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=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 4733FC433DB for ; Wed, 17 Mar 2021 16:05:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 01E8B64DD1 for ; Wed, 17 Mar 2021 16:05:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232163AbhCQQEu (ORCPT ); Wed, 17 Mar 2021 12:04:50 -0400 Received: from mail.xmyslivec.cz ([83.167.247.77]:49662 "EHLO mail.xmyslivec.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231993AbhCQQEi (ORCPT ); Wed, 17 Mar 2021 12:04:38 -0400 X-Greylist: delayed 536 seconds by postgrey-1.27 at vger.kernel.org; Wed, 17 Mar 2021 12:04:38 EDT Received: from [172.23.0.68] (mh1-fw.logicworks.mh.etn.cz [82.113.58.199]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.xmyslivec.cz (Postfix) with ESMTPSA id 60EF640246; Wed, 17 Mar 2021 16:55:38 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=xmyslivec.cz; s=master; t=1615996538; bh=JBMyqbIihgalcArsZ+QbCW8HrguuuQNErHtTO+I+rG0=; h=To:Cc:References:From:Subject:Date:In-Reply-To:From; b=Y4kAB/OmYBJU7x2IkPa+FBCO9lXmtna1WDvYmgg/bZrDZhYbdHbq+f/2QyPDpzF/u VpcR9fLwzAByj5lEIFKWWrehQV2eeeOJA2s9sBmAhUPuRYM3fCslJNzM34XdPEBDVn F3DDwC3XQhrGNrG+YiRFjBRrVnCVqMSo5AQZblmvE2iUpQEh1LaEE/mLBBeVBxs4k8 hVjnLBcbFnxY5n1OdecPeE+vxdiI8pal1P29pM/QAkbRlzQc+sAs4MR85EymrrQxrk 7v+jZ+pSg2M1pq+uzc+rxd4Hsc90Jd+XYj2A72WFbM04HUeI7t9i3gU8QkgV7pQ2xS T8u0H5KsJHAOQ== To: Manuel Riel Cc: Chris Murphy , Michal Moravec , songliubraving@fb.com, guoqing.jiang@cloud.ionos.com, Btrfs BTRFS , Linux-RAID References: <29509e08-e373-b352-d696-fcb9f507a545@xmyslivec.cz> <695936b4-67a2-c862-9cb6-5545b4ab3c42@xmyslivec.cz> <2f2f1c21-c81b-55aa-6f77-e2d3f32d32cb@xmyslivec.cz> <4b0dd0aa-f77b-16c8-107b-0182378f34e6@xmyslivec.cz> <5e79d1f8-7632-48ef-de56-9e79cba87434@xmyslivec.cz> <0c792470-6ee9-8254-dd57-a7a90ac95bcd@xmyslivec.cz> <56AD80D0-6853-4E3A-A94C-AD1477D3FDA4@snapdragon.cc> From: Vojtech Myslivec Subject: Re: Linux RAID with btrfs stuck and consume 100 % CPU Message-ID: <5e9e627f-7f73-c243-8084-58f156b984c5@xmyslivec.cz> Date: Wed, 17 Mar 2021 16:55:36 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <56AD80D0-6853-4E3A-A94C-AD1477D3FDA4@snapdragon.cc> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org Thanks a lot Manuel for your findings and information. It's good to know btrfs is not causing this issue and the common symptom is an MD journal on another RAID device. I have moved journal from logical volume on RAID1 to a plain partition on a SSD and I will monitor the state. Vojtech On 17. 03. 21 5:35, Manuel Riel wrote: > Final update on this issue for anyone who encounters a similar problem in the future: > > I didn't observe any "hanging" RAID devices after using an ordinary NVMe partition as journal. So using e.g. another md-RAID1 array as journal doesn't seem to be supported. > > The docs[1] say "This means the cache disk must be ... sustainable." The sustainable part motivated me to use a md-RAID1 array. I think the docs should mention that the journal can't be on another RAID array. > > I'm sending in a patch to emphasize this in the docs. > > > 1: https://www.kernel.org/doc/html/latest/driver-api/md/raid5-cache.html > >> On Feb 28, 2021, at 4:34 PM, Manuel Riel wrote: >> >> Hit another mdadm "hanger" today. No more reading possible and md4_raid6 stuck at 100% CPU. >> >> I've now moved the write journal off the RAID1 device. So it's not a "nested" RAID any more. Hope this will help. >> >> With only one hardware device used as write cache, I suppose only write-through mode[1] is suggested now. >> >> >> 1: https://www.kernel.org/doc/Documentation/md/raid5-cache.txt >