From nobody Mon Feb 9 19:37:39 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1675731863; cv=none; d=zohomail.com; s=zohoarc; b=DtgM2XsfHXMfecP6MupLQpHfi1iJbl8o8aKD9Ari9YNLoFS2lbFpZg/RRq65lFWt43wMMV7+F6Uk0SU1IGFmKZC/kB+F7jQ0vgDvwZHh0L4eqe4c6k/SJ0lsDZAc1dnSeMgChTGJOPohoFzRpoYIjvUyI92Bgb/skKRqL8fbkj0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1675731863; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=/vi3kUI9VRzfEdyEafXxBkT0bxSOiapenyEEaiH00lY=; b=INk9JwvKJ28jakZGzHqykKfbNUliH7HPvpGXxGiuV0WT0X9OaXC7vzi9qBX7aB6dT2gSPr22DWXpISvUSoI5kumfbryY/OzBPKwYN4CbaPOlBWKAZ7CT6pyW1CtZQrfxygOR86Q8+apqSY0jNbB2rNXhgIReZLtz8EFdieNbvFw= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=none dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1675731863950649.283532291459; Mon, 6 Feb 2023 17:04:23 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pPCKl-0002BH-6k; Mon, 06 Feb 2023 19:59:43 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pPCKZ-0001UC-CM for qemu-devel@nongnu.org; Mon, 06 Feb 2023 19:59:34 -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 1pPCKW-00040I-Tq for qemu-devel@nongnu.org; Mon, 06 Feb 2023 19:59:31 -0500 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-582-KPEAZe1yNMqDu1WeIVDh4Q-1; Mon, 06 Feb 2023 19:59:24 -0500 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 69AA6811E6E; Tue, 7 Feb 2023 00:59:23 +0000 (UTC) Received: from secure.mitica (unknown [10.39.192.29]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9E951492C3C; Tue, 7 Feb 2023 00:59:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675731568; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=/vi3kUI9VRzfEdyEafXxBkT0bxSOiapenyEEaiH00lY=; b=SMavTxTgGZ92fqEpOT2jQ8VR9vTLT42s142eDn3QwmWJKwulPAUWxqX4BhIWtHkUpWFUSd ZfUO7Sis+48euuYQXvPUcYaKEcK8W7Ds8v3iuf2tzeZz4BQJ/GMrlaEV25owzDXPutBql7 L67EKY/iC1xcMNA82ZGcxo15s+Qlayg= X-MC-Unique: KPEAZe1yNMqDu1WeIVDh4Q-1 From: Juan Quintela To: qemu-devel@nongnu.org Cc: qemu-block@nongnu.org, Stefan Berger , Stefan Hajnoczi , Halil Pasic , John Snow , David Hildenbrand , Fam Zheng , Thomas Huth , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= , Laurent Vivier , Vladimir Sementsov-Ogievskiy , qemu-s390x@nongnu.org, Christian Borntraeger , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , "Michael S. Tsirkin" , Juan Quintela , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , "Dr. David Alan Gilbert" , Marcel Apfelbaum , Coiby Xu , Ilya Leoshkevich , Eduardo Habkost , Yanan Wang , Richard Henderson , Markus Armbruster , Paolo Bonzini , Alex Williamson , Eric Blake , Eric Farman , Zhenzhong Duan Subject: [PULL 27/30] multifd: Fix a race on reading MultiFDPages_t.block Date: Tue, 7 Feb 2023 01:56:47 +0100 Message-Id: <20230207005650.1810-28-quintela@redhat.com> In-Reply-To: <20230207005650.1810-1-quintela@redhat.com> References: <20230207005650.1810-1-quintela@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=quintela@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_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1675731865029100001 Content-Type: text/plain; charset="utf-8" From: Zhenzhong Duan In multifd_queue_page() MultiFDPages_t.block is checked twice. Between the two checks, MultiFDPages_t.block may be reset to NULL by multifd thread. This lead to the 2nd check always true then a redundant page submitted to multifd thread again. Signed-off-by: Zhenzhong Duan Reviewed-by: Juan Quintela Signed-off-by: Juan Quintela --- migration/multifd.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/migration/multifd.c b/migration/multifd.c index eeb4fb87ee..ad89293b4e 100644 --- a/migration/multifd.c +++ b/migration/multifd.c @@ -442,6 +442,7 @@ static int multifd_send_pages(QEMUFile *f) int multifd_queue_page(QEMUFile *f, RAMBlock *block, ram_addr_t offset) { MultiFDPages_t *pages =3D multifd_send_state->pages; + bool changed =3D false; =20 if (!pages->block) { pages->block =3D block; @@ -454,14 +455,16 @@ int multifd_queue_page(QEMUFile *f, RAMBlock *block, = ram_addr_t offset) if (pages->num < pages->allocated) { return 1; } + } else { + changed =3D true; } =20 if (multifd_send_pages(f) < 0) { return -1; } =20 - if (pages->block !=3D block) { - return multifd_queue_page(f, block, offset); + if (changed) { + return multifd_queue_page(f, block, offset); } =20 return 1; --=20 2.39.1