Comment 2 for bug 1871613

This file:
prog_tests/sockmap_basic.c

seems to be a new file added to the tree recently with this commit [1]:
7c57edd selftests/bpf: Test freeing sockmap/sockhash with a socket in it

$ git tag --contains 7c57edd8018e70b4faebf0569a1fa3f35a21829c
Ubuntu-5.3.0-47.39

[1] https://github.com/torvalds/linux/commit/5d3919a953c3c96c02fc7a337f8376cde43ae31f#diff-a31a85d33b7885d4715bb97dffe88ab9