Re: [PATCH 2/2] mm: fix undefined reference to `.kernel_map_pages' on PPC builds

[josh@joshtriplett.org]

On Tue, Jan 20, 2015 at 02:02:00PM -0600, Kim Phillips wrote:
> It's possible to configure DEBUG_PAGEALLOC without PAGE_POISONING on
> ppc.  Fix building the generic kernel_map_pages() implementation in
> this case:
> 
>   LD      init/built-in.o
> mm/built-in.o: In function `free_pages_prepare':
> mm/page_alloc.c:770: undefined reference to `.kernel_map_pages'
> mm/built-in.o: In function `prep_new_page':
> mm/page_alloc.c:933: undefined reference to `.kernel_map_pages'
> mm/built-in.o: In function `map_pages':
> mm/compaction.c:61: undefined reference to `.kernel_map_pages'
> make: *** [vmlinux] Error 1
> 
> Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
> ---
>  mm/Makefile | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/Makefile b/mm/Makefile
> index 4bf586e..2956467 100644
> --- a/mm/Makefile
> +++ b/mm/Makefile
> @@ -46,6 +46,7 @@ obj-$(CONFIG_SLOB) += slob.o
>  obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
>  obj-$(CONFIG_KSM) += ksm.o
>  obj-$(CONFIG_PAGE_POISONING) += debug-pagealloc.o
> +obj-$(CONFIG_DEBUG_PAGEALLOC) += debug-pagealloc.o

Does it work correctly to list the same object file twice?  Doesn't seem
like it would.  Shouldn't this do something like the following instead:

ifneq ($(CONFIG_DEBUG_PAGEALLOC)$(CONFIG_PAGE_POISONING),)
obj-y += debug-pagealloc.o
endif

?

>  obj-$(CONFIG_SLAB) += slab.o
>  obj-$(CONFIG_SLUB) += slub.o
>  obj-$(CONFIG_KMEMCHECK) += kmemcheck.o
> -- 
> 2.2.2
>