Hi Andrii, [FYI, it's a private test report for your RFC patch.] [auto build test WARNING on bpf-next/master] url: https://github.com/0day-ci/linux/commits/Andrii-Nakryiko/Support-kernel-m... base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master config: i386-randconfig-r036-20201209 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce (this is a W=1 build): # https://github.com/0day-ci/linux/commit/6612e8dbf119471e023d79a56d7834fce... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Andrii-Nakryiko/Support-kernel-module-ksym-variables/20201211-123414 git checkout 6612e8dbf119471e023d79a56d7834fceeb3e33b # save the attached .config to linux build tree make W=1 ARCH=i386 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/bpf/core.c:1350:12: warning: no previous prototype for 'bpf_probe_read_kernel' [-Wmissing-prototypes] 1350 | u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr) | ^~~~~~~~~~~~~~~~~~~~~ In file included from kernel/bpf/core.c:21: kernel/bpf/core.c: In function '___bpf_prog_run': include/linux/filter.h:888:3: warning: cast between incompatible function types from 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} to 'u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, const struct bpf_insn *)'} [-Wcast-function-type] 888 | ((u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)) \ | ^ kernel/bpf/core.c:1518:13: note: in expansion of macro '__bpf_call_base_args' 1518 | BPF_R0 = (__bpf_call_base_args + insn->imm)(BPF_R1, BPF_R2, | ^~~~~~~~~~~~~~~~~~~~ kernel/bpf/core.c: At top level: kernel/bpf/core.c:1704:6: warning: no previous prototype for 'bpf_patch_call_args' [-Wmissing-prototypes] 1704 | void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth) | ^~~~~~~~~~~~~~~~~~~ In file included from kernel/bpf/core.c:21: kernel/bpf/core.c: In function 'bpf_patch_call_args': include/linux/filter.h:888:3: warning: cast between incompatible function types from 'u64 (*)(u64, u64, u64, u64, u64)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int)'} to 'u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)' {aka 'long long unsigned int (*)(long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, long long unsigned int, const struct bpf_insn *)'} [-Wcast-function-type] 888 | ((u64 (*)(u64, u64, u64, u64, u64, const struct bpf_insn *)) \ | ^ kernel/bpf/core.c:1709:3: note: in expansion of macro '__bpf_call_base_args' 1709 | __bpf_call_base_args; | ^~~~~~~~~~~~~~~~~~~~ kernel/bpf/core.c: At top level: kernel/bpf/core.c:2102:6: warning: no previous prototype for '__bpf_free_used_maps' [-Wmissing-prototypes] 2102 | void __bpf_free_used_maps(struct bpf_prog_aux *aux, | ^~~~~~~~~~~~~~~~~~~~ 2122 | void __bpf_free_used_btfs(struct bpf_prog_aux *aux, | ^~~~~~~~~~~~~~~~~~~~ vim +/__bpf_free_used_btfs +2122 kernel/bpf/core.c 2121 2123 struct btf_mod_pair *used_btfs, u32 len) 2124 { 2125 #ifdef CONFIG_BPF_SYSCALL 2126 struct btf_mod_pair *btf_mod; 2127 u32 i; 2128 2129 for (i = 0; i < len; i++) { 2130 btf_mod = &used_btfs[i]; 2131 if (btf_mod->module) 2132 module_put(btf_mod->module); 2133 btf_put(btf_mod->btf); 2134 } 2135 #endif 2136 } 2137 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org