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Date: Thu, 4 Feb 2016 15:02:21 +0900
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Luiz Capitulino <lcapitulino@redhat.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Zhang Yanfei <zhangyanfei@cn.fujitsu.com>,
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        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
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        Davidlohr Bueso <dave@stgolabs.net>,
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        Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: [PATCH] mm, hugetlb: don't require CMA for runtime gigantic pages
Message-ID: <20160204060221.GA14877@js1304-P5Q-DELUXE>
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On Wed, Feb 03, 2016 at 06:50:11PM +0100, Vlastimil Babka wrote:
> Commit 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at
> runtime") has added the runtime gigantic page allocation via
> alloc_contig_range(), making this support available only when CONFIG_CMA is
> enabled. Because it doesn't depend on MIGRATE_CMA pageblocks and the
> associated infrastructure, it is possible with few simple adjustments to
> require only CONFIG_MEMORY_ISOLATION instead of full CONFIG_CMA.
> 
> After this patch, alloc_contig_range() and related functions are available
> and used for gigantic pages with just CONFIG_MEMORY_ISOLATION enabled. Note
> CONFIG_CMA selects CONFIG_MEMORY_ISOLATION. This allows supporting runtime
> gigantic pages without the CMA-specific checks in page allocator fastpaths.

You need to set CONFIG_COMPACTION or CONFIG_CMA to use
isolate_migratepages_range() and others in alloc_contig_range().

Thanks.