[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,