linux-kernel - Re: [PATCH] lazy freeing of memory through MADV

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Message-ID: <462A52BF.7000801@redhat.com>
Date:	Sat, 21 Apr 2007 14:06:55 -0400
From:	Rik van Riel <riel@...hat.com>
To:	Hugh Dickins <hugh@...itas.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>
Subject: Re: [PATCH] lazy freeing of memory through MADV_FREE

Hugh Dickins wrote:
> On Fri, 20 Apr 2007, Rik van Riel wrote:
>> Andrew Morton wrote:
>>
>>>   I do go on about that.  But we're adding page flags at about one per
>>>   year, and when we run out we're screwed - we'll need to grow the
>>>   pageframe.
>> If you want, I can take a look at folding this into the
>> ->mapping pointer.  I can guarantee you it won't be
>> pretty, though :)
> 
> Please don't.  If we're going to stuff another pageflag into there,
> let it be PageSwapCache the natural partner of PageAnon, rather than
> whatever our latest pageflag happens to be. 

I looked at doing what Andrew wanted, and it did indeed not
look like the right thing to do.  The locking on page->mapping
is the kind of locking we want to avoid during zap_page_range
and in the pageout code.

I like your suggestion better.

-- 
Politics is the struggle between those who want to make their country
the best in the world, and those who believe it already is.  Each group
calls the other unpatriotic.
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