Kernel prepatch 6.9-rc1

The 6.9-rc1 kernel prepatch is out for
testing. Linus Torvalds described some rather large updates to the core
kernel code that are coming for 6.9:

The timer subsystem had a fairly big rewrite, to have per-cpu timer
wheels to improve performance of timers, which can be a big deal
particularly for networking. The other fairly notable core update is
to the workqueue subsystem, where one notable addition is for BH
workqueue support. That's notable mainly because it means we finally
have a way away from tasklets. The tasklet interface has basically
been deprecated for a long while, but we've never really had any good
alternatives (with threaded interrupt handlers being one suggested
use-case, but not realistic in many cases).