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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755062199; bh=QHGINcBtgZyN5lwSuC4ihOdgAfkWxrXCvNILJWMOBVA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=NJ8kdtSmVYuDmZ9UTC9uyVZDWkHKpE44JmKlAUuCa7NZxop2ZK8q7CC++ZZVKGYqf 2FtFO5vBHtDjYhIFJTJjQSsJRbxUaf0a5k9GCO/vI0kEc2Amu0RlAFK5LI+90qUwE8 Wt/HmHsp350LKxT3V5edx5EIk5k5/dHroc1gWPsZBPQTy3e4Ep/IgKDgKWQmnFs0sw 6cqFtidy2jtFeD3RQfgLFaCCGVcqzgmOXefeTkU64Ioo3+VbGhOKm4ArnHUoBv87xd 3Pvm2U1X+nJMrmwtp/okmHBkuSQR3Yb1oCRfS+C3ip0SypefYd4i8fT0xp5j3V9lPt 9tySUkpa34FBg== Date: Tue, 12 Aug 2025 22:16:33 -0700 From: Nathan Chancellor To: kernel test robot Cc: Dominique Martinet via B4 Relay , "Matthew Wilcox (Oracle)" , Christian Brauner , David Howells , Alexander Viro , Andrew Morton , llvm@lists.linux.dev, oe-kbuild-all@lists.linux.dev, Linux Memory Management List , Maximilian Bosch , Ryan Lahfa , Christian Theune , Arnout Engelen , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, Dominique Martinet , stable@vger.kernel.org Subject: Re: [PATCH 1/2] iov_iter: iterate_folioq: fix handling of offset >= folio size Message-ID: <20250813051633.GA3895812@ax162> References: <20250811-iot_iter_folio-v1-1-d9c223adf93c@codewreck.org> <202508120250.Eooq2ydr-lkp@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202508120250.Eooq2ydr-lkp@intel.com> X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 2452D1C000C X-Stat-Signature: 6i9o5ki51bhzq8c9duqq9n3oh84xxfnh X-HE-Tag: 1755062201-716088 X-HE-Meta: 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 SA3haRjn 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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@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/20250812/202508120250.Eooq2ydr-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 > | Closes: https://lore.kernel.org/oe-kbuild-all/202508120250.Eooq2ydr-lkp@intel.com/ > > 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