Thanks, I just found it. 

On Mon, Jun 26, 2017 at 04:30:12PM +1000, Stephen Rothwell wrote:
>Hi Andrew,
>
>After merging the akpm tree, today's linux-next build (x86_64
>allmodconfig) produced this warning:
>
>mm/memory_hotplug.c: In function 'move_pfn_range_to_zone':
>mm/memory_hotplug.c:891:16: warning: unused variable 'i' [-Wunused-variable]
>  unsigned long i;
>                ^
>
>Introduced by commit
>
>  7fb537987bb3 ("mm/memory_hotplug: remove duplicate call for set_page_links")
>
>-- 
>Cheers,
>Stephen Rothwell

-- 
Wei Yang
Help you, Help me