[PATCH] fix alloc_large_system_hash roundup

[hawkes@sgi.com]

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>

Index: linux/mm/page_alloc.c
===================================================================
--- linux.orig/mm/page_alloc.c	2006-03-14 15:25:40.000000000 -0800
+++ linux/mm/page_alloc.c	2006-03-14 16:06:48.000000000 -0800
@@ -2686,7 +2686,7 @@ void *__init alloc_large_system_hash(con
 			numentries <<= (PAGE_SHIFT - scale);
 	}
 	/* rounded up to nearest power of 2 in size */
-	numentries = 1UL << (long_log2(numentries) + 1);
+	numentries = 1UL << (long_log2(2*numentries - 1));
 
 	/* limit allocation size to 1/16 total memory by default */
 	if (max == 0) {
-
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