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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,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 B07F2C43142 for ; Thu, 2 Aug 2018 22:26:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D9B7215EA for ; Thu, 2 Aug 2018 22:26:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6D9B7215EA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732147AbeHCATk (ORCPT ); Thu, 2 Aug 2018 20:19:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:34854 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726702AbeHCATj (ORCPT ); Thu, 2 Aug 2018 20:19:39 -0400 Received: from localhost.localdomain (c-98-220-238-81.hsd1.il.comcast.net [98.220.238.81]) (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 E273A215E5; Thu, 2 Aug 2018 22:26:27 +0000 (UTC) From: Tom Zanussi To: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org Cc: rostedt@goodmis.org, tglx@linutronix.de, C.Emde@osadl.org, jkacur@redhat.com, bigeasy@linutronix.de, daniel.wagner@siemens.com, julia@ni.com, Philipp Schrader , stable-rt@vger.kernel.org, Tom Zanussi Subject: [PATCH 04/15] tracing: Fix rcu splat from idle CPU on boot Date: Thu, 2 Aug 2018 17:25:19 -0500 Message-Id: <22a1b5d78156e46ecd575079f9b7f29b117c26e7.1533242791.git.tom.zanussi@linux.intel.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Philipp Schrader With PREEMPT_RT and most of the lockdep-related options enabled I encountered this splat when booting our DRA7 evaluation module: [ 0.055073] [ 0.055076] =============================== [ 0.055079] [ INFO: suspicious RCU usage. ] [ 0.055084] 4.1.6+ #2 Not tainted [ 0.055086] ------------------------------- [ 0.055090] include/trace/events/hist.h:31 suspicious rcu_dereference_check() usage! [ 0.055093] [ 0.055093] other info that might help us debug this: [ 0.055093] [ 0.055097] [ 0.055097] RCU used illegally from idle CPU! [ 0.055097] rcu_scheduler_active = 1, debug_locks = 1 [ 0.055100] RCU used illegally from extended quiescent state! [ 0.055104] no locks held by swapper/0/0. [ 0.055106] [ 0.055106] stack backtrace: [ 0.055112] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.1.6+ #2 [ 0.055116] Hardware name: Generic DRA74X (Flattened Device Tree) [ 0.055130] [] (unwind_backtrace) from [] (show_stack+0x20/0x24) [ 0.055146] [] (show_stack) from [] (dump_stack+0x84/0xa0) [ 0.055160] [] (dump_stack) from [] (lockdep_rcu_suspicious+0xb0/0x110) [ 0.055172] [] (lockdep_rcu_suspicious) from [] (time_hardirqs_off+0x2b8/0x3c8) [ 0.055184] [] (time_hardirqs_off) from [] (trace_hardirqs_off_caller+0x2c/0xf4) [ 0.055194] [] (trace_hardirqs_off_caller) from [] (trace_hardirqs_off+0x14/0x18) [ 0.055204] [] (trace_hardirqs_off) from [] (rcu_idle_enter+0x78/0xcc) [ 0.055213] [] (rcu_idle_enter) from [] (cpu_startup_entry+0x190/0x518) [ 0.055222] [] (cpu_startup_entry) from [] (rest_init+0x13c/0x17c) [ 0.055231] [] (rest_init) from [] (start_kernel+0x320/0x380) [ 0.055238] [] (start_kernel) from [<8000807c>] (0x8000807c) As per Steve Rotstedt's suggestion I changed the trace_* calls to trace_*_rcuidle calls. He pointed out that the trace points were getting triggered when rcu wasn't watching. Signed-off-by: Thomas Gleixner Cc: Steven Rostedt Cc: stable-rt@vger.kernel.org (cherry picked from commit ac56e4167d84ada099f2af0d1d53f4742d577ce9) Signed-off-by: Tom Zanussi --- kernel/trace/trace_irqsoff.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c index d1940b095d85..9cbc38722905 100644 --- a/kernel/trace/trace_irqsoff.c +++ b/kernel/trace/trace_irqsoff.c @@ -452,7 +452,7 @@ EXPORT_SYMBOL_GPL(stop_critical_timings); #ifdef CONFIG_PROVE_LOCKING void time_hardirqs_on(unsigned long a0, unsigned long a1) { - trace_preemptirqsoff_hist(IRQS_ON, 0); + trace_preemptirqsoff_hist_rcuidle(IRQS_ON, 0); if (!preempt_trace() && irq_trace()) stop_critical_timing(a0, a1); } @@ -461,7 +461,7 @@ void time_hardirqs_off(unsigned long a0, unsigned long a1) { if (!preempt_trace() && irq_trace()) start_critical_timing(a0, a1); - trace_preemptirqsoff_hist(IRQS_OFF, 1); + trace_preemptirqsoff_hist_rcuidle(IRQS_OFF, 1); } #else /* !CONFIG_PROVE_LOCKING */ -- 2.14.1