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Violators will be prosecuted for from ; Fri, 14 Jul 2017 10:26:54 -0400 Date: Fri, 14 Jul 2017 09:26:45 -0500 From: Reza Arbab Subject: Re: [PATCH 2/2] mm, memory_hotplug: remove zone restrictions References: <20170714121233.16861-1-mhocko@kernel.org> <20170714121233.16861-3-mhocko@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20170714121233.16861-3-mhocko@kernel.org> Message-Id: <20170714142645.dmetqyfucnc7jeur@arbab-laptop.localdomain> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , Mel Gorman , Vlastimil Babka , Andrea Arcangeli , Yasuaki Ishimatsu , qiuxishi@huawei.com, Kani Toshimitsu , slaoub@gmail.com, Joonsoo Kim , Daniel Kiper , Igor Mammedov , Vitaly Kuznetsov , Wei Yang , linux-mm@kvack.org, LKML , Michal Hocko , Joonsoo Kim , linux-api@vger.kernel.org On Fri, Jul 14, 2017 at 02:12:33PM +0200, Michal Hocko wrote: >Historically we have enforced that any kernel zone (e.g ZONE_NORMAL) has >to precede the Movable zone in the physical memory range. The purpose of >the movable zone is, however, not bound to any physical memory restriction. >It merely defines a class of migrateable and reclaimable memory. > >There are users (e.g. CMA) who might want to reserve specific physical >memory ranges for their own purpose. Moreover our pfn walkers have to be >prepared for zones overlapping in the physical range already because we >do support interleaving NUMA nodes and therefore zones can interleave as >well. This means we can allow each memory block to be associated with a >different zone. > >Loosen the current onlining semantic and allow explicit onlining type on >any memblock. That means that online_{kernel,movable} will be allowed >regardless of the physical address of the memblock as long as it is >offline of course. This might result in moveble zone overlapping with >other kernel zones. Default onlining then becomes a bit tricky but still >sensible. echo online > memoryXY/state will online the given block to > 1) the default zone if the given range is outside of any zone > 2) the enclosing zone if such a zone doesn't interleave with > any other zone > 3) the default zone if more zones interleave for this range >where default zone is movable zone only if movable_node is enabled >otherwise it is a kernel zone. > >Here is an example of the semantic with (movable_node is not present but >it work in an analogous way). We start with following memblocks, all of >them offline >memory34/valid_zones:Normal Movable >memory35/valid_zones:Normal Movable >memory36/valid_zones:Normal Movable >memory37/valid_zones:Normal Movable >memory38/valid_zones:Normal Movable >memory39/valid_zones:Normal Movable >memory40/valid_zones:Normal Movable >memory41/valid_zones:Normal Movable > >Now, we online block 34 in default mode and block 37 as movable >root@test1:/sys/devices/system/node/node1# echo online > memory34/state >root@test1:/sys/devices/system/node/node1# echo online_movable > memory37/state >memory34/valid_zones:Normal >memory35/valid_zones:Normal Movable >memory36/valid_zones:Normal Movable >memory37/valid_zones:Movable >memory38/valid_zones:Normal Movable >memory39/valid_zones:Normal Movable >memory40/valid_zones:Normal Movable >memory41/valid_zones:Normal Movable > >As we can see all other blocks can still be onlined both into Normal and >Movable zones and the Normal is default because the Movable zone spans >only block37 now. >root@test1:/sys/devices/system/node/node1# echo online_movable > memory41/state >memory34/valid_zones:Normal >memory35/valid_zones:Normal Movable >memory36/valid_zones:Normal Movable >memory37/valid_zones:Movable >memory38/valid_zones:Movable Normal >memory39/valid_zones:Movable Normal >memory40/valid_zones:Movable Normal >memory41/valid_zones:Movable > >Now the default zone for blocks 37-41 has changed because movable zone >spans that range. >root@test1:/sys/devices/system/node/node1# echo online_kernel > memory39/state >memory34/valid_zones:Normal >memory35/valid_zones:Normal Movable >memory36/valid_zones:Normal Movable >memory37/valid_zones:Movable >memory38/valid_zones:Normal Movable >memory39/valid_zones:Normal >memory40/valid_zones:Movable Normal >memory41/valid_zones:Movable > >Note that the block 39 now belongs to the zone Normal and so block38 >falls into Normal by default as well. > >For completness >root@test1:/sys/devices/system/node/node1# for i in memory[34]? >do > echo online > $i/state 2>/dev/null >done > >memory34/valid_zones:Normal >memory35/valid_zones:Normal >memory36/valid_zones:Normal >memory37/valid_zones:Movable >memory38/valid_zones:Normal >memory39/valid_zones:Normal >memory40/valid_zones:Movable >memory41/valid_zones:Movable > >Implementation wise the change is quite straightforward. We can get rid >of allow_online_pfn_range altogether. online_pages allows only offline >nodes already. The original default_zone_for_pfn will become >default_kernel_zone_for_pfn. New default_zone_for_pfn implements the >above semantic. zone_for_pfn_range is slightly reorganized to implement >kernel and movable online type explicitly and MMOP_ONLINE_KEEP becomes >a catch all default behavior. > >Acked-by: Joonsoo Kim Acked-by: Reza Arbab >Cc: >Signed-off-by: Michal Hocko -- 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