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=-6.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 3C557C433DB for ; Thu, 11 Feb 2021 11:30:07 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C7BC764E30 for ; Thu, 11 Feb 2021 11:30:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C7BC764E30 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2B0506B00CE; Thu, 11 Feb 2021 06:30:06 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 25EC26B00CF; Thu, 11 Feb 2021 06:30:06 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 14E016B00D0; Thu, 11 Feb 2021 06:30:06 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0226.hostedemail.com [216.40.44.226]) by kanga.kvack.org (Postfix) with ESMTP id EEE316B00CE for ; Thu, 11 Feb 2021 06:30:05 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id B9BC7181AEF00 for ; Thu, 11 Feb 2021 11:30:05 +0000 (UTC) X-FDA: 77805767970.30.tub11_5f1461d27618 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin30.hostedemail.com (Postfix) with ESMTP id 906B9180B3C83 for ; Thu, 11 Feb 2021 11:30:05 +0000 (UTC) X-HE-Tag: tub11_5f1461d27618 X-Filterd-Recvd-Size: 4162 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf11.hostedemail.com (Postfix) with ESMTP for ; Thu, 11 Feb 2021 11:30:05 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 2C89C601FF; Thu, 11 Feb 2021 11:29:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1613043004; bh=JtJHuqvnhxNyM0cSP3Qe3tSMfjdJGVz3S+tERJXfo4M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=PEXygoi6R9pVpb0NPj47+Ko3f1Ah21CxDjueYWnlQAO/uRVErOda0UIyi9V6v9rYs 6NXsauRjapfptBwBvo70ls3AAnv08VDhhWUxi7yLuKhQOTQa31mGOOLAdVpQ8B16uZ SzyBJMAmkReTwWmxT4Tjvg8ZAL2HyRIawjk70IsH5WPDvqJ9dQdETycAuzkDATgNju gOL/aozy2VFMdzBaSlauwv+UBb82EKAQG3vL++P2TTqj9pWtgKqRk4VcEXI1wyFYG+ 5DJMf90zHF2E2ie9ZUU2VlL1vbBwnzXXk30WzSnRm7nZHI33uXE/tbEgH+TreMHc5x BblQZ8rwiMN2Q== Date: Thu, 11 Feb 2021 13:29:46 +0200 From: Mike Rapoport To: David Hildenbrand Cc: Michal Hocko , Mike Rapoport , Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dan Williams , Dave Hansen , Elena Reshetova , "H. Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Matthew Wilcox , Mark Rutland , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , 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-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org, Hagen Paul Pfeifer , Palmer Dabbelt Subject: Re: [PATCH v17 07/10] mm: introduce memfd_secret system call to create "secret" memory areas Message-ID: <20210211112946.GJ242749@kernel.org> References: <20210208212605.GX242749@kernel.org> <20210209090938.GP299309@linux.ibm.com> <20210211071319.GF242749@kernel.org> <0d66baec-1898-987b-7eaf-68a015c027ff@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Feb 11, 2021 at 11:02:07AM +0100, David Hildenbrand wrote: > > Another thought regarding "doesn't have _any_ backing storage" > > What are the right semantics when it comes to memory accounting/commit? > > As secretmem does not have > a) any backing storage > b) cannot go to swap > > The MAP_NORESERVE vs. !MAP_NORESERVE handling gets a little unclear. Why > "reserve swap space" if the allocations cannot ever go to swap? Sure, we > want to "reserve physical memory", but in contrast to other users that can > go to swap. > > Of course, this is only relevant for MAP_PRIVATE secretmem mappings. Other > MAP_SHARED assumes there is no need for reserving swap space as it can just > go to the backing storage. (yeah, tmpfs/shmem is weird in that regard as > well, but again, it's a bit different) In that sense seceremem is as weird as tmpfs and it only allows MAP_SHARED. -- Sincerely yours, Mike.