Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752161AbdFLE2h (ORCPT ); Mon, 12 Jun 2017 00:28:37 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:34395 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752022AbdFLE2g (ORCPT ); Mon, 12 Jun 2017 00:28:36 -0400 Date: Mon, 12 Jun 2017 12:28:32 +0800 From: Wei Yang To: Michal Hocko Cc: Andrew Morton , linux-mm@kvack.org, Mel Gorman , Vlastimil Babka , Andrea Arcangeli , Reza Arbab , 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 Subject: Re: [PATCH] mm, memory_hotplug: support movable_node for hotplugable nodes Message-ID: <20170612042832.GA7429@WeideMBP.lan> Reply-To: Wei Yang References: <20170608122318.31598-1-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="uAKRQypu60I7Lcqm" Content-Disposition: inline In-Reply-To: <20170608122318.31598-1-mhocko@kernel.org> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4362 Lines: 113 --uAKRQypu60I7Lcqm Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jun 08, 2017 at 02:23:18PM +0200, Michal Hocko wrote: >From: Michal Hocko > >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). > When movable_node is enabled, we would have overlapped zones, right? To be specific, only ZONE_MOVABLE could have memory ranges belongs to other zones. This looks a little different in the whole ZONE design. >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 ^^^ Here is memblock or a memory_block? >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 So the semantic you want to change here is to make the memory_block in ZONE_MOVABLE when movable_node is enabled. Besides this, movable_node is enabled, what other requirements? Like, this memory_block should next to current ZONE_MOVABLE ? or something else? >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 ^^^ Hmm... "Not to mentions" looks more understandable. BTW, I am not a native speaker. If this usage is correct, just ignore this comment. >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. > Let me try to understand your purpose of this change. If a memblock has MEMBLOCK_HOTPLU set, it would be in ZONE_MOVABLE during bootup. While a hotplugged memory_block would be in ZONE_NORMAL without special care. So you want to make sure when movable_node is enabled, the hotplugged memory_block would be in ZONE_MOVABLE. Is this correct? One more thing is do we have MEMBLOCK_HOTPLU for a hotplugged memory_block? >Signed-off-by: Michal Hocko >--- > --=20 Wei Yang Help you, Help me --uAKRQypu60I7Lcqm Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJZPhhwAAoJEKcLNpZP5cTd6gcQAJWNUicqVhEHH4o+F6ZC5Ly7 SpW0zoYfqbGlLBzMOFP0E8KXSkUZ77QfidzrsiFSD9sCYtKf0JEnxwODbHrdg1m4 RM3EddbHXxGYkQpbIEAAdCWTcSJRSFRZUWE/glSHdtMHc8dqK3eHltYNGPRoPrFX eAk/6A4Zi2kQkzGMkemw3AEac1fWOfvDRbxGejO1nSRkiPLQdsbvyc6QVqtRuAoX gSOxUQ4zy6flNQMOgeoZi0ylUjwBcktbSkP39NgzhMUpTABdBzv3jf8TBgEwCbQa mh/RmrouUKKDPIy9w4eLTMlco4sT4aTDbZYRtdlSZ35YkN9eakWqBIXxVNfgNwxG 4uedGuUztHrk/12SZm7ihU92+R11kyIWGcovNlpASjSexbbTipWRWQA1vdCUXg8s LGet5y4xHU9fibFyQTB2IOo8xdxTvdjYYzi3Yz0h0+DEiRJP8h4lhpFqiS0veKLE ALDiF7NAP/7kqYW8k41DCG/qvwHRZzCKidrhwqffx4FEmLkSmqfT5lyfnabIB66s fTSOUivrP49kVocvDLqNXTLdGsFz1UbgbaoPg18Q5iSggK4R3TacbzmllKJRK2ul mAvvGZQLpo6s1wkhrXVVedccBvXTgpblZMUSwxs4EC4xnh7b63pm9HRAdY1+gzUb zkQVWhQH+CYQUVHvtRK2 =Dq6P -----END PGP SIGNATURE----- --uAKRQypu60I7Lcqm--