From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755015Ab2DWKTk (ORCPT ); Mon, 23 Apr 2012 06:19:40 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:29914 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754818Ab2DWKTj (ORCPT ); Mon, 23 Apr 2012 06:19:39 -0400 Message-ID: <4F952CAD.5070405@openvz.org> Date: Mon, 23 Apr 2012 14:19:25 +0400 From: Kinsbursky Stanislav User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120412 Thunderbird/11.0.1 MIME-Version: 1.0 To: "akpm@linux-foundation.org" CC: "serge.hallyn@canonical.com" , "dhowells@redhat.com" , "arnd@arndb.de" , "lucas.demarchi@profusion.mobi" , "linux-kernel@vger.kernel.org" , "criu@openvz.org" , "mtk.manpages@gmail.com" Subject: Re: [CRIU] [PATCH v2 0/2] IPC: message queue checkpoint/restore - requested updates References: <20120416140235.653.36996.stgit@localhost6.localdomain6> In-Reply-To: <20120416140235.653.36996.stgit@localhost6.localdomain6> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Andrew. I'm very sorry, but a critical flaw has been found in this feature: copying of kernel data to user is done under spinlock. Since message queue size can be increased up to INT_MAX, then copying to temporary kernel buffer while passing message queue in not a solution. So, please, drop both patches (feature implementation and test). Most probably Ill replace them with MSG_PEEK feature (the same logic, but only for one message - like it's done for sockets). -- Best regards, Stanislav Kinsbursky