On Fri, 29 Apr 2016 16:15:23 -0700 Yu Zhao <yuz...@google.com> wrote:
> struct page->flags is unsigned long, so when shifting bits we should > use UL suffix to match it. > > Found this problem after I added 64-bit CPU specific page flags and > failed to compile the kernel: > mm/page_alloc.c: In function '__free_one_page': > mm/page_alloc.c:672:2: error: integer overflow in expression > [-Werror=overflow] > Fair enough. > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -474,7 +474,7 @@ static inline void ClearPageCompound(struct page *page) > } > #endif > > -#define PG_head_mask ((1L << PG_head)) > +#define PG_head_mask ((1UL << PG_head)) We do have the BIT() macro. I don't think it would add a lot of value here; I'd be OK with it either way.
