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SubjectRe: [PATCH 5/6] introduce thp_ptep_get()
On Fri, 27 Jan 2012 18:02:52 -0500
Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> wrote:

> Casting pmd into pte_t to handle thp is strongly architecture dependent.
> This patch introduces a new function to separate this dependency from
> independent part.
>
> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> ---
> arch/x86/include/asm/pgtable.h | 5 +++++
> fs/proc/task_mmu.c | 4 ++--
> include/asm-generic/pgtable.h | 4 ++++
> 3 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git 3.3-rc1.orig/arch/x86/include/asm/pgtable.h 3.3-rc1/arch/x86/include/asm/pgtable.h
> index 49afb3f..4cfcc7e 100644
> --- 3.3-rc1.orig/arch/x86/include/asm/pgtable.h
> +++ 3.3-rc1/arch/x86/include/asm/pgtable.h
> @@ -165,6 +165,11 @@ static inline int has_transparent_hugepage(void)
> {
> return cpu_has_pse;
> }
> +
> +static inline pte_t thp_ptep_get(pmd_t *pmd)
> +{
> + return *(pte_t *)pmd;
> +}

I'm sorry but I don't think the name is good.
(But I know my sense of naming is bad ;)

How about pmd_to_pte_t ?

And, I wonder you can add error check as VM_BUG_ON(!pmd_trans_huge(*pmd));


Thanks,
-Kame




> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>
> static inline pte_t pte_set_flags(pte_t pte, pteval_t set)
> diff --git 3.3-rc1.orig/fs/proc/task_mmu.c 3.3-rc1/fs/proc/task_mmu.c
> index 2622b64..e2063d9 100644
> --- 3.3-rc1.orig/fs/proc/task_mmu.c
> +++ 3.3-rc1/fs/proc/task_mmu.c
> @@ -395,7 +395,7 @@ static int smaps_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
> spinlock_t *ptl;
>
> if (pmd_trans_huge_lock(pmd, vma) == 1) {
> - smaps_pte_entry(*(pte_t *)pmd, addr, HPAGE_PMD_SIZE, walk);
> + smaps_pte_entry(thp_ptep_get(pmd), addr, HPAGE_PMD_SIZE, walk);
> spin_unlock(&walk->mm->page_table_lock);
> mss->anonymous_thp += HPAGE_PMD_SIZE;
> return 0;
> @@ -964,7 +964,7 @@ static int gather_pte_stats(pmd_t *pmd, unsigned long addr,
> md = walk->private;
>
> if (pmd_trans_huge_lock(pmd, md->vma) == 1) {
> - pte_t huge_pte = *(pte_t *)pmd;
> + pte_t huge_pte = thp_ptep_get(pmd);
> struct page *page;
>
> page = can_gather_numa_stats(huge_pte, md->vma, addr);
> diff --git 3.3-rc1.orig/include/asm-generic/pgtable.h 3.3-rc1/include/asm-generic/pgtable.h
> index 76bff2b..f346bdc 100644
> --- 3.3-rc1.orig/include/asm-generic/pgtable.h
> +++ 3.3-rc1/include/asm-generic/pgtable.h
> @@ -434,6 +434,10 @@ static inline int pmd_trans_splitting(pmd_t pmd)
> {
> return 0;
> }
> +static inline pte_t thp_ptep_get(pmd_t *pmd)
> +{
> + return 0;
> +}
> #ifndef __HAVE_ARCH_PMD_WRITE
> static inline int pmd_write(pmd_t pmd)
> {
> --
> 1.7.7.6
>
>



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