From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id 47B9A6B026F for ; Wed, 15 Nov 2017 09:58:40 -0500 (EST) Received: by mail-pf0-f200.google.com with SMTP id u70so21121753pfa.2 for ; Wed, 15 Nov 2017 06:58:40 -0800 (PST) Received: from bombadil.infradead.org (bombadil.infradead.org. [65.50.211.133]) by mx.google.com with ESMTPS id d12si15472525pgn.478.2017.11.15.06.58.38 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 15 Nov 2017 06:58:39 -0800 (PST) Date: Wed, 15 Nov 2017 06:58:35 -0800 From: Matthew Wilcox Subject: Re: [PATCH v6 03/11] mm, x86: Add support for eXclusive Page Frame Ownership (XPFO) Message-ID: <20171115145835.GB319@bombadil.infradead.org> References: <34454a32-72c2-c62e-546c-1837e05327e1@intel.com> <20170920223452.vam3egenc533rcta@smitten> <97475308-1f3d-ea91-5647-39231f3b40e5@intel.com> <20170921000901.v7zo4g5edhqqfabm@docker> <20171110010907.qfkqhrbtdkt5y3hy@smitten> <7237ae6d-f8aa-085e-c144-9ed5583ec06b@intel.com> <2aa64bf6-fead-08cc-f4fe-bd353008ca59@intel.com> <20171115034430.GA24257@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Tycho Andersen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com, Marco Benatto , Juerg Haefliger , x86@kernel.org On Tue, Nov 14, 2017 at 11:00:20PM -0800, Dave Hansen wrote: > On 11/14/2017 07:44 PM, Matthew Wilcox wrote: > > We don't need to kmap in order to access MOVABLE allocations. kmap is > > only needed for HIGHMEM allocations. So there's nothing wrong with ext4 > > or set_bh_page(). > > Yeah, it's definitely not _buggy_. > > Although, I do wonder what we should do about these for XPFO. Should we > just stick a kmap() in there and comment it? What we really need is a > mechanism to say "use this as a kernel page" and "stop using this as a > kernel page". kmap() does that... kinda. It's not a perfect fit, but > it's pretty close. It'd be kind of funny if getting XPFO working better means improving how well Linux runs on 32-bit machines with HIGHMEM. I think there's always going to be interest in those -- ARM developed 36 bit physmem before biting the bullet and going to arm64. Maybe OpenRISC will do that next ;-) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org