Re: [PATCHv4 37/39] thp: handle write-protect exception tofile-backed huge pages

[Hillf Danton]

On Sun, May 12, 2013 at 9:23 AM, Kirill A. Shutemov
<kirill.shutemov@xxxxxxxxxxxxxxx> wrote:
> @@ -1120,7 +1119,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
>
>         page = pmd_page(orig_pmd);
>         VM_BUG_ON(!PageCompound(page) || !PageHead(page));
> -       if (page_mapcount(page) == 1) {
> +       if (PageAnon(page) && page_mapcount(page) == 1) {

Could we avoid copying huge page if
no-one else is using it, no matter anon?

>                 pmd_t entry;
>                 entry = pmd_mkyoung(orig_pmd);
>                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
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