I finally managed to reproduce this problem consistently and within 30 secs. Bisecting the kernel points at [1] to be problematic. Whether that commit introduces a real regression or merely exposes a different underlying issue is unclear at the moment. I wasn't able to reproduce the problem with a Realtek USB NIC attached to the Pi 3B+ so that points more towards a lan78xx driver/HW issue.
Reverting commit [1] plus two follow-on fixes makes the problem go away.
I finally managed to reproduce this problem consistently and within 30 secs. Bisecting the kernel points at [1] to be problematic. Whether that commit introduces a real regression or merely exposes a different underlying issue is unclear at the moment. I wasn't able to reproduce the problem with a Realtek USB NIC attached to the Pi 3B+ so that points more towards a lan78xx driver/HW issue.
Reverting commit [1] plus two follow-on fixes makes the problem go away.
This looks similar to [2].
[1] https:/ /github. com/torvalds/ linux/commit/ 4f693b55c3d2d22 39b8a0094b518a1 e533cf75d5
[2] https://<email address hidden>/