SLUB: Simplify dma index -> size calculation

There is no need to caculate the dma slab size ourselves. We can simply
lookup the size of the corresponding non dma slab.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/slub.c

@@ -2289,15 +2289,7 @@ static noinline struct kmem_cache *dma_kmalloc_cache(int index, gfp_t flags)
 	if (!x)
 		panic("Unable to allocate memory for dma cache\n");
 
-	if (index <= KMALLOC_SHIFT_HIGH)
-		realsize = 1 << index;
-	else {
-		if (index == 1)
-			realsize = 96;
-		else
-			realsize = 192;
-	}
-
+	realsize = kmalloc_caches[index].objsize;
 	text = kasprintf(flags & ~SLUB_DMA, "kmalloc_dma-%d",
 			(unsigned int)realsize);
 	s = create_kmalloc_cache(x, text, realsize, flags);