Hi Tanner, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on net-next/master] url: https://github.com/0day-ci/linux/commits/Tanner-Love/virtio_net-add-optio... base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git c7654495916e109f76a67fd3ae68f8fa70ab4faa config: um-x86_64_defconfig (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # https://github.com/0day-ci/linux/commit/7d159f648961a7849f67e1c3d7ecb3d18... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Tanner-Love/virtio_net-add-optional-flow-dissection-in-virtio_net_hdr_to_skb/20210616-193224 git checkout 7d159f648961a7849f67e1c3d7ecb3d18bf5c7c2 # save the attached .config to linux build tree make W=1 ARCH=um SUBARCH=x86_64 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 >>): 8334 | int check_flow_keys_access(int off, int size, enum bpf_access_type t, | ^~~~~~~~~~~~~~~~~~~~~~ vim +/check_flow_keys_access +8334 net/core/filter.c 8333 8335 struct bpf_insn_access_aux *info) 8336 { 8337 if (size < 0 || off < 0 || 8338 (u64)off + size > sizeof(struct bpf_flow_keys)) 8339 return -EACCES; 8340 8341 switch (off) { 8342 case bpf_ctx_range_ptr(struct bpf_flow_keys, vhdr): 8343 if (t == BPF_WRITE || off % size != 0 || size != sizeof(__u64)) 8344 return -EACCES; 8345 8346 if (!bpf_flow_dissector_btf_ids[0]) 8347 return -EINVAL; 8348 8349 info->btf_id = bpf_flow_dissector_btf_ids[0]; 8350 8351 break; 8352 case offsetof(struct bpf_flow_keys, vhdr_is_little_endian): 8353 if (t == BPF_WRITE) 8354 return -EACCES; 8355 8356 break; 8357 } 8358 8359 return 0; 8360 } 8361 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org