From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id CD1206B0292 for ; Thu, 15 Jun 2017 11:43:30 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id w12so14231427pfk.1 for ; Thu, 15 Jun 2017 08:43:30 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id 3si307292plo.141.2017.06.15.08.43.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 15 Jun 2017 08:43:30 -0700 (PDT) Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v5FFcqpo076086 for ; Thu, 15 Jun 2017 11:43:29 -0400 Received: from e13.ny.us.ibm.com (e13.ny.us.ibm.com [129.33.205.203]) by mx0a-001b2d01.pphosted.com with ESMTP id 2b3spr27k7-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 15 Jun 2017 11:43:29 -0400 Received: from localhost by e13.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 15 Jun 2017 11:43:27 -0400 Date: Thu, 15 Jun 2017 10:43:20 -0500 From: Reza Arbab Subject: Re: [PATCH] mm, memory_hotplug: support movable_node for hotplugable nodes References: <20170608122318.31598-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20170608122318.31598-1-mhocko@kernel.org> Message-Id: <20170615154320.tzpkjxeuckkua2zm@arbab-laptop.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , linux-mm@kvack.org, Mel Gorman , Vlastimil Babka , Andrea Arcangeli , Yasuaki Ishimatsu , qiuxishi@huawei.com, Kani Toshimitsu , slaoub@gmail.com, Joonsoo Kim , Andi Kleen , David Rientjes , Daniel Kiper , Igor Mammedov , Vitaly Kuznetsov , LKML , Michal Hocko On Thu, Jun 08, 2017 at 02:23:18PM +0200, Michal Hocko wrote: >movable_node kernel parameter allows to make hotplugable NUMA >nodes to put all the hotplugable memory into movable zone which >allows more or less reliable memory hotremove. At least this >is the case for the NUMA nodes present during the boot (see >find_zone_movable_pfns_for_nodes). > >This is not the case for the memory hotplug, though. > > echo online > /sys/devices/system/memory/memoryXYZ/status > >will default to a kernel zone (usually ZONE_NORMAL) unless the >particular memblock is already in the movable zone range which is not >the case normally when onlining the memory from the udev rule context >for a freshly hotadded NUMA node. The only option currently is to have a >special udev rule to echo online_movable to all memblocks belonging to >such a node which is rather clumsy. Not the mention this is inconsistent >as well because what ended up in the movable zone during the boot will >end up in a kernel zone after hotremove & hotadd without special care. > >It would be nice to reuse memblock_is_hotpluggable but the runtime >hotplug doesn't have that information available because the boot and >hotplug paths are not shared and it would be really non trivial to >make them use the same code path because the runtime hotplug doesn't >play with the memblock allocator at all. > >Teach move_pfn_range that MMOP_ONLINE_KEEP can use the movable zone if >movable_node is enabled and the range doesn't overlap with the existing >normal zone. This should provide a reasonable default onlining strategy. > >Strictly speaking the semantic is not identical with the boot time >initialization because find_zone_movable_pfns_for_nodes covers only the >hotplugable range as described by the BIOS/FW. From my experience this >is usually a full node though (except for Node0 which is special and >never goes away completely). If this turns out to be a problem in the >real life we can tweak the code to store hotplug flag into memblocks >but let's keep this simple now. > >Signed-off-by: Michal Hocko Acked-by: Reza Arbab -- Reza Arbab -- 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