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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C4AA4C6FA83 for ; Tue, 13 Sep 2022 01:56:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229880AbiIMB4S (ORCPT ); Mon, 12 Sep 2022 21:56:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229833AbiIMB4P (ORCPT ); Mon, 12 Sep 2022 21:56:15 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF88B52466 for ; Mon, 12 Sep 2022 18:56:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663034172; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=H19OXg6EPz5UTCCwATfQC0KcwPAzRjXZ1tHwdeetkOA=; b=TerZ5sd+ajCOrw8iY9glyw0wJ7nr8OFOsy8nXZZJqqWf3dzLRrNEcxonvV55c6x4xg3u/s 9y15XwPB/+xEbwzNgbG+nDNKS1OogEr8zBOfsLtFhtfo6m30woTNdGeGaBhliZKfW+cgZp +dzbGTKFdycVd/g39lwqULjJLT9aP5w= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-481-iPiUOx5dNDOBcDUyHR6stQ-1; Mon, 12 Sep 2022 21:56:09 -0400 X-MC-Unique: iPiUOx5dNDOBcDUyHR6stQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7050E38164C1; Tue, 13 Sep 2022 01:56:08 +0000 (UTC) Received: from T590 (ovpn-8-17.pek2.redhat.com [10.72.8.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 42F19C15BA4; Tue, 13 Sep 2022 01:56:02 +0000 (UTC) Date: Tue, 13 Sep 2022 09:55:57 +0800 From: Ming Lei To: Christoph Hellwig Cc: Dusty Mabe , Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, ming.lei@redhat.com Subject: Re: regression caused by block: freeze the queue earlier in del_gendisk Message-ID: References: <017845ae-fbae-70f6-5f9e-29aff2742b8c@dustymabe.com> <20220907073324.GB23826@lst.de> <20220912071618.GA4971@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220912071618.GA4971@lst.de> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 12, 2022 at 09:16:18AM +0200, Christoph Hellwig wrote: > On Fri, Sep 09, 2022 at 04:24:40PM +0800, Ming Lei wrote: > > On Wed, Sep 07, 2022 at 09:33:24AM +0200, Christoph Hellwig wrote: > > > On Thu, Sep 01, 2022 at 03:06:08PM +0800, Ming Lei wrote: > > > > It is a bit hard to associate the above commit with reported issue. > > > > > > So the messages clearly are about something trying to open a device > > > that went away at the block layer, but somehow does not get removed > > > in time by udev (which seems to be a userspace bug in CoreOS). But > > > even with that we really should not hang. > > > > Xiao Ni provides one script[1] which can reproduce the issue more or less. > > I've run the reproduced 10000 times on current mainline, and while > it prints one of the autoloading messages per run, I've not actually > seen any kind of hang. I can't reproduce the hang too. What I meant is that new raid disk can be added by mdadm after stopping the imsm container and raid disk with the autoloading messages printed, I understand this behavior isn't correct, but I am not familiar with raid enough. It might be related with the delay deleting gendisk from wq & md kobj release handler. During reboot, if mdadm does this stupid thing without stopping, the hang could be caused. I think the root cause is that why mdadm tries to open/add new raid bdev crazily during reboot. Thanks, Ming