From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTP id CFA29AB2 for ; Wed, 11 Jun 2014 20:16:15 +0000 (UTC) Received: from mail-ve0-f178.google.com (mail-ve0-f178.google.com [209.85.128.178]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id BCED0201AE for ; Wed, 11 Jun 2014 20:16:13 +0000 (UTC) Received: by mail-ve0-f178.google.com with SMTP id jx11so591864veb.23 for ; Wed, 11 Jun 2014 13:16:13 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Andy Lutomirski Date: Wed, 11 Jun 2014 13:15:52 -0700 Message-ID: To: Christoph Lameter Content-Type: text/plain; charset=UTF-8 Cc: "ksummit-discuss@lists.linuxfoundation.org" Subject: Re: [Ksummit-discuss] [CORE TOPIC] Redesign Memory Management layer and more core subsystem List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, Jun 11, 2014 at 12:03 PM, Christoph Lameter wrote: > > 3. Allocation "Zones". These are problematic because the zones often do > not reflect the capabilities of devices to allocate in certain ranges. > They are used for other purposes like MOVABLE pages but then the pages are > not really movable because they are pinnned for other reasons. Argh. > What if you just couldn't sleep while you have a MOVABLE page pinned? Or what if you had to pin it and provide a callback to forcibly unpin it? This would complicate direct IO and such, but it would make movable pages really movable. It would also solve an annoyance with the sealing thing: the sealing code wants to take writable pages and make them really readonly. This interacts very badly with existing pins. We have IOMMU in many cases. Would it be so bad to say that direct IO is only really direct if there's an IOMMU? --Andy