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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 118D6C43381 for ; Sat, 16 Mar 2019 15:02:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D8358218E0 for ; Sat, 16 Mar 2019 15:02:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727054AbfCPPCr (ORCPT ); Sat, 16 Mar 2019 11:02:47 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:18805 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726902AbfCPPCr (ORCPT ); Sat, 16 Mar 2019 11:02:47 -0400 Received: from fsav106.sakura.ne.jp (fsav106.sakura.ne.jp [27.133.134.233]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id x2GF2YRV008354; Sun, 17 Mar 2019 00:02:34 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav106.sakura.ne.jp (F-Secure/fsigk_smtp/530/fsav106.sakura.ne.jp); Sun, 17 Mar 2019 00:02:34 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/530/fsav106.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 x2GF2XrV008350 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NO); Sun, 17 Mar 2019 00:02:33 +0900 (JST) (envelope-from penguin-kernel@i-love.sakura.ne.jp) Subject: Re: [syzbot? printk?] no WARN_ON() messages printed before "Kernel panic - not syncing: panic_on_warn set ..." To: Dmitry Vyukov Cc: Sergey Senozhatsky , Petr Mladek , Sergey Senozhatsky , LKML , syzkaller References: <0a0d282b-6757-5f42-b888-ef52b040aaa1@i-love.sakura.ne.jp> <20190316141410.GA18654@tigerII.localdomain> <647012f4-c221-addf-51ab-586014e8f435@i-love.sakura.ne.jp> From: Tetsuo Handa Message-ID: <2a48dee7-b649-65a4-be5d-8b3374013cee@i-love.sakura.ne.jp> Date: Sun, 17 Mar 2019 00:02:28 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.3 MIME-Version: 1.0 In-Reply-To: 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 On 2019/03/16 23:57, Dmitry Vyukov wrote: > On Sat, Mar 16, 2019 at 3:53 PM Tetsuo Handa > wrote: >> >> On 2019/03/16 23:16, Dmitry Vyukov wrote: >>>>> Maybe try running with "ignore_loglevel" kernel command line option added? >>>> >>>> Right, that's something I would expect 0-day and syzkaller to do. >>> >>> to double-check: enabling this won't lead to verbose/debug level of logging? >>> >> >> I don't know what "verbose/debug level" means. But enabling this option causes >> KERN_{EMERG,ALERT,CRIT,ERR,WARNING,NOTICE,INFO,DEBUG} be printed equally. >> >> "ignore loglevel setting (prints all kernel messages to the console)" >> >> static bool suppress_message_printing(int level) >> { >> return (level >= console_loglevel && !ignore_loglevel); >> } > > Then I don't think it's suitable: there will be too much output. > Then, we need to find what test is changing console_loglevel. Maybe add debug BUG_ON() in linux-next.git using CONFIG_DEBUG_AID_FOR_SYZBOT ?