tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: 18250b538735142307082e4e99e3ae5c12d44013 commit: b26e8f27253a47bff90972b987112fd8396e9b8d [12102/13394] powerpc/mem: Move cache flushing functions into mm/cacheflush.c config: powerpc64-randconfig-r012-20210417 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project f549176ad976caa3e19edd036df9a7e12770af7c) 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 # install powerpc64 cross compiling tool for clang build # apt-get install binutils-powerpc64-linux-gnu # 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 b26e8f27253a47bff90972b987112fd8396e9b8d # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=powerpc64 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 >>): int __weak create_section_mapping(unsigned long start, unsigned long end, ^ arch/powerpc/mm/mem.c:53:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int __weak create_section_mapping(unsigned long start, unsigned long end, ^ static 1 warning generated. vim +/create_section_mapping +53 arch/powerpc/mm/mem.c bc02af93dd2bbd Yasunori Goto 2006-06-27 52 4e00c5affdd4b0 Logan Gunthorpe 2020-04-10 @53 int __weak create_section_mapping(unsigned long start, unsigned long end, 4e00c5affdd4b0 Logan Gunthorpe 2020-04-10 54 int nid, pgprot_t prot) fecbfabe1dc940 Benjamin Herrenschmidt 2016-07-05 55 { fecbfabe1dc940 Benjamin Herrenschmidt 2016-07-05 56 return -ENODEV; fecbfabe1dc940 Benjamin Herrenschmidt 2016-07-05 57 } fecbfabe1dc940 Benjamin Herrenschmidt 2016-07-05 58 :::::: The code at line 53 was first introduced by commit :::::: 4e00c5affdd4b04e6392001716333971932f3d0c powerpc/mm: thread pgprot_t through create_section_mapping() :::::: TO: Logan Gunthorpe <logang(a)deltatee.com&gt; :::::: CC: Linus Torvalds <torvalds(a)linux-foundation.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org