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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 A3164CA9EAE for ; Tue, 29 Oct 2019 10:12:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 67EE82083E for ; Tue, 29 Oct 2019 10:12:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 67EE82083E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 04AFE6B0005; Tue, 29 Oct 2019 06:12:06 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id F3D536B0006; Tue, 29 Oct 2019 06:12:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E53D86B0007; Tue, 29 Oct 2019 06:12:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0087.hostedemail.com [216.40.44.87]) by kanga.kvack.org (Postfix) with ESMTP id BC8306B0005 for ; Tue, 29 Oct 2019 06:12:05 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 48789181AEF2A for ; Tue, 29 Oct 2019 10:12:05 +0000 (UTC) X-FDA: 76096406610.25.plant63_869ae3003383b X-HE-Tag: plant63_869ae3003383b X-Filterd-Recvd-Size: 2512 Received: from gentwo.org (gentwo.org [3.19.106.255]) by imf07.hostedemail.com (Postfix) with ESMTP for ; Tue, 29 Oct 2019 10:12:04 +0000 (UTC) Received: by gentwo.org (Postfix, from userid 1002) id 199B33EF15; Tue, 29 Oct 2019 10:12:04 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by gentwo.org (Postfix) with ESMTP id 1877F3EF14; Tue, 29 Oct 2019 10:12:04 +0000 (UTC) Date: Tue, 29 Oct 2019 10:12:04 +0000 (UTC) From: Christopher Lameter X-X-Sender: cl@www.lameter.com To: Mike Rapoport cc: "Kirill A. Shutemov" , linux-kernel@vger.kernel.org, Alexey Dobriyan , Andrew Morton , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Dave Hansen , James Bottomley , Peter Zijlstra , Steven Rostedt , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , linux-api@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, Mike Rapoport Subject: Re: [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings In-Reply-To: <20191029085551.GA18773@rapoport-lnx> Message-ID: References: <1572171452-7958-1-git-send-email-rppt@kernel.org> <1572171452-7958-2-git-send-email-rppt@kernel.org> <20191028123124.ogkk5ogjlamvwc2s@box> <20191028130018.GA7192@rapoport-lnx> <20191028131623.zwuwguhm4v4s5imh@box> <20191029085551.GA18773@rapoport-lnx> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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 Tue, 29 Oct 2019, Mike Rapoport wrote: > I've talked with Thomas yesterday and he suggested something similar: > > When the MAP_EXCLUSIVE request comes for the first time, we allocate a huge > page for it and then use this page as a pool of 4K pages for subsequent > requests. Once this huge page is full we allocate a new one and append it > to the pool. When all the 4K pages that comprise the huge page are freed > the huge page is collapsed. Or write a device driver that allows you to mmap a secure area and avoid all core kernel modifications? /dev/securemem or so? It may exist already.