Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759380AbcJYPzT (ORCPT ); Tue, 25 Oct 2016 11:55:19 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:35718 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755273AbcJYPzR (ORCPT ); Tue, 25 Oct 2016 11:55:17 -0400 Date: Tue, 25 Oct 2016 10:55:07 -0500 From: Reza Arbab To: Balbir Singh Cc: Michael Ellerman , 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 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: Organization: IBM Linux Technology Center User-Agent: Mutt/1.6.2-neo (2016-08-21) X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16102515-0020-0000-0000-00000A1968A7 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00005977; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000188; SDB=6.00772592; UDB=6.00370857; IPR=6.00549415; BA=6.00004832; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00013102; XFM=3.00000011; UTC=2016-10-25 15:55:14 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16102515-0021-0000-0000-000056BAAC2E Message-Id: <20161025155507.37kv5akdlgo6m2be@arbab-laptop.austin.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-10-25_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000 definitions=main-1610250265 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1063 Lines: 30 On Tue, Oct 25, 2016 at 11:15:40PM +1100, Balbir Singh wrote: >After the ack, I realized there were some more checks needed, IOW >questions for you :) Hey! No takebacks! The short answer is that neither of these is a concern. 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. >1. Have you checked to see if our memblock allocations spill >over to probably hotpluggable nodes? Since our nodes don't exist at boot, we don't have that short window before the zones are drawn where the node has normal memory, and a kernel allocation might occur within. >2. Shouldn't we be marking nodes discovered as movable via >memblock_mark_hotplug()? Again, this early boot marking mechanism only applies to movable_node. -- Reza Arbab