tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: 8ca403f3e7a23c4513046ad8d107adfbe4703362 commit: 284e3a59cc20335f65f2fb5215230d63b32f25d4 [6848/6860] Merge remote-tracking branch 'folio/for-next' config: mips-buildonly-randconfig-r005-20210810 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 767496d19cb9a1fbba57ff08095faa161998ee36) 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 284e3a59cc20335f65f2fb5215230d63b32f25d4 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips 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 >>): void flush_dcache_folio(struct folio *folio) ^ mm/util.c:1105:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void flush_dcache_folio(struct folio *folio) ^ static 1 warning generated. vim +/flush_dcache_folio +1105 mm/util.c d1089c128effba Matthew Wilcox (Oracle 2020-12-16 1103) d1089c128effba Matthew Wilcox (Oracle 2020-12-16 1104) #ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO d1089c128effba Matthew Wilcox (Oracle 2020-12-16 @1105) void flush_dcache_folio(struct folio *folio) :::::: The code at line 1105 was first introduced by commit :::::: d1089c128effba5c3f298e277b0422193ae1a943 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