On Thu, Oct 18, 2012 at 6:12 PM, Bob Liu <lliubbo@xxxxxxxxx> wrote:
> Introduce hugepage_get_pmd() to simple code.
>
> Signed-off-by: Bob Liu <lliubbo@xxxxxxxxx>
> ---
> mm/huge_memory.c | 68 ++++++++++++++++++++++--------------------------------
> 1 file changed, 27 insertions(+), 41 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 462d6ea..e575b29 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -1115,6 +1115,25 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
> return ret;
> }
>
> +static pmd_t *hugepage_get_pmd(struct mm_struct *mm, unsigned long address)
> +{
> + pgd_t *pgd;
> + pud_t *pud;
> + pmd_t *pmd = NULL;
> +
> + pgd = pgd_offset(mm, address);
> + if (!pgd_present(*pgd))
> + goto out;
> +
> + pud = pud_offset(pgd, address);
> + if (!pud_present(*pud))
> + goto out;
> +
> + pmd = pmd_offset(pud, address);
> +out:
> + return pmd;
> +}
> +
> /*
> * Returns 1 if a given pmd maps a stable (not under splitting) thp.
> * Returns -1 if it maps a thp under splitting. Returns 0 otherwise.
> @@ -1145,22 +1164,14 @@ pmd_t *page_check_address_pmd(struct page *page,
> unsigned long address,
> enum page_check_address_pmd_flag flag)
> {
> - pgd_t *pgd;
> - pud_t *pud;
> pmd_t *pmd, *ret = NULL;
>
> if (address & ~HPAGE_PMD_MASK)
> goto out;
>
> - pgd = pgd_offset(mm, address);
> - if (!pgd_present(*pgd))
> - goto out;
> -
> - pud = pud_offset(pgd, address);
> - if (!pud_present(*pud))
> + pmd = hugepage_get_pmd(mm, address);
> + if (!pmd)
> goto out;
> -
> - pmd = pmd_offset(pud, address);
> if (pmd_none(*pmd))
> goto out;
> if (pmd_page(*pmd) != page)
> @@ -1908,8 +1919,6 @@ static void collapse_huge_page(struct mm_struct *mm,
> struct vm_area_struct *vma,
> int node)
> {
> - pgd_t *pgd;
> - pud_t *pud;
> pmd_t *pmd, _pmd;
> pte_t *pte;
> pgtable_t pgtable;
> @@ -1955,16 +1964,9 @@ static void collapse_huge_page(struct mm_struct *mm,
> goto out;
> VM_BUG_ON(vma->vm_flags & VM_NO_THP);
>
> - pgd = pgd_offset(mm, address);
> - if (!pgd_present(*pgd))
> + pmd = hugepage_get_pmd(mm, address);
> + if (!pmd)
> goto out;
> -
> - pud = pud_offset(pgd, address);
> - if (!pud_present(*pud))
> - goto out;
> -
> - pmd = pmd_offset(pud, address);
> - /* pmd can't go away or become huge under us */
> if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
> goto out;
>
> @@ -2048,8 +2050,6 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
> unsigned long address,
> struct page **hpage)
> {
> - pgd_t *pgd;
> - pud_t *pud;
> pmd_t *pmd;
> pte_t *pte, *_pte;
> int ret = 0, referenced = 0, none = 0;
> @@ -2060,15 +2060,9 @@ static int khugepaged_scan_pmd(struct mm_struct *mm,
>
> VM_BUG_ON(address & ~HPAGE_PMD_MASK);
>
> - pgd = pgd_offset(mm, address);
> - if (!pgd_present(*pgd))
> - goto out;
> -
> - pud = pud_offset(pgd, address);
> - if (!pud_present(*pud))
> + pmd = hugepage_get_pmd(mm, address);
> + if (!pmd)
> goto out;
> -
> - pmd = pmd_offset(pud, address);
> if (!pmd_present(*pmd) || pmd_trans_huge(*pmd))
> goto out;
>
> @@ -2363,21 +2357,13 @@ void __split_huge_page_pmd(struct mm_struct *mm, pmd_t *pmd)
> static void split_huge_page_address(struct mm_struct *mm,
> unsigned long address)
> {
> - pgd_t *pgd;
> - pud_t *pud;
> pmd_t *pmd;
>
> VM_BUG_ON(!(address & ~HPAGE_PMD_MASK));
>
> - pgd = pgd_offset(mm, address);
> - if (!pgd_present(*pgd))
> - return;
> -
> - pud = pud_offset(pgd, address);
> - if (!pud_present(*pud))
> + pmd = hugepage_get_pmd(mm, address);
> + if (!pmd)
> return;
> -
> - pmd = pmd_offset(pud, address);
> if (!pmd_present(*pmd))
> return;
> /*
> --
> 1.7.9.5
>
>
--
Regards,
--Bob
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