The reuseport_lb_test regression test is consuming a lot of sockets, but once ended the system will kept all those sockets open waiting for the TIME_WAIT. And if another tests, consuming a lot of sockets too is started just after, this could reach the system limit and fail. Patch and review here: https://reviews.freebsd.org/D26549
A commit references this bug: Author: olivier Date: Fri Sep 25 16:02:13 UTC 2020 New revision: 366159 URL: https://svnweb.freebsd.org/changeset/base/366159 Log: Enable SO_LINGER to the so_reuseport_lb_test regression tests, preventing many sockets in TIME_WAIT state at the end of the test. PR: 249885 Reviewed by: markj Approved by: markj Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D26549 Changes: head/tests/sys/netinet/so_reuseport_lb_test.c