On Tue, Aug 12, 2025 at 02:55:55AM +0800, kernel test robot wrote: > Hi Dominique, > > kernel test robot noticed the following build warnings: > > [auto build test WARNING on 8f5ae30d69d7543eee0d70083daf4de8fe15d585] > > url: https://github.com/intel-lab-lkp/linux/commits/Dominique-Martinet-via-B4-Relay/iov_iter-iterate_folioq-fix-handling-of-offset-folio-size/20250811-154319 > base: 8f5ae30d69d7543eee0d70083daf4de8fe15d585 > patch link: https://lore.kernel.org/r/20250811-iot_iter_folio-v1-1-d9c223adf93c%40codewreck.org > patch subject: [PATCH 1/2] iov_iter: iterate_folioq: fix handling of offset >= folio size > config: i386-buildonly-randconfig-002-20250811 (https://download.01.org/0day-ci/archive/20250812/202508120250.Eooq2ydr-lkp@xxxxxxxxx/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/20250812/202508120250.Eooq2ydr-lkp@xxxxxxxxx/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@xxxxxxxxx> > | Closes: https://lore.kernel.org/oe-kbuild-all/202508120250.Eooq2ydr-lkp@xxxxxxxxx/ > > All warnings (new ones prefixed by >>): > > In file included from lib/iov_iter.c:14: > >> include/linux/iov_iter.h:171:7: warning: variable 'remain' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] > 171 | if (skip >= fsize) > | ^~~~~~~~~~~~~ > include/linux/iov_iter.h:190:7: note: uninitialized use occurs here > 190 | if (remain) > | ^~~~~~ > include/linux/iov_iter.h:171:3: note: remove the 'if' if its condition is always false > 171 | if (skip >= fsize) > | ^~~~~~~~~~~~~~~~~~ > 172 | goto next; > | ~~~~~~~~~ > include/linux/iov_iter.h:163:22: note: initialize the variable 'remain' to silence this warning > 163 | size_t part, remain, consumed; > | ^ > | = 0 > 1 warning generated. I see this in -next now, should remain be zero initialized or is there some other fix that is needed? > vim +171 include/linux/iov_iter.h > > 143 > 144 /* > 145 * Handle ITER_FOLIOQ. > 146 */ > 147 static __always_inline > 148 size_t iterate_folioq(struct iov_iter *iter, size_t len, void *priv, void *priv2, > 149 iov_step_f step) > 150 { > 151 const struct folio_queue *folioq = iter->folioq; > 152 unsigned int slot = iter->folioq_slot; > 153 size_t progress = 0, skip = iter->iov_offset; > 154 > 155 if (slot == folioq_nr_slots(folioq)) { > 156 /* The iterator may have been extended. */ > 157 folioq = folioq->next; > 158 slot = 0; > 159 } > 160 > 161 do { > 162 struct folio *folio = folioq_folio(folioq, slot); > 163 size_t part, remain, consumed; > 164 size_t fsize; > 165 void *base; > 166 > 167 if (!folio) > 168 break; > 169 > 170 fsize = folioq_folio_size(folioq, slot); > > 171 if (skip >= fsize) > 172 goto next; > 173 base = kmap_local_folio(folio, skip); > 174 part = umin(len, PAGE_SIZE - skip % PAGE_SIZE); > 175 remain = step(base, progress, part, priv, priv2); > 176 kunmap_local(base); > 177 consumed = part - remain; > 178 len -= consumed; > 179 progress += consumed; > 180 skip += consumed; > 181 if (skip >= fsize) { > 182 next: > 183 skip = 0; > 184 slot++; > 185 if (slot == folioq_nr_slots(folioq) && folioq->next) { > 186 folioq = folioq->next; > 187 slot = 0; > 188 } > 189 } > 190 if (remain) > 191 break; > 192 } while (len); > 193 > 194 iter->folioq_slot = slot; > 195 iter->folioq = folioq; > 196 iter->iov_offset = skip; > 197 iter->count -= progress; > 198 return progress; > 199 } > 200 > > -- > 0-DAY CI Kernel Test Service > https://github.com/intel/lkp-tests/wiki
