Yes, he is in charge of merging changes from ~200 subsystem git trees into the new release, every week. Every ~8 weeks they do a major version with big changes,

Yes, he is in charge of merging changes from ~200 subsystem git trees into the new release, every week. Every ~8 weeks they do a major version with big changes, and then they do weekly releases with bugfixes, and then they do a major version with big changes again. The major releases are then maintained by Greg Kroah-Hartman (the number 2 person in Linux), who cherry-picks fixes from mainline that should go to stable. Distros have kernel teams that also maintain their own stable trees, with or without help from upstream stable maintainer. Linus can't code review all the changes queued for the next major release, but he does make sure that in case the subsystem maintainer says "this is safe to merge, it has been tested" but actually it doesn't compile, then Linus will yell at him and call him bad words in Finnish. Because the subsystem maintainer is an important job, people rely on them, they have years of experience, they know better than to do pull requests with junk. He is also involved with resolving disputes and fixing things that affects his own workflow.