From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S969274AbdEYNkL (ORCPT ); Thu, 25 May 2017 09:40:11 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:46866 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965789AbdEYNkJ (ORCPT ); Thu, 25 May 2017 09:40:09 -0400 Subject: Re: [Patch 2/2]: powerpc/hotplug/mm: Fix hot-add memory node assoc To: Michael Ellerman , Reza Arbab References: <3bb44d92-b2ff-e197-4bdf-ec6d588d6dab@linux.vnet.ibm.com> <20170523155251.bqwc5mc4jpgzkqlm@arbab-laptop.localdomain> <1c1d70e3-4e45-b035-0e75-1b0f531c111b@linux.vnet.ibm.com> <20170523214922.bns675oqzqj4pkhc@arbab-laptop.localdomain> <87poeya4dt.fsf@concordia.ellerman.id.au> <8e2417d8-d108-2949-40f2-997d53a3f367@linux.vnet.ibm.com> <87a861a25y.fsf@concordia.ellerman.id.au> Cc: linux-kernel@vger.kernel.org, Paul Mackerras , "Aneesh Kumar K.V" , Bharata B Rao , Shailendra Singh , Thomas Gleixner , linuxppc-dev@lists.ozlabs.org, Sebastian Andrzej Siewior From: Michael Bringmann Organization: IBM Linux Technology Center Date: Thu, 25 May 2017 08:40:00 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <87a861a25y.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17052513-0048-0000-0000-0000018EC2FB X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007116; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000212; SDB=6.00865453; UDB=6.00429733; IPR=6.00645230; BA=6.00005374; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015579; XFM=3.00000015; UTC=2017-05-25 13:40:05 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17052513-0049-0000-0000-0000414335B6 Message-Id: <847696cc-69b2-c228-20fd-132b265b50c5@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-25_09:,, 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=8.0.1-1703280000 definitions=main-1705250259 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/25/2017 01:19 AM, Michael Ellerman wrote: > Michael Bringmann writes: > >> On 05/24/2017 06:19 AM, Michael Ellerman wrote: >>> Michael Bringmann writes: >>>> >>>> With or without 3af229f2071f, we would still need to add something, somewhere to add new >>>> bits to the 'node_possible_map'. That is not being done. >>> >>> You mustn't add bits to the possible map after boot. >>> >>> That's its purpose, to tell you what nodes could ever *possibly* exist. >> >> The problem that I have been encountering is that the 'possible map' did *not* >> show all of the possible nodes. > > OK so how did that happen? > > The commit message for 3af229f2071f says: > > In practice, we never see a system with 256 NUMA nodes, and in fact, we > do not support node hotplug on power in the first place, so the nodes > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > that are online when we come up are the nodes that will be present for > the lifetime of this kernel. > > Is that no longer true? Take a look at the last part of commit 3af229f2071f for file numa.c. It undoes a piece of code that restricts the 'node possible map', created earlier, to the set of online nodes. That piece of code has not made it into the mainline, at least not into 4.12. I am testing to verify whether it is sufficient for my configuration now. > > cheers > Regards. -- Michael W. Bringmann Linux Technology Center IBM Corporation Tie-Line 363-5196 External: (512) 286-5196 Cell: (512) 466-0650 mwb@linux.vnet.ibm.com