Re: [PATCH v3 4/4] slub: Force on no_hash_pointers when slub_debug is enabled

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 2 Jun 2021 06:45:55 +0800 kernel test robot <lkp@intel.com> wrote:

> >> mm/slub.c:4464:30: error: use of undeclared identifier 'slub_debug_enabled'
>            if (static_branch_unlikely(&slub_debug_enabled))
>                                        ^
> >> mm/slub.c:4464:30: error: use of undeclared identifier 'slub_debug_enabled'
> >> mm/slub.c:4464:30: error: use of undeclared identifier 'slub_debug_enabled'
> >> mm/slub.c:4464:30: error: use of undeclared identifier 'slub_debug_enabled'
> >> mm/slub.c:4464:6: error: invalid argument type 'void' to unary expression
>            if (static_branch_unlikely(&slub_debug_enabled))
>                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Thanks.  Stephen, how about this?

--- a/mm/slub.c~slub-force-on-no_hash_pointers-when-slub_debug-is-enabled-fix
+++ a/mm/slub.c
@@ -117,12 +117,26 @@
  */
 
 #ifdef CONFIG_SLUB_DEBUG
+
 #ifdef CONFIG_SLUB_DEBUG_ON
 DEFINE_STATIC_KEY_TRUE(slub_debug_enabled);
 #else
 DEFINE_STATIC_KEY_FALSE(slub_debug_enabled);
 #endif
-#endif
+
+static inline bool __slub_debug_enabled(void)
+{
+	return static_branch_unlikely(&slub_debug_enabled);
+}
+
+#else		/* CONFIG_SLUB_DEBUG */
+
+static inline bool __slub_debug_enabled(void)
+{
+	return false;
+}
+
+#endif		/* CONFIG_SLUB_DEBUG */
 
 static inline bool kmem_cache_debug(struct kmem_cache *s)
 {
@@ -4493,7 +4507,7 @@ void __init kmem_cache_init(void)
 		slub_max_order = 0;
 
 	/* Print slub debugging pointers without hashing */
-	if (static_branch_unlikely(&slub_debug_enabled))
+	if (__slub_debug_enabled())
 		no_hash_pointers_enable(NULL);
 
 	kmem_cache_node = &boot_kmem_cache_node;
_