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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable 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 1E71EC2BC61 for ; Tue, 30 Oct 2018 18:03:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DD6932080A for ; Tue, 30 Oct 2018 18:03:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DD6932080A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-security-module-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727776AbeJaC6W (ORCPT ); Tue, 30 Oct 2018 22:58:22 -0400 Received: from mga04.intel.com ([192.55.52.120]:50973 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726532AbeJaC6V (ORCPT ); Tue, 30 Oct 2018 22:58:21 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Oct 2018 11:03:51 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,445,1534834800"; d="scan'208";a="270058406" Received: from htphan-mobl4.amr.corp.intel.com (HELO [10.251.5.56]) ([10.251.5.56]) by orsmga005.jf.intel.com with ESMTP; 30 Oct 2018 11:03:51 -0700 Subject: Re: [PATCH 10/17] prmem: documentation To: Matthew Wilcox , Andy Lutomirski Cc: Kees Cook , Peter Zijlstra , Igor Stoppa , Mimi Zohar , Dave Chinner , James Morris , Michal Hocko , Kernel Hardening , linux-integrity , linux-security-module , Igor Stoppa , Dave Hansen , Jonathan Corbet , Laura Abbott , Randy Dunlap , Mike Rapoport , "open list:DOCUMENTATION" , LKML , Thomas Gleixner References: <20181023213504.28905-1-igor.stoppa@huawei.com> <20181023213504.28905-11-igor.stoppa@huawei.com> <20181026092609.GB3159@worktop.c.hoisthospitality.com> <20181028183126.GB744@hirez.programming.kicks-ass.net> <40cd77ce-f234-3213-f3cb-0c3137c5e201@gmail.com> <20181030152641.GE8177@hirez.programming.kicks-ass.net> <0A7AFB50-9ADE-4E12-B541-EC7839223B65@amacapital.net> <20181030175814.GB10491@bombadil.infradead.org> From: Dave Hansen Openpgp: preference=signencrypt Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181030175814.GB10491@bombadil.infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: On 10/30/18 10:58 AM, Matthew Wilcox wrote: > Does this satisfy Igor's requirements? We wouldn't be able to > copy_to/from_user() while rare_mm was active. I think that's a feature > though! It certainly satisfies my interests (kernel code be able to > mark things as dynamically-allocated-and-read-only-after-initialisation) It has to be more than copy_to/from_user(), though, I think. rare_modify(q) either has to preempt_disable(), or we need to teach the context-switching code when and how to switch in/out of the rare_mm. preempt_disable() would also keep us from sleeping.