[PATCH] optional ZONE_DMA: optional ZONE_DMA in the VM

Make ZONE_DMA optional in core code.

- ifdef all code for ZONE_DMA and related definitions following the example
  for ZONE_DMA32 and ZONE_HIGHMEM.

- Without ZONE_DMA, ZONE_HIGHMEM and ZONE_DMA32 we get to a ZONES_SHIFT of
  0.

- Modify the VM statistics to work correctly without a DMA zone.

- Modify slab to not create DMA slabs if there is no ZONE_DMA.

[[email protected]: cleanup]
[[email protected]: build fix]
[[email protected]: Simplify calculation of the number of bits we need for ZONES_SHIFT]
Signed-off-by: Christoph Lameter <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: "Luck, Tony" <[email protected]>
Cc: Kyle McMartin <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: James Bottomley <[email protected]>
Cc: Paul Mundt <[email protected]>
Signed-off-by: Andy Whitcroft <[email protected]>
Signed-off-by: Jeff Dike <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index 4b463e6..5e43646 100644
--- a/include/linux/slab_def.h
+++ b/include/linux/slab_def.h
@@ -19,7 +19,9 @@
 struct cache_sizes {
 	size_t		 	cs_size;
 	struct kmem_cache	*cs_cachep;
+#ifdef CONFIG_ZONE_DMA
 	struct kmem_cache	*cs_dmacachep;
+#endif
 };
 extern struct cache_sizes malloc_sizes[];
 
@@ -39,9 +41,12 @@
 			__you_cannot_kmalloc_that_much();
 		}
 found:
-		return kmem_cache_alloc((flags & GFP_DMA) ?
-			malloc_sizes[i].cs_dmacachep :
-			malloc_sizes[i].cs_cachep, flags);
+#ifdef CONFIG_ZONE_DMA
+		if (flags & GFP_DMA)
+			return kmem_cache_alloc(malloc_sizes[i].cs_dmacachep,
+						flags);
+#endif
+		return kmem_cache_alloc(malloc_sizes[i].cs_cachep, flags);
 	}
 	return __kmalloc(size, flags);
 }
@@ -62,9 +67,12 @@
 			__you_cannot_kzalloc_that_much();
 		}
 found:
-		return kmem_cache_zalloc((flags & GFP_DMA) ?
-			malloc_sizes[i].cs_dmacachep :
-			malloc_sizes[i].cs_cachep, flags);
+#ifdef CONFIG_ZONE_DMA
+		if (flags & GFP_DMA)
+			return kmem_cache_zalloc(malloc_sizes[i].cs_dmacachep,
+						flags);
+#endif
+		return kmem_cache_zalloc(malloc_sizes[i].cs_cachep, flags);
 	}
 	return __kzalloc(size, flags);
 }
@@ -88,9 +96,13 @@
 			__you_cannot_kmalloc_that_much();
 		}
 found:
-		return kmem_cache_alloc_node((flags & GFP_DMA) ?
-			malloc_sizes[i].cs_dmacachep :
-			malloc_sizes[i].cs_cachep, flags, node);
+#ifdef CONFIG_ZONE_DMA
+		if (flags & GFP_DMA)
+			return kmem_cache_alloc_node(malloc_sizes[i].cs_dmacachep,
+						flags, node);
+#endif
+		return kmem_cache_alloc_node(malloc_sizes[i].cs_cachep,
+						flags, node);
 	}
 	return __kmalloc_node(size, flags, node);
 }