Re: [RFC 2/2] Prevent promotion of page in madvise_dontneed

From: Minchan Kim
Date: Sun Nov 21 2010 - 19:31:15 EST


On Mon, Nov 22, 2010 at 1:34 AM, Ben Gamari <bgamari@xxxxxxxxx> wrote:
> On Sun, 21 Nov 2010 23:30:24 +0900, Minchan Kim <minchan.kim@xxxxxxxxx> 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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