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=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 B9777C10F14 for ; Thu, 3 Oct 2019 15:56:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8B86520700 for ; Thu, 3 Oct 2019 15:56:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570118167; bh=wUdez5E++Sj6shH4LQ9hAWtNYPLsTqGJAVh5eLB9kQY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=EToCeSXe5V1duq29D9Vl72MXXA+bCndv9/QbJ0FcY+ztd98M1dPVauR8e7B1CgvNe ckEW7MU2Ej7yzhhu7ZF0x39nDjJW7P5iNsTKCjLVMXgadReOHjvlKH50mErDyK9V18 aAk2dxKNRd3JrZ3+f4goekyLiKURISVu1CRqvtBQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730487AbfJCP4G (ORCPT ); Thu, 3 Oct 2019 11:56:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:37750 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730433AbfJCP4E (ORCPT ); Thu, 3 Oct 2019 11:56:04 -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 A42FB21848; Thu, 3 Oct 2019 15:56:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570118163; bh=wUdez5E++Sj6shH4LQ9hAWtNYPLsTqGJAVh5eLB9kQY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=d5FHn9Aqsy7imEfN+qnCDWQVD4YMIEP+RjE/9IU509trDs3QU8q9vSWkC260J7PJJ kIV1LYbyAc/Ax8C2Nde2mXj+/VNed3y7fvkcSh+FC2Wb54M4cCParqlFQkYdenm/9L q/sXoV501YLlmGIIthhxh/9UH7VwWIsAcHBT0h1w= 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 4.4 13/99] locking/lockdep: Add debug_locks check in __lock_downgrade() Date: Thu, 3 Oct 2019 17:52:36 +0200 Message-Id: <20191003154300.292791604@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191003154252.297991283@linuxfoundation.org> References: <20191003154252.297991283@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 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 f2df5f86af28a..a419696709a1a 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -3314,6 +3314,9 @@ __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