[PATCH] initialise total_memory() earlier

Initialise total_memory earlier in boot.  Because if for some reason we run
page reclaim early in boot, we don't want total_memory to be zero when we use
it as a divisor.

And rename total_memory to vm_total_pages to avoid naming clashes with
architectures.

Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Martin Bligh <mbligh@google.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

include/linux/swap.h

@@ -185,6 +185,7 @@ extern unsigned long try_to_free_pages(struct zone **, gfp_t);
 extern unsigned long shrink_all_memory(unsigned long nr_pages);
 extern int vm_swappiness;
 extern int remove_mapping(struct address_space *mapping, struct page *page);
+extern long vm_total_pages;
 
 #ifdef CONFIG_NUMA
 extern int zone_reclaim_mode;

mm/page_alloc.c

@@ -1725,9 +1725,9 @@ void __meminit build_all_zonelists(void)
 		stop_machine_run(__build_all_zonelists, NULL, NR_CPUS);
 		/* cpuset refresh routine should be here */
 	}
-
-	printk("Built %i zonelists\n", num_online_nodes());
-
+	vm_total_pages = nr_free_pagecache_pages();
+	printk("Built %i zonelists.  Total pages: %ld\n",
+			num_online_nodes(), vm_total_pages);
 }
 
 /*

mm/vmscan.c

@@ -110,7 +110,7 @@ struct shrinker {
  * From 0 .. 100.  Higher means more swappy.
  */
 int vm_swappiness = 60;
-static long total_memory;
+long vm_total_pages;	/* The total number of pages which the VM controls */
 
 static LIST_HEAD(shrinker_list);
 static DECLARE_RWSEM(shrinker_rwsem);
@@ -743,7 +743,7 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 		 * how much memory
 		 * is mapped.
 		 */
-		mapped_ratio = (sc->nr_mapped * 100) / total_memory;
+		mapped_ratio = (sc->nr_mapped * 100) / vm_total_pages;
 
 		/*
 		 * Now decide how much we really want to unmap some pages.  The
@@ -1482,7 +1482,6 @@ static int __init kswapd_init(void)
 		pgdat->kswapd = find_task_by_pid(pid);
 		read_unlock(&tasklist_lock);
 	}
-	total_memory = nr_free_pagecache_pages();
 	hotcpu_notifier(cpu_callback, 0);
 	return 0;
 }