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=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 BC8CFC432C0 for ; Wed, 27 Nov 2019 09:18:52 +0000 (UTC) Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 559CE2070A for ; Wed, 27 Nov 2019 09:18:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 559CE2070A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=vt.edu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernelnewbies-bounces@kernelnewbies.org Received: from localhost ([::1] helo=shelob.surriel.com) by shelob.surriel.com with esmtp (Exim 4.92.3) (envelope-from ) id 1iZtSf-0006WD-8N; Wed, 27 Nov 2019 04:18:13 -0500 Received: from omr2.cc.ipv6.vt.edu ([2607:b400:92:8400:0:33:fb76:806e] helo=omr2.cc.vt.edu) by shelob.surriel.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92.3) (envelope-from ) id 1iZtSc-0006W7-3i for kernelnewbies@kernelnewbies.org; Wed, 27 Nov 2019 04:18:10 -0500 Received: from mr2.cc.vt.edu (junk.cc.ipv6.vt.edu [IPv6:2607:b400:92:9:0:9d:8fcb:4116]) by omr2.cc.vt.edu (8.14.4/8.14.4) with ESMTP id xAR9I89x002760 for ; Wed, 27 Nov 2019 04:18:08 -0500 Received: from mail-qk1-f197.google.com (mail-qk1-f197.google.com [209.85.222.197]) by mr2.cc.vt.edu (8.14.7/8.14.7) with ESMTP id xAR9I3Se009633 for ; Wed, 27 Nov 2019 04:18:08 -0500 Received: by mail-qk1-f197.google.com with SMTP id c4so13552259qkl.6 for ; Wed, 27 Nov 2019 01:18:08 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:in-reply-to:references :mime-version:content-transfer-encoding:date:message-id; bh=tWOUg+6JVNIdzoHAIHzf09i+0IzAChiJrk6kmM1lKQ0=; b=HfRukeU3+xJh/JZs0PsrdYe1gcz0hI3Ra7PWQ+rvmUUBOF07Ljpa2hlkVdQ3vG1CQy mV0LZ0gK7NfoCPAW7bRMWxywHOkadWyK0trODMICaazBksIbU7UvQ+y4TZi0/CCfNsN6 aMAmKp0JFoV+y2fSVLp6aQtDUpBcis//rFmUWfgeMwn7vfRGwD6WQptYMFftJSRJDLBb zF1uxoIFZbAZgUcoy+3W1TGxmt/Kpnq8wHk7FlmKgUdu2VDnKG9rSMy2PC7cjnn/GhFa pVIRvqNulDm5RFN6ROeFjfcIGP+Qtt7RyjUovVkjh2/HmSveK6dnNxLAjjqRozyB3IKG ikbQ== X-Gm-Message-State: APjAAAWi8LYwSrtaVLaCRQS+hCPWZfGaipMk214Tuc8hZq/5l57Y/8QE xhNcDWCOFRN1+9CGz0BPiWM5scTKaQ3KCE8fHeO0C4VzQ7jzd+X1i0gMITBoM646VI4rsY4x2tc mlJoCliJ1jp/+u9PksX+sbePRNlJEVpaVH5YolOg= X-Received: by 2002:ac8:37d0:: with SMTP id e16mr6600677qtc.311.1574846283536; Wed, 27 Nov 2019 01:18:03 -0800 (PST) X-Google-Smtp-Source: APXvYqzdCA4VOXcrIw/vCwRa5F4rLlK1QBcxZp0pUk82ZdpzwkDH7ltXGrsGx5oz1XBnoppqtr0y+A== X-Received: by 2002:ac8:37d0:: with SMTP id e16mr6600662qtc.311.1574846283246; Wed, 27 Nov 2019 01:18:03 -0800 (PST) Received: from turing-police ([2601:5c0:c001:c9e1::359]) by smtp.gmail.com with ESMTPSA id f22sm7618470qtc.43.2019.11.27.01.18.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Nov 2019 01:18:01 -0800 (PST) From: "Valdis Kl=?utf-8?Q?=c4=93?=tnieks" X-Google-Original-From: "Valdis Kl=?utf-8?Q?=c4=93?=tnieks" X-Mailer: exmh version 2.9.0 11/07/2018 with nmh-1.7+dev To: tanure@linux.com Subject: Re: How to printk synchronously In-Reply-To: References: Mime-Version: 1.0 Date: Wed, 27 Nov 2019 04:18:00 -0500 Message-ID: <548800.1574846280@turing-police> Cc: "kernelnewbies@kernelnewbies.org" , aleave X-BeenThere: kernelnewbies@kernelnewbies.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Learn about the Linux kernel List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============7787528773763910302==" Errors-To: kernelnewbies-bounces@kernelnewbies.org --===============7787528773763910302== Content-Type: multipart/signed; boundary="==_Exmh_1574846280_2911P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit --==_Exmh_1574846280_2911P Content-Type: text/plain; charset=us-ascii On Tue, 26 Nov 2019 22:31:08 +0000, Lucas Tanure said: > Hi, > > What about ftrace ? Documentation/trace/ftrace.txt That won't help - his ^@^@^@ is a result of the system stopping and no longer writing to disk, so his logfile has blocks allocated to it but not yet written to. Using ftrace will have the same problem, if his kernel is locking up and not syncing to disk. A better approach would be to use netconsole to send all the console output to another machine, or serial console if that's an option. Though I have to wonder how he's determining it's a deadlock issue rather than a panic that's just plain stopping the system - building the kernel with lockdep support should reveal the issue before a lockup. And if it *is* a deadlock, there should be sufficient info in the watchdog logging (assuming the hardware has some sort of watchdog support, as most systems do). --==_Exmh_1574846280_2911P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Comment: Exmh version 2.9.0 11/07/2018 iQIVAwUBXd4/SAdmEQWDXROgAQLhqQ/+MXDBWzmtwNXUx0S9/aLU8MS6WbyaoQw/ mecjpLTp8NNtcoWtmoIqpE/2FZlYBYAbBFBxEFaosUMsRhDnhpXsiebzfHo7+QIg JUfnpPZKNndtl7ZqWyBEKwQuC7z0gxYr94Ly+D6BPA+kWWI43TBxeLWhy1zuNx7S zPCOQqopu73YTd/1YyAYrLeaovDr9Gy4aLq2peSZNfSdtufzRX0uX+cAfe4B7GhR iM0Qu7CANr124Lu20duSbODOub8HlzxhLdoU24t4mEW13yORtd29akosCTuFREQE HXjV8ZxVFIjSiZDA0LSFpybvglLFk/0KRcFtjUddPRUjaSZokLgO4KSlMzrWVeH5 BDJxO/SMYlEp4ndNdK5j1WCgN9bkBXM0qEKSPfEJUhe7W+qFXqbKYQnCKiMwiQiq uoU7pTsXTJyJmY0uJ1r1DpLitjAgfnQb6peopLja1A3qKUniy0BuPU9GfaeUNUnS 6TkyWXvuTGD8pOMg7FJSJqWNgc6S6eNi93eFzvQLzH7DK+aLs80V9Zh8J2IbshHD V/ktXZScojBNdQh31Cov8IpL7B45DpVDJcpNH1Luq1lidvMyYEx2uOdTyN/SdvXB +MX/haO0NeF2gcabqDPapSn/esh7CsnOPBQDynfcJP+LqCRtjAt1OQSMPfH0qIwv CygtmeK1SV0= =QJac -----END PGP SIGNATURE----- --==_Exmh_1574846280_2911P-- --===============7787528773763910302== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies --===============7787528773763910302==--