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 73084C43381 for ; Tue, 26 Mar 2019 06:40:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4490E2087E for ; Tue, 26 Mar 2019 06:40:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553582422; bh=MWI4RXkWJZsDxRFqx0YQQNIiZg9Bn5a/LmvDGROxMBE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=R4W275NYRcot80+mP25fAaoyPgRgCiBlXgwYjNpU1SJMKjtmOpcNffYdo+5EjSjLQ 8cVpPsXRg7ou+f6cmLORv3bMQdCvUj+hXBmpokUiwxzSFu9NuSiUiMRGLkOdfnP09v 4gxWMMJaWDqM9dvZhtBBu3Y+Dup/aj0O071eEovc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732813AbfCZGkU (ORCPT ); Tue, 26 Mar 2019 02:40:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:56590 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732360AbfCZGkT (ORCPT ); Tue, 26 Mar 2019 02:40:19 -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 C7DDC2087C; Tue, 26 Mar 2019 06:40:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553582418; bh=MWI4RXkWJZsDxRFqx0YQQNIiZg9Bn5a/LmvDGROxMBE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Fh1oosbv0ed3h+CpDD2urjUpR9Nhaza/dnEb+w+tjDJmq1WaNoSGqRoy2ji7Dlqna N/5KmIGbBw/JuoBin+YNtXF6VMcOvu1F6tvQ4t17/GzNChjKX88vZ0/Zs5BVzyC3pw buU2tMOL4wpLACGH5MoPf8h6LkSCuqSWJp+NPOvM= 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 5.0 49/52] locking/lockdep: Add debug_locks check in __lock_downgrade() Date: Tue, 26 Mar 2019 15:30:36 +0900 Message-Id: <20190326042703.598339291@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190326042700.963224437@linuxfoundation.org> References: <20190326042700.963224437@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 5.0-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 @@ -3535,6 +3535,9 @@ static int __lock_downgrade(struct lockd 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,