From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 486A6606A324 for ; Wed, 11 Nov 2026 16:20:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=RPqFHLaC Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1xRB3p-00031K-LC; Wed, 11 Nov 2026 11:20:33 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xRB3j-0002z9-Os for qemu-devel@nongnu.org; Wed, 11 Nov 2026 11:20:27 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1xRB3h-0002AY-R3 for qemu-devel@nongnu.org; Wed, 11 Nov 2026 11:20:27 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1794414024; 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=EAUJusRuCXumGYReCY/WQ7XDC+XVnqwfC1SRWSLCEO8=; b=RPqFHLaCi2pVYyMpwsxrVyllP6MCrKamNPkXwpiP+cV/DZ/uVM9YcYVzEsdTjoXdq7/GkG 8kcCsxF+5w43kXQ42DnK37MX2oNHreMDNDH/sLLf3SBrHZSXXQhrPxXFaZmIsL82Cwe4I+ dEtN3+rIQzUgDXJmwLZIhLCwgxap54A= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-318-dtSaRQPgOT2b7-FuAYr-PQ-1; Wed, 11 Nov 2026 11:20:18 -0500 X-MC-Unique: dtSaRQPgOT2b7-FuAYr-PQ-1 X-Mimecast-MFC-AGG-ID: dtSaRQPgOT2b7-FuAYr-PQ_1794414017 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 786161955D42; Wed, 11 Nov 2026 16:20:17 +0000 (UTC) Received: from redhat.com (headnet04.pony-001.prod.iad2.dc.redhat.com [10.2.32.116]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id E17AE1955DB9; Wed, 11 Nov 2026 16:20:15 +0000 (UTC) Date: Wed, 11 Nov 2026 10:20:13 -0600 From: Eric Blake To: "Denis V. Lunev" Cc: qemu-devel@nongnu.org, Peter Xu , Fabiano Rosas , Juraj Marcin Subject: Re: [PATCH v2 1/5] migration/postcopy: report COMPLETED only after the run BH has run Message-ID: References: <20261110183257.2930908-1-den@openvz.org> <20261110183257.2930908-2-den@openvz.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261110183257.2930908-2-den@openvz.org> User-Agent: NeoMutt/20260616 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 5 X-Spam_score: 0.5 X-Spam_bar: / X-Spam_report: (0.5 / 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_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org X-Spam-Status: No, score=-17.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Tue, Nov 10, 2026 at 07:32:53PM +0100, Denis V. Lunev wrote: > From: Denis V. Lunev > > The postcopy listen thread waits for main_thread_load_event before it > reports COMPLETED. That event is set as soon as qemu_loadvm_state_main() > returns in the main thread, while the run state is changed later, in > loadvm_postcopy_handle_run_bh(). The listen thread can therefore report > COMPLETED while the VM is still in RUN_STATE_INMIGRATE, easily so in a > bitmap-only postcopy where it has little to load. > > Management reacting to COMPLETED then finds the VM still incoming: a > blockdev-add creates an inactive node, since bds_tree_init() forces > BDRV_O_INACTIVE in RUN_STATE_INMIGRATE, and attaching a device to it > fails with "Block node is read-only". Precopy gets this right: > process_incoming_migration_bh() changes the run state before it reports > COMPLETED. > > Once CMD_POSTCOPY_RUN has scheduled the run BH, set the event at the > end of the BH instead. qemu_loadvm_state() keeps setting it in every > other case, including a load that failed before CMD_POSTCOPY_RUN. The > postcopy state it checks only becomes RUNNING on the main thread, right > before the BH is scheduled. > > Signed-off-by: Denis V. Lunev > Cc: Peter Xu > Cc: Fabiano Rosas > Cc: Juraj Marcin > --- > migration/migration.h | 2 +- > migration/savevm.c | 6 +++++- > 2 files changed, 6 insertions(+), 2 deletions(-) Reviewed-by: Eric Blake -- Eric Blake, Principal Software Engineer Red Hat, Inc. Virtualization: qemu.org | libguestfs.org