[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);

mm/slab.c

@@ -700,6 +700,14 @@ static enum {
 	FULL
 } g_cpucache_up;
 
+/*
+ * used by boot code to determine if it can use slab based allocator
+ */
+int slab_is_available(void)
+{
+	return g_cpucache_up == FULL;
+}
+
 static DEFINE_PER_CPU(struct work_struct, reap_work);
 
 static void free_block(struct kmem_cache *cachep, void **objpp, int len,

mm/sparse.c

@@ -32,7 +32,7 @@ static struct mem_section *sparse_index_alloc(int nid)
 	unsigned long array_size = SECTIONS_PER_ROOT *
 				   sizeof(struct mem_section);
 
-	if (system_state == SYSTEM_RUNNING)
+	if (slab_is_available())
 		section = kmalloc_node(array_size, GFP_KERNEL, nid);
 	else
 		section = alloc_bootmem_node(NODE_DATA(nid), array_size);