From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967467AbdAFQXd (ORCPT ); Fri, 6 Jan 2017 11:23:33 -0500 Received: from userp1040.oracle.com ([156.151.31.81]:34080 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967312AbdAFQXQ (ORCPT ); Fri, 6 Jan 2017 11:23:16 -0500 Subject: Re: [RFC PATCH v3] sparc64: Add support for Application Data Integrity (ADI) To: Dave Hansen , Michal Hocko References: <8612e7db-97c5-f757-0aae-24c3acedbc29@oracle.com> <2c0502d0-20ef-44ac-db5b-7f651a70b978@linux.intel.com> <5a0270ea-b29a-0751-a27f-2412a8588561@oracle.com> <7532a1d6-6562-b10b-dacd-931cb2a9e536@linux.intel.com> <92d55a69-b400-8461-53a1-d505de089700@oracle.com> <75c31c99-cff7-72dc-f593-012fe5acd405@linux.intel.com> <7fbc4ca1-22ef-8ef5-5c1b-dd075852e512@oracle.com> <20170106091934.GF5556@dhcp22.suse.cz> Cc: Rob Gardner , davem@davemloft.net, corbet@lwn.net, arnd@arndb.de, akpm@linux-foundation.org, hpa@zytor.com, viro@zeniv.linux.org.uk, nitin.m.gupta@oracle.com, chris.hyser@oracle.com, tushar.n.dave@oracle.com, sowmini.varadhan@oracle.com, mike.kravetz@oracle.com, adam.buchbinder@gmail.com, minchan@kernel.org, hughd@google.com, kirill.shutemov@linux.intel.com, keescook@chromium.org, allen.pais@oracle.com, aryabinin@virtuozzo.com, atish.patra@oracle.com, joe@perches.com, pmladek@suse.com, jslaby@suse.cz, cmetcalf@mellanox.com, paul.gortmaker@windriver.com, jmarchan@redhat.com, lstoakes@gmail.com, 0x7f454c46@gmail.com, vbabka@suse.cz, tglx@linutronix.de, mingo@redhat.com, dan.j.williams@intel.com, iamjoonsoo.kim@lge.com, mgorman@techsingularity.net, vdavydov.dev@gmail.com, hannes@cmpxchg.org, namit@vmware.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, linux-arch@vger.kernel.org, x86@kernel.org, linux-mm@kvack.org, Khalid Aziz From: Khalid Aziz Organization: Oracle Corp Message-ID: Date: Fri, 6 Jan 2017 09:22:13 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/06/2017 08:36 AM, Dave Hansen wrote: > On 01/06/2017 07:32 AM, Khalid Aziz wrote: >> I agree with you on simplicity first. Subpage granularity is complex, >> but the architecture allows for subpage granularity. Maybe the right >> approach is to support this at page granularity first for swappable >> pages and then expand to subpage granularity in a subsequent patch? >> Pages locked in memory can already use subpage granularity with my patch. > > What do you mean by "locked in memory"? mlock()'d memory can still be > migrated around and still requires "swap" ptes, for instance. You are right. Page migration can invalidate subpage granularity even for locked pages. Is it possible to use cpusets to keep a task and its memory locked on a single node? Just wondering if there are limited cases where subpage granularity could work without supporting subpage granularity for tags in swap. It still sounds like the right thing to do is to get a reliable implementation in place with page size granularity and then add the complexity of subpage granularity. Thanks, Khalid