From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S968806AbdEXIUp (ORCPT ); Wed, 24 May 2017 04:20:45 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:39906 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S966983AbdEXIUf (ORCPT ); Wed, 24 May 2017 04:20:35 -0400 Date: Wed, 24 May 2017 10:20:22 +0200 From: Heiko Carstens To: Michal Hocko Cc: Gerald Schaefer , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [-next] memory hotplug regression MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 17052408-0040-0000-0000-000003B50D8F X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17052408-0041-0000-0000-000020406F8B Message-Id: <20170524082022.GC5427@osiris> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-24_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=1 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705240039 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Michal, I just re-tested linux-next with respect to your memory hotplug changes and actually (finally) figured out that your patch ("mm, memory_hotplug: do not associate hotadded memory to zones until online)" changes behaviour on s390: before your patch memory blocks that were offline and located behind the last online memory block were added by default to ZONE_MOVABLE: # cat /sys/devices/system/memory/memory16/valid_zones Movable Normal With your patch this changes, so that they will be added to ZONE_NORMAL by default instead: # cat /sys/devices/system/memory/memory16/valid_zones Normal Movable Sorry, that I didn't realize this earlier! Having the ZONE_MOVABLE default was actually the only point why s390's arch_add_memory() was rather complex compared to other architectures. We always had this behaviour, since we always wanted to be able to offline memory after it was brought online. Given that back then "online_movable" did not exist, the initial s390 memory hotplug support simply added all additional memory to ZONE_MOVABLE. Keeping the default the same would be quite important. FWIW, and a bit unrelated: we had/have very basic lsmem and chmem tools which can be used to list memory states and bring memory online and offline. These tools were part of the s390-tools package and only recently moved to util-linux. 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Violators will be prosecuted for from ; Wed, 24 May 2017 09:20:27 +0100 Date: Wed, 24 May 2017 10:20:22 +0200 From: Heiko Carstens Subject: [-next] memory hotplug regression MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Message-Id: <20170524082022.GC5427@osiris> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Gerald Schaefer , linux-mm@kvack.org, linux-kernel@vger.kernel.org Hello Michal, I just re-tested linux-next with respect to your memory hotplug changes and actually (finally) figured out that your patch ("mm, memory_hotplug: do not associate hotadded memory to zones until online)" changes behaviour on s390: before your patch memory blocks that were offline and located behind the last online memory block were added by default to ZONE_MOVABLE: # cat /sys/devices/system/memory/memory16/valid_zones Movable Normal With your patch this changes, so that they will be added to ZONE_NORMAL by default instead: # cat /sys/devices/system/memory/memory16/valid_zones Normal Movable Sorry, that I didn't realize this earlier! Having the ZONE_MOVABLE default was actually the only point why s390's arch_add_memory() was rather complex compared to other architectures. We always had this behaviour, since we always wanted to be able to offline memory after it was brought online. Given that back then "online_movable" did not exist, the initial s390 memory hotplug support simply added all additional memory to ZONE_MOVABLE. Keeping the default the same would be quite important. FWIW, and a bit unrelated: we had/have very basic lsmem and chmem tools which can be used to list memory states and bring memory online and offline. These tools were part of the s390-tools package and only recently moved to util-linux. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org