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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,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 87147C388F7 for ; Thu, 5 Nov 2020 23:10:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 362BA20715 for ; Thu, 5 Nov 2020 23:10:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604617817; bh=EBKXRZA+WNZ0UpWX3ui1bG5r7mNNDBe5p8zeNiIflb8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OalMNGPQxD+BP1ldk2kRs8hSNUqbOx4ObOyPhFPaMxQp/NILGWoEopcXJP2la1vY6 WRa3XgfLceRi2xng/bjrYBCOZI/THu3ZgS8ruRe1K55UcoI12AQbf/FNjlrkbBn7l/ SH8kFvBSh8NNdYlXKCOc2Qnk0fwcPYL9kwjaTwjI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732560AbgKEXJ0 (ORCPT ); Thu, 5 Nov 2020 18:09:26 -0500 Received: from mail.kernel.org ([198.145.29.99]:34390 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732046AbgKEXJZ (ORCPT ); Thu, 5 Nov 2020 18:09:25 -0500 Received: from paulmck-ThinkPad-P72.home (50-39-104-11.bvtn.or.frontiernet.net [50.39.104.11]) (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 0A46E2083B; Thu, 5 Nov 2020 23:09:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604617764; bh=EBKXRZA+WNZ0UpWX3ui1bG5r7mNNDBe5p8zeNiIflb8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o8Ua1NiRJ8Rbdv1uV/ra8fr0Vd0Yrwn7KZlEshvKSauOBekyA5sUlNmT+fV+ZgqZg IDpMn9qQhFzQufq8URe7JHfY1T1GlkyQIruMCN+qmIbGOhajNnCZYH+g0iitKAsggT Q4tY1vVPi3q3AJo8yoW/BrQ9YNitd+kjrlRJlUgw= 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, 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 tip/core/rcu 02/16] x86/smpboot: Move rcu_cpu_starting() earlier Date: Thu, 5 Nov 2020 15:09:07 -0800 Message-Id: <20201105230921.19017-2-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20201105230856.GA18904@paulmck-ThinkPad-P72> References: <20201105230856.GA18904@paulmck-ThinkPad-P72> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" The call to rcu_cpu_starting() in mtrr_ap_init() is not early enough in the CPU-hotplug onlining process, which results in lockdep splats as follows: ============================= WARNING: suspicious RCU usage 5.9.0+ #268 Not tainted ----------------------------- kernel/kprobes.c:300 RCU-list traversed in non-reader section!! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 no locks held by swapper/1/0. stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.9.0+ #268 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-1ubuntu1 04/01/2014 Call Trace: dump_stack+0x77/0x97 __is_insn_slot_addr+0x15d/0x170 kernel_text_address+0xba/0xe0 ? get_stack_info+0x22/0xa0 __kernel_text_address+0x9/0x30 show_trace_log_lvl+0x17d/0x380 ? dump_stack+0x77/0x97 dump_stack+0x77/0x97 __lock_acquire+0xdf7/0x1bf0 lock_acquire+0x258/0x3d0 ? vprintk_emit+0x6d/0x2c0 _raw_spin_lock+0x27/0x40 ? vprintk_emit+0x6d/0x2c0 vprintk_emit+0x6d/0x2c0 printk+0x4d/0x69 start_secondary+0x1c/0x100 secondary_startup_64_no_verify+0xb8/0xbb This is avoided by moving the call to rcu_cpu_starting up near the beginning of the start_secondary() function. Note that the raw_smp_processor_id() is required in order to avoid calling into lockdep before RCU has declared the CPU to be watched for readers. Link: https://lore.kernel.org/lkml/160223032121.7002.1269740091547117869.tip-bot2@tip-bot2/ Reported-by: Qian Cai Suggested-by: Peter Zijlstra Signed-off-by: Paul E. McKenney --- arch/x86/kernel/cpu/mtrr/mtrr.c | 2 -- arch/x86/kernel/smpboot.c | 1 + 2 files changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/mtrr/mtrr.c b/arch/x86/kernel/cpu/mtrr/mtrr.c index 6a80f36..5f436cb 100644 --- a/arch/x86/kernel/cpu/mtrr/mtrr.c +++ b/arch/x86/kernel/cpu/mtrr/mtrr.c @@ -794,8 +794,6 @@ void mtrr_ap_init(void) if (!use_intel() || mtrr_aps_delayed_init) return; - rcu_cpu_starting(smp_processor_id()); - /* * Ideally we should hold mtrr_mutex here to avoid mtrr entries * changed, but this routine will be called in cpu boot time, diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index de776b2..99bdceb 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -229,6 +229,7 @@ static void notrace start_secondary(void *unused) #endif cpu_init_exception_handling(); cpu_init(); + rcu_cpu_starting(raw_smp_processor_id()); x86_cpuinit.early_percpu_clock_init(); preempt_disable(); smp_callin(); -- 2.9.5