Make pfn_valid work early in boot

It needs num_physpages, so initialize it early. It's later overwritten
again.

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

---
 arch/x86_64/kernel/setup.c |    1 +
 1 files changed, 1 insertion(+)

Index: linux/arch/x86_64/kernel/setup.c
===================================================================
--- linux.orig/arch/x86_64/kernel/setup.c
+++ linux/arch/x86_64/kernel/setup.c
@@ -614,6 +614,7 @@ void __init setup_arch(char **cmdline_p)
 	 * we are rounding upwards:
 	 */
 	end_pfn = e820_end_of_ram();
+	num_physpages = end_pfn;		/* for pfn_valid */
 
 	check_efer();