tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master head: fb57b1fabcb28f358901b2df90abd2b48abc1ca8 commit: 7fa3e10f0f3646108a1018004d0f571c3222dc9f [2551/10701] x86/mm: Move pgprot2cachemode out of line config: i386-randconfig-r015-20200519 (attached as .config) compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0 reproduce: git checkout 7fa3e10f0f3646108a1018004d0f571c3222dc9f # 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 <<): arch/x86/mm/init.c:74:6: warning: no previous prototype for 'x86_has_pat_wp' [-Wmissing-prototypes] bool x86_has_pat_wp(void) ^~~~~~~~~~~~~~ enum page_cache_mode pgprot2cachemode(pgprot_t pgprot) ^~~~~~~~~~~~~~~~ arch/x86/mm/init.c:484:21: warning: no previous prototype for 'init_memory_mapping' [-Wmissing-prototypes] unsigned long __ref init_memory_mapping(unsigned long start, ^~~~~~~~~~~~~~~~~~~ arch/x86/mm/init.c:726:13: warning: no previous prototype for 'poking_init' [-Wmissing-prototypes] void __init poking_init(void) ^~~~~~~~~~~ arch/x86/mm/init.c:875:13: warning: no previous prototype for 'mem_encrypt_free_decrypted_mem' [-Wmissing-prototypes] void __weak mem_encrypt_free_decrypted_mem(void) { } ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ vim +/pgprot2cachemode +79 arch/x86/mm/init.c 78 80 { 81 unsigned long masked; 82 83 masked = pgprot_val(pgprot) & _PAGE_CACHE_MASK; 84 if (likely(masked == 0)) 85 return 0; 86 return __pte2cachemode_tbl[__pte2cm_idx(masked)]; 87 } 88 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org