[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, 60 insertions, 15 deletions

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 063799ea6be..2a7d15bcde4 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -85,8 +85,10 @@ struct vm_area_struct;
 
 static inline enum zone_type gfp_zone(gfp_t flags)
 {
+#ifdef CONFIG_ZONE_DMA
 	if (flags & __GFP_DMA)
 		return ZONE_DMA;
+#endif
 #ifdef CONFIG_ZONE_DMA32
 	if (flags & __GFP_DMA32)
 		return ZONE_DMA32;
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 398f2ec55f5..ee9e3143df4 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -96,6 +96,7 @@ struct per_cpu_pageset {
 #endif
 
 enum zone_type {
+#ifdef CONFIG_ZONE_DMA
 	/*
 	 * ZONE_DMA is used when there are devices that are not able
 	 * to do DMA to all of addressable memory (ZONE_NORMAL). Then we
@@ -116,6 +117,7 @@ enum zone_type {
 	 * 			<16M.
 	 */
 	ZONE_DMA,
+#endif
 #ifdef CONFIG_ZONE_DMA32
 	/*
 	 * x86_64 needs two ZONE_DMAs because it supports devices that are
@@ -152,11 +154,27 @@ enum zone_type {
  * match the requested limits. See gfp_zone() in include/linux/gfp.h
  */
 
-#if !defined(CONFIG_ZONE_DMA32) && !defined(CONFIG_HIGHMEM)
+/*
+ * Count the active zones.  Note that the use of defined(X) outside
+ * #if and family is not necessarily defined so ensure we cannot use
+ * it later.  Use __ZONE_COUNT to work out how many shift bits we need.
+ */
+#define __ZONE_COUNT (			\
+	  defined(CONFIG_ZONE_DMA)	\
+	+ defined(CONFIG_ZONE_DMA32)	\
+	+ 1				\
+	+ defined(CONFIG_HIGHMEM)	\
+)
+#if __ZONE_COUNT < 2
+#define ZONES_SHIFT 0
+#elif __ZONE_COUNT <= 2
 #define ZONES_SHIFT 1
-#else
+#elif __ZONE_COUNT <= 4
 #define ZONES_SHIFT 2
+#else
+#error ZONES_SHIFT -- too many zones configured adjust calculation
 #endif
+#undef __ZONE_COUNT
 
 struct zone {
 	/* Fields commonly accessed by the page allocator */
@@ -523,7 +541,11 @@ static inline int is_dma32(struct zone *zone)
 
 static inline int is_dma(struct zone *zone)
 {
+#ifdef CONFIG_ZONE_DMA
 	return zone == zone->zone_pgdat->node_zones + ZONE_DMA;
+#else
+	return 0;
+#endif
 }
 
 /* These two functions are used to setup the per zone pages min values */
diff --git a/include/linux/slab_def.h b/include/linux/slab_def.h
index 4b463e66dde..5e4364644ed 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 @@ static inline void *kmalloc(size_t size, gfp_t flags)
 			__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 @@ static inline void *kzalloc(size_t size, gfp_t flags)
 			__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 @@ static inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 			__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);
 }
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 77caf911969..7ba91f2839f 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -19,6 +19,12 @@
  * generated will simply be the increment of a global address.
  */
 
+#ifdef CONFIG_ZONE_DMA
+#define DMA_ZONE(xx) xx##_DMA,
+#else
+#define DMA_ZONE(xx)
+#endif
+
 #ifdef CONFIG_ZONE_DMA32
 #define DMA32_ZONE(xx) xx##_DMA32,
 #else
@@ -31,7 +37,7 @@
 #define HIGHMEM_ZONE(xx)
 #endif
 
-#define FOR_ALL_ZONES(xx) xx##_DMA, DMA32_ZONE(xx) xx##_NORMAL HIGHMEM_ZONE(xx)
+#define FOR_ALL_ZONES(xx) DMA_ZONE(xx) DMA32_ZONE(xx) xx##_NORMAL HIGHMEM_ZONE(xx)
 
 enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		FOR_ALL_ZONES(PGALLOC),
@@ -96,7 +102,8 @@ static inline void vm_events_fold_cpu(int cpu)
 #endif /* CONFIG_VM_EVENT_COUNTERS */
 
 #define __count_zone_vm_events(item, zone, delta) \
-			__count_vm_events(item##_DMA + zone_idx(zone), delta)
+		__count_vm_events(item##_NORMAL - ZONE_NORMAL + \
+		zone_idx(zone), delta)
 
 /*
  * Zone based page accounting with per cpu differentials.
@@ -143,14 +150,16 @@ static inline unsigned long node_page_state(int node,
 	struct zone *zones = NODE_DATA(node)->node_zones;
 
 	return
+#ifdef CONFIG_ZONE_DMA
+		zone_page_state(&zones[ZONE_DMA], item) +
+#endif
 #ifdef CONFIG_ZONE_DMA32
 		zone_page_state(&zones[ZONE_DMA32], item) +
 #endif
-		zone_page_state(&zones[ZONE_NORMAL], item) +
 #ifdef CONFIG_HIGHMEM
 		zone_page_state(&zones[ZONE_HIGHMEM], item) +
 #endif
-		zone_page_state(&zones[ZONE_DMA], item);
+		zone_page_state(&zones[ZONE_NORMAL], item);
 }
 
 extern void zone_statistics(struct zonelist *, struct zone *);