commit 21a3c96 uses node_start/end_pfn(nid) for detection start/end
of nodes. But, it's not defined in linux/mmzone.h but defined in
/arch/???/include/mmzone.h which is included only under
CONFIG_NEED_MULTIPLE_NODES=y.

Then, we see
  mm/page_cgroup.c: In function 'page_cgroup_init':
  mm/page_cgroup.c:308: error: implicit declaration of function 'node_start_pfn'
  mm/page_cgroup.c:309: error: implicit declaration of function 'node_end_pfn'

So, fixiing page_cgroup.c is an idea...

But node_start_pfn()/node_end_pfn() is a very generic macro and
should be implemented in the same manner for all archs.
(m32r has different implementation...)

This patch removes definitions of node_start/end_pfn() in each archs
and defines a unified one in linux/mmzone.h. It's not under
CONFIG_NEED_MULTIPLE_NODES, now.

A result of macro expansion is here (mm/page_cgroup.c)

for !NUMA
 start_pfn = ((&contig_page_data)->node_start_pfn);
  end_pfn = ({ pg_data_t *__pgdat = (&contig_page_data); __pgdat->node_start_pfn + __pgdat->node_spanned_pages;});

for NUMA (x86-64)
  start_pfn = ((node_data[nid])->node_start_pfn);
  end_pfn = ({ pg_data_t *__pgdat = (node_data[nid]); __pgdat->node_start_pfn + __pgdat->node_spanned_pages;});

Changelog:
 - fixed to avoid using "nid" twice in node_end_pfn() macro.

Reported-and-acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Reported-and-tested-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Impact: build fix for powerpc and sparc

Today's linux-next build (powerpc allyesconfig) failed like this:

> In file included from include/linux/mmzone.h:776,
>                  from include/linux/gfp.h:5,
>                  from include/linux/kmod.h:23,
>                  from include/linux/module.h:14,
>                  from init/version.c:11:
> arch/powerpc/include/asm/mmzone.h:32: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'numa_cpumask_lookup_table'

Caused by commit 082edb7bf443eb8eda15b482d16ad9dd8137ad24 ("numa,
cpumask: move numa_node_id default implementation to topology.h") from
the cpus4096 tree which removed the include of linux/topology.h from
linux/mmzone.h.

Same for sparc64 defconfig.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-b: Rusty Russell <rusty@rustcorp.com.au>
Cc: ppc-dev <linuxppc-dev@ozlabs.org>
LKML-Reference: <20090319220322.3baa4613.sfr@canb.auug.org.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

The majority of this patch was created by the following script:

***
ASM=arch/sparc/include/asm
mkdir -p $ASM
git mv include/asm-sparc64/ftrace.h $ASM
git rm include/asm-sparc64/*
git mv include/asm-sparc/* $ASM
sed -ie 's/asm-sparc64/asm/g' $ASM/*
sed -ie 's/asm-sparc/asm/g' $ASM/*
***

The rest was an update of the top-level Makefile to use sparc
for header files when sparc64 is being build.
And a small fixlet to pick up the correct unistd.h from
sparc64 code.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>