Indeed, the opposite of what I described may well happen, as you say. A runaway process grabbing way too much memory is just as disruptive as a memory limit that is too low, killing the process too soon.
I’ll have to look into this. That being said, it seems I also misinterpreted the meaning of “buffer” RAM.
If I understand correctly, this is actually a part of RAM where data is written to, because it is faster, and then later this data will be written to disk.
That would explain why the buffer RAM was filling up.
Am I seeing that right?