Greg has released three stable kernel updates: 188.8.131.52, 184.108.40.206 and 220.127.116.11. There aren't many changes to 18.104.22.168. That series will not be supported much longer. Both 22.214.171.124 and 126.96.36.199 have a fix for a really nasty sigreturn bug on ARM systems, among other changes. Users of these kernel series must upgrade.