tree: https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-5.10.y-rt-rebase head: 16966f1ba0ebb5c8032e87e7e6d46f1bfd38c780 commit: d414e1e3d51bf67ed765419477b3545e9d54b01b [165/194] sched: Add support for lazy preemption config: mips-randconfig-r023-20201028 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 772aaa602383cf82795572ebcd86b0e660f3579f) 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 # https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/com... git remote add linux-rt-devel https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git git fetch --no-tags linux-rt-devel linux-5.10.y-rt-rebase git checkout d414e1e3d51bf67ed765419477b3545e9d54b01b # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): kernel/sched/core.c:2883:6: warning: no previous prototype for function 'sched_set_stop_task' void sched_set_stop_task(int cpu, struct task_struct ^ kernel/sched/core.c:2883:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void sched_set_stop_task(int cpu, struct task_struct ^ static static inline int preemptible_lazy(void) ^ fatal error: error in backend: Nested variants found in inline asm string: '.if ( 0x00 ) != -1)) 0x00 ) != -1)) : ($( static struct ftrace_branch_data __attribute__((__aligned__(4))) __attribute__((__section__("_ftrace_branch"))) __if_trace = $( .func = __func__, .file = "arch/mips/include/asm/barrier.h", .line = 21, $); 0x00 ) != -1)) : $))) ) && ( (1 << 0) ); .set push; .set mips64r2; .rept 1; sync 0x00; .endr; .set pop; .else; ; .endif' clang-12: error: clang frontend command failed with exit code 70 (use -v to see invocation) clang version 12.0.0 (git://gitmirror/llvm_project 772aaa602383cf82795572ebcd86b0e660f3579f) Target: mipsel-unknown-linux-gnu Thread model: posix InstalledDir: /opt/cross/clang-772aaa6023/bin clang-12: note: diagnostic msg: Makefile arch include kernel scripts source usr vim +/preemptible_lazy +5320 kernel/sched/core.c 5319 5321 { 5322 return 1; 5323 } 5324 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org