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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 BDCF6C433B4 for ; Mon, 17 May 2021 07:23:33 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 504D761002 for ; Mon, 17 May 2021 07:23:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 504D761002 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 0077E100EB82F; Mon, 17 May 2021 00:23:33 -0700 (PDT) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=rppt@kernel.org; receiver= Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 23408100EB82C for ; Mon, 17 May 2021 00:23:31 -0700 (PDT) Received: by mail.kernel.org (Postfix) with ESMTPSA id 5E2C3611BF; Mon, 17 May 2021 07:23:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1621236207; bh=amReGMStusi8xn7FAECc6Whc3fPD7LuG3b6+xADdY7M=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tdRnG7f8obysw+K28IshiY9r+18IQ1tTvDIIZzARqpPv8mn+ML38PW74E0CX/ofM1 lH6pTkkY5oaht2o74BmWs/L5cRTvCHKxgeuP4jlFuWVFCF97iHrjOxSm63DzM1+DLM 1Lt2mIb6RklOXBbNwT8EFBOEFDI0quAKtHVOhSk40zR+fT+bXp9P4dQI/i7dt6KsqW i1EeofYd4+AfTy3Bm/k+ha4JFLM3skrOayJ1PRDU9e6OwKoW/gcpiHeHcQCbsChuuw eqw8dBOD6kfdNYVMzKFpdKGTDDpXVdsVBQ+yiaI5bgEAr6nOfPYGv21bcodQb5kVaQ lUziwbXpWVN1w== Date: Mon, 17 May 2021 10:23:09 +0300 From: Mike Rapoport To: David Hildenbrand Subject: Re: [PATCH v19 5/8] mm: introduce memfd_secret system call to create "secret" memory areas Message-ID: References: <20210513184734.29317-1-rppt@kernel.org> <20210513184734.29317-6-rppt@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Message-ID-Hash: C3SHWSECOFPMD27MY7EEP7WG5L4XF4WP X-Message-ID-Hash: C3SHWSECOFPMD27MY7EEP7WG5L4XF4WP X-MailFrom: rppt@kernel.org X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: Andrew Morton , Alexander Viro , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Catalin Marinas , Christopher Lameter , Dave Hansen , Elena Reshetova , "H. Peter Anvin" , Hagen Paul Pfeifer , Ingo Molnar , James Bottomley , Kees Cook , "Kirill A. Shutemov" , Matthew Wilcox , Matthew Garrett , Mark Rutland , Michal Hocko , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , "Rafael J. Wysocki" , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , Yury Norov , 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 X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Fri, May 14, 2021 at 10:50:55AM +0200, David Hildenbrand wrote: > On 13.05.21 20:47, Mike Rapoport wrote: > > From: Mike Rapoport > > > > Removing of the pages from the direct map may cause its fragmentation > > on architectures that use large pages to map the physical memory > > which affects the system performance. However, the original Kconfig > > text for CONFIG_DIRECT_GBPAGES said that gigabyte pages in the direct > > map "... can improve the kernel's performance a tiny bit ..." (commit > > 00d1c5e05736 ("x86: add gbpages switches")) and the recent report [1] > > showed that "... although 1G mappings are a good default choice, > > there is no compelling evidence that it must be the only choice". > > Hence, it is sufficient to have secretmem disabled by default with > > the ability of a system administrator to enable it at boot time. > > Maybe add a link to the Intel performance evaluation. " ... the recent report [1]" and the link below. > > Pages in the secretmem regions are unevictable and unmovable to > > avoid accidental exposure of the sensitive data via swap or during > > page migration. ... > > A page that was a part of the secret memory area is cleared when it > > is freed to ensure the data is not exposed to the next user of that > > page. > > You could skip that with init_on_free (and eventually also with > init_on_alloc) set to avoid double clearing. Right, but for now I'd prefer to keep this explicit in the secretmem implementation. We may add the check for init_on_free/init_on_alloc later on. > > [1] > > https://lore.kernel.org/linux-mm/213b4567-46ce-f116-9cdf-bbd0c884eb3c@linux.intel.com/ > -- Sincerely yours, Mike. _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org