[$] Recent RCU changes

In a combined filesystem and memory-management session at the 2022 Linux Storage,Filesystem, Memory-management and BPF Summit (LSFMM), Paul McKenneygave an update onthe changes to the read-copy-update (RCU) subsystem that had been made overthe last several years. He started with a quick overview of what RCU isand why it exists at all. He did not go into anyreal depth, though, since many of the topics could take a 90-minute session of theirown, he said, but he did provide some descriptions of the work that has gone intoRCU recently.