At the recently concluded Maintainers Summit, Linus Torvalds said he had been using a large language model to work on a patch series addressing a longstanding problem. He has now posted that series for review.
The fairly short series of ten patches enhances folio lookup by noticing when folios are hot and setting a "delay releasing this folio until after an RCU period." It then uses that RCU delay not only for the folio lookup itself, which has been done under RCU for a long time, but also for the actual folio data accesses. No refcount taking is needed for the fast path, where data can be read from the folio entirely within an RCU-protected region when the user copy doesn't cause page faults.
The end result is an order-of-magnitude speedup for a read()-heavy benchmark. Review has already identified a race condition in the code, though, so further work will be needed.
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Source: Hacker News · Summarized by HeadlinesBriefing