Messages in this thread | | | Date | Tue, 25 Aug 2015 06:12:21 -0700 (PDT) | From | Yasuaki Ishimatsu <> | Subject | Re: [PATCH V2] mm:memory hot-add: memory can not been added to movable zone |
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On Thu, 20 Aug 2015 03:28:05 -0400 Changsheng Liu <liuchangsheng@inspur.com> wrote:
> From: Changsheng Liu <liuchangcheng@inspur.com> > > When memory is hot added, should_add_memory_movable() always returns 0 > because the movable zone is empty, so the memory that was hot added will > add to the normal zone even if we want to remove the memory. > > So we change should_add_memory_movable(): if the user config > CONFIG_MOVABLE_NODE it will return 1 when the movable zone is empty. > > Reviewed-by: Andrew Morton <akpm@linux-foundation.org> > Signed-off-by: Changsheng Liu <liuchangcheng@inspur.com> > Tested-by: Dongdong Fan <fandd@inspur.com> > --- > mm/memory_hotplug.c | 3 +-- > 1 files changed, 1 insertions(+), 2 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 26fbba7..ff658f2 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1199,8 +1199,7 @@ static int should_add_memory_movable(int nid, u64 start, u64 size) > struct zone *movable_zone = pgdat->node_zones + ZONE_MOVABLE; >
> if (zone_is_empty(movable_zone)) > - return 0; > - > + return IS_ENABLED(CONFIG_MOVABLE_NODE); > if (movable_zone->zone_start_pfn <= start_pfn) > return 1;
Currently, kernel allows to create ZONE_MOVABLE after ZONE_NORMAL as follows: PFN low high ---|-------------|-------------|--- ZONE_NORMAL ZONE_MOVABLE
But kernel does not allow to create ZONE_MOVABLE before ZONE_NORMAL as follows: PFN low high ---|-------------|-------------|--- ZONE_MOVABLE ZONE_NORMAL
Also, kernel does not allow to create ZONE_MOVABLE in ZOME_NORMAL as follows: PFN low high ---|-------------|-------------|-------------|--- ZONE_NORMAL ZONE_MOVABLE ZONE_NORMAL
So should_add_memory_movable() checks them.
Accoring to your patch, when movable_zone is empty, the hot added memory is always managed to ZONE_MOVABLE. It means that ZONE_MOVALBE will puts before/in ZONE_NORMAL.
You must prevent from creating ZONE_MOVABLE before/in ZONE_NORMAL.
Thanks, Yasuaki Ishimatsu
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