[PATCH] x86_64: Use correct PUD for memory hotadd

Memory >39bits has a different PUD.

Cc: "Tolentino, Matthew E" <matthew.e.tolentino@intel.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

arch/x86_64/mm/init.c

@@ -344,7 +344,7 @@ void __meminit init_memory_mapping(unsigned long start, unsigned long end)
 		pud_t *pud;
 
 		if (after_bootmem)
-			pud = pud_offset_k(pgd, __PAGE_OFFSET);
+			pud = pud_offset_k(pgd, start & PGDIR_MASK);
 		else
 			pud = alloc_low_page(&map, &pud_phys);