[PATCH] add slab_is_available() routine for boot code

slab_is_available() indicates slab based allocators are available for use.
SPARSEMEM code needs to know this as it can be called at various times
during the boot process.

Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/slab.h

@@ -150,6 +150,7 @@ static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
 
 extern void kfree(const void *);
 extern unsigned int ksize(const void *);
+extern int slab_is_available(void);
 
 #ifdef CONFIG_NUMA
 extern void *kmem_cache_alloc_node(kmem_cache_t *, gfp_t flags, int node);