linux-kernel - Re: [RFC 2/2] Prevent promotion of page in madvise

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Message-ID: <AANLkTikWz6kmgwebUsO--hohSFG__Uwpxp=JZ70Vwr=t@mail.gmail.com>
Date:	Mon, 22 Nov 2010 09:31:09 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	Ben Gamari <bgamari@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Nick Piggin <npiggin@...nel.dk>
Subject: Re: [RFC 2/2] Prevent promotion of page in madvise_dontneed

On Mon, Nov 22, 2010 at 1:34 AM, Ben Gamari <bgamari@...il.com> wrote:
> On Sun, 21 Nov 2010 23:30:24 +0900, Minchan Kim <minchan.kim@...il.com> wrote:
>> Now zap_pte_range alwayas promotes pages which are pte_young &&
>> !VM_SequentialReadHint(vma). But in case of calling MADV_DONTNEED,
>> it's unnecessary since the page wouldn't use any more.
>>
> Is this not against master? If it is, I think you might have forgotten
> to update the zap_page_range() reference on mm/memory.c:1226 (in
> zap_vma_ptes()). Should promote be true or false in this case? Cheers,

Thanks. I missed that. Whatever, It's okay. :)
That's because it is used by only VM_PFNMAP.
It means the VMA doesn't have struct page descriptor of pages.
So zap_pte_range never promote the page.

Anyway, by semantic, it should be "zero".
Will fix.
Thanks, Ben.

>
> - Ben
>



-- 
Kind regards,
Minchan Kim
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