slub: Dynamically size kmalloc cache allocations

kmalloc caches are statically defined and may take up a lot of space just
because the sizes of the node array has to be dimensioned for the largest
node count supported.

This patch makes the size of the kmem_cache structure dynamic throughout by
creating a kmem_cache slab cache for the kmem_cache objects. The bootstrap
occurs by allocating the initial one or two kmem_cache objects from the
page allocator.

C2->C3
	- Fix various issues indicated by David
	- Make create kmalloc_cache return a kmem_cache * pointer.

Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 9f63538928c0..a6c43ec6a4a5 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -139,19 +139,16 @@ struct kmem_cache {
 
 #ifdef CONFIG_ZONE_DMA
 #define SLUB_DMA __GFP_DMA
-/* Reserve extra caches for potential DMA use */
-#define KMALLOC_CACHES (2 * SLUB_PAGE_SHIFT)
 #else
 /* Disable DMA functionality */
 #define SLUB_DMA (__force gfp_t)0
-#define KMALLOC_CACHES SLUB_PAGE_SHIFT
 #endif
 
 /*
  * We keep the general caches in an array of slab caches that are used for
  * 2^x bytes of allocations.
  */
-extern struct kmem_cache kmalloc_caches[KMALLOC_CACHES];
+extern struct kmem_cache *kmalloc_caches[SLUB_PAGE_SHIFT];
 
 /*
  * Sorry that the following has to be that ugly but some versions of GCC
@@ -216,7 +213,7 @@ static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
         if (index == 0)
                 return NULL;
 
-        return &kmalloc_caches[index];
+        return kmalloc_caches[index];
 }
 
 void *kmem_cache_alloc(struct kmem_cache *, gfp_t);