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Date: Tue, 28 Apr 2015 15:14:20 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] compaction: fix isolate_migratepages_block() for THP=n
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On Mon, 27 Apr 2015 14:26:46 +0300 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> wrote:

> PageTrans* helpers are always-false if THP is disabled compile-time.
> It means the fucntion will fail to detect hugetlb pages in this case.
> 
> Let's use PageCompound() instead. With small tweak to how we calculate
> next low_pfn it will make function ready to see tail pages.

<scratches head>

So this patch has no runtime effects at present?  It is preparation for
something else?