGIF/dz9Zo7wrRTl1/JXfyQS90EQoAs+oqFFW5L9SZC RT+sD7HaVJDt3YhIWuIBa74IM0uh24/BeWSYLXIfT8b4hZo6MjRF9rssLA2Ib8CEOC AVxL7KmXQ34FEQYjwcx3sLFhVLPs5y8WQ7YfttDY= From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH RFC tip/core/rcu 03/16] rcutorture: Add flag to produce non-busy-wait task stalls Date: Thu, 12 Mar 2020 11:16:49 -0700 Message-Id: <20200312181702.8443-3-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200312181618.GA21271@paulmck-ThinkPad-P72> References: <20200312181618.GA21271@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" This commit aids testing of RCU task stall warning messages by adding an rcutorture.stall_cpu_block module parameter that results in the induced stall sleeping within the RCU read-side critical section. Spinning with interrupts disabled is still available via the rcutorture.stall_cpu_irqsoff module parameter, and specifying neither of these two module parameters will spin with preemption disabled. Note that sleeping (as opposed to preemption) results in additional complaints from RCU at context-switch time, so yet more testing. Signed-off-by: Paul E. McKenney --- Documentation/admin-guide/kernel-parameters.txt | 5 +++++ kernel/rcu/rcutorture.c | 13 ++++++++----- 2 files changed, 13 insertions(+), 5 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 6d16b78..17eff15 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4161,6 +4161,11 @@ Duration of CPU stall (s) to test RCU CPU stall warnings, zero to disable. + rcutorture.stall_cpu_block= [KNL] + Sleep while stalling if set. This will result + in warnings from preemptible RCU in addition + to any other stall-related activity. + rcutorture.stall_cpu_holdoff= [KNL] Time to wait (s) after boot before inducing stall. diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index b3301f3..f75d466 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -102,6 +102,7 @@ torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable."); torture_param(int, stall_cpu_holdoff, 10, "Time to wait before starting stall (s)."); torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling."); +torture_param(int, stall_cpu_block, 0, "Sleep while stalling."); 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"); @@ -1599,6 +1600,7 @@ static int rcutorture_booster_init(unsigned int cpu) */ static int rcu_torture_stall(void *args) { + int idx; unsigned long stop_at; VERBOSE_TOROUT_STRING("rcu_torture_stall task started"); @@ -1610,21 +1612,22 @@ static int rcu_torture_stall(void *args) if (!kthread_should_stop()) { stop_at = ktime_get_seconds() + stall_cpu; /* RCU CPU stall is expected behavior in following code. */ - rcu_read_lock(); + idx = cur_ops->readlock(); if (stall_cpu_irqsoff) local_irq_disable(); - else + else if (!stall_cpu_block) preempt_disable(); pr_alert("rcu_torture_stall start on CPU %d.\n", smp_processor_id()); while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(), stop_at)) - continue; /* Induce RCU CPU stall warning. */ + if (stall_cpu_block) + schedule_timeout_uninterruptible(HZ); if (stall_cpu_irqsoff) local_irq_enable(); - else + else if (!stall_cpu_block) preempt_enable(); - rcu_read_unlock(); + cur_ops->readunlock(idx); pr_alert("rcu_torture_stall end.\n"); } torture_shutdown_absorb("rcu_torture_stall"); -- 2.9.5