[vbabka:slub-percpu-sheaves-v1r0 8/12] mm/slub.c:5029:18: warning: 'i' is used uninitialized

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

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vbabka/linux.git slub-percpu-sheaves-v1r0
head:   9cb4096680ee90fe6be1b22ff3961174fa8e3ee4
commit: 6912a14dbbe63891a545d4cd35b60bcd3dee3d40 [8/12] mm/slub: add opt-in caching layer of percpu sheaves
config: openrisc-allnoconfig (https://download.01.org/0day-ci/archive/20240713/202407131305.sMLSPyd9-lkp@intel.com/config)
compiler: or1k-linux-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240713/202407131305.sMLSPyd9-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/202407131305.sMLSPyd9-lkp@intel.com/

All warnings (new ones prefixed by >>):

   mm/slub.c: In function 'pcs_flush_all':
   mm/slub.c:2434:36: warning: variable 'rcu_free' set but not used [-Wunused-but-set-variable]
    2434 |         struct slab_sheaf *spare, *rcu_free;
         |                                    ^~~~~~~~
   mm/slub.c: In function 'slab_post_alloc_hook':
   mm/slub.c:4299:29: warning: variable 'obj_exts' set but not used [-Wunused-but-set-variable]
    4299 |         struct slabobj_ext *obj_exts;
         |                             ^~~~~~~~
   mm/slub.c: In function 'free_to_pcs_bulk':
>> mm/slub.c:5029:18: warning: 'i' is used uninitialized [-Wuninitialized]
    5029 |         while (i < size) {
         |                ~~^~~~~~
   mm/slub.c:5024:25: note: 'i' was declared here
    5024 |         unsigned batch, i;
         |                         ^


vim +/i +5029 mm/slub.c

  5013	
  5014	/*
  5015	 * Bulk free objects to the percpu sheaves.
  5016	 * Unlike free_to_pcs() this has includes the calls to all necessary hooks
  5017	 * and the fallback to freeing to slab pages.
  5018	 */
  5019	static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p)
  5020	{
  5021		struct slub_percpu_sheaves *pcs;
  5022		struct slab_sheaf *main;
  5023		unsigned long flags;
  5024		unsigned batch, i;
  5025		bool init;
  5026	
  5027		init = slab_want_init_on_free(s);
  5028	
> 5029		while (i < size) {
  5030			struct slab *slab = virt_to_slab(p[i]);
  5031	
  5032			memcg_slab_free_hook(s, slab, p[i], 1);
  5033			alloc_tagging_slab_free_hook(s, slab, p[i], 1);
  5034	
  5035			if (unlikely(!slab_free_hook(s, p[i], init))) {
  5036				p[i] = p[--size];
  5037				if (!size)
  5038					return;
  5039				continue;
  5040			}
  5041	
  5042			i++;
  5043		}
  5044	
  5045	next_batch:
  5046		local_lock_irqsave(&s->cpu_sheaves->lock, flags);
  5047		pcs = this_cpu_ptr(s->cpu_sheaves);
  5048	
  5049		if (unlikely(pcs->main->size == s->sheaf_capacity)) {
  5050	
  5051			struct slab_sheaf *empty;
  5052	
  5053			if (!pcs->spare) {
  5054				empty = barn_get_empty_sheaf(pcs->barn);
  5055				if (empty) {
  5056					pcs->spare = pcs->main;
  5057					pcs->main = empty;
  5058					goto do_free;
  5059				}
  5060				goto no_empty;
  5061			}
  5062	
  5063			if (pcs->spare->size < s->sheaf_capacity) {
  5064				stat(s, SHEAF_SWAP);
  5065				swap(pcs->main, pcs->spare);
  5066				goto do_free;
  5067			}
  5068	
  5069			empty = barn_replace_full_sheaf(pcs->barn, pcs->main);
  5070	
  5071			if (!IS_ERR(empty)) {
  5072				pcs->main = empty;
  5073				goto do_free;
  5074			}
  5075	
  5076	no_empty:
  5077			local_unlock_irqrestore(&s->cpu_sheaves->lock, flags);
  5078	
  5079			/*
  5080			 * if we depleted all empty sheafs in the barn or there are to
  5081			 * many full sheafs, free the rest to slab pages
  5082			 */
  5083	
  5084			__kmem_cache_free_bulk(s, size, p);
  5085			return;
  5086		}
  5087	
  5088	do_free:
  5089		main = pcs->main;
  5090		batch = min(size, s->sheaf_capacity - main->size);
  5091	
  5092		memcpy(main->objects + main->size, p, batch * sizeof(void *));
  5093		main->size += batch;
  5094	
  5095		local_unlock_irqrestore(&s->cpu_sheaves->lock, flags);
  5096	
  5097		stat_add(s, FREE_PCS, batch);
  5098	
  5099		if (batch < size) {
  5100			p += batch;
  5101			size -= batch;
  5102			goto next_batch;
  5103		}
  5104	}
  5105	

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