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From: Reza Arbab <>
To: Michal Hocko <>
Cc: Andrew Morton <>,
	Mel Gorman <>, Vlastimil Babka <>,
	Andrea Arcangeli <>,
	Yasuaki Ishimatsu <>,, Kani Toshimitsu <>,, Joonsoo Kim <>,
	Daniel Kiper <>,
	Igor Mammedov <>,
	Vitaly Kuznetsov <>,
	Wei Yang <>,, LKML <>,
	Michal Hocko <>,
	Joonsoo Kim <>,
Subject: Re: [PATCH 2/2] mm, memory_hotplug: remove zone restrictions
Date: Fri, 14 Jul 2017 09:26:45 -0500	[thread overview]
Message-ID: <20170714142645.dmetqyfucnc7jeur@arbab-laptop.localdomain> (raw)
In-Reply-To: <>

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
>memory35/valid_zones:Normal Movable
>memory36/valid_zones:Normal 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
>memory35/valid_zones:Normal Movable
>memory36/valid_zones:Normal Movable
>memory38/valid_zones:Movable Normal
>memory39/valid_zones:Movable Normal
>memory40/valid_zones:Movable Normal
>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
>memory35/valid_zones:Normal Movable
>memory36/valid_zones:Normal Movable
>memory38/valid_zones:Normal Movable
>memory40/valid_zones:Movable Normal
>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]?
>	echo online > $i/state 2>/dev/null
>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

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  parent reply	other threads:[~2017-07-14 14:26 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-14 12:12 [PATCH 0/2] mm, memory_hotplug: remove zone onlining restriction Michal Hocko
2017-07-14 12:12 ` [PATCH 1/2] mm, memory_hotplug: display allowed zones in the preferred ordering Michal Hocko
2017-07-14 12:12 ` [PATCH 2/2] mm, memory_hotplug: remove zone restrictions Michal Hocko
2017-07-14 12:17   ` Vlastimil Babka
2017-07-14 14:26   ` Reza Arbab [this message]
  -- strict thread matches above, loose matches on Subject: below --
2017-06-29  7:35 [RFC PATCH 0/2] mm, memory_hotplug: remove zone onlining restriction Michal Hocko
2017-06-29  7:35 ` [PATCH 2/2] mm, memory_hotplug: remove zone restrictions Michal Hocko
2017-06-30  1:16   ` Joonsoo Kim
2017-06-30  3:09   ` Wei Yang
2017-06-30  8:39     ` Michal Hocko
2017-06-30  9:39       ` Wei Yang
2017-06-30  9:55         ` Michal Hocko
2017-06-30 11:01           ` Michal Hocko
2017-07-05 23:16             ` Wei Yang
2017-07-06  6:56               ` Michal Hocko
2017-07-07  8:37                 ` Wei Yang
2017-07-07 12:41                   ` Michal Hocko
2017-07-07 15:02   ` Vlastimil Babka
2017-07-10  6:45     ` Michal Hocko
2017-07-10 11:11       ` Vlastimil Babka
2017-07-10 11:17         ` Michal Hocko
2017-07-10 12:12           ` Vlastimil Babka
2017-07-10 12:30             ` Michal Hocko
2017-07-12 12:49   ` Michal Hocko

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