I have a system that works fine on 5.1. When updating to 5.2-rc1, it hangs at boot waiting on an instance of systemd-udevd. The kernel backtrace (https://photos.app.goo.gl/EV8rf7FofWouvdeE8) looks like it's doing an finit_module() that dives into the hid code and is waiting on a request_module(). This hang only occurs if I have a particular USB device inserted: > Bus 001 Device 007: ID 046d:c52b Logitech, Inc. Unifying Receiver Bisecting the issue points at this (unlikely to be the culprit) commit: > [161f62cd07fde123fd52bf6d5b6fd6513cca968e] HID: macally: Add support for Macally ikey keyboard This bisect result is probably just a bisect artifact. The first real, bad commit is a merge commit: 63b6f0b827d. This commit merges a bunch of stuff, but includes changes to the hid request_module() code and to the logitech-hidpp which is the driver for the above device. I also have a picture of the hang which includes __request_module() dumping out the string it is passed: https://photos.app.goo.gl/tUETiCBZHJfKqWPu8 This is easy enough to work around, and the system works fine if I just unplug the Logitech device and plug it in after boot. But, it would be nice to figure out what's going wrong. I guess it could easily be some interaction between systemd, the driver and the request_module() ordering.
