x86_64/setup: unconditionally populate the pgd

When allocating a new pud, unconditionally populate the pgd (why did
we bother to create a new pud if we weren't going to populate it?).

This will only happen if the pgd slot was empty, since any existing
pud will be reused.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/init_64.c

@@ -616,9 +616,8 @@ unsigned long __init_refok init_memory_mapping(unsigned long start, unsigned lon
 
 		last_map_addr = phys_pud_init(pud, __pa(start), __pa(next));
 		unmap_low_page(pud);
-		if (!after_bootmem)
-			pgd_populate(&init_mm, pgd_offset_k(start),
-				     __va(pud_phys));
+		pgd_populate(&init_mm, pgd_offset_k(start),
+			     __va(pud_phys));
 	}
 
 	if (!after_bootmem)