tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: fb57b1fabcb28f358901b2df90abd2b48abc1ca8 commit: 1f6f655e01adebf5bd5e6c3da2e843c104ded051 [2550/10701] x86/mm: Add a x86_has_pat_wp() helper config: i386-randconfig-r015-20200519 (attached as .config) compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0 reproduce: git checkout 1f6f655e01adebf5bd5e6c3da2e843c104ded051 # save the attached .config to linux build tree make ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): bool x86_has_pat_wp(void) ^~~~~~~~~~~~~~ arch/x86/mm/init.c:475:21: warning: no previous prototype for 'init_memory_mapping' [-Wmissing-prototypes] unsigned long __ref init_memory_mapping(unsigned long start, ^~~~~~~~~~~~~~~~~~~ arch/x86/mm/init.c:717:13: warning: no previous prototype for 'poking_init' [-Wmissing-prototypes] void __init poking_init(void) ^~~~~~~~~~~ arch/x86/mm/init.c:866:13: warning: no previous prototype for 'mem_encrypt_free_decrypted_mem' [-Wmissing-prototypes] void __weak mem_encrypt_free_decrypted_mem(void) { } ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ vim +/x86_has_pat_wp +75 arch/x86/mm/init.c 73 74 /* Check that the write-protect PAT entry is set for write-protect */ 76 { 77 return __pte2cachemode_tbl[_PAGE_CACHE_MODE_WP] == _PAGE_CACHE_MODE_WP; 78 } 79 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org