On Thu, 7 Dec 2017 18:54:19 +0800 changbin.du@xxxxxxxxx wrote:
> From: Changbin Du <changbin.du@xxxxxxxxx>
>
> This patch introduced 4 new interfaces to allocate a prepared transparent
> huge page. These interfaces merge distributed two-step allocation as simple
> single step. And they can avoid issue like forget to call prep_transhuge_page()
> or call it on wrong page. A real fix:
> 40a899e ("mm: migrate: fix an incorrect call of prep_transhuge_page()")
>
> Anyway, I just want to prove that expose direct allocation interfaces is
> better than a interface only do the second part of it.
>
> These are similar to alloc_hugepage_xxx which are for hugetlbfs pages. New
> interfaces are:
> - alloc_transhuge_page_vma
> - alloc_transhuge_page_nodemask
> - alloc_transhuge_page_node
> - alloc_transhuge_page
>
> These interfaces implicitly add __GFP_COMP gfp mask which is the minimum
> flags used for huge page allocation. More flags leave to the callers.
>
> This patch does below changes:
> - define alloc_transhuge_page_xxx interfaces
> - apply them to all existing code
> - declare prep_transhuge_page as static since no others use it
> - remove alloc_hugepage_vma definition since it no longer has users
>
> ...
>
> @@ -261,7 +272,10 @@ static inline bool transparent_hugepage_enabled(struct vm_area_struct *vma)
> return false;
> }
>
> -static inline void prep_transhuge_page(struct page *page) {}
> +#define alloc_transhuge_page_vma(gfp_mask, vma, addr) NULL
> +#define alloc_transhuge_page_nodemask(gfp_mask, preferred_nid, nmask) NULL
> +#define alloc_transhuge_page_node(nid, gfp_maskg) NULL
> +#define alloc_transhuge_page(gfp_mask) NULL
Ugly. And such things can cause unused-variable warnings in calling
code. Whereas
static inline struct page *alloc_transhuge_page_vma(gfp_t gfp_mask,
struct vm_area_struct *vma, unsigned long addr)
{
return NULL;
}
will avoid such warnings.
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