[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>

4 files changed, 30 insertions, 8 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index 50f7cfc..79360cf 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -161,3 +161,9 @@ config RESOURCES_64BIT
 	default 64BIT
 	help
 	  This option allows memory and IO resources to be 64 bit.
+
+config ZONE_DMA_FLAG
+	int
+	default "0" if !ZONE_DMA
+	default "1"
+
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6cff138..d461b23 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -73,7 +73,9 @@ static void __free_pages_ok(struct page *page, unsigned int order);
  * don't need any ZONE_NORMAL reservation
  */
 int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
+#ifdef CONFIG_ZONE_DMA
 	 256,
+#endif
 #ifdef CONFIG_ZONE_DMA32
 	 256,
 #endif
@@ -85,7 +87,9 @@ int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = {
 EXPORT_SYMBOL(totalram_pages);
 
 static char * const zone_names[MAX_NR_ZONES] = {
+#ifdef CONFIG_ZONE_DMA
 	 "DMA",
+#endif
 #ifdef CONFIG_ZONE_DMA32
 	 "DMA32",
 #endif
diff --git a/mm/slab.c b/mm/slab.c
index caa8f87..348396d 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,
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 5ffa8c2..6c488d6 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -408,6 +408,12 @@ const struct seq_operations fragmentation_op = {
 	.show	= frag_show,
 };
 
+#ifdef CONFIG_ZONE_DMA
+#define TEXT_FOR_DMA(xx) xx "_dma",
+#else
+#define TEXT_FOR_DMA(xx)
+#endif
+
 #ifdef CONFIG_ZONE_DMA32
 #define TEXT_FOR_DMA32(xx) xx "_dma32",
 #else
@@ -420,7 +426,7 @@ const struct seq_operations fragmentation_op = {
 #define TEXT_FOR_HIGHMEM(xx)
 #endif
 
-#define TEXTS_FOR_ZONES(xx) xx "_dma", TEXT_FOR_DMA32(xx) xx "_normal", \
+#define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
 					TEXT_FOR_HIGHMEM(xx)
 
 static const char * const vmstat_text[] = {