Explore the challenges and best practices of maintaining long-term out-of-tree patches in this insightful conference talk from the Linux Plumbers Conference. Learn from the experiences of the PREEMPT_RT patchset, one of the longest-existing large patchsets outside the Linux kernel. Discover effective workflows, tooling, and release management strategies that have proven scalable over time. Gain valuable insights into handling upstream changes and modifications to the patchset itself. As the PREEMPT_RT patchset prepares to merge upstream, benefit from the shared knowledge of seasoned developers on maintaining external patchsets with stable releases. This talk is particularly relevant for those involved in or planning to maintain out-of-tree patches for extended periods.