diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index fcb535560028fc59a82a4b1e56c6db728fe5bf37..8827f4d081d430b4eade28d9d22157aab2cf1fce 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1342,7 +1342,6 @@ static inline struct mem_section *__nr_to_section(unsigned long nr)
 		return NULL;
 	return &mem_section[SECTION_NR_TO_ROOT(nr)][nr & SECTION_ROOT_MASK];
 }
-extern unsigned long __section_nr(struct mem_section *ms);
 extern size_t mem_section_usage_size(void);
 
 /*
diff --git a/mm/sparse.c b/mm/sparse.c
index 8018ee7fcda52980c2bd23866c953dc2079d54a2..d85655242ed9878ef4af7d4c59b2f790e075c41b 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -109,32 +109,6 @@ static inline int sparse_index_init(unsigned long section_nr, int nid)
 }
 #endif
 
-#ifdef CONFIG_SPARSEMEM_EXTREME
-unsigned long __section_nr(struct mem_section *ms)
-{
-	unsigned long root_nr;
-	struct mem_section *root = NULL;
-
-	for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
-		root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
-		if (!root)
-			continue;
-
-		if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
-		     break;
-	}
-
-	VM_BUG_ON(!root);
-
-	return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
-}
-#else
-unsigned long __section_nr(struct mem_section *ms)
-{
-	return (unsigned long)(ms - mem_section[0]);
-}
-#endif
-
 /*
  * During early boot, before section_mem_map is used for an actual
  * mem_map, we use section_mem_map to store the section's NUMA