Provide protection against starvation of the ll/sc loops when accessing userpace.
https://reviews.freebsd.org/D20772 [reviews.freebsd.org]
2019-07-08 15:43
Casueword(9) on ll/sc architectures must be prepared for userspace constantly modifying the same cache line as containing the CAS word, and not loop infinitely. Otherwise, rogue userspace livelock kernel.
source: vermaden