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=-6.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 BDB5CC43381 for ; Tue, 26 Mar 2019 06:32:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8BA1120857 for ; Tue, 26 Mar 2019 06:32:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553581955; bh=1BlmUYHoXMCEz5q+dEcoCXwg3+xIfA+4eYIG+eWIa0s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=TETulrm0kRw+7rX3hM/DjYqbI96qYJ5sBMix5SRkFhfNCsSA4vzDvRpETb52Q5Uhh nulxo5HyCgk9ibKa4C/CUCBximEKrnsO7rZBzMGeE8a1AinZMJKDV1sLpOWlJsS06g px4mvLJRlQv8oPsh/YKK1SFUUXC28QONARbiKqXA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731460AbfCZGce (ORCPT ); Tue, 26 Mar 2019 02:32:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:41916 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726279AbfCZGcb (ORCPT ); Tue, 26 Mar 2019 02:32:31 -0400 Received: from localhost (unknown [104.132.152.111]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EA7EB20823; Tue, 26 Mar 2019 06:32:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553581950; bh=1BlmUYHoXMCEz5q+dEcoCXwg3+xIfA+4eYIG+eWIa0s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GKdengsF9q7x9R4FE3vy94Rka6HGq2+SUcWC0XIGMZoWuH/dPT3du+sd/TBYZD1Uy zqmzGDdPBDPHYDPv6FyDK1RPeBfPGuqUxVhNP9bUZSMZgRjy6GgQPf8dQQulemhjBU m/VSUmSYYaYfafo4mNq8vFhGodM+Lkj6S4sCDIwY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tetsuo Handa , syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com, Waiman Long , "Peter Zijlstra (Intel)" , Andrew Morton , Linus Torvalds , "Paul E. McKenney" , Thomas Gleixner , Will Deacon , Ingo Molnar Subject: [PATCH 4.9 16/30] locking/lockdep: Add debug_locks check in __lock_downgrade() Date: Tue, 26 Mar 2019 15:29:55 +0900 Message-Id: <20190326042608.120387869@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190326042607.558087893@linuxfoundation.org> References: <20190326042607.558087893@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Waiman Long commit 71492580571467fb7177aade19c18ce7486267f5 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- kernel/locking/lockdep.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3446,6 +3446,9 @@ __lock_set_class(struct lockdep_map *loc 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,