linux-kernel - Re: page-flags behavior on compound pages: a worry

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Message-ID: <alpine.DEB.2.11.1508061542200.8172@east.gentwo.org>
Date:	Thu, 6 Aug 2015 15:45:31 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Hugh Dickins <hughd@...gle.com>
cc:	"Kirill A. Shutemov" <kirill@...temov.name>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	David Rientjes <rientjes@...gle.com>,
	Dave Hansen <dave.hansen@...el.com>,
	Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Steve Capper <steve.capper@...aro.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>,
	Jerome Marchand <jmarchan@...hat.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: page-flags behavior on compound pages: a worry

On Thu, 6 Aug 2015, Hugh Dickins wrote:

> > I know a patchset which solves this! ;)
>
> Oh, and I know a patchset which avoids these problems completely,
> by not using compound pages at all ;)

Another dumb idea: Stop the insanity of splitting pages on the fly?
Splitting pages should work like page migration: Lock everything down and
ensure no one is using the page and then do it. That way the compound pages
and its metadata are as stable as a regular page.

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