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=-4.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 00C04C433FE for ; Thu, 6 Aug 2020 11:17:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BEC622D02 for ; Thu, 6 Aug 2020 11:17:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="q44JM/Mh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726126AbgHFLES (ORCPT ); Thu, 6 Aug 2020 07:04:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41970 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729389AbgHFKgX (ORCPT ); Thu, 6 Aug 2020 06:36:23 -0400 Received: from mail-lj1-x244.google.com (mail-lj1-x244.google.com [IPv6:2a00:1450:4864:20::244]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7C3E5C0617A2 for ; Thu, 6 Aug 2020 03:27:52 -0700 (PDT) Received: by mail-lj1-x244.google.com with SMTP id g6so38507638ljn.11 for ; Thu, 06 Aug 2020 03:27:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=kMBgMZhsaHkiYpNXe6mnulxBmErGl6mZVT718X/hP1s=; b=q44JM/MhPtGS1X8CEtdPT8jY1IsznRmL/EUJCRVKZ0SQjpJuKmiF3MRSg0V201k6/0 7wdleRwGXgcpS6GBcJQn3aN4+K1pHDGZuvFRDvTF9APAIhXb+a2xl9Jp+eur4UHwQKOG a+RLO7aCLHiHjNUkqDHv3KHpAByqNpYKygFYVYfjG2rDRNZ1boVJjHid9G6QxHXMRDHj lxu6G5SWy3EMKBtlkZJxRZeLycn9DXYVVNUnw64xSNl8FhKmMBKmB/5GaDUrg6bknGVy 69EcKcUZE3qqrUPWzoTffaHacemMJWCOZb/G6QEBjYa8rAKMuVSkNGFwC876gdtvvS/j Xp6w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=kMBgMZhsaHkiYpNXe6mnulxBmErGl6mZVT718X/hP1s=; b=MicB6UYtVbEvwqu/izBCe05+CqIU8Y04ZgEIj3STDMj83F9fSmmEjDPA1xk1RusZMr ITX4YVyUFvYfLSNkP4+zQJlx9BeFlQK63FDdpgrT8l/z2cYABMUddtzDFAi1SOqnBVSU RxFXwl/bTyhJnzFlZqrpk1Cpu86wAFcPtMwG6hmeuiljGj4CIwMYDt6zvrsgfzXx5vcR DdIP7fHxX+cu1KtlCaYobnw6a4rSHmK4lnfiNYXodMDaw/kOJsegz9pU3HweAo/USLwZ zViukYQbEaVkMK4/uKqfgULgpTd3qXO56R0SgXaKKWQMhpJ5pxj3F417O4IG8HW2kZWW HqFQ== X-Gm-Message-State: AOAM531Ok4zo4B9+GGpJ7l7WGqcL1vHt2gW/MuyOHRs0YaeVhX9dAKep Bnbu9GzehOwRyx9WD8+Apn1pow== X-Google-Smtp-Source: ABdhPJwKs0kOBphzk4nhXY72GuBZVVKvwfIRMs8kMWmC7io4Zo82tk1RHZ72Ob2Qcz50sTYcK1DvmA== X-Received: by 2002:a05:651c:201b:: with SMTP id s27mr3653296ljo.468.1596709669841; Thu, 06 Aug 2020 03:27:49 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id h18sm2208204ljk.7.2020.08.06.03.27.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Aug 2020 03:27:49 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 80A47102E1B; Thu, 6 Aug 2020 13:27:57 +0300 (+03) Date: Thu, 6 Aug 2020 13:27:57 +0300 From: "Kirill A. Shutemov" To: Mike Rapoport Cc: linux-kernel@vger.kernel.org, Alexander Viro , Andrew Morton , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , Elena Reshetova , "H. Peter Anvin" , Idan Yaniv , Ingo Molnar , James Bottomley , Matthew Wilcox , Mark Rutland , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Thomas Gleixner , Tycho Andersen , Will Deacon , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org Subject: Re: [PATCH v3 3/6] mm: introduce memfd_secret system call to create "secret" memory areas Message-ID: <20200806102757.7vobcaewdukr2xdl@box> References: <20200804095035.18778-1-rppt@kernel.org> <20200804095035.18778-4-rppt@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200804095035.18778-4-rppt@kernel.org> Sender: linux-api-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Tue, Aug 04, 2020 at 12:50:32PM +0300, Mike Rapoport wrote: > From: Mike Rapoport > > Introduce "memfd_secret" system call with the ability to create memory > areas visible only in the context of the owning process and not mapped not > only to other processes but in the kernel page tables as well. > > The user will create a file descriptor using the memfd_secret() system call > where flags supplied as a parameter to this system call will define the > desired protection mode for the memory associated with that file > descriptor. Currently there are two protection modes: > > * exclusive - the memory area is unmapped from the kernel direct map and it > is present only in the page tables of the owning mm. > * uncached - the memory area is present only in the page tables of the > owning mm and it is mapped there as uncached. I'm not sure why flag for exclusive mode is needed. It has to be default. And if you want uncached on top of that set the flag. What am I missing? -- Kirill A. Shutemov