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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 DF0F5C43381 for ; Tue, 19 Mar 2019 12:35:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF47020857 for ; Tue, 19 Mar 2019 12:35:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NkEq/QVU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727506AbfCSMfJ (ORCPT ); Tue, 19 Mar 2019 08:35:09 -0400 Received: from mail-pf1-f181.google.com ([209.85.210.181]:37576 "EHLO mail-pf1-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726002AbfCSMfI (ORCPT ); Tue, 19 Mar 2019 08:35:08 -0400 Received: by mail-pf1-f181.google.com with SMTP id 8so10185553pfr.4 for ; Tue, 19 Mar 2019 05:35:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=pXGSMCvAzf0HNFwl1hqaFl2ShpygrFyoDN27PoiJjBM=; b=NkEq/QVUKfyuZF2yUTyx3afhfmTtMovZt7E7I40TiQ1dqDmvBC5FDan6/ooh5fw3/L cHGwrYtYFqKr0P8yMjpRiibiHIwfPFb+8BtSQTQ7VIeesgmm1Zg1AFOaC4hvSVev4ilT 3gc8N52qYr5kNYjy83iPKRvaTDm62AdYQvXcorcp154m/v/HNgkEF5wKU1TrdzRueylX UmnPXKUJDK045AVd3kh0Q2VOQ4gnZQtzEbk8U+a1vVaHUrYooNqtZO1UNkwygwLdwAeR ckRzmXUH7ytBRB/IqtK+rjGH4qLDeEry+24I87xLxoY6kfuFakEFBNZBtOmdqFmnbRTD 2D2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:date:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=pXGSMCvAzf0HNFwl1hqaFl2ShpygrFyoDN27PoiJjBM=; b=gcsSKY9hlG27hx8alLuRGXLY4xfZaz6eKhu8ZI4IAU3BcEs15hy0/Qg2RKG+m/ibl0 rKM3pp+v6GyqScXrukYL14Ezf4/XKl7RfSosZv8U7P/IEGAwlIQzznlI72Y0hrqTf6lb 4iqCZ8cL28XaVa2F3nG/PBbkkut4BktqyvOvRQgocKIcUvPGI0VcAbvTeSq09fzR8Zmw vNXpsVcvZ4Zsi59OJTPSbxdKJorwBqG84+CsvGr4M6Sg+jvBJEaY+kIR4DT5niV4AlvJ yQyd7Jv1NiP6ktKuQc17hXMMyt9gzNVmhWtwbJOAyM8VuP0qFMhQbplTDeFa9QxMbRwe BZdw== X-Gm-Message-State: APjAAAVYau/ApdTUEh4+Tm7kUNZonOYEwk4wgq+gr2CJOs19gZxmBbRD MCv+ZTqjOtDwLLC+kcPpsnE= X-Google-Smtp-Source: APXvYqwvHnnKPfoAS9B90y2qNHbj+ZrP7RJZ8PJMuppQHy48S5+pOCRl4IW1KK1msFb97HKdsfD8vA== X-Received: by 2002:a17:902:8bc7:: with SMTP id r7mr1940127plo.163.1552998906657; Tue, 19 Mar 2019 05:35:06 -0700 (PDT) Received: from localhost ([121.137.63.184]) by smtp.gmail.com with ESMTPSA id g2sm31808778pfm.144.2019.03.19.05.35.04 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 19 Mar 2019 05:35:05 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Tue, 19 Mar 2019 21:35:00 +0900 To: Dmitry Vyukov Cc: Sergey Senozhatsky , Tetsuo Handa , Petr Mladek , Sergey Senozhatsky , LKML , syzkaller Subject: Re: [syzbot? printk?] no WARN_ON() messages printed before "Kernel panic - not syncing: panic_on_warn set ..." Message-ID: <20190319123500.GA18754@tigerII.localdomain> References: <2a48dee7-b649-65a4-be5d-8b3374013cee@i-love.sakura.ne.jp> <201903180527.x2I5RQVp009981@www262.sakura.ne.jp> <20190318125019.GA2686@tigerII.localdomain> <20190318140937.GA29374@tigerII.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (03/19/19 09:10), Dmitry Vyukov wrote: [..] > In some setups we read out output with "dmesg -w" (should stream > output as well) in absence of a better solution. Will this be affected > by SYSLOG_ACTION_CLEAR? There is a small chance that syslog/devkmsg can be affected syslog_clear() { clear_seq = log_next_seq; clear_idx = log_next_idx; } syslog_print_all() { ... seq = clear_seq; idx = clear_idx; while (seq < log_next_seq) { ... len += msg_print_text(msg, true, time, NULL, 0); } ... } devkmsg also may be affected syslog_clear() { clear_seq = log_next_seq; clear_idx = log_next_idx; } devkmsg_llseek() { ... case SEEK_DATA: user->idx = clear_idx; user->seq = clear_seq; break; ... } user->idx/user->seq then are used in devkmsg poll()/read(). syslog is more likely to be affected, I think. -ss