[PATCH] mempool: add missing include

[David Rientjes]

On Thu, 9 Apr 2015, Arnd Bergmann wrote:

> This is a fix^3 for the mempool poisoning patch, which introduces
> a compile-time error on some ARM randconfig builds:
> 
> mm/mempool.c: In function 'check_element':
> mm/mempool.c:65:16: error: implicit declaration of function 'kmap_atomic' [-Werror=implicit-function-declaration]
>    void *addr = kmap_atomic((struct page *)element);
> 
> The problem is clearly the missing declaration, and including
> linux/highmem.h fixes it.
> 
> Signed-off-by: Arnd Bergmann <arnd at arndb.de>
> Fixes: a3db5a8463b0db ("mm, mempool: poison elements backed by page allocator fix fix")

Acked-by: David Rientjes <rientjes at google.com>

Thanks!  Can you confirm that this is because CONFIG_BLOCK is disabled and 
not something else?