Re: [linux-next:master 5933/6583] include/linux/page_ext.h:131:20: error: call to undeclared function 'page_to_section'; ISO C99 and later do not support implicit function declarations

["Arnd Bergmann" <arnd@arndb.de>]

On Wed, Feb 26, 2025, at 10:46, kernel test robot wrote:
> commit: a2d6e9c1a867bb9f13943cb8483e2ab85b630bcd [5933/6583] mm: 
> page_ext: add an iteration API for page extensions
> config: i386-buildonly-randconfig-004-20250226 

>
>    In file included from arch/x86/kernel/asm-offsets.c:14:
>    In file included from include/linux/suspend.h:5:
>    In file included from include/linux/swap.h:9:
>    In file included from include/linux/memcontrol.h:21:
>    In file included from include/linux/mm.h:8:
>    In file included from include/linux/pgalloc_tag.h:12:
>>> include/linux/page_ext.h:131:20: error: call to undeclared function 'page_to_section'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
>      131 |         iter->start_pfn = page_to_pfn(page);
>          |                           ^
>    include/asm-generic/memory_model.h:64:21: note: expanded from macro 
> 'page_to_pfn'
>       64 | #define page_to_pfn __page_to_pfn

I'm getting this on all configurations that set CONFIG_SPARSEMEM
but not CONFIG_SPARSEMEM_VMMEMMAP.

There is also a possible problem with linux/page_ext.h
including pgtable.h and mmzone.h, which I think can lead
to circular header inclusions with linux/mm.h.

      Arnd