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=-2.3 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 1E806C04AB1 for ; Thu, 9 May 2019 10:18:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E078C21479 for ; Thu, 9 May 2019 10:18:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="TxuD70Ue" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726526AbfEIKSf (ORCPT ); Thu, 9 May 2019 06:18:35 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:39423 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725869AbfEIKSf (ORCPT ); Thu, 9 May 2019 06:18:35 -0400 Received: by mail-pf1-f195.google.com with SMTP id z26so1079609pfg.6 for ; Thu, 09 May 2019 03:18:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=CTf90VjXEEHOLCaxdp+kSOHPoaCpeiePTqliSxM7Esc=; b=TxuD70Ueav4V9V1FkiuTlBH0HoblqulrviNdWDNq20n+MOyg6aETAY8hC6FbpaRzKV 6cmiAp8kZ49gRmNXnRK5+lZ+IPkfGBouJtULN/Qvr/UxGg9iZ1Y7/oR5Rvo/JGFD0WJ1 5IWZ6sf8OGJNWfGbv1AscP9MRpZVHJ+j85rgWO5h74cmseWfSgV8k0MAKuC/3TZn8nAL 20eFsmgnMBZgUcfhDXezNmoRcqKoFVQ+5Oxp7rNjD+QYQUBzBwGGwn0fDB2f0aVtkRV5 mZPz47k3YTnUwHqryA3v7oTYovnU/wCUnieVa5c1CRRwkv+dQSyR6jrBuV9ij7Oknc9f 6S/w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=CTf90VjXEEHOLCaxdp+kSOHPoaCpeiePTqliSxM7Esc=; b=YxsU+9yvjoQnxYfJzER6KctF94idI9KCozLvDPnbaEIgtBWlACl2Te1Ena4+CGPLMX rt392DpmQGrsrlJTy8DeY1rcc50tB7jE7hbngiSF1Z+2bbrwQRPz97BmpUUgV2lKQnuH +kCPuqKWqYcrPy1WaYxq70ky1Ji8dbxQctmTvTWBysgHfEU60iba2YsmJA8fhvN3XzYc OgJS5RMXmqaikStRmUyMmRj+T75rKjqhT5ejLMydTIQAsG4HKridoVPhPYmz0eZKpEVp ogJYyoDOp1d0MScHBehuy7KjjNoeo06vek4qVBL963uirVwaNZAr2xXqtvBy/kIyPznt /1Tw== X-Gm-Message-State: APjAAAU2OOPw0vuhPnLqrjCuIMBJDxzIzkE/uVtA1fKtBSb8syQTnRKo 8+ZnWXApSqcUk5GuPQIguKc= X-Google-Smtp-Source: APXvYqz90vv990h5LnzY4pVlQS/SgbMqxCbU6ebVhmKqBVpkXce0eDMRNMzba9wg6AoZ7sLfTQ513w== X-Received: by 2002:aa7:90ce:: with SMTP id k14mr3642062pfk.239.1557397114828; Thu, 09 May 2019 03:18:34 -0700 (PDT) Received: from localhost ([39.7.47.21]) by smtp.gmail.com with ESMTPSA id f20sm3506265pff.176.2019.05.09.03.18.33 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 09 May 2019 03:18:33 -0700 (PDT) Date: Thu, 9 May 2019 19:18:30 +0900 From: Sergey Senozhatsky To: Tetsuo Handa Cc: Dmitry Vyukov , Sergey Senozhatsky , Petr Mladek , LKML , syzkaller , Sergey Senozhatsky Subject: Re: [syzbot? printk?] no WARN_ON() messages printed before "Kernel panic - not syncing: panic_on_warn set ..." Message-ID: <20190509101830.GB23572@jagdpanzerIV> References: <20190318125019.GA2686@tigerII.localdomain> <20190318140937.GA29374@tigerII.localdomain> <20190319123500.GA18754@tigerII.localdomain> <127c9c3b-f878-174f-7065-66dc50fcabcf@i-love.sakura.ne.jp> <20190509095823.GA23572@jagdpanzerIV> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190509095823.GA23572@jagdpanzerIV> 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 (05/09/19 18:58), Sergey Senozhatsky wrote: > On (05/08/19 19:31), Tetsuo Handa wrote: > [..] > > We are again getting corrupted reports where message from WARN() is missing. > > For example, https://syzkaller.appspot.com/text?tag=CrashLog&x=1720cac8a00000 was > > titled as "WARNING in cgroup_exit" because the > > "WARNING: CPU: 0 PID: 7870 at kernel/cgroup/cgroup.c:6008 cgroup_exit+0x51a/0x5d0" > > line is there but https://syzkaller.appspot.com/text?tag=CrashLog&x=1670a602a00000 > > was titled as "corrupted report (2)" because the > > "WARNING: CPU: 0 PID: 10223 at kernel/cgroup/cgroup.c:6008 cgroup_exit+0x51a/0x5d0" > > line is missing. Also, it is unlikely that there was no printk() for a few minutes. > > Thus, I suspect something is again suppressing console output. > > Hmm... That's interesting... What are these lines right before the kernel panic output? TTY writes (user space logging)? 03:54:05 executing program 5: syz_mount_image$xfs(&(0x7f0000000000)='xfs\x00', &(0x7f0000000040)='./file0\x00', 0x0, 0x0, 0x0, 0xe003, &(0x7f00000005c0)={[{@nolargeio='nolargeio'}]}) 03:54:06 executing program 2: syz_emit_ethernet(0x66, &(0x7f0000000080)={@local, @random="029cce98941b", [], {@ipv6={0x86dd, {0x0, 0x6, 'v`Q', 0x30, 0x3a, 0xffffffffffffffff, @remote={0xfe, 0x80, [0x29c, 0x0, 0x700, 0x5], 0xffffffffffffffff}, @mcast2={0xff, 0x2, [0x0, 0xfffffffffffff000]}, {[], @icmpv6=@dest_unreach={0xffffff86, 0x0, 0x0, 0x0, [0x7], {0x0, 0x6, "c5961e", 0x0, 0x0, 0x0, @mcast1={0xff, 0x1, [0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x3, 0x3, 0x0, 0x0, 0x8906], 0x8200}, @mcast2}}}}}}}, 0x0) [ 2396.035331][T10223] Kernel panic - not syncing: panic_on_warn set ... [ 2396.042217][T10223] CPU: 0 PID: 10223 Comm: syz-executor.1 Not tainted 5.1.0-next-20190507 #2 Hmm... Dunno... Don't really have any explanations yet... Can you add if (oops_in_progress) return IRQ_HANDLED; to you console driver's IRQ handler (xmit TX/RX path)? Just to check if this will change anything... -ss