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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 F132BC32793 for ; Mon, 30 Sep 2019 00:28:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BDEC121882 for ; Mon, 30 Sep 2019 00:28:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569803311; bh=18Xoe49n0LwJ985Z5rDsuGb/OZgAqt2Ye8XtTlaCTqY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=CTQJSeK3qZQtY6pQSSxuWfP/cCq5gzrmANgSHlAywv0ZtIa7S6opHrrwuWYA2XKcT 2aXYQk1N7fRL2V2DJjy83CzmjRVGbQ61p6SQ4Q5EXjxECxpxYUv3m1t+KAd/qrlDh2 YnJMStSEPyjXbvqv1xxZGnKO5JeEeOoyxO57kk+4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729241AbfI3A2b (ORCPT ); Sun, 29 Sep 2019 20:28:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:37454 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726360AbfI3A2a (ORCPT ); Sun, 29 Sep 2019 20:28:30 -0400 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 059E02082F; Mon, 30 Sep 2019 00:28:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569803310; bh=18Xoe49n0LwJ985Z5rDsuGb/OZgAqt2Ye8XtTlaCTqY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1vl6AlM68mcxrKNKJrSd1tVhtyrR6+F6y2tUi5gN2GnhyJag2mk3rTFfiyB5FDf6/ P1TIgQV/HLhaBfAd0e+KhMXzNw/OLO8i9JYKM0Mt9RPT4dCjzkygjXeqkwUspy2jzU k4+Ae1hTd6qXM15QQ+6FNvNqvskZNA3o+ydOY5mI= Date: Sun, 29 Sep 2019 20:28:28 -0400 From: Sasha Levin To: Tetsuo Handa Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com, Waiman Long , "Peter Zijlstra (Intel)" , Andrew Morton , Linus Torvalds , "Paul E. McKenney" , Thomas Gleixner , Will Deacon , Ingo Molnar Subject: Re: [PATCH 4.19 36/63] locking/lockdep: Add debug_locks check in __lock_downgrade() Message-ID: <20190930002828.GQ8171@sasha-vm> References: <20190929135031.382429403@linuxfoundation.org> <20190929135038.482721804@linuxfoundation.org> <801c81d2-ce72-8eb3-a18b-1b0943270fc4@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <801c81d2-ce72-8eb3-a18b-1b0943270fc4@i-love.sakura.ne.jp> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 29, 2019 at 11:43:38PM +0900, Tetsuo Handa wrote: >On 2019/09/29 22:54, Greg Kroah-Hartman wrote: >> 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(). > >Please drop "[PATCH 4.19 36/63] locking/lockdep: Add debug_locks check in __lock_downgrade()". >We had a revert patch shown below in the past. We had a revert in the stable trees, but that revert was incorrect. Take a look at commit 513e1073d52e55 upstream, it patches __lock_set_class() (even though the subject line says __lock_downgrade()). So this is not a backporting error as the revert said it is, but is rather the intended location to be patched. If this is actually wrong, then it should be addressed upstream first. -- Thanks, Sasha