[ARM] 3927/1: Allow show_mem() to work with holes in memory map.

show_mem() was not correctly handling holes in the memory
map.  It was treating the freed sections of the map as
though they contained valid struct page entries.  This
could cause incorrect debugging output or even a kernel
panic.

This patch keeps the struct meminfo around after system
initialization so that show_mem() can use it when
scanning memory.  show_mem() now walks over each bank
of each online node, rather than assuming that each node
contains a single contiguous bank.
Signed-off-by: NRay Lehtiniemi <rayl@mail.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/init.c

@@ -32,40 +32,51 @@ extern unsigned long phys_initrd_start;
 extern unsigned long phys_initrd_size;
 
 /*
- * The sole use of this is to pass memory configuration
- * data from paging_init to mem_init.
+ * This is used to pass memory configuration data from paging_init
+ * to mem_init, and by show_mem() to skip holes in the memory map.
  */
-static struct meminfo meminfo __initdata = { 0, };
+static struct meminfo meminfo = { 0, };
+
+#define for_each_nodebank(iter,mi,no)			\
+	for (iter = 0; iter < mi->nr_banks; iter++)	\
+		if (mi->bank[iter].node == no)
 
 void show_mem(void)
 {
 	int free = 0, total = 0, reserved = 0;
-	int shared = 0, cached = 0, slab = 0, node;
+	int shared = 0, cached = 0, slab = 0, node, i;
+	struct meminfo * mi = &meminfo;
 
 	printk("Mem-info:\n");
 	show_free_areas();
 	printk("Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
 
 	for_each_online_node(node) {
-		struct page *page, *end;
-
-		page = NODE_MEM_MAP(node);
-		end  = page + NODE_DATA(node)->node_spanned_pages;
-
-		do {
-			total++;
-			if (PageReserved(page))
-				reserved++;
-			else if (PageSwapCache(page))
-				cached++;
-			else if (PageSlab(page))
-				slab++;
-			else if (!page_count(page))
-				free++;
-			else
-				shared += page_count(page) - 1;
-			page++;
-		} while (page < end);
+		for_each_nodebank (i,mi,node) {
+			unsigned int pfn1, pfn2;
+			struct page *page, *end;
+
+			pfn1 = mi->bank[i].start >> PAGE_SHIFT;
+			pfn2 = (mi->bank[i].size + mi->bank[i].start) >> PAGE_SHIFT;
+
+			page = NODE_MEM_MAP(node) + pfn1;
+			end  = NODE_MEM_MAP(node) + pfn2;
+
+			do {
+				total++;
+				if (PageReserved(page))
+					reserved++;
+				else if (PageSwapCache(page))
+					cached++;
+				else if (PageSlab(page))
+					slab++;
+				else if (!page_count(page))
+					free++;
+				else
+					shared += page_count(page) - 1;
+				page++;
+			} while (page < end);
+		}
 	}
 
 	printk("%d pages of RAM\n", total);
@@ -76,10 +87,6 @@ void show_mem(void)
 	printk("%d pages swap cached\n", cached);
 }
 
-#define for_each_nodebank(iter,mi,no)			\
-	for (iter = 0; iter < mi->nr_banks; iter++)	\
-		if (mi->bank[iter].node == no)
-
 /*
  * FIXME: We really want to avoid allocating the bootmap bitmap
  * over the top of the initrd.  Hopefully, this is located towards