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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 0825AC10F14 for ; Thu, 3 Oct 2019 17:40:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D544220865 for ; Thu, 3 Oct 2019 17:39:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570124399; bh=CknWvKtX5BmSgd+yGV+0i6mZncWjE5nHtScPrEPnwYs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UehJeC7SXfnA2HO41mPq17vxvsBtApZ3A20dO9+qcD3RJMBhj2j0hoeSNQpAaApI+ KEGFJamtNV0Cgmd4TXzYO6ahY1KWus2ddSsOryRECeoWsjjaJyy9VXFL5KVjoxrxqP stMSozQ8sxRIl9809XdfmhzjiHUYKbhWtYm14u/0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731626AbfJCQAs (ORCPT ); Thu, 3 Oct 2019 12:00:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:44692 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730115AbfJCQAr (ORCPT ); Thu, 3 Oct 2019 12:00:47 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 E00E721D81; Thu, 3 Oct 2019 16:00:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570118446; bh=CknWvKtX5BmSgd+yGV+0i6mZncWjE5nHtScPrEPnwYs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vesGmSXDxf1VoIZHbnm/cZD6SqA6G/4jKgd0JAOOFfRCBM403/lGE6jYvgqs8Y34k mcREor9TkOdyOoSD9b9r57/N9QG8MST6qacVs1eg4RQNIw3H0fYtDVt0FmTK3Tc1Ly lUzoOfTmytSk8yrhS9PHa0KTzRe6vo5vJluobv30= 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 , Sasha Levin Subject: [PATCH 4.9 015/129] locking/lockdep: Add debug_locks check in __lock_downgrade() Date: Thu, 3 Oct 2019 17:52:18 +0200 Message-Id: <20191003154325.692683799@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191003154318.081116689@linuxfoundation.org> References: <20191003154318.081116689@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Waiman Long [ Upstream commit 513e1073d52e55b8024b4f238a48de7587c64ccf ] 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(). 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: Sasha Levin --- kernel/locking/lockdep.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 4b27aaffdf352..d7f425698a4a1 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3446,6 +3446,9 @@ __lock_set_class(struct lockdep_map *lock, const char *name, 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, -- 2.20.1