Hi, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on linux/master] [also build test WARNING on linus/master hnaz-linux-mm/master v5.12-rc2 next-20210311] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/qiang-zhang-windriver-com/ARM-Fi... base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git a74e6a014c9d4d4161061f770c9b4f98372ac778 config: arm-pxa168_defconfig (attached as .config) compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 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 # https://github.com/0day-ci/linux/commit/b31b47976c6f81426cc00c99cc1452a60... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review qiang-zhang-windriver-com/ARM-Fix-incorrect-use-of-smp_processor_id-by-syzbot-report/20210312-121529 git checkout b31b47976c6f81426cc00c99cc1452a60e89d972 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm 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 >>): In file included from arch/arm/mm/fault.c:21: arch/arm/include/asm/system_misc.h: In function 'harden_branch_predictor': 25 | harden_branch_predictor_fn_t fn = per_cpu(harden_branch_predictor_fn, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/arm/mm/fault.c: At top level: arch/arm/mm/fault.c:518:1: warning: no previous prototype for 'do_DataAbort' [-Wmissing-prototypes] 518 | do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs) | ^~~~~~~~~~~~ arch/arm/mm/fault.c:548:1: warning: no previous prototype for 'do_PrefetchAbort' [-Wmissing-prototypes] 548 | do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs) | ^~~~~~~~~~~~~~~~ -- In file included from arch/arm/mm/proc-v7-bugs.c:9: arch/arm/include/asm/system_misc.h: In function 'harden_branch_predictor': 25 | harden_branch_predictor_fn_t fn = per_cpu(harden_branch_predictor_fn, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/arm/mm/proc-v7-bugs.c: At top level: arch/arm/mm/proc-v7-bugs.c:142:6: warning: no previous prototype for 'cpu_v7_ca8_ibe' [-Wmissing-prototypes] 142 | void cpu_v7_ca8_ibe(void) | ^~~~~~~~~~~~~~ arch/arm/mm/proc-v7-bugs.c:148:6: warning: no previous prototype for 'cpu_v7_ca15_ibe' [-Wmissing-prototypes] 148 | void cpu_v7_ca15_ibe(void) | ^~~~~~~~~~~~~~~ arch/arm/mm/proc-v7-bugs.c:154:6: warning: no previous prototype for 'cpu_v7_bugs_init' [-Wmissing-prototypes] 154 | void cpu_v7_bugs_init(void) | ^~~~~~~~~~~~~~~~ vim +25 arch/arm/include/asm/system_misc.h 9f97da78bf0182 David Howells 2012-03-28 18 f5fe12b1eaee22 Russell King 2018-05-14 19 #ifdef CONFIG_HARDEN_BRANCH_PREDICTOR f5fe12b1eaee22 Russell King 2018-05-14 20 typedef void (*harden_branch_predictor_fn_t)(void); f5fe12b1eaee22 Russell King 2018-05-14 21 DECLARE_PER_CPU(harden_branch_predictor_fn_t, harden_branch_predictor_fn); f5fe12b1eaee22 Russell King 2018-05-14 22 static inline void harden_branch_predictor(void) f5fe12b1eaee22 Russell King 2018-05-14 23 { b31b47976c6f81 Zqiang 2021-03-12 24 preempt_disable(); f5fe12b1eaee22 Russell King 2018-05-14 @25 harden_branch_predictor_fn_t fn = per_cpu(harden_branch_predictor_fn, f5fe12b1eaee22 Russell King 2018-05-14 26 smp_processor_id()); b31b47976c6f81 Zqiang 2021-03-12 27 preempt_enable(); f5fe12b1eaee22 Russell King 2018-05-14 28 if (fn) f5fe12b1eaee22 Russell King 2018-05-14 29 fn(); f5fe12b1eaee22 Russell King 2018-05-14 30 } f5fe12b1eaee22 Russell King 2018-05-14 31 #else f5fe12b1eaee22 Russell King 2018-05-14 32 #define harden_branch_predictor() do { } while (0) f5fe12b1eaee22 Russell King 2018-05-14 33 #endif f5fe12b1eaee22 Russell King 2018-05-14 34 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org