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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 084B2C2D0E4 for ; Fri, 20 Nov 2020 16:40:47 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 442BF2225B for ; Fri, 20 Nov 2020 16:40:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OuxnvxGt" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 442BF2225B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:35084 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kg9Sm-0006EY-Mj for qemu-devel@archiver.kernel.org; Fri, 20 Nov 2020 11:40:44 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:37724) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kg9Ot-0002oh-6H for qemu-devel@nongnu.org; Fri, 20 Nov 2020 11:36:43 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:44366) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kg9Oq-0008Q4-Ud for qemu-devel@nongnu.org; Fri, 20 Nov 2020 11:36:42 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1605890198; 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=lSfGDM+Og87hOI3jTZ7+dTzH+hujXO89q6cWN8uAUtE=; b=OuxnvxGtpwc37YvWA+CJXoAJSenYH4qzOgQs1JuXICegEBYfWtY7TNozqbaQgghNQzoFDS XAwsttQHHQ5c/3Uir1ZOlnuk1Qiwtv1+Or/LXqm+Rx9iKiPD6mzZyBof6hG9nUO4q5+zjn gIGW/8FL2oibNoexgKwBwoIf5E5Oadg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-486-lNaQXMCLPPC7ZWvTT4vmHw-1; Fri, 20 Nov 2020 11:36:37 -0500 X-MC-Unique: lNaQXMCLPPC7ZWvTT4vmHw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 98CF61052A1D; Fri, 20 Nov 2020 16:36:35 +0000 (UTC) Received: from merkur.fritz.box (ovpn-115-21.ams2.redhat.com [10.36.115.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 32AF75D9D5; Fri, 20 Nov 2020 16:36:29 +0000 (UTC) Date: Fri, 20 Nov 2020 17:36:27 +0100 From: Kevin Wolf To: Vladimir Sementsov-Ogievskiy Subject: Re: [PATCH RFC 0/5] Fix accidental crash in iotest 30 Message-ID: <20201120163627.GD5599@merkur.fritz.box> References: <20201120161622.1537-1-vsementsov@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: <20201120161622.1537-1-vsementsov@virtuozzo.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=kwolf@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=63.128.21.124; envelope-from=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org, berto@igalia.com, qemu-block@nongnu.org, jsnow@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com, den@openvz.org, pbonzini@redhat.com, philmd@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 20.11.2020 um 17:16 hat Vladimir Sementsov-Ogievskiy geschrieben: > Hi all! > > As Peter recently noted, iotest 30 accidentally fails. > > I found that Qemu crashes due to interleaving of graph-update > operations of parallel mirror and stream block-jobs. I haven't found the time yet to properly look into this or your other thread where you had a similar question, but there is one thing I'm wondering: Why can the nested job even make progress and run its completion handler? When we modify the graph, we should have drained the subtree in question, so in theory while one job finishes and modifies the graph, there should be no way for the other job to make progress and get interleaved - it shouldn't be able to start I/O requests and much less to run its completion handler and modify the graph. Are we missing drained sections somewhere or do they fail to achieve what I think they should achieve? Kevin