Re: [linux-next:master 10352/10516] include/linux/mm.h:101:35: error: 'MAX_PHYSMEM_BITS' undeclared

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 10 Sep 2024 13:42:30 +0800 "Huang, Ying" <ying.huang@intel.com> wrote:

> >>       93 |         ({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
> >>          |                                      ^
> >
> > Thanks. "resource, kunit: add test case for region_intersects" is the culprit.
> 
> Yes.  Although the definition in include/linux/mm.h introduced in
> 
>   commit ea72ce5da228 ("x86/kaslr: Expose and use the end of the physical memory address space")
> 
> doesn't compile on m68k.  There are no users of PHYSMEM_END before patch
> "resource, kunit: add test case for region_intersects".  This can be
> fixed via the following patch.
> 
> ---------------------------------8<--------------------------------------
> >From 00d176e0cd07e3df1ea37a5e56ca576c819b585a Mon Sep 17 00:00:00 2001
> From: Huang Ying <ying.huang@intel.com>
> Date: Tue, 10 Sep 2024 13:20:40 +0800
> Subject: [PATCH] mm: fix PHYSMEM_END build error on m68k
> 
> 0Day build system reported build error on m68k architecture for missing
> the definition of MAX_PHYSMEM_BITS when defining PHYSMEM_END.  Fixed it
> via making PHYSMEM_END definition depends on MAX_PHYSMEM_BITS definition
> conditionally.
> 
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Reported-by: kernel test robot <lkp@intel.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202409100913.RxkfrKU6-lkp@intel.com/
> ---
>  include/linux/mm.h | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 147073601716..62bb7e7e0a17 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -98,7 +98,11 @@ extern int mmap_rnd_compat_bits __read_mostly;
>  #endif
>  
>  #ifndef PHYSMEM_END
> -# define PHYSMEM_END	((1ULL << MAX_PHYSMEM_BITS) - 1)
> +# ifdef MAX_PHYSMEM_BITS
> +#  define PHYSMEM_END		((1ULL << MAX_PHYSMEM_BITS) - 1)
> +# else
> +#  define PHYSMEM_END		(-1ULL)
> +# endif
>  #endif
>  
>  #include <asm/page.h>

I'm not really understanding.  This patch (which I assume is against
linux-next?) requires the presence of ea72ce5da228 ("x86/kaslr: Expose
and use the end of the physical memory address space"), which is not
present in mm.git.  Yet mm.git exhibits the build failure.