Kernel update 4.4.132 enables log_ecn_error in sit module by default now, syslog spam
 

For various network tunnel users, HE, openvpn...

Updated to kernel 4.4.132, rebooted, saw syslog spam:

May 23 16:27:36 dns1 kernel:[14781.521951] sit: non-ECT from 31.16.5.81 with TOS=0xe
May 23 16:27:38 dns1 kernel:[14783.518102] sit: non-ECT from 31.16.5.81 with TOS=0xe
May 23 16:27:40 dns1 kernel:[14785.521994] sit: non-ECT from 31.16.5.81 with TOS=0xe
May 23 16:27:42 dns1 kernel:[14787.522471] sit: non-ECT from 31.16.5.81 with TOS=0xe
May 23 16:27:44 dns1 kernel:[14789.523235] sit: non-ECT from 31.16.5.81 with TOS=0xe
May 23 16:27:46 dns1 kernel:[14791.524710] sit: non-ECT from 31.16.5.81 with TOS=0xe
May 23 16:27:48 dns1 kernel:[14793.524595] sit: non-ECT from 31.16.5.81 with TOS=0xe
May 23 16:27:50 dns1 kernel:[14795.521521] sit: non-ECT from 31.16.5.81 with TOS=0xe

Turns out the default for sit module option log_ecn_error is now enabled by default.

sit is loaded for use with Hurricane Electric IPv6 tunnels, and openvpn tunnels.

Can be temporarily disabled by:
echo N > /sys/module/sit/parameters/log_ecn_error

Permanent fix:
echo "options sit log_ecn_error=0" > /etc/modprobe.d/sit.conf