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 X-Spam-Level: X-Spam-Status: No, score=-10.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 398EEC07E96 for ; Thu, 8 Jul 2021 09:52:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F88460231 for ; Thu, 8 Jul 2021 09:52:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231415AbhGHJzD (ORCPT ); Thu, 8 Jul 2021 05:55:03 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:10432 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231360AbhGHJzC (ORCPT ); Thu, 8 Jul 2021 05:55:02 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GLBMP60LjzZpW0; Thu, 8 Jul 2021 17:49:05 +0800 (CST) Received: from dggpeml500016.china.huawei.com (7.185.36.70) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 8 Jul 2021 17:52:18 +0800 Received: from [10.174.148.223] (10.174.148.223) by dggpeml500016.china.huawei.com (7.185.36.70) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Thu, 8 Jul 2021 17:52:17 +0800 Subject: Re: [RFC PATCH 0/5] madvise MADV_DOEXEC To: Anthony Yznaga , , , , CC: , , , , , , , , , , , , , , , , , , , , , "Gonglei (Arei)" References: <1595869887-23307-1-git-send-email-anthony.yznaga@oracle.com> From: "Longpeng (Mike, Cloud Infrastructure Service Product Dept.)" Message-ID: Date: Thu, 8 Jul 2021 17:52:16 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <1595869887-23307-1-git-send-email-anthony.yznaga@oracle.com> Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.148.223] X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To dggpeml500016.china.huawei.com (7.185.36.70) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Hi Anthony and Steven, ÔÚ 2020/7/28 1:11, Anthony Yznaga дµÀ: > This patchset adds support for preserving an anonymous memory range across > exec(3) using a new madvise MADV_DOEXEC argument. The primary benefit for > sharing memory in this manner, as opposed to re-attaching to a named shared > memory segment, is to ensure it is mapped at the same virtual address in > the new process as it was in the old one. An intended use for this is to > preserve guest memory for guests using vfio while qemu exec's an updated > version of itself. By ensuring the memory is preserved at a fixed address, > vfio mappings and their associated kernel data structures can remain valid. > In addition, for the qemu use case, qemu instances that back guest RAM with > anonymous memory can be updated. > We have a requirement like yours, but ours seems more complex. We want to isolate some memory regions from the VM's memory space and the start a child process who will using these memory regions. I've wrote a draft to support this feature, but I just find that my draft is pretty like yours. It seems that you've already abandoned this patchset, why ? > Patches 1 and 2 ensure that loading of ELF load segments does not silently > clobber existing VMAS, and remove assumptions that the stack is the only > VMA in the mm when the stack is set up. Patch 1 re-introduces the use of > MAP_FIXED_NOREPLACE to load ELF binaries that addresses the previous issues > and could be considered on its own. > > Patches 3, 4, and 5 introduce the feature and an opt-in method for its use > using an ELF note. > > Anthony Yznaga (5): > elf: reintroduce using MAP_FIXED_NOREPLACE for elf executable mappings > mm: do not assume only the stack vma exists in setup_arg_pages() > mm: introduce VM_EXEC_KEEP > exec, elf: require opt-in for accepting preserved mem > mm: introduce MADV_DOEXEC > > arch/x86/Kconfig | 1 + > fs/binfmt_elf.c | 196 +++++++++++++++++++++++++-------- > fs/exec.c | 33 +++++- > include/linux/binfmts.h | 7 +- > include/linux/mm.h | 5 + > include/uapi/asm-generic/mman-common.h | 3 + > kernel/fork.c | 2 +- > mm/madvise.c | 25 +++++ > mm/mmap.c | 47 ++++++++ > 9 files changed, 266 insertions(+), 53 deletions(-) > -- Sincerely yours, Longpeng(Mike)