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 AD869C433F5 for ; Sun, 15 May 2022 19:25:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238406AbiEOTZT (ORCPT ); Sun, 15 May 2022 15:25:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229587AbiEOTZS (ORCPT ); Sun, 15 May 2022 15:25:18 -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 ESMTP id B4F0325E95 for ; Sun, 15 May 2022 12:25:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1652642713; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=3tgm7FkhgZMI1Knq5BCXmzxRNBZ0f9T8FBbOE8N4Q1k=; b=F29WF6BWni1hLstxrT13hr0DnInDSSk0pS4CpWLBUBmoxHA6cgsUVCM76YWaBdh+B1F8F9 TTJRnvd6KuUDZxLtLUHjHyX8soRKkGdwRxQZJI6qAFPI8u3oJMg6/poVjNdlE5GdNb7VXi ZboWYlKltORtNP3SzgfK2QrIP7aOhts= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-315-JWgn8x6QO-yE8dxgjrf9sg-1; Sun, 15 May 2022 15:25:11 -0400 X-MC-Unique: JWgn8x6QO-yE8dxgjrf9sg-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 9477F801E80; Sun, 15 May 2022 19:25:11 +0000 (UTC) Received: from localhost (unknown [10.39.192.39]) by smtp.corp.redhat.com (Postfix) with ESMTP id 56ADD111E411; Sun, 15 May 2022 19:25:06 +0000 (UTC) Date: Sun, 15 May 2022 20:25:05 +0100 From: "Richard W.M. Jones" To: libguestfs@redhat.com, linux-block@vger.kernel.org, Josef Bacik Subject: Re: [Libguestfs] Communication issues between NBD driver and NBDKit server Message-ID: <20220515192505.GJ1127@redhat.com> References: <04a0a06b-e6dc-48b7-bc29-105dab888a56@www.fastmail.com> <20220515180525.GF8021@redhat.com> <87czgelidg.fsf@vostro.rath.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87czgelidg.fsf@vostro.rath.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Sun, May 15, 2022 at 08:12:59PM +0100, Nikolaus Rath wrote: > Do you see any way for this to happen? I think it's impossible. A more likely explanation follows. If you look at the kernel code, the NBD_CMD_INFLIGHT command flag is cleared when a command times out: https://github.com/torvalds/linux/blob/0cdd776ec92c0fec768c7079331804d3e52d4b27/drivers/block/nbd.c#L407 That's the place where it would have printed the "Possible stuck request" message. Some time later, nbdkit actually replies to the message (for the first and only time) and in that code the flag is checked and found to be clear already, causing the "Suspicious reply" message to be printed: https://github.com/torvalds/linux/blob/0cdd776ec92c0fec768c7079331804d3e52d4b27/drivers/block/nbd.c#L749 I'd say you need to increase the timeout and/or work out why the S3 plugin is taking so long to respond. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org