tree: https://github.com/weiny2/linux-kernel.git lm-misc head: 8c385a87dc5cb4d98fa417d3dd9481f3fbe4c625 commit: 2cc4682a3d63e481c63fe72c4149b0bf98cc4b65 [5/8] arch/kmap: Remove redundant arch specific kmaps config: sparc-defconfig (attached as .config) compiler: sparc-linux-gcc (GCC) 9.3.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout 2cc4682a3d63e481c63fe72c4149b0bf98cc4b65 # save the attached .config to linux build tree GCC_VERSION=9.3.0 make.cross ARCH=sparc If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): In file included from include/linux/pagemap.h:11, 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/tracehook.h:50, from arch/sparc/kernel/signal_32.c:22: 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] 40 | return __kmap(page); | ^~~~~~ | kmap 40 | return __kmap(page); | ^~~~~~~~~~~~ cc1: all warnings being treated as errors 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