[$] The ongoing search for mmap_lock scalability

There are certain themes that recur regularly at the Linux Storage,
Filesystem, Memory-Management, and BPF Summit; among the most reliable is
the scalability problems posed by the mmap_lock (formerly
mmap_sem) lock. This topic has come up in (at least)
2013,
2018 (twice),
and 2019. The 2022 event was no
exception, with three consecutive sessions led by Liam Howlett, Michel
Lespinasse, and Suren Baghdasaryan
dedicated to the topic. There are improvements on the horizon, but the problem
is far from solved.