[PATCH] remove non-DISCONTIG use of pgdat->node_mem_map

This patch effectively eliminates direct use of pgdat->node_mem_map outside
of the DISCONTIG code.  On a flat memory system, these fields aren't
currently used, neither are they on a sparsemem system.

There was also a node_mem_map(nid) macro on many architectures.  Its use
along with the use of ->node_mem_map itself was not consistent.  It has
been removed in favor of two new, more explicit, arch-independent macros:

	pgdat_page_nr(pgdat, pagenr)
	nid_page_nr(nid, pagenr)

I called them "pgdat" and "nid" because we overload the term "node" to mean
"NUMA node", "DISCONTIG node" or "pg_data_t" in very confusing ways.  I
believe the newer names are much clearer.

These macros can be overridden in the sparsemem case with a theoretically
slower operation using node_start_pfn and pfn_to_page(), instead.  We could
make this the only behavior if people want, but I don't want to change too
much at once.  One thing at a time.

This patch removes more code than it adds.

Compile tested on alpha, alpha discontig, arm, arm-discontig, i386, i386
generic, NUMAQ, Summit, ppc64, ppc64 discontig, and x86_64.  Full list
here: http://sr71.net/patches/2.6.12/2.6.12-rc1-mhp2/configs/

Boot tested on NUMAQ, x86 SMP and ppc64 power4/5 LPARs.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Martin J. Bligh <mbligh@aracnet.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/alpha/mm/numa.c

@@ -327,8 +327,6 @@ void __init mem_init(void)
 	extern char _text, _etext, _data, _edata;
 	extern char __init_begin, __init_end;
 	unsigned long nid, i;
-	struct page * lmem_map;
-
 	high_memory = (void *) __va(max_low_pfn << PAGE_SHIFT);
 
 	reservedpages = 0;
@@ -338,10 +336,10 @@ void __init mem_init(void)
 		 */
 		totalram_pages += free_all_bootmem_node(NODE_DATA(nid));
 
-		lmem_map = node_mem_map(nid);
 		pfn = NODE_DATA(nid)->node_start_pfn;
 		for (i = 0; i < node_spanned_pages(nid); i++, pfn++)
-			if (page_is_ram(pfn) && PageReserved(lmem_map+i))
+			if (page_is_ram(pfn) &&
+			    PageReserved(nid_page_nr(nid, i)))
 				reservedpages++;
 	}
 
@@ -373,18 +371,18 @@ show_mem(void)
 	show_free_areas();
 	printk("Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
 	for_each_online_node(nid) {
-		struct page * lmem_map = node_mem_map(nid);
 		i = node_spanned_pages(nid);
 		while (i-- > 0) {
+			struct page *page = nid_page_nr(nid, i);
 			total++;
-			if (PageReserved(lmem_map+i))
+			if (PageReserved(page))
 				reserved++;
-			else if (PageSwapCache(lmem_map+i))
+			else if (PageSwapCache(page))
 				cached++;
-			else if (!page_count(lmem_map+i))
+			else if (!page_count(page))
 				free++;
 			else
-				shared += page_count(lmem_map + i) - 1;
+				shared += page_count(page) - 1;
 		}
 	}
 	printk("%ld pages of RAM\n",total);