Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755034AbcJZKxY (ORCPT ); Wed, 26 Oct 2016 06:53:24 -0400 Received: from ozlabs.org ([103.22.144.67]:44387 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754907AbcJZKw6 (ORCPT ); Wed, 26 Oct 2016 06:52:58 -0400 From: Michael Ellerman To: Reza Arbab , Balbir Singh Cc: Benjamin Herrenschmidt , Paul Mackerras , Rob Herring , Frank Rowand , Andrew Morton , Bharata B Rao , Nathan Fontenot , Stewart Smith , Alistair Popple , "Aneesh Kumar K.V" , Tang Chen , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, devicetree@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v4 4/5] mm: make processing of movable_node arch-specific In-Reply-To: <20161026004929.h6v54dhehk4yvmwm@arbab-vm> References: <1475778995-1420-1-git-send-email-arbab@linux.vnet.ibm.com> <1475778995-1420-5-git-send-email-arbab@linux.vnet.ibm.com> <235f2d20-cf84-08df-1fb4-08ee258fdc52@gmail.com> <20161025155507.37kv5akdlgo6m2be@arbab-laptop.austin.ibm.com> <112504e9-561d-e0da-7a40-73996c678b56@gmail.com> <20161026004929.h6v54dhehk4yvmwm@arbab-vm> User-Agent: Notmuch/0.21 (https://notmuchmail.org) Date: Wed, 26 Oct 2016 21:52:53 +1100 Message-ID: <87vawfwfei.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1538 Lines: 37 Reza Arbab writes: > On Wed, Oct 26, 2016 at 09:34:18AM +1100, Balbir Singh wrote: >>I still believe we need your changes, I was wondering if we've tested >>it against normal memory nodes and checked if any memblock >>allocations end up there. Michael showed me some memblock >>allocations on node 1 of a two node machine with movable_node > > The movable_node option is x86-only. Both of those nodes contain normal > memory, so allocations on both are allowed. > >>> Longer; if you use "movable_node", x86 can identify these nodes at >>> boot. They call memblock_mark_hotplug() while parsing the SRAT. Then, >>> when the zones are initialized, those markings are used to determine >>> ZONE_MOVABLE. >>> >>> We have no analog of this SRAT information, so our movable nodes can >>> only be created post boot, by hotplugging and explicitly onlining >>> with online_movable. >> >>Is this true for all of system memory as well or only for nodes >>hotplugged later? > > As far as I know, power has nothing like the SRAT that tells us, at > boot, which memory is hotpluggable. On pseries we have the ibm,dynamic-memory device tree property, which can contain ranges of memory that are not yet "assigned to the partition" - ie. can be hotplugged later. So in general that statement is not true. But I think you're focused on bare-metal, in which case you might be right. But that doesn't mean we couldn't have a similar property, if skiboot/hostboot knew what the ranges of memory were going to be. cheers