Reverse order of bootmem lists

This leads to bootmem allocating first from node 0 instead
of from the last node.  This avoids swiotlb allocating on the last node, which
doesn't really work on a machine with >4GB.

Note: there is a better patch around from someone else that gets
rid of the pgdat list completely.

Signed-off-by: Andi Kleen <ak@suse.de>

Index: linux/mm/bootmem.c
===================================================================
--- linux.orig/mm/bootmem.c
+++ linux/mm/bootmem.c
@@ -61,9 +61,17 @@ static unsigned long __init init_bootmem
 {
 	bootmem_data_t *bdata = pgdat->bdata;
 	unsigned long mapsize = ((end - start)+7)/8;
+	static struct pglist_data *pgdat_last;
 
-	pgdat->pgdat_next = pgdat_list;
-	pgdat_list = pgdat;
+	pgdat->pgdat_next = NULL;
+	/* Add new nodes last so that bootmem always starts 
+	   searching in the first nodes, not the last ones */
+	if (pgdat_last)
+		pgdat_last->pgdat_next = pgdat;
+	else {
+		pgdat_list = pgdat; 	
+		pgdat_last = pgdat;
+	}
 
 	mapsize = ALIGN(mapsize, sizeof(long));
 	bdata->node_bootmem_map = phys_to_virt(mapstart << PAGE_SHIFT);