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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 23EB3C61CE8 for ; Sun, 20 Jan 2019 02:56:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DD45D2084F for ; Sun, 20 Jan 2019 02:56:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730068AbfATCvO (ORCPT ); Sat, 19 Jan 2019 21:51:14 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:13253 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729996AbfATCvO (ORCPT ); Sat, 19 Jan 2019 21:51:14 -0500 Received: from fsav110.sakura.ne.jp (fsav110.sakura.ne.jp [27.133.134.237]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id x0K2ooal028244; Sun, 20 Jan 2019 11:50:50 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav110.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav110.sakura.ne.jp); Sun, 20 Jan 2019 11:50:50 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav110.sakura.ne.jp) Received: from [192.168.1.8] (softbank126126163036.bbtec.net [126.126.163.36]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id x0K2ooHt028240 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Sun, 20 Jan 2019 11:50:50 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [PATCH] locking/lockdep: Add debug_locks check in __lock_downgrade() To: Peter Zijlstra , Dmitry Vyukov Cc: Waiman Long , Ingo Molnar , Will Deacon , LKML References: <1547093005-26085-1-git-send-email-longman@redhat.com> <20190114133650.GC10486@hirez.programming.kicks-ass.net> From: Tetsuo Handa Message-ID: <250f311c-a686-d4b3-d88f-6d39ff3b1492@i-love.sakura.ne.jp> Date: Sun, 20 Jan 2019 11:50:49 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190114133650.GC10486@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Peter, will this fix be sent to linux.git shortly? syzbot is generating many corrupted reports due to this race. On 2019/01/14 22:36, Peter Zijlstra wrote: > On Thu, Jan 10, 2019 at 11:21:13AM +0100, Dmitry Vyukov wrote: >> On Thu, Jan 10, 2019 at 5:04 AM Waiman Long wrote: >>> >>> 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(). >>> >>> Signed-off-by: Waiman Long >>> Reported-by: Tetsuo Handa >> >> Please also add: >> >> Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com >> >> for tracking purposes. But Tetsuo deserves lots of credit for debugging it. > > I made that: > > Reported-by: Tetsuo Handa > Debugged-by: Tetsuo Handa > Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com