On 6/2/21 3:03 AM, Stephen Boyd wrote:

Quoting Andrew Morton (2021-06-01 17:26:59)

quoted

On Wed, 2 Jun 2021 06:45:55 +0800 kernel test robot [off-list ref] wrote:

quoted

quoted

quoted

mm/slub.c:4464:30: error: use of undeclared identifier 'slub_debug_enabled'

           if (static_branch_unlikely(&slub_debug_enabled))
                                       ^

quoted

quoted

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?

Looks good to me. Thanks for the quick fix!

quoted

--- 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);

To make this even better it could be

	return static_branch_maybe(CONFIG_SLUB_DEBUG_ON, &slub_debug_enabled);

quoted

+}
+
+#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())

A minimal fix would be to put this under #ifdef CONFIG_SLUB_DEBUG
and use static_key_enabled() as we don't need the jump label optimization for
init code. But the current fix works.

It would be super cool if static branches could be optimized out when
they're never changed by any code, nor exported to code, just tested in
conditions. I've no idea if that is the case though.

quoted

                no_hash_pointers_enable(NULL);

        kmem_cache_node = &boot_kmem_cache_node;