linux-kernel - Re: [PATCH 1/2] mm, thp: introduce dedicated transparent huge page allocation interfaces

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Date:   Tue, 17 Oct 2017 14:12:46 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     changbin.du@...el.com
Cc:     akpm@...ux-foundation.org, corbet@....net, hughd@...gle.com,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH 1/2] mm, thp: introduce dedicated transparent huge page
 allocation interfaces

On Mon, Oct 16, 2017 at 05:19:16PM +0800, changbin.du@...el.com wrote:
> @@ -501,6 +501,45 @@ void prep_transhuge_page(struct page *page)
>  	set_compound_page_dtor(page, TRANSHUGE_PAGE_DTOR);
>  }
>  
> +struct page *alloc_transhuge_page_vma(gfp_t gfp_mask,
> +		struct vm_area_struct *vma, unsigned long addr)
> +{
> +	struct page *page;
> +
> +	page = alloc_pages_vma(gfp_mask | __GFP_COMP, HPAGE_PMD_ORDER,
> +			       vma, addr, numa_node_id(), true);
> +	if (unlikely(!page))
> +		return NULL;
> +	prep_transhuge_page(page);
> +	return page;
> +}
> +
> +struct page *alloc_transhuge_page_nodemask(gfp_t gfp_mask,
> +		int preferred_nid, nodemask_t *nmask)
> +{
> +	struct page *page;
> +
> +	page = __alloc_pages_nodemask(gfp_mask | __GFP_COMP, HPAGE_PMD_ORDER,
> +				      preferred_nid, nmask);
> +	if (unlikely(!page))
> +		return NULL;
> +	prep_transhuge_page(page);
> +	return page;
> +}
> +
> +struct page *alloc_transhuge_page(gfp_t gfp_mask)
> +{
> +	struct page *page;
> +
> +	VM_BUG_ON(!(gfp_mask & __GFP_COMP));

Why do you check for __GFP_COMP only in this helper?

> +	page = alloc_pages(gfp_mask | __GFP_COMP, HPAGE_PMD_ORDER);

And still apply __GFP_COMP anyway?

> +	if (unlikely(!page))
> +		return NULL;
> +	prep_transhuge_page(page);
> +	return page;
> +}
> +
>  unsigned long __thp_get_unmapped_area(struct file *filp, unsigned long len,
>  		loff_t off, unsigned long flags, unsigned long size)
>  {

-- 
 Kirill A. Shutemov