From nobody Wed Nov 5 02:29:56 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1532349346126829.1296781831009; Mon, 23 Jul 2018 05:35:46 -0700 (PDT) Received: from localhost ([::1]:34383 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fha3v-00053o-4d for importer@patchew.org; Mon, 23 Jul 2018 08:35:39 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38413) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fha1f-0003c5-C3 for qemu-devel@nongnu.org; Mon, 23 Jul 2018 08:33:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fha1e-0004pO-Da for qemu-devel@nongnu.org; Mon, 23 Jul 2018 08:33:19 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:32876 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fha1e-0004pB-8D for qemu-devel@nongnu.org; Mon, 23 Jul 2018 08:33:18 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D895D401EF01 for ; Mon, 23 Jul 2018 12:33:17 +0000 (UTC) Received: from xz-mi.redhat.com (ovpn-12-73.pek2.redhat.com [10.72.12.73]) by smtp.corp.redhat.com (Postfix) with ESMTP id CDC482026D65; Mon, 23 Jul 2018 12:33:15 +0000 (UTC) From: Peter Xu To: qemu-devel@nongnu.org Date: Mon, 23 Jul 2018 20:33:03 +0800 Message-Id: <20180723123305.24792-3-peterx@redhat.com> In-Reply-To: <20180723123305.24792-1-peterx@redhat.com> References: <20180723123305.24792-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Mon, 23 Jul 2018 12:33:17 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.5]); Mon, 23 Jul 2018 12:33:17 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'peterx@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH for-3.0 2/4] migration: disallow recovery for release-ram X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Dr . David Alan Gilbert" , peterx@redhat.com, Juan Quintela Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Postcopy recovery won't work well with release-ram capability since release-ram will drop the page buffer as long as the page is put into the send buffer. So if there is a network failure happened, any page buffers that have not yet reached the destination VM but have already been sent from the source VM will be lost forever. Let's refuse the client from resuming such a postcopy migration. Luckily release-ram was designed to only be used when src and destination VMs are on the same host, so it should be fine. Signed-off-by: Peter Xu Reviewed-by: Juan Quintela --- migration/migration.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/migration/migration.c b/migration/migration.c index 8d56d56930..09447f2bb5 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -1629,6 +1629,25 @@ static bool migrate_prepare(MigrationState *s, bool = blk, bool blk_inc, "paused migration"); return false; } + + /* + * Postcopy recovery won't work well with release-ram + * capability since release-ram will drop the page buffer as + * long as the page is put into the send buffer. So if there + * is a network failure happened, any page buffers that have + * not yet reached the destination VM but have already been + * sent from the source VM will be lost forever. Let's refuse + * the client from resuming such a postcopy migration. + * Luckily release-ram was designed to only be used when src + * and destination VMs are on the same host, so it should be + * fine. + */ + if (migrate_release_ram()) { + error_setg(errp, "Postcopy recovery cannot work " + "when release-ram capability is set"); + return false; + } + /* This is a resume, skip init status */ return true; } --=20 2.17.1