Hi Waiman, I love your patch! Perhaps something to improve: [auto build test WARNING on axboe-block/for-next] [also build test WARNING on linus/master next-20220601] [cannot apply to v5.18] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/intel-lab-lkp/linux/commits/Waiman-Long/blk-cgroup-Correctly-free-percpu-iostat_cpu-in-blkg-on-error-exit/20220602-005557 base: https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next config: x86_64-randconfig-a005 (https://download.01.org/0day-ci/archive/20220602/202206020948.yBhTYYDS-lkp@xxxxxxxxx/config) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project c825abd6b0198fb088d9752f556a70705bc99dfd) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # https://github.com/intel-lab-lkp/linux/commit/7f5ef1493e681454e71c11b2547638b94665a78f git remote add linux-review https://github.com/intel-lab-lkp/linux git fetch --no-tags linux-review Waiman-Long/blk-cgroup-Correctly-free-percpu-iostat_cpu-in-blkg-on-error-exit/20220602-005557 git checkout 7f5ef1493e681454e71c11b2547638b94665a78f # save the config file mkdir build_dir && cp config build_dir/.config COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash If you fix the issue, kindly add following tag where applicable Reported-by: kernel test robot <lkp@xxxxxxxxx> All warnings (new ones prefixed by >>): >> block/blk-cgroup.c:1239:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (!blkcg->lhead) ^~~~~~~~~~~~~ block/blk-cgroup.c:1290:9: note: uninitialized use occurs here return ret; ^~~ block/blk-cgroup.c:1239:2: note: remove the 'if' if its condition is always false if (!blkcg->lhead) ^~~~~~~~~~~~~~~~~~ block/blk-cgroup.c:1223:33: note: initialize the variable 'ret' to silence this warning struct cgroup_subsys_state *ret; ^ = NULL 1 warning generated. vim +1239 block/blk-cgroup.c 1218 1219 static struct cgroup_subsys_state * 1220 blkcg_css_alloc(struct cgroup_subsys_state *parent_css) 1221 { 1222 struct blkcg *blkcg; 1223 struct cgroup_subsys_state *ret; 1224 int i; 1225 1226 mutex_lock(&blkcg_pol_mutex); 1227 1228 if (!parent_css) { 1229 blkcg = &blkcg_root; 1230 } else { 1231 blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); 1232 if (!blkcg) { 1233 ret = ERR_PTR(-ENOMEM); 1234 goto unlock; 1235 } 1236 } 1237 1238 blkcg->lhead = alloc_percpu_gfp(struct llist_head, GFP_KERNEL); > 1239 if (!blkcg->lhead) 1240 goto free_blkcg; 1241 init_blkcg_llists(blkcg); 1242 1243 for (i = 0; i < BLKCG_MAX_POLS ; i++) { 1244 struct blkcg_policy *pol = blkcg_policy[i]; 1245 struct blkcg_policy_data *cpd; 1246 1247 /* 1248 * If the policy hasn't been attached yet, wait for it 1249 * to be attached before doing anything else. Otherwise, 1250 * check if the policy requires any specific per-cgroup 1251 * data: if it does, allocate and initialize it. 1252 */ 1253 if (!pol || !pol->cpd_alloc_fn) 1254 continue; 1255 1256 cpd = pol->cpd_alloc_fn(GFP_KERNEL); 1257 if (!cpd) { 1258 ret = ERR_PTR(-ENOMEM); 1259 goto free_pd_blkcg; 1260 } 1261 blkcg->cpd[i] = cpd; 1262 cpd->blkcg = blkcg; 1263 cpd->plid = i; 1264 if (pol->cpd_init_fn) 1265 pol->cpd_init_fn(cpd); 1266 } 1267 1268 spin_lock_init(&blkcg->lock); 1269 refcount_set(&blkcg->online_pin, 1); 1270 INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN); 1271 INIT_HLIST_HEAD(&blkcg->blkg_list); 1272 #ifdef CONFIG_CGROUP_WRITEBACK 1273 INIT_LIST_HEAD(&blkcg->cgwb_list); 1274 #endif 1275 list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); 1276 1277 mutex_unlock(&blkcg_pol_mutex); 1278 return &blkcg->css; 1279 1280 free_pd_blkcg: 1281 for (i--; i >= 0; i--) 1282 if (blkcg->cpd[i]) 1283 blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); 1284 free_percpu(blkcg->lhead); 1285 free_blkcg: 1286 if (blkcg != &blkcg_root) 1287 kfree(blkcg); 1288 unlock: 1289 mutex_unlock(&blkcg_pol_mutex); 1290 return ret; 1291 } 1292 -- 0-DAY CI Kernel Test Service https://01.org/lkp
