tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git locking/jump_label head: 8fb8d36194a6d1ac0ea7ae64a4044c203177828f commit: db137d1c529ef853ec57d11e258e299804b8d599 [10/13] jump_label,x86: Emit short JMP config: x86_64-randconfig-m001-20210318 (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?... git remote add peterz-queue https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git git fetch --no-tags peterz-queue locking/jump_label git checkout db137d1c529ef853ec57d11e258e299804b8d599 # save the attached .config to linux build tree make W=1 ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): arch/x86/kernel/jump_label.c: In function 'arch_jump_entry_size': arch/x86/kernel/jump_label.c:23:9: error: variable 'insn' has initializer but incomplete type 23 | struct insn insn = {}; | ^~~~ 23 | struct insn insn = {}; | ^~~~ arch/x86/kernel/jump_label.c:25:2: error: implicit declaration of function 'insn_decode_kernel' [-Werror=implicit-function-declaration] 25 | insn_decode_kernel(&insn, (void *)jump_entry_code(entry)); | ^~~~~~~~~~~~~~~~~~ arch/x86/kernel/jump_label.c:23:14: warning: unused variable 'insn' [-Wunused-variable] 23 | struct insn insn = {}; | ^~~~ arch/x86/kernel/jump_label.c:29:1: error: control reaches end of non-void function [-Werror=return-type] 29 | } | ^ cc1: some warnings being treated as errors vim +23 arch/x86/kernel/jump_label.c 20 21 int arch_jump_entry_size(struct jump_entry *entry) 22 { 24 25 insn_decode_kernel(&insn, (void *)jump_entry_code(entry)); 26 BUG_ON(insn.length != 2 && insn.length != 5); 27 28 return insn.length; 29 } 30 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org