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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 2C10BC433B4 for ; Thu, 8 Apr 2021 13:47:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3F9F61107 for ; Thu, 8 Apr 2021 13:47:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229741AbhDHNr6 (ORCPT ); Thu, 8 Apr 2021 09:47:58 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:53837 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231371AbhDHNrz (ORCPT ); Thu, 8 Apr 2021 09:47:55 -0400 Received: from fsav302.sakura.ne.jp (fsav302.sakura.ne.jp [153.120.85.133]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 138DlP9k044243; Thu, 8 Apr 2021 22:47:25 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav302.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav302.sakura.ne.jp); Thu, 08 Apr 2021 22:47:25 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav302.sakura.ne.jp) Received: from [192.168.1.9] (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 138DlPXr044239 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NO); Thu, 8 Apr 2021 22:47:25 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [PATCH 05/13] tty: remove tty_warn() To: Greg Kroah-Hartman Cc: Jiri Slaby , linux-kernel@vger.kernel.org, Petr Mladek , Sergey Senozhatsky References: <20210408125134.3016837-1-gregkh@linuxfoundation.org> <20210408125134.3016837-6-gregkh@linuxfoundation.org> From: Tetsuo Handa Message-ID: <92b1f39d-9c9c-c319-a351-f3cb9a1c0497@i-love.sakura.ne.jp> Date: Thu, 8 Apr 2021 22:47:21 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <20210408125134.3016837-6-gregkh@linuxfoundation.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/04/08 21:51, Greg Kroah-Hartman wrote: > Remove users of tty_warn() and replace them with calls to dev_warn() > which provides more information about the tty that has the error and > uses the standard formatting logic. Ouch. This series would be good for clean up, but this series might be bad for handling lockdep warning syzbot is reporting. Since tty_warn() is using plain printk(), we can avoid lockdep warning by using printk_deferred(). If we use dev_warn() instead, we need to modify __dev_printk() to use printk_deferred(), which means that all dev_*() users are affected by this change. Also, we need to modify dev_printk_emit()/dev_vprintk_emit() callers to embed loglevel into the format string so that we pass LOGLEVEL_SCHED to vprintk_emit() ... maybe just change from "if (!in_sched)" to "if (!in_sched && !dev_info)" instead ? Also, dev_vprintk_emit() need to start calling defer_console_output() after returning from vprintk_emit() in order to behave like printk_deferred(). I'm not sure whether this change is safe.