Hi Arjun, 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/Arjun-Roy/Perf-optimizations-for... base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git e545f86573937142b8a90bd65d476b9f001088cf config: nds32-defconfig (attached as .config) compiler: nds32le-linux-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/5c20c7c34817692f87427a655374172f6... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Arjun-Roy/Perf-optimizations-for-TCP-Recv-Zerocopy/20201113-030506 git checkout 5c20c7c34817692f87427a655374172f6666d8ed # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=nds32 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 >>): net/ipv4/tcp.c: In function 'tcp_copy_straggler_data': 1754 | err = import_single_range(READ, (void __user *)zc->copybuf_address, | ^ vim +1754 net/ipv4/tcp.c 1745 1746 static int tcp_copy_straggler_data(struct tcp_zerocopy_receive *zc, 1747 struct sk_buff *skb, u32 copylen, 1748 u32 *offset, u32 *seq) 1749 { 1750 struct msghdr msg = {}; 1751 struct iovec iov; 1752 int err; 1753 1755 copylen, &iov, &msg.msg_iter); 1756 if (err) 1757 return err; 1758 err = skb_copy_datagram_msg(skb, *offset, &msg, copylen); 1759 if (err) 1760 return err; 1761 zc->recv_skip_hint -= copylen; 1762 *offset += copylen; 1763 *seq += copylen; 1764 return (__s32)copylen; 1765 } 1766 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org