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Date: Thu, 20 Nov 2014 14:06:53 -0600 (CST)
From: Christoph Lameter <cl@linux.com>
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To: "Kirill A. Shutemov" <kirill@shutemov.name>
cc: Jerome Marchand <jmarchan@redhat.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Mel Gorman <mgorman@suse.de>, Rik van Riel <riel@redhat.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
        Steve Capper <steve.capper@linaro.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
        Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@suse.cz>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 06/19] mm: store mapcount for compound page separate
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References: <1415198994-15252-1-git-send-email-kirill.shutemov@linux.intel.com> <1415198994-15252-7-git-send-email-kirill.shutemov@linux.intel.com> <546C761D.6050407@redhat.com> <20141119130050.GA29884@node.dhcp.inet.fi>
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On Wed, 19 Nov 2014, Kirill A. Shutemov wrote:

> I don't think we want to bloat struct page description: nobody outside of
> helpers should use it direcly. And it's exactly what we did to store
> compound page destructor and compound page order.

This is more like a description what overloading is occurring. Either
add the new way of using it there including a comment explainng things or
please do not overload the field.