[PATCH] x86_64: Add a real pfn_valid

Add a real pfn_valid

This adds a real pfn_valid.  Needed together with the SRAT patch which can
generated memmap less holes for mmio.  In general it will help to handle
memory holes better.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-x86_64/mmzone.h

@@ -57,9 +57,8 @@ static inline __attribute__((pure)) int phys_to_nid(unsigned long addr)
 #define page_to_pfn(page) \
 	(long)(((page) - page_zone(page)->zone_mem_map) + page_zone(page)->zone_start_pfn)
 
-/* AK: !DISCONTIGMEM just forces it to 1. Can't we too? */
-#define pfn_valid(pfn)          ((pfn) < num_physpages)
-
-
+#define pfn_valid(pfn) ((pfn) >= num_physpages ? 0 : \
+			({ u8 nid__ = pfn_to_nid(pfn); \
+			   nid__ != 0xff && (pfn) >= node_start_pfn(nid__) && (pfn) <= node_end_pfn(nid__); }))
 #endif
 #endif