Created attachment 278193 [details] dmesg and hwinfo output (I am reporting this upstream as instructed by OpenSUSE, where I had originally reported this problem.) After upgrading to kernel 4.18 (originally noticed the problem with kernel 4.18.0, the problem persists with kernel 4.18.5), I could no longer connect to the network. A similar machine, which I upgraded at the same time, had no problem, so I thought that the problem might be due to my using a network card instead of the motherboard's built-in network controller. Sure enough, configuring the built-in controller and connecting that to the network worked fine. According to lspci, the card that doesn't work with the new kernel is: U.S. Robotics USR997902 10/100/1000 Mbps PCI Network Card (rev 10) Ifconfig shows that the network controller has been recognized as such, but that it has not obtained an IP address. The problem did not occur with kernel 4.17.14. I have attached the output of hwinfo and dmesg for kernels 4.17.14 and 4.18.5, with the network cable connected to the U.S. Robotics controller (enp5s0).
Created attachment 278195 [details] Correct dmesg and hwinfo output The files for kernel 4.18.5 that I uploaded in the previous attachment were obtained with the network cable connected to the motherboard's network controller, not the US Robotics one. (The files for kernel 4.17.14 were correct, but I'm re-uploading them for completeness.)
The problem seems to have been fixed with commit 05212ba.