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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 C2F63C352AA for ; Tue, 1 Oct 2019 19:34:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F9A821783 for ; Tue, 1 Oct 2019 19:34:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727097AbfJATey (ORCPT ); Tue, 1 Oct 2019 15:34:54 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:56743 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726043AbfJATey (ORCPT ); Tue, 1 Oct 2019 15:34:54 -0400 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1iFNuW-0003ZJ-L1; Tue, 01 Oct 2019 21:34:12 +0200 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id F09D91C03AB; Tue, 1 Oct 2019 21:34:11 +0200 (CEST) Date: Tue, 01 Oct 2019 19:34:11 -0000 From: "tip-bot2 for Peter Zijlstra" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: sched/urgent] membarrier: Fix RCU locking bug caused by faulty merge Cc: Ingo Molnar , "Peter Zijlstra (Intel)" , Borislav Petkov , Chris Metcalf , Christoph Lameter , "Eric W. Biederman" , Kirill Tkhai , Linus Torvalds , Mathieu Desnoyers , Mike Galbraith , Oleg Nesterov , "Paul E. McKenney" , "Russell King - ARM Linux admin" , Thomas Gleixner , linux-tip-commits@vger.kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20191001085033.GP4519@hirez.programming.kicks-ass.net> References: <20191001085033.GP4519@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Message-ID: <156995845178.9978.16309965770056877944.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the sched/urgent branch of tip: Commit-ID: 73956fc07dd7b25d4a33ab3fdd6247c60d0b237c Gitweb: https://git.kernel.org/tip/73956fc07dd7b25d4a33ab3fdd6247c60d0b237c Author: Peter Zijlstra AuthorDate: Tue, 01 Oct 2019 10:50:33 +02:00 Committer: Ingo Molnar CommitterDate: Tue, 01 Oct 2019 21:27:50 +02:00 membarrier: Fix RCU locking bug caused by faulty merge The following commit: 227a4aadc75b ("sched/membarrier: Fix p->mm->membarrier_state racy load") got fat fingered by me when merging it with other patches. It meant to move the RCU section out of the for loop but ended up doing it partially, leaving a superfluous rcu_read_lock() inside, causing havok. Reported-by: Ingo Molnar Signed-off-by: Peter Zijlstra (Intel) Cc: Borislav Petkov Cc: Chris Metcalf Cc: Christoph Lameter Cc: Eric W. Biederman Cc: Kirill Tkhai Cc: Linus Torvalds Cc: Mathieu Desnoyers Cc: Mike Galbraith Cc: Oleg Nesterov Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Russell King - ARM Linux admin Cc: Thomas Gleixner Cc: linux-tip-commits@vger.kernel.org Fixes: 227a4aadc75b ("sched/membarrier: Fix p->mm->membarrier_state racy load") Link: https://lkml.kernel.org/r/20191001085033.GP4519@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/sched/membarrier.c | 1 - 1 file changed, 1 deletion(-) diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index a39bed2..168479a 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -174,7 +174,6 @@ static int membarrier_private_expedited(int flags) */ if (cpu == raw_smp_processor_id()) continue; - rcu_read_lock(); p = rcu_dereference(cpu_rq(cpu)->curr); if (p && p->mm == mm) __cpumask_set_cpu(cpu, tmpmask);