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From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Andrew Morton <akpm@linux-foundation.org>
CC: Hugh Dickins <hughd@google.com>, Michal Hocko <mhocko@suse.cz>,
        Mel Gorman <mgorman@suse.de>, Johannes Weiner <hannes@cmpxchg.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Naoya Horiguchi <nao.horiguchi@gmail.com>
Subject: Re: [PATCH v2] mm, hugetlb: set PageLRU for in-use/active hugepages
Thread-Topic: [PATCH v2] mm, hugetlb: set PageLRU for in-use/active hugepages
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Date: Wed, 18 Feb 2015 01:07:29 +0000
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On Tue, Feb 17, 2015 at 04:02:49PM -0800, Andrew Morton wrote:
> On Tue, 17 Feb 2015 15:57:44 -0800 Andrew Morton <akpm@linux-foundation.org> wrote:
> 
> > So if I'm understanding this correctly, hugepages never have PG_lru set
> > and so you are overloading that bit on hugepages to indicate that the
> > page is present on hstate->hugepage_activelist?
> 
> And maybe we don't need to overload PG_lru at all?  There's plenty of
> free space in the compound page's *(page + 1).

Right, that's not necessary. So I'll use PG_private in *(page + 1), that's
unused now and no worry about conflicting with other usage.

Thanks,
Naoya Horiguchi