tree: https://github.com/weiny2/linux-kernel.git lm-misc head: 8c385a87dc5cb4d98fa417d3dd9481f3fbe4c625 commit: 2cc4682a3d63e481c63fe72c4149b0bf98cc4b65 [5/8] arch/kmap: Remove redundant arch specific kmaps config: i386-allyesconfig (attached as .config) compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0 reproduce: git checkout 2cc4682a3d63e481c63fe72c4149b0bf98cc4b65 # 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 >>): In file included from include/linux/pagemap.h:11:0, from include/linux/blkdev.h:16, from include/linux/blk-cgroup.h:23, from include/linux/writeback.h:14, from include/linux/memcontrol.h:22, from include/linux/swap.h:9, from include/linux/suspend.h:5, from arch/x86/kernel/asm-offsets.c:13: include/linux/highmem.h: In function 'kmap': include/linux/highmem.h:40:9: error: implicit declaration of function '__kmap'; did you mean 'kmap'? [-Werror=implicit-function-declaration] return __kmap(page); ^~~~~~ kmap return __kmap(page); ^~~~~~~~~~~~ cc1: some warnings being treated as errors make[2]: *** [scripts/Makefile.build:100: arch/x86/kernel/asm-offsets.s] Error 1 make[2]: Target '__build' not remade because of errors. make[1]: *** [Makefile:1141: prepare0] Error 2 make[1]: Target 'prepare' not remade because of errors. make: *** [Makefile:180: sub-make] Error 2 18 real 5 user 8 sys 77.29% cpu make prepare vim +40 include/linux/highmem.h 36 37 #ifndef ARCH_HAS_KMAP 38 static inline void *kmap(struct page *page) 39 { 41 } 42 #endif 43 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org