Samba 4.10 and later versions have a process restart capability to greatly reduce the impact of crashes due to a NULL pointer de-reference or abort().
However SIGKILL was deliberatly omitted.
Sadly this is the most likely case, due to the OOM killer, as raised here:
Subsequent discussion (offline) has been to agree that we should restart in this case.
i had smbd killed by oom due to a bug and found no smbd processes running afterwards.
isn't that systemd's job to restart failed services ?