Linus Torvalds let Claude Code fix the Linux page cache. Then reviewers found a race.
Linux creator Linus Torvalds used Anthropic's Claude Code to generate a patch series aimed at fixing a long-standing kernel performance bottleneck. While the code initially showed significant performance gains, reviewers later discovered a race condition, leading to further development by other kernel maintainers.
Why it matters
This incident illustrates both the potential and the current limitations of using AI assistants in high-stakes, complex software engineering environments like the Linux kernel.
Linux creator and longtime lead maintainer Linus Torvalds turned to Anthropic’s Claude Code to tackle a kernel performance problem that developers have struggled with for more than two years. On Tuesday, he submitted a 10-patch series that delivered a 23-fold throughput improvement in a synthetic benchmark running on his Ryzen Threadripper.
Torvalds had spent 18 months running a broken version of his own fix for the page-cache reference-counting bottleneck, while other developers had encountered problems with their approaches. The new patches eliminate folio reference-count operations from a common buffered-read path, although Torvalds warned that the benchmark gains would be considerably smaller in real-world workloads.
Reviewers have since identified a race condition and raised concerns about memory reclamation. Torvalds has handed further development to Kiryl Shutsemau , a Linux kernel developer who previously worked on the same bottleneck.
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