Re: [PATCH v2] mm, page_alloc: disallow __GFP_COMP in alloc_pages_exact()

["Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>]

On Thu, Mar 14, 2019 at 09:42:49AM +0000, Vlastimil Babka wrote:
> @@ -4752,7 +4752,7 @@ static void *make_alloc_exact(unsigned long addr, unsigned int order,
>  /**
>   * alloc_pages_exact - allocate an exact number physically-contiguous pages.
>   * @size: the number of bytes to allocate
> - * @gfp_mask: GFP flags for the allocation
> + * @gfp_mask: GFP flags for the allocation, must not contain __GFP_COMP
>   *
>   * This function is similar to alloc_pages(), except that it allocates the
>   * minimum number of pages to satisfy the request.  alloc_pages() can only
> @@ -4768,6 +4768,10 @@ void *alloc_pages_exact(size_t size, gfp_t gfp_mask)
>  	unsigned long addr;
>  
>  	addr = __get_free_pages(gfp_mask, order);
> +
> +	if (WARN_ON_ONCE(gfp_mask & __GFP_COMP))
> +		return NULL;
> +

Shouldn't it be before __get_free_pages() call? :P

>  	return make_alloc_exact(addr, order, size);
>  }
>  EXPORT_SYMBOL(alloc_pages_exact);

-- 
 Kirill A. Shutemov