Re: [PATCH 1/2] thp: fix anononymous page accounting in fallbackpath for COW of HZP

From: Kirill A. Shutemov
Date: Mon Dec 03 2012 - 03:14:04 EST


On Mon, Dec 03, 2012 at 11:14:38AM +0800, Bob Liu wrote:
> On Fri, Nov 30, 2012 at 11:03 PM, Kirill A. Shutemov
> <kirill.shutemov@xxxxxxxxxxxxxxx> wrote:
> > From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> >
> > Don't forget to account newly allocated page in fallback path for
> > copy-on-write of huge zero page.
> >
>
> What about fallback path in do_huge_pmd_wp_page_fallback()?
> I think we should also account newly allocated page in it.

No. Normal huge pages has already accounted on fork(). See
copy_huge_pmd().

Huge zero page (as 4k zero page) doesn't contribute to RSS, so we need to
account the page which replaces huge zero page on COW.
--
Kirill A. Shutemov

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