[PATCH] fix alloc_large_system_hash() roundup

The "rounded up to nearest power of 2 in size" algorithm in
alloc_large_system_hash is not correct.  As coded, it takes an otherwise
acceptable power-of-2 value and doubles it.  For example, we see the error
if we boot with thash_entries=2097152 which produces a hash table with
4194304 entries.
Signed-off-by: John Hawkes <hawkes@sgi.com>
Cc: Roland Dreier <rdreier@cisco.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

mm/page_alloc.c

@@ -2702,8 +2702,7 @@ void *__init alloc_large_system_hash(const char *tablename,
 		else
 			numentries <<= (PAGE_SHIFT - scale);
 	}
-	/* rounded up to nearest power of 2 in size */
-	numentries = 1UL << (long_log2(numentries) + 1);
+	numentries = roundup_pow_of_two(numentries);
 
 	/* limit allocation size to 1/16 total memory by default */
 	if (max == 0) {