x86/mm/numa: Fix 32-bit memblock range truncation bug on 32-bit NUMA kernels

The following commit:

  a0acda917284 ("acpi, numa, mem_hotplug: mark all nodes the kernel resides un-hotpluggable")

Introduced numa_clear_kernel_node_hotplug(), which function is executed
during early bootup, and which marks all currently reserved memblock
regions as hot-memory-unswappable as well.

y14sg1 <y14sg1@comcast.net> reported that when running 32-bit NUMA kernels,
the grsecurity/PAX kernel patch flagged a size overflow in this function:

  PAX: size overflow detected in function x86_numa_init arch/x86/mm/numa.c:691 [...]

... the reason for the overflow is that memblock_clear_hotplug() takes physical
addresses as arguments, while the start/end variables used by
numa_clear_kernel_node_hotplug() are 'unsigned long', which is 32-bit on PAE
kernels, but which has 64-bit physical addresses.

So on 32-bit PAE kernels that have physical memory above the 4GB boundary,
we truncate a 64-bit physical address range to 32 bits and pass it to
memblock_clear_hotplug(), which at minimum prevents the original memory-hotplug
bugfix from working, but might have other side effects as well.

The fix is to use the proper type to handle physical addresses, phys_addr_t.

Reported-by: y14sg1 <y14sg1@comcast.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Brad Spengler <spender@grsecurity.net>
Cc: Chen Tang <imtangchen@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/mm/numa.c

@@ -469,7 +469,7 @@ static void __init numa_clear_kernel_node_hotplug(void)
 {
 	int i, nid;
 	nodemask_t numa_kernel_nodes = NODE_MASK_NONE;
-	unsigned long start, end;
+	phys_addr_t start, end;
 	struct memblock_region *r;
 
 	/*