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=-12.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 E1C91C7112F for ; Mon, 21 Jan 2019 11:30:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B566F20663 for ; Mon, 21 Jan 2019 11:30:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728276AbfAULaA (ORCPT ); Mon, 21 Jan 2019 06:30:00 -0500 Received: from terminus.zytor.com ([198.137.202.136]:37605 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727881AbfAULaA (ORCPT ); Mon, 21 Jan 2019 06:30:00 -0500 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id x0LBTWuO2496239 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 21 Jan 2019 03:29:32 -0800 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id x0LBTUKV2496230; Mon, 21 Jan 2019 03:29:30 -0800 Date: Mon, 21 Jan 2019 03:29:30 -0800 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Waiman Long Message-ID: Cc: peterz@infradead.org, will.deacon@arm.com, penguin-kernel@i-love.sakura.ne.jp, akpm@linux-foundation.org, mingo@kernel.org, torvalds@linux-foundation.org, paulmck@linux.vnet.ibm.com, tglx@linutronix.de, longman@redhat.com, linux-kernel@vger.kernel.org, hpa@zytor.com Reply-To: longman@redhat.com, linux-kernel@vger.kernel.org, hpa@zytor.com, paulmck@linux.vnet.ibm.com, torvalds@linux-foundation.org, tglx@linutronix.de, penguin-kernel@i-love.sakura.ne.jp, akpm@linux-foundation.org, mingo@kernel.org, peterz@infradead.org, will.deacon@arm.com In-Reply-To: <1547093005-26085-1-git-send-email-longman@redhat.com> References: <1547093005-26085-1-git-send-email-longman@redhat.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] locking/lockdep: Add debug_locks check in __lock_downgrade() Git-Commit-ID: 71492580571467fb7177aade19c18ce7486267f5 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 71492580571467fb7177aade19c18ce7486267f5 Gitweb: https://git.kernel.org/tip/71492580571467fb7177aade19c18ce7486267f5 Author: Waiman Long AuthorDate: Wed, 9 Jan 2019 23:03:25 -0500 Committer: Ingo Molnar CommitDate: Mon, 21 Jan 2019 11:18:51 +0100 locking/lockdep: Add debug_locks check in __lock_downgrade() Tetsuo Handa had reported he saw an incorrect "downgrading a read lock" warning right after a previous lockdep warning. It is likely that the previous warning turned off lock debugging causing the lockdep to have inconsistency states leading to the lock downgrade warning. Fix that by add a check for debug_locks at the beginning of __lock_downgrade(). Debugged-by: Tetsuo Handa Reported-by: Tetsuo Handa Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com Signed-off-by: Waiman Long Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Linus Torvalds Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Link: https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com Signed-off-by: Ingo Molnar --- kernel/locking/lockdep.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 95932333a48b..e805fe3bf87f 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3535,6 +3535,9 @@ static int __lock_downgrade(struct lockdep_map *lock, unsigned long ip) unsigned int depth; int i; + if (unlikely(!debug_locks)) + return 0; + depth = curr->lockdep_depth; /* * This function is about (re)setting the class of a held lock,