Re: [PATCH] mm/THP: Don't use HPAGE_SHIFT in transparent hugepage code

["Kirill A. Shutemov" <kirill@shutemov.name>]

On Tue, May 07, 2013 at 02:22:32AM +0530, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
> 
> For architectures like powerpc that support multiple explicit hugepage
> sizes, HPAGE_SHIFT indicate the default explicit hugepage shift. For
> THP to work the hugepage size should be same as PMD_SIZE. So use
> PMD_SHIFT directly. So move the define outside CONFIG_TRANSPARENT_HUGEPAGE
> #ifdef because we want to use these defines in generic code with
> if (pmd_trans_huge()) conditional.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
>  include/linux/huge_mm.h | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 528454c..cc276d2 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -58,12 +58,11 @@ extern pmd_t *page_check_address_pmd(struct page *page,
>  
>  #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
>  #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
> +#define HPAGE_PMD_SHIFT PMD_SHIFT

What about:

#ifndef HPAGE_PMD_SHIFT
#define HPAGE_PMD_SHIFT HPAGE_SHIFT
#endif

And define HPAGE_PMD_SHIFT in arch code if HPAGE_SHIFT is not suitable?


> +#define HPAGE_PMD_SIZE	((1UL) << HPAGE_PMD_SHIFT)
> +#define HPAGE_PMD_MASK	(~(HPAGE_PMD_SIZE - 1))
>  
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> -#define HPAGE_PMD_SHIFT HPAGE_SHIFT
> -#define HPAGE_PMD_MASK HPAGE_MASK
> -#define HPAGE_PMD_SIZE HPAGE_SIZE
> -
>  extern bool is_vma_temporary_stack(struct vm_area_struct *vma);
>  
>  #define transparent_hugepage_enabled(__vma)				\
> @@ -181,9 +180,6 @@ extern int do_huge_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vm
>  				unsigned long addr, pmd_t pmd, pmd_t *pmdp);
>  
>  #else /* CONFIG_TRANSPARENT_HUGEPAGE */
> -#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
> -#define HPAGE_PMD_MASK ({ BUILD_BUG(); 0; })
> -#define HPAGE_PMD_SIZE ({ BUILD_BUG(); 0; })
>  
>  #define hpage_nr_pages(x) 1
>  
> -- 
> 1.8.1.2
> 
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-- 
 Kirill A. Shutemov

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