From: Heiko Carstens <heiko.carstens@de.ibm.com> To: Michal Hocko <mhocko@suse.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [-next] memory hotplug regression Date: Wed, 24 May 2017 10:20:22 +0200 [thread overview] Message-ID: <20170524082022.GC5427@osiris> (raw) 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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From: Heiko Carstens <heiko.carstens@de.ibm.com> To: Michal Hocko <mhocko@suse.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [-next] memory hotplug regression Date: Wed, 24 May 2017 10:20:22 +0200 [thread overview] Message-ID: <20170524082022.GC5427@osiris> (raw) 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next reply other threads:[~2017-05-24 8:20 UTC|newest] Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-05-24 8:20 Heiko Carstens [this message] 2017-05-24 8:20 ` [-next] memory hotplug regression Heiko Carstens 2017-05-24 8:39 ` Michal Hocko 2017-05-24 8:39 ` Michal Hocko 2017-05-26 12:25 ` Heiko Carstens 2017-05-26 12:25 ` Heiko Carstens 2017-05-29 8:52 ` Michal Hocko 2017-05-29 8:52 ` Michal Hocko 2017-05-29 10:11 ` Heiko Carstens 2017-05-29 10:11 ` Heiko Carstens 2017-05-29 10:45 ` Michal Hocko 2017-05-29 10:45 ` Michal Hocko 2017-05-30 12:18 ` Michal Hocko 2017-05-30 12:18 ` Michal Hocko 2017-05-30 12:37 ` Heiko Carstens 2017-05-30 12:37 ` Heiko Carstens 2017-05-30 14:32 ` Michal Hocko 2017-05-30 14:32 ` Michal Hocko 2017-05-30 14:55 ` Heiko Carstens 2017-05-30 14:55 ` Heiko Carstens 2017-05-30 15:04 ` Michal Hocko 2017-05-30 15:04 ` Michal Hocko 2017-05-31 6:24 ` Michal Hocko 2017-05-31 6:24 ` Michal Hocko 2017-05-31 6:25 ` [PATCH 1/2] mm, memory_hotplug: fix MMOP_ONLINE_KEEP behavior Michal Hocko 2017-05-31 6:25 ` Michal Hocko 2017-05-31 6:26 ` [PATCH 2/2] mm, memory_hotplug: do not assume ZONE_NORMAL is default kernel zone Michal Hocko 2017-05-31 6:26 ` Michal Hocko 2017-06-01 6:49 ` [-next] memory hotplug regression Heiko Carstens 2017-06-01 6:49 ` Heiko Carstens 2017-06-01 7:13 ` Michal Hocko 2017-06-01 7:13 ` Michal Hocko
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