mm/slub.c:3905:29: error: variable 'obj_exts' set but not used

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   c286c21ff94252f778515b21b6bebe749454a852
commit: 4b8736964640fe160724e7135dc62883bddcdace mm/slab: add allocation accounting into slab allocation and free paths
date:   7 weeks ago
config: x86_64-sof-customedconfig-atom-defconfig (https://download.01.org/0day-ci/archive/20240615/[email protected]/config)
compiler: gcc-11 (Ubuntu 11.4.0-4ubuntu1) 11.4.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240615/[email protected]/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 <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

mm/slub.c: In function 'slab_post_alloc_hook':

Quoted 1 line

Quoted 1 line

mm/slub.c:3905:29: error: variable 'obj_exts' set but not used [-Werror=unused-but-set-variable]

    3905 |         struct slabobj_ext *obj_exts;
         |                             ^~~~~~~~

cc1: all warnings being treated as errors

vim +/obj_exts +3905 mm/slub.c

3898
3899 static __fastpath_inline
3900 void slab_post_alloc_hook(struct kmem_cache *s, struct obj_cgroup *objcg,
3901 gfp_t flags, size_t size, void **p, bool init,
3902 unsigned int orig_size)
3903 {

  3904          unsigned int zero_size = s->object_size;
> 3905          struct slabobj_ext *obj_exts;
  3906          bool kasan_init = init;
  3907          size_t i;
  3908          gfp_t init_flags = flags & gfp_allowed_mask;
  3909
  3910          /*
  3911           * For kmalloc object, the allocated memory size(object_size) is likely
  3912           * larger than the requested size(orig_size). If redzone check is
  3913           * enabled for the extra space, don't zero it, as it will be redzoned
  3914           * soon. The redzone operation for this extra space could be seen as a
  3915           * replacement of current poisoning under certain debug option, and
  3916           * won't break other sanity checks.
  3917           */
  3918          if (kmem_cache_debug_flags(s, SLAB_STORE_USER | SLAB_RED_ZONE) &&
  3919              (s->flags & SLAB_KMALLOC))
  3920                  zero_size = orig_size;
  3921
  3922          /*
  3923           * When slab_debug is enabled, avoid memory initialization integrated
  3924           * into KASAN and instead zero out the memory via the memset below with
  3925           * the proper size. Otherwise, KASAN might overwrite SLUB redzones and
  3926           * cause false-positive reports. This does not lead to a performance
  3927           * penalty on production builds, as slab_debug is not intended to be
  3928           * enabled there.
  3929           */
  3930          if (__slub_debug_enabled())
  3931                  kasan_init = false;
  3932
  3933          /*
  3934           * As memory initialization might be integrated into KASAN,
  3935           * kasan_slab_alloc and initialization memset must be
  3936           * kept together to avoid discrepancies in behavior.
  3937           *
  3938           * As p[i] might get tagged, memset and kmemleak hook come after KASAN.
  3939           */
  3940          for (i = 0; i < size; i++) {
  3941                  p[i] = kasan_slab_alloc(s, p[i], init_flags, kasan_init);
  3942                  if (p[i] && init && (!kasan_init ||
  3943                                       !kasan_has_integrated_init()))
  3944                          memset(p[i], 0, zero_size);
  3945                  kmemleak_alloc_recursive(p[i], s->object_size, 1,
  3946                                           s->flags, init_flags);
  3947                  kmsan_slab_alloc(s, p[i], init_flags);
  3948                  if (need_slab_obj_ext()) {
  3949                          obj_exts = prepare_slab_obj_exts_hook(s, flags, p[i]);
  3950  #ifdef CONFIG_MEM_ALLOC_PROFILING
  3951                          /*
  3952                           * Currently obj_exts is used only for allocation profiling.
  3953                           * If other users appear then mem_alloc_profiling_enabled()
  3954                           * check should be added before alloc_tag_add().
  3955                           */

3956 if (likely(obj_exts))
3957 alloc_tag_add(&obj_exts->ref, current->alloc_tag, s->size);
3958 #endif
3959 }
3960 }
3961
3962 memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
3963 }
3964

--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki