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Subject: Re: [RFC] mm/migrate: Add new migration reason MR_HUGETLB
To:     Michal Hocko <mhocko@kernel.org>,
        Anshuman Khandual <khandual@linux.vnet.ibm.com>
References: <20180130030714.6790-1-khandual@linux.vnet.ibm.com>
 <20180130075949.GN21609@dhcp22.suse.cz>
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        akpm@linux-foundation.org
From:   Anshuman Khandual <khandual@linux.vnet.ibm.com>
Date:   Wed, 31 Jan 2018 07:55:05 +0530
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On 01/30/2018 01:29 PM, Michal Hocko wrote:
> On Tue 30-01-18 08:37:14, Anshuman Khandual wrote:
>> alloc_contig_range() initiates compaction and eventual migration for
>> the purpose of either CMA or HugeTLB allocation. At present, reason
>> code remains the same MR_CMA for either of those cases. Lets add a
>> new reason code which will differentiate the purpose of migration
>> as HugeTLB allocation instead.
> Why do we need it?

The same reason why we have MR_CMA (maybe some other ones as well) at
present, for reporting purpose through traces at the least. It just
seemed like same reason code is being used for two different purpose
of migration.