Make ashmem driver loadable as kernel module

kernel/ashmem/ashmem.c

@@ -18,6 +18,7 @@
 
 #define pr_fmt(fmt) "ashmem: " fmt
 
+#include <linux/module.h>
 #include <linux/init.h>
 #include <linux/export.h>
 #include <linux/file.h>
@@ -857,8 +858,20 @@ static int __init ashmem_init(void)
 
 	register_shrinker(&ashmem_shrinker);
 
-	pr_info("initialized\n");
-
 	return 0;
 }
-device_initcall(ashmem_init);
+
+static void __exit ashmem_exit(void)
+{
+	unregister_shrinker(&ashmem_shrinker);
+
+	misc_deregister(&ashmem_misc);
+
+	kmem_cache_destroy(ashmem_range_cachep);
+	kmem_cache_destroy(ashmem_area_cachep);
+}
+
+module_init(ashmem_init);
+module_exit(ashmem_exit);
+
+MODULE_LICENSE("GPL");