Hi Al, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: dcc0b49040c70ad827a7f3d58a21b01fdb14e749 commit: 808b49da54e640cba5c5c92dee658018a529226b alpha: turn csum_partial_copy_from_user() into csum_and_copy_from_user() date: 9 months ago config: alpha-randconfig-r031-20210211 (attached as .config) compiler: alpha-linux-gcc (GCC) 9.3.0 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://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout 808b49da54e640cba5c5c92dee658018a529226b # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=alpha If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): 328 | csum_and_copy_from_user(const void __user *src, void *dst, int len, | ^~~~~~~~~~~~~~~~~~~~~~~ arch/alpha/lib/csum_partial_copy.c:375:1: error: no previous prototype for 'csum_partial_copy_nocheck' [-Werror=missing-prototypes] 375 | csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum) | ^~~~~~~~~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors vim +/csum_and_copy_from_user +328 arch/alpha/lib/csum_partial_copy.c 326 327 __wsum 329 __wsum sum, int *errp) 330 { 331 unsigned long checksum = (__force u32) sum; 332 unsigned long soff = 7 & (unsigned long) src; 333 unsigned long doff = 7 & (unsigned long) dst; 334 335 if (len) { 336 if (!access_ok(src, len)) { 337 if (errp) *errp = -EFAULT; 338 memset(dst, 0, len); 339 return sum; 340 } 341 if (!doff) { 342 if (!soff) 343 checksum = csum_partial_cfu_aligned( 344 (const unsigned long __user *) src, 345 (unsigned long *) dst, 346 len-8, checksum, errp); 347 else 348 checksum = csum_partial_cfu_dest_aligned( 349 (const unsigned long __user *) src, 350 (unsigned long *) dst, 351 soff, len-8, checksum, errp); 352 } else { 353 unsigned long partial_dest; 354 ldq_u(partial_dest, dst); 355 if (!soff) 356 checksum = csum_partial_cfu_src_aligned( 357 (const unsigned long __user *) src, 358 (unsigned long *) dst, 359 doff, len-8, checksum, 360 partial_dest, errp); 361 else 362 checksum = csum_partial_cfu_unaligned( 363 (const unsigned long __user *) src, 364 (unsigned long *) dst, 365 soff, doff, len-8, checksum, 366 partial_dest, errp); 367 } 368 checksum = from64to16 (checksum); 369 } 370 return (__force __wsum)checksum; 371 } 372 EXPORT_SYMBOL(csum_and_copy_from_user); 373 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org