The linux kernel has made breaking changes [1] and deprecated APIs [2] internal APIs before. Specifically, your example brings up the danger that ZoL is in. Th

The linux kernel has made breaking changes [1] and deprecated APIs [2] internal APIs before. Specifically, your example brings up the danger that ZoL is in. The Linux kernel does everything in their power to not break User Land APIs. ZoL isn't User Land, and it replaced the previously extremely slow User Land ZFS Linux implementation. It is a Linux kernel module, and as [2] notes, Linux kernel devs are absolutely allowed to make breaking changes to internal APIs. The cost of the increased speed of a Kernel module is the risk of internal API breaking changes. I highly doubt that Linus would scream anywhere near as much about an internal API change that broke a separately maintained linux module with non-GPL code. 1. https://stackoverflow.com/questions/24897511/what-is-the-replacement-of-daemonize-kernal-api-in-3-x-kernel https://stackoverflow.com/questions/24897511/what-is-the-rep... 2. https://lwn.net/Articles/769365/ https://lwn.net/Articles/769365/