slab: rename slab_break_gfp_order to slab_max_order

slab_break_gfp_order is more appropriately named slab_max_order since it
enforces the maximum order size of slabs as long as a single object will
still fit.

Also rename BREAK_GFP_ORDER_{LO,HI} accordingly.
Acked-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

mm/slab.c

@@ -481,9 +481,9 @@ EXPORT_SYMBOL(slab_buffer_size);
 /*
  * Do not go above this order unless 0 objects fit into the slab.
  */
-#define	BREAK_GFP_ORDER_HI	1
-#define	BREAK_GFP_ORDER_LO	0
-static int slab_break_gfp_order = BREAK_GFP_ORDER_LO;
+#define	SLAB_MAX_ORDER_HI	1
+#define	SLAB_MAX_ORDER_LO	0
+static int slab_max_order = SLAB_MAX_ORDER_LO;
 
 /*
  * Functions for storing/retrieving the cachep and or slab from the page
@@ -1502,7 +1502,7 @@ void __init kmem_cache_init(void)
 	 * page orders on machines with more than 32MB of memory.
 	 */
 	if (totalram_pages > (32 << 20) >> PAGE_SHIFT)
-		slab_break_gfp_order = BREAK_GFP_ORDER_HI;
+		slab_max_order = SLAB_MAX_ORDER_HI;
 
 	/* Bootstrap is tricky, because several objects are allocated
 	 * from caches that do not exist yet:
@@ -2112,7 +2112,7 @@ static size_t calculate_slab_order(struct kmem_cache *cachep,
 		 * Large number of objects is good, but very large slabs are
 		 * currently bad for the gfp()s.
 		 */
-		if (gfporder >= slab_break_gfp_order)
+		if (gfporder >= slab_max_order)
 			break;
 
 		/*