Re: [PATCH V4 4/8] mm/slab: abstract slabobj_ext access via new slab_obj_ext() helper

[kernel test robot <lkp@intel.com>]

Hi Harry,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Harry-Yoo/mm-slab-use-unsigned-long-for-orig_size-to-ensure-proper-metadata-align/20251222-191144
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20251222110843.980347-5-harry.yoo%40oracle.com
patch subject: [PATCH V4 4/8] mm/slab: abstract slabobj_ext access via new slab_obj_ext() helper
config: x86_64-buildonly-randconfig-001-20251223 (https://download.01.org/0day-ci/archive/20251223/202512230850.bBE4pAZ5-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251223/202512230850.bBE4pAZ5-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512230850.bBE4pAZ5-lkp@intel.com/

All errors (new ones prefixed by >>):

>> mm/slub.c:2056:33: error: passing 'union codetag_ref' to parameter of incompatible type 'union codetag_ref *'; take the address with &
    2056 |                 if (unlikely(is_codetag_empty(ext->ref)))
         |                                               ^~~~~~~~
         |                                               &
   include/linux/compiler.h:47:41: note: expanded from macro 'unlikely'
      47 | #  define unlikely(x)   (__branch_check__(x, 0, __builtin_constant_p(x)))
         |                                           ^
   include/linux/compiler.h:32:34: note: expanded from macro '__branch_check__'
      32 |                         ______r = __builtin_expect(!!(x), expect);      \
         |                                                       ^
   include/linux/alloc_tag.h:52:56: note: passing argument to parameter 'ref' here
      52 | static inline bool is_codetag_empty(union codetag_ref *ref)
         |                                                        ^
>> mm/slub.c:2056:33: error: passing 'union codetag_ref' to parameter of incompatible type 'union codetag_ref *'; take the address with &
    2056 |                 if (unlikely(is_codetag_empty(ext->ref)))
         |                                               ^~~~~~~~
         |                                               &
   include/linux/compiler.h:47:68: note: expanded from macro 'unlikely'
      47 | #  define unlikely(x)   (__branch_check__(x, 0, __builtin_constant_p(x)))
         |                                                                      ^
   include/linux/compiler.h:34:19: note: expanded from macro '__branch_check__'
      34 |                                              expect, is_constant);      \
         |                                                      ^~~~~~~~~~~
   include/linux/alloc_tag.h:52:56: note: passing argument to parameter 'ref' here
      52 | static inline bool is_codetag_empty(union codetag_ref *ref)
         |                                                        ^
   2 errors generated.


vim +2056 mm/slub.c

  2042	
  2043	static inline void mark_objexts_empty(struct slabobj_ext *obj_exts)
  2044	{
  2045		unsigned long slab_exts;
  2046		struct slab *obj_exts_slab;
  2047	
  2048		obj_exts_slab = virt_to_slab(obj_exts);
  2049		slab_exts = slab_obj_exts(obj_exts_slab);
  2050		if (slab_exts) {
  2051			unsigned int offs = obj_to_index(obj_exts_slab->slab_cache,
  2052							 obj_exts_slab, obj_exts);
  2053			struct slabobj_ext *ext = slab_obj_ext(obj_exts_slab,
  2054							       slab_exts, offs);
  2055	
> 2056			if (unlikely(is_codetag_empty(ext->ref)))
  2057				return;
  2058	
  2059			/* codetag should be NULL here */
  2060			WARN_ON(ext->ref.ct);
  2061			set_codetag_empty(&ext->ref);
  2062		}
  2063	}
  2064	

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