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 1F7E9C388F3 for ; Mon, 30 Sep 2019 11:36:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EB40D2190F for ; Mon, 30 Sep 2019 11:36:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569843361; bh=9WEhA8JA+UBptPyxfyomZDl3eE0Son1at5a6dFCkZpA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=t2caD1my7wOMw0ok7mKLhqv7JS7TGl73SJdr/wLga8/MDG1Dmeq4uARvMwoPHSvPx acvi5gIw6m9WphnZYCE15q/pj4NNgRdYgp41lxSepBj90lwGAnRGRYzNwrhOScAogT DDpOmPf7FdMzOMyWlVx2W6d5HlEv5fFr5UPn/RG8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729913AbfI3LgA (ORCPT ); Mon, 30 Sep 2019 07:36:00 -0400 Received: from mail.kernel.org ([198.145.29.99]:38082 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727215AbfI3Lf7 (ORCPT ); Mon, 30 Sep 2019 07:35:59 -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 D4C17206BB; Mon, 30 Sep 2019 11:35:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1569843359; bh=9WEhA8JA+UBptPyxfyomZDl3eE0Son1at5a6dFCkZpA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bHxPk2ypvO+UY24J4mkRO/KKATPjdvWvN/rfnLCOSf35scy1gjE532dFE2JC0LvqA BW//GlJwH8DzlwwfXAKUZ8P2Qk6BniW6WeiQHqYIC3UVTnNJlmrBrcLKp88EReX7Z8 a+nOWkYgM8MMhS4ZSeRlo4EHQzx/ACsmMpbdINeQ= Date: Mon, 30 Sep 2019 07:35:57 -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: <20190930113557.GR8171@sasha-vm> References: <20190929135031.382429403@linuxfoundation.org> <20190929135038.482721804@linuxfoundation.org> <801c81d2-ce72-8eb3-a18b-1b0943270fc4@i-love.sakura.ne.jp> <20190930002828.GQ8171@sasha-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: 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 Mon, Sep 30, 2019 at 10:46:39AM +0900, Tetsuo Handa wrote: >On 2019/09/30 9:28, Sasha Levin wrote: >> 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. >> > >Hmm, upstream has two commits with same author, same date, same subject, different hash, different content. >I couldn't find from https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com that >we want to patch both __lock_set_class() and __lock_downgrade(), but I found that the tip-bot has patched >__lock_downgrade() on "2019-01-21 11:29" and __lock_set_class() on "2019-02-04 8:56". >Seems that we by error patched both functions, though patching both functions should be harmless... Right, there's a lot of confusion between the duplicate subject lines and what this patch actually does. My point was that this is an upstream issue rather than a stable issue, we're just aligning with upstream here. -- Thanks, Sasha