tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: aa14a3016182213f022068500486ef3bcacb9006 commit: b2e613c28653c91721a932a18d2d29df663c2dd4 [12277/12292] Merge remote-tracking branch 'folio/for-next' config: m68k-randconfig-r021-20210910 (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/next/linux-next.git/commi... git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git git fetch --no-tags linux-next master git checkout b2e613c28653c91721a932a18d2d29df663c2dd4 # 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 >>): 1094 | void flush_dcache_folio(struct folio *folio) | ^~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors vim +/flush_dcache_folio +1094 mm/util.c 3431c15c5e0a26 Matthew Wilcox (Oracle 2020-12-16 1092) 3431c15c5e0a26 Matthew Wilcox (Oracle 2020-12-16 1093) #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO 3431c15c5e0a26 Matthew Wilcox (Oracle 2020-12-16 @1094) void flush_dcache_folio(struct folio *folio) :::::: The code at line 1094 was first introduced by commit :::::: 3431c15c5e0a2605e09d999eaa25db784d6f827f mm: Add flush_dcache_folio() :::::: TO: Matthew Wilcox (Oracle) <willy(a)infradead.org&gt; :::::: CC: Matthew Wilcox (Oracle) <willy(a)infradead.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org