Hi Dmytro, Thank you for the patch! Yet something to improve: [auto build test ERROR on net-next/master] url: https://github.com/0day-ci/linux/commits/Dmytro-Shytyi/net-Variable-SLAAC... base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 39e222bfd7f37e7a98069869375b903d7096c113 config: x86_64-randconfig-r013-20211014 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 6c76d0101193aa4eb891a6954ff047eda2f9cf71) 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/780991c4b4a62473ddc2bd73ea399061a... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Dmytro-Shytyi/net-Variable-SLAAC-SLAAC-with-prefixes-of-arbitrary-length-in-PIO/20211014-072015 git checkout 780991c4b4a62473ddc2bd73ea399061a1c41afd # save the attached .config to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): static bool ipv6_reserved_interfaceid(struct in6_addr address) ^ net/ipv6/addrconf.c:2711:13: note: previous definition is here static bool ipv6_reserved_interfaceid(struct in6_addr address) ^ 1 error generated. vim +/ipv6_reserved_interfaceid +3355 net/ipv6/addrconf.c ^1da177e4c3f41 Linus Torvalds 2005-04-16 3354 622c81d57b392c Hannes Frederic Sowa 2015-03-23 @3355 static bool ipv6_reserved_interfaceid(struct in6_addr address) 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3356 { 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3357 if ((address.s6_addr32[2] | address.s6_addr32[3]) == 0) 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3358 return true; 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3359 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3360 if (address.s6_addr32[2] == htonl(0x02005eff) && 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3361 ((address.s6_addr32[3] & htonl(0xfe000000)) == htonl(0xfe000000))) 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3362 return true; 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3363 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3364 if (address.s6_addr32[2] == htonl(0xfdffffff) && 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3365 ((address.s6_addr32[3] & htonl(0xffffff80)) == htonl(0xffffff80))) 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3366 return true; 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3367 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3368 return false; 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3369 } 622c81d57b392c Hannes Frederic Sowa 2015-03-23 3370 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org