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/commit/?id=f66349ff51ddf0c0cfb99f59cad5a02f942bcca3
        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@intel.com>

All errors (new ones prefixed by >>):

>> mm/util.c:1081:6: error: no previous prototype for 'flush_dcache_folio' [-Werror=missing-prototypes]
    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
> 1081	void flush_dcache_folio(struct folio *folio)

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org