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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 EB2B0CA9EAF for ; Wed, 30 Oct 2019 07:11:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE84820663 for ; Wed, 30 Oct 2019 07:11:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572419507; bh=L+Zc5GlfgcbUGe7jxxdb2RAXncs48MBZ7tOee6QAN9U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ZZY4uAiBdsN/NsHAjZNdTjgnVLiiCcIlhKIA74gesByEMm9xlmZIj7iG3mO65BLDK 8etIQc2FkMt3cPDxUyCMSc9sEdoZWR6nzxF18JpL/ojKQjg4m+Qxx3O07j5z1X46Nt vnGyJWBvHGaZi8VfUtVuL5tsbRq2VSn+YWqfrdd0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726551AbfJ3HLq (ORCPT ); Wed, 30 Oct 2019 03:11:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:43462 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726070AbfJ3HLq (ORCPT ); Wed, 30 Oct 2019 03:11:46 -0400 Received: from rapoport-lnx (190.228.71.37.rev.sfr.net [37.71.228.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 32A5520874; Wed, 30 Oct 2019 07:11:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1572419505; bh=L+Zc5GlfgcbUGe7jxxdb2RAXncs48MBZ7tOee6QAN9U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VLe5bn2ysOr1LFizjdvtRzqnw6w/qP4cy8721MX6qc21c54PKgBcQOPj/vGxd6B9y 5R0IecChBiyW6rGRhVYM3FaX+EEzwYWxMgodHWNKs8LldpbuyxLLKSaMl1Ud/OWcHz 7yw8UC37KH4Ty1LMPJast9JF/+4ZEAWUMh3awa4o= Date: Wed, 30 Oct 2019 08:11:37 +0100 From: Mike Rapoport To: Christopher Lameter 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 Message-ID: <20191030071136.GA20624@rapoport-lnx> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 29, 2019 at 10:12:04AM +0000, Christopher Lameter wrote: > > > 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? A device driver will need to remove the secure area from the direct map and then we back to square one. > It may exist already. > -- Sincerely yours, Mike.