[jasonkeene]

> * Everyone who clones the git repo either forgets or doesn't know that they have to do 'git submodule init' (and maybe update too? even I'm forgetting ...)...

‘git clone --recursive’ Add that to your README’s getting started section. Sounds a bit like you aren’t providing a good onramp for contributors.

> * You cannot add downstream patches to Linux this way...

> * The link is to a non-fast-forward branch of Linux, so the commit hash sometimes becomes invalid... You'd think that because both the module and submodule are hosted on github, that github wouldn't garbage collect the old commit hash, but that's apparently not how it works.

Commits will not get GCed if you have a ref pointing at them. Relying on commits that do not have a ref means they are not part of the official history of that project. You should fork linux and have a branch where you land your custom changes. You can track whatever upstream you want, third party or mainline linux, and rebase your changes on top of them.