[PATCH] Allow an arch to expand node boundaries

Arch-independent zone-sizing determines the size of a node
(pgdat->node_spanned_pages) based on the physical memory that was
registered by the architecture.  However, when
CONFIG_MEMORY_HOTPLUG_RESERVE is set, the architecture expects that the
spanned_pages will be much larger and that mem_map will be allocated that
is used lated on memory hot-add.

This patch allows an architecture that sets CONFIG_MEMORY_HOTPLUG_RESERVE
to call push_node_boundaries() which will set the node beginning and end to
at *least* the requested boundary.

Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Andi Kleen <ak@muc.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Keith Mannthey" <kmannth@gmail.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/mm/srat.c b/arch/x86_64/mm/srat.c
index db1b2e1..f8c04d6 100644
--- a/arch/x86_64/mm/srat.c
+++ b/arch/x86_64/mm/srat.c
@@ -324,6 +324,8 @@
 	       nd->start, nd->end);
 	e820_register_active_regions(node, nd->start >> PAGE_SHIFT,
 						nd->end >> PAGE_SHIFT);
+	push_node_boundaries(node, nd->start >> PAGE_SHIFT,
+						nd->end >> PAGE_SHIFT);
 
 #ifdef RESERVE_HOTADD
  	if (ma->flags.hot_pluggable && reserve_hotadd(node, start, end) < 0) {