On 6/2/21 3:03 AM, Stephen Boyd wrote:
> Quoting Andrew Morton (2021-06-01 17:26:59)
>> On Wed, 2 Jun 2021 06:45:55 +0800 kernel test robot <lkp@xxxxxxxxx> 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?
>
> Looks good to me. Thanks for the quick fix!
>
>>
>> --- 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);
>
>> +}
>> +
>> +#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.
>
>> no_hash_pointers_enable(NULL);
>>
>> kmem_cache_node = &boot_kmem_cache_node;
>
