tree: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git folio head: a49ddcf53fc0ec32009a8433826aa5e6989319bf commit: f66349ff51ddf0c0cfb99f59cad5a02f942bcca3 [53/90] mm: Add flush_dcache_folio() config: m68k-allyesconfig (attached as .config) compiler: m68k-linux-gcc (GCC) 11.2.0 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/dhowells/linux-fs.git/com... git remote add dhowells-fs https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git git fetch --no-tags dhowells-fs folio git checkout f66349ff51ddf0c0cfb99f59cad5a02f942bcca3 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=m68k 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 >>): 1081 | void flush_dcache_folio(struct folio *folio) | ^~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors vim +/flush_dcache_folio +1081 mm/util.c 1079 1080 #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org