tree: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/core head: 2a0a24ebb499c9d499eea948d3fc108f936e36d4 commit: 90b5363acd4739769c3f38c1aff16171bd133e8c [1/2] sched: Clean up scheduler_ipi() config: mips-randconfig-r006-20200521 (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 3393cc4cebf9969db94dc424b7a2b6195589c33b) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install mips cross compiling tool for clang build # apt-get install binutils-mips-linux-gnu git checkout 90b5363acd4739769c3f38c1aff16171bd133e8c # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): kernel/sched/core.c:4190:35: warning: no previous prototype for function 'schedule_user' asmlinkage __visible void __sched schedule_user(void) ^ kernel/sched/core.c:4190:22: note: declare 'static' if the function is not intended to be used outside of this translation unit asmlinkage __visible void __sched schedule_user(void) ^ static rq_csd_init(struct rq call_single_data_t smp_call_func_t func) ^ kernel/sched/core.c:3744:20: warning: unused function 'sched_tick_start' static inline void sched_tick_start(int cpu) { } ^ kernel/sched/core.c:3745:20: warning: unused function 'sched_tick_stop' static inline void sched_tick_stop(int cpu) { } ^ fatal error: error in backend: Nested variants found in inline asm string: ' .set push .set noat .set push .set arch=r4000 .if ( 0x00 ) != -1)) 0x00 ) != -1)) : ($( static struct ftrace_branch_data __attribute__((__aligned__(4))) __attribute__((__section__("_ftrace_branch"))) __if_trace = $( .func = __func__, .file = "arch/mips/include/asm/cmpxchg.h", .line = 163, $); 0x00 ) != -1)) : $))) ) && ( 0 ); .set push; .set mips64r2; .rept 1; sync 0x00; .endr; .set pop; .else; ; .endif 1: ll $0, $2 # __cmpxchg_asm bne $0, ${3:z}, 2f .set pop move $$1, ${4:z} .set arch=r4000 sc $$1, $1 beqz $$1, 1b .set pop 2: .if ( 0x00 ) != -1)) 0x00 ) != -1)) : ($( static struct ftrace_branch_data __attribute__((__aligned__(4))) __attribute__((__section__("_ftrace_branch"))) __if_trace = $( .func = __func__, .file = "arch/mips/include/asm/cmpxchg.h", .line = 163, $); 0x00 ) != -1)) : $))) ) && ( 0 ); .set push; .set mips64r2; .rept 1; sync 0x00; .endr; .set pop; .else; ; .endif ' clang-11: error: clang frontend command failed with exit code 70 (use -v to see invocation) clang version 11.0.0 (git://gitmirror/llvm_project 3393cc4cebf9969db94dc424b7a2b6195589c33b) Target: mipsel-unknown-linux-gnu Thread model: posix InstalledDir: /opt/cross/clang-3393cc4ceb/bin clang-11: note: diagnostic msg: Makefile arch include kernel null.dwo scripts source usr vim +/rq_csd_init +223 kernel/sched/core.c 221 222 static inline void 224 { 225 csd->flags = 0; 226 csd->func = func; 227 csd->info = rq; 228 } 229 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org