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Date:   Thu, 26 Nov 2020 10:51:34 +0000
From:   Mel Gorman <mgorman@suse.de>
To:     David Hildenbrand <david@redhat.com>
Cc:     Mike Rapoport <rppt@linux.ibm.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        Qian Cai <cai@lca.pw>, Michal Hocko <mhocko@kernel.org>,
        linux-kernel@vger.kernel.org, Baoquan He <bhe@redhat.com>
Subject: Re: [PATCH 1/1] mm: compaction: avoid fast_isolate_around() to set
 pageblock_skip on reserved pages
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On Wed, Nov 25, 2020 at 03:42:37PM +0100, David Hildenbrand wrote:
> > Now the loop is for interesection of [zone_start_pfn, zone_end_pfn] with
> > memblock.memory and for x86 reserved ranges are not in memblock.memory,
> > so the memmap for them remains semi-initialized.
> 
> As far as I understood Mel, rounding these ranges up/down to cover full
> MAX_ORDER blocks/pageblocks might work.
> 

Yes, round down the lower end of the hole and round up the higher end to
the MAX_ORDER boundary for the purposes of having valid zone/node
linkages even if the underlying page is PageReserved.

-- 
Mel Gorman
SUSE Labs