tree: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git devel/btrfs-fix head: 64dd8f004e6e4f285d66f54c3515a1ee2f5dae47 commit: 68a2a8c422d312c1d717be2a0dda51ca6282b28c [1/2] uaccess: Introduce __copy_{to,from}_user_nofault() returning the bytes not copied config: arm-randconfig-c002-20211011 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project c3dcf39554dbea780d6cb7e12239451ba47a2668) 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 # install arm cross compiling tool for clang build # apt-get install binutils-arm-linux-gnueabi # https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/commit/?i... git remote add arm64 https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git git fetch --no-tags arm64 devel/btrfs-fix git checkout 68a2a8c422d312c1d717be2a0dda51ca6282b28c # save the attached .config to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): vim +222 mm/maccess.c 3d7081822f7f9e Masami Hiramatsu 2019-05-15 211 fc3562d79456bf Christoph Hellwig 2020-06-08 212 /** c0ee37e85e0e47 Christoph Hellwig 2020-06-17 213 * copy_from_user_nofault(): safely attempt to read from a user-space location fc3562d79456bf Christoph Hellwig 2020-06-08 214 * @dst: pointer to the buffer that shall take the data fc3562d79456bf Christoph Hellwig 2020-06-08 215 * @src: address to read from. This must be a user address. fc3562d79456bf Christoph Hellwig 2020-06-08 216 * @size: size of the data chunk fc3562d79456bf Christoph Hellwig 2020-06-08 217 * fc3562d79456bf Christoph Hellwig 2020-06-08 218 * Safely read from user address @src to the buffer at @dst. If a kernel fault fc3562d79456bf Christoph Hellwig 2020-06-08 219 * happens, handle that and return -EFAULT. fc3562d79456bf Christoph Hellwig 2020-06-08 220 */ 68a2a8c422d312 Catalin Marinas 2021-10-09 221 unsigned long __copy_from_user_nofault(void *dst, const void __user *src, size_t size) fc3562d79456bf Christoph Hellwig 2020-06-08 @222 { 68a2a8c422d312 Catalin Marinas 2021-10-09 223 unsigned long ret = size; 3d13f313ce4c34 Christoph Hellwig 2020-08-11 224 mm_segment_t old_fs = force_uaccess_begin(); fc3562d79456bf Christoph Hellwig 2020-06-08 225 fc3562d79456bf Christoph Hellwig 2020-06-08 226 if (access_ok(src, size)) { fc3562d79456bf Christoph Hellwig 2020-06-08 227 pagefault_disable(); fc3562d79456bf Christoph Hellwig 2020-06-08 228 ret = __copy_from_user_inatomic(dst, src, size); fc3562d79456bf Christoph Hellwig 2020-06-08 229 pagefault_enable(); fc3562d79456bf Christoph Hellwig 2020-06-08 230 } 3d13f313ce4c34 Christoph Hellwig 2020-08-11 231 force_uaccess_end(old_fs); fc3562d79456bf Christoph Hellwig 2020-06-08 232 68a2a8c422d312 Catalin Marinas 2021-10-09 233 return ret; fc3562d79456bf Christoph Hellwig 2020-06-08 234 } 68a2a8c422d312 Catalin Marinas 2021-10-09 235 EXPORT_SYMBOL_GPL(__copy_from_user_nofault); fc3562d79456bf Christoph Hellwig 2020-06-08 236 fc3562d79456bf Christoph Hellwig 2020-06-08 237 /** c0ee37e85e0e47 Christoph Hellwig 2020-06-17 238 * copy_to_user_nofault(): safely attempt to write to a user-space location fc3562d79456bf Christoph Hellwig 2020-06-08 239 * @dst: address to write to fc3562d79456bf Christoph Hellwig 2020-06-08 240 * @src: pointer to the data that shall be written fc3562d79456bf Christoph Hellwig 2020-06-08 241 * @size: size of the data chunk fc3562d79456bf Christoph Hellwig 2020-06-08 242 * fc3562d79456bf Christoph Hellwig 2020-06-08 243 * Safely write to address @dst from the buffer at @src. If a kernel fault fc3562d79456bf Christoph Hellwig 2020-06-08 244 * happens, handle that and return -EFAULT. fc3562d79456bf Christoph Hellwig 2020-06-08 245 */ 68a2a8c422d312 Catalin Marinas 2021-10-09 246 unsigned long __copy_to_user_nofault(void __user *dst, const void *src, size_t size) fc3562d79456bf Christoph Hellwig 2020-06-08 @247 { 68a2a8c422d312 Catalin Marinas 2021-10-09 248 unsigned long ret = size; 3d13f313ce4c34 Christoph Hellwig 2020-08-11 249 mm_segment_t old_fs = force_uaccess_begin(); fc3562d79456bf Christoph Hellwig 2020-06-08 250 fc3562d79456bf Christoph Hellwig 2020-06-08 251 if (access_ok(dst, size)) { fc3562d79456bf Christoph Hellwig 2020-06-08 252 pagefault_disable(); fc3562d79456bf Christoph Hellwig 2020-06-08 253 ret = __copy_to_user_inatomic(dst, src, size); fc3562d79456bf Christoph Hellwig 2020-06-08 254 pagefault_enable(); fc3562d79456bf Christoph Hellwig 2020-06-08 255 } 3d13f313ce4c34 Christoph Hellwig 2020-08-11 256 force_uaccess_end(old_fs); fc3562d79456bf Christoph Hellwig 2020-06-08 257 68a2a8c422d312 Catalin Marinas 2021-10-09 258 return ret; fc3562d79456bf Christoph Hellwig 2020-06-08 259 } 68a2a8c422d312 Catalin Marinas 2021-10-09 260 EXPORT_SYMBOL_GPL(__copy_to_user_nofault); fc3562d79456bf Christoph Hellwig 2020-06-08 261 :::::: The code at line 222 was first introduced by commit :::::: fc3562d79456bf1740b44d84b8726d20de8d39bd maccess: move user access routines together :::::: TO: Christoph Hellwig <hch(a)lst.de&gt; :::::: CC: Linus Torvalds <torvalds(a)linux-foundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org