mm: alloc_large_system_hash check order

On an x86_64 with 4GB ram, tcp_init()'s call to alloc_large_system_hash(),
to allocate tcp_hashinfo.ehash, is now triggering an mmotm WARN_ON_ONCE on
order >= MAX_ORDER - it's hoping for order 11.  alloc_large_system_hash()
had better make its own check on the order.

Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: David Miller <davem@davemloft.net>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -4511,7 +4511,10 @@ void *__init alloc_large_system_hash(const char *tablename,
 			table = __vmalloc(size, GFP_ATOMIC, PAGE_KERNEL);
 		else {
 			unsigned long order = get_order(size);
-			table = (void*) __get_free_pages(GFP_ATOMIC, order);
+
+			if (order < MAX_ORDER)
+				table = (void *)__get_free_pages(GFP_ATOMIC,
+								order);
 			/*
 			 * If bucketsize is not a power-of-two, we may free
 			 * some pages at the end of hash table.