On Fri, Jun 17, 2011 at 09:46:28AM +0900, KAMEZAWA Hiroyuki wrote:

On Thu, 16 Jun 2011 11:35:59 +0100
Mel Gorman [off-list ref] wrote:

quoted

A caller that does node_end_pfn(nid++) will get a nasty surprise
due to side-effects. I know architectures currently get this wrong
including x86_64 but we might as well fix it up now. The definition
in arch/x86/include/asm/mmzone_32.h is immune to side-effects and
might be a better choice despite the use of a temporary variable.

Ok, here is a fixed one. Thank you for comments/review.
==
From 507cc95c5ba2351bff16c5421255d1395a3b555b Mon Sep 17 00:00:00 2001
From: KAMEZAWA Hiroyuki <redacted>
Date: Thu, 16 Jun 2011 17:28:07 +0900
Subject: [PATCH] Fix node_start/end_pfn() definition for mm/page_cgroup.c

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;});


Reported-by: Randy Dunlap <redacted>
Reported-by: Ingo Molnar <redacted>
Signed-off-by: KAMEZAWA Hiroyuki <redacted>

Thanks.

Acked-by: Mel Gorman <mgorman@suse.de>

-- 
Mel Gorman
SUSE Labs

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