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=-6.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 8F403C433E0 for ; Wed, 29 Jul 2020 21:06:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 599112082E for ; Wed, 29 Jul 2020 21:06:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cloud.ionos.com header.i=@cloud.ionos.com header.b="Lb5y+h6H" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727053AbgG2VGk (ORCPT ); Wed, 29 Jul 2020 17:06:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726496AbgG2VGk (ORCPT ); Wed, 29 Jul 2020 17:06:40 -0400 Received: from mail-ed1-x542.google.com (mail-ed1-x542.google.com [IPv6:2a00:1450:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C695FC0619D2 for ; Wed, 29 Jul 2020 14:06:39 -0700 (PDT) Received: by mail-ed1-x542.google.com with SMTP id a14so1448678edx.7 for ; Wed, 29 Jul 2020 14:06:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloud.ionos.com; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=I87fUIB3jW1Ap9Jvzk/GcIhatEkQtaMOon/TETB9VtA=; b=Lb5y+h6HgMBCZmzEra1RFNQdb2cMSGgnTDXvDM1xALQmuk/B1Wg1JZ5spC3oJhNplz rm/UnnI4A0Usrnb9AWNhKJaHhyb8IMHRZXLi397BtsyWR4ystxAcnYzNTNgUUIR3LlDV IOSvbkjdcqafmiFcZy4EMCphUKRS7FxdR+zIaiE43h0b33D+TAryoKp++FOcZ088FRsq /k6ReZqg4kfG771bOuz1Eg6YbDi4Cp18iHd8vV+H+tY8v5vNxSuYO8j9RkiQY0d/IWpS 2qrgsozrutNMH5o4tSf6IJkpuMOQ990JSuHvTACIcHmnVfOVPloSR5XexPU2Y6NPVohN i98A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=I87fUIB3jW1Ap9Jvzk/GcIhatEkQtaMOon/TETB9VtA=; b=RPzMZyXhuPK31Nc6ube4qOjimYT33gHHTUCJ3LNwztlhSZ0Xt8ZbFjEKSCZbWZmLyq KQGnFNkZn7Wn5G2nRGYp86GMFSm1jW1deZRyx20HXP4qTh+Z6IBuPZqTJKCJnm0xGhLs utOt9fGgc75i4U5vvA3POOslw3K7qEOjH/isExNmHnlA2KGhsDY30cx++OAdQeg0BvGE tdR+Przq5M0i9ft0/fwic17Onr2s4bv7/YA28uBuN0qdXg+JBlQck9Kuoj9me242TKYv pn8pCE7k7fwhnwUON9U6Qa83cLmdliSJnIk6d8EDeUhfGV+CoPhAMRbTfWsGp2FDRBdY bWEQ== X-Gm-Message-State: AOAM5326hpg9Fk2BZAso8O9aZH2Z68IcsQjGnIydmT1PDdjYEidhE0is PabgvAg6XkBsrVTJ4uiAPUWBqmkkNWs= X-Google-Smtp-Source: ABdhPJx3wVG6rl455uP0QYriZY/DjVBLtOtjangIpyuXtnHHwbsuV5Fmiy1lhPJQYvjUUx1k+vfTqQ== X-Received: by 2002:a05:6402:b4c:: with SMTP id bx12mr139710edb.157.1596056798451; Wed, 29 Jul 2020 14:06:38 -0700 (PDT) Received: from ?IPv6:2001:16b8:4867:e700:c8e8:c32e:dd0d:709? ([2001:16b8:4867:e700:c8e8:c32e:dd0d:709]) by smtp.gmail.com with ESMTPSA id d20sm3041248edy.9.2020.07.29.14.06.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 29 Jul 2020 14:06:37 -0700 (PDT) Subject: Re: Linux RAID with btrfs stuck and consume 100 % CPU To: Vojtech Myslivec , linux-btrfs@vger.kernel.org, linux-raid@vger.kernel.org Cc: Michal Moravec , Song Liu References: From: Guoqing Jiang Message-ID: Date: Wed, 29 Jul 2020 23:06:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org Hi, On 7/22/20 10:47 PM, Vojtech Myslivec wrote: > 1. What should be the cause of this problem? Just a quick glance based on the stacks which you attached, I guess it could be a deadlock issue of raid5 cache super write. Maybe the commit 8e018c21da3f ("raid5-cache: fix a deadlock in superblock write") didn't fix the problem completely.  Cc Song. And I am curious why md thread is not waked if mddev_trylock fails, you can give it a try but I can't promise it helps ... --- a/drivers/md/raid5-cache.c +++ b/drivers/md/raid5-cache.c @@ -1337,8 +1337,10 @@ static void r5l_write_super_and_discard_space(struct r5l_log *log,          */         set_mask_bits(&mddev->sb_flags, 0,                 BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_PENDING)); -       if (!mddev_trylock(mddev)) +       if (!mddev_trylock(mddev)) { +               md_wakeup_thread(mddev->thread);                 return; +       }         md_update_sb(mddev, 1);         mddev_unlock(mddev); Thanks, Guoqing