[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.

[akpm@osdl.org: cleanup]
[jdike@addtoit.com: build fix]
[apw@shadowen.org: Simplify calculation of the number of bits we need for ZONES_SHIFT]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Matthew Wilcox <willy@debian.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 7 deletions

diff --git a/mm/slab.c b/mm/slab.c
index caa8f87e04eb..348396d691a1 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -793,8 +793,10 @@ static inline struct kmem_cache *__find_general_cachep(size_t size,
 	 * has cs_{dma,}cachep==NULL. Thus no special case
 	 * for large kmalloc calls required.
 	 */
+#ifdef CONFIG_ZONE_DMA
 	if (unlikely(gfpflags & GFP_DMA))
 		return csizep->cs_dmacachep;
+#endif
 	return csizep->cs_cachep;
 }
 
@@ -1493,13 +1495,15 @@ void __init kmem_cache_init(void)
 					ARCH_KMALLOC_FLAGS|SLAB_PANIC,
 					NULL, NULL);
 		}
-
-		sizes->cs_dmacachep = kmem_cache_create(names->name_dma,
+#ifdef CONFIG_ZONE_DMA
+		sizes->cs_dmacachep = kmem_cache_create(
+					names->name_dma,
 					sizes->cs_size,
 					ARCH_KMALLOC_MINALIGN,
 					ARCH_KMALLOC_FLAGS|SLAB_CACHE_DMA|
 						SLAB_PANIC,
 					NULL, NULL);
+#endif
 		sizes++;
 		names++;
 	}
@@ -2321,7 +2325,7 @@ kmem_cache_create (const char *name, size_t size, size_t align,
 	cachep->slab_size = slab_size;
 	cachep->flags = flags;
 	cachep->gfpflags = 0;
-	if (flags & SLAB_CACHE_DMA)
+	if (CONFIG_ZONE_DMA_FLAG && (flags & SLAB_CACHE_DMA))
 		cachep->gfpflags |= GFP_DMA;
 	cachep->buffer_size = size;
 	cachep->reciprocal_buffer_size = reciprocal_value(size);
@@ -2643,10 +2647,12 @@ static void cache_init_objs(struct kmem_cache *cachep,
 
 static void kmem_flagcheck(struct kmem_cache *cachep, gfp_t flags)
 {
-	if (flags & GFP_DMA)
-		BUG_ON(!(cachep->gfpflags & GFP_DMA));
-	else
-		BUG_ON(cachep->gfpflags & GFP_DMA);
+	if (CONFIG_ZONE_DMA_FLAG) {
+		if (flags & GFP_DMA)
+			BUG_ON(!(cachep->gfpflags & GFP_DMA));
+		else
+			BUG_ON(cachep->gfpflags & GFP_DMA);
+	}
 }
 
 static void *slab_get_obj(struct kmem_cache *cachep, struct slab *slabp,