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SubjectRe: [PATCH] mm: hugetlb: bail out unmapping after serving reference page
On Thu, 23 Feb 2012 21:05:41 +0800
Hillf Danton <dhillf@gmail.com> wrote:

> and a follow-up cleanup also attached.

Please, never put more than one patches in an email - it is rather a
pain to manually unpick everything.

> When unmapping given VM range, a couple of code duplicate, such as pte_page()
> and huge_pte_none(), so a cleanup needed to compact them together.
>
> Signed-off-by: Hillf Danton <dhillf@gmail.com>
> ---
>
> --- a/mm/hugetlb.c Thu Feb 23 20:13:06 2012
> +++ b/mm/hugetlb.c Thu Feb 23 20:30:16 2012
> @@ -2245,16 +2245,23 @@ void __unmap_hugepage_range(struct vm_ar
> if (huge_pmd_unshare(mm, &address, ptep))
> continue;
>
> + pte = huge_ptep_get(ptep);
> + if (huge_pte_none(pte))
> + continue;
> +
> + /*
> + * HWPoisoned hugepage is already unmapped and dropped reference
> + */
> + if (unlikely(is_hugetlb_entry_hwpoisoned(pte)))
> + continue;
> +
> + page = pte_page(pte);
> /*
> * If a reference page is supplied, it is because a specific
> * page is being unmapped, not a range. Ensure the page we
> * are about to unmap is the actual page of interest.
> */
> if (ref_page) {
> - pte = huge_ptep_get(ptep);
> - if (huge_pte_none(pte))
> - continue;
> - page = pte_page(pte);
> if (page != ref_page)
> continue;
>
> @@ -2267,16 +2274,6 @@ void __unmap_hugepage_range(struct vm_ar
> }
>
> pte = huge_ptep_get_and_clear(mm, address, ptep);
> - if (huge_pte_none(pte))
> - continue;
> -
> - /*
> - * HWPoisoned hugepage is already unmapped and dropped reference
> - */
> - if (unlikely(is_hugetlb_entry_hwpoisoned(pte)))
> - continue;
> -
> - page = pte_page(pte);
> if (pte_dirty(pte))
> set_page_dirty(page);
> list_add(&page->lru, &page_list);

This changes behaviour when ref_page refers to a hwpoisoned page.


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