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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 340DEC282CE for ; Wed, 24 Apr 2019 18:12:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02BA120652 for ; Wed, 24 Apr 2019 18:12:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556129540; bh=Jf7iOWgv3cBQOxUJ/zKkTLbcNGyFtUjhgdruu2HmMOM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=sMi+HhndOnF2Z1HCsY5hIJJC8Mm1dzllGPIps7l0MKJrMNblL5Wez2uODyY9ufZxb kMt7Cha0EGHCAEOyviNGkqoaDics17cQ0pxkGoQRrxVc8+5fN77Qf1QwhMdxZ1HCzq fNikTVLRC0EEgt0knS7PBIP2sJVxKSpGUnasD4qc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387776AbfDXRM7 (ORCPT ); Wed, 24 Apr 2019 13:12:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:36802 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387742AbfDXRMx (ORCPT ); Wed, 24 Apr 2019 13:12:53 -0400 Received: from localhost (62-193-50-229.as16211.net [62.193.50.229]) (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 36F8A218B0; Wed, 24 Apr 2019 17:12:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556125972; bh=Jf7iOWgv3cBQOxUJ/zKkTLbcNGyFtUjhgdruu2HmMOM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lsYt3n5pPherzKVGxvESpbBNsworNjEDog2P9QAg1tnrWlnpAB6UquT5ljYgefvxs MqcqktgeWRues/FKl41KC7kjqt+O4DO8gzoyrkkf4a+L+KSsLStRH5bzfSK36ksEzw CMk3iWf0VHYoYOZv7zkCzXbyWmE6OKBkimwWjePk= 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 3.18 031/104] locking/lockdep: Add debug_locks check in __lock_downgrade() Date: Wed, 24 Apr 2019 19:08:48 +0200 Message-Id: <20190424170857.262137613@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190424170839.996641496@linuxfoundation.org> References: <20190424170839.996641496@linuxfoundation.org> User-Agent: quilt/0.66 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 [ Upstream commit 71492580571467fb7177aade19c18ce7486267f5 ] 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: 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 fb90ca3a296e..27de98428367 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3312,6 +3312,9 @@ __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, -- 2.19.1