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Date: Fri, 28 Jul 2017 14:01:42 +0200
From: Michal Hocko <mhocko@kernel.org>
To: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@suse.de>, Vlastimil Babka <vbabka@suse.cz>,
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        Will Deacon <will.deacon@arm.com>
Subject: Re: [RFC PATCH 0/5] mm, memory_hotplug: allocate memmap from
 hotadded memory
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References: <20170726083333.17754-1-mhocko@kernel.org>
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On Wed 26-07-17 10:33:28, Michal Hocko wrote:
[...]
> There is also one potential drawback, though. If somebody uses memory
> hotplug for 1G (gigantic) hugetlb pages then this scheme will not work
> for them obviously because each memory section will contain 2MB reserved
> area.

Actually I am wrong here. It is not each section in general. I have
completely forgot that we do large memblocks on x86_64 with a lot of
memory and then we hotadd 2GB memblocks and the altmap will allocate
from the beginign of the _memblock_ and so all the memmaps will end up
in the first memory section.
-- 
Michal Hocko
SUSE Labs