Re: [PATCH v2] mm: incorporate zero pages into transparent huge pages

From: Andrea Arcangeli
Date: Wed Feb 11 2015 - 17:33:40 EST


On Thu, Feb 12, 2015 at 12:21:40AM +0200, Kirill A. Shutemov wrote:
> On Wed, Feb 11, 2015 at 11:16:00PM +0100, Andrea Arcangeli wrote:
> > On Wed, Feb 11, 2015 at 11:03:55PM +0200, Ebru Akagunduz wrote:
> > > Changes in v2:
> > > - Check zero pfn in release_pte_pages() (Andrea Arcangeli)
> >
> > .. and in:
> >
> > > @@ -2237,7 +2237,7 @@ static void __collapse_huge_page_copy(pte_t *pte, struct page *page,
> > > pte_t pteval = *_pte;
> > > struct page *src_page;
> > >
> > > - if (pte_none(pteval)) {
> > > + if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) {
> > > clear_user_highpage(page, address);
> > > add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1);
> > > } else {
> >
> > __collapse_huge_page_copy, both were needed as far as I can tell.
>
> There was is_zero_pfn(pte_pfn(pteval)) in __collapse_huge_page_copy() in
> original patch.

That clarifies things ok.
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