The Future of Rust Code in the Linux Kernel: Progress Amid Controversy

Introduction

Since the first integration of Rust code into the Linux kernel in 2022, the controversy surrounding its introduction has never ceased. The Rust language is praised for its excellent memory safety features and is seen by many governments and security experts as a solution to reduce high-risk memory vulnerabilities. However, there is a significant divide within the community regarding whether Rust should be widely used in the Linux kernel.

This article will take you through the story behind the debate over Rust and the Linux kernel, as well as its potential impact on the open-source ecosystem.

The Controversy of Rust in the Linux Kernel

1. “Is a Mixed Language Codebase a Cancer?”

Some Linux kernel maintainers are strongly opposed to the introduction of Rust. Core developer Christoph Hellwig has openly stated in emails that a mixed language codebase (i.e., using both C and Rust) could lead to uncontrollable complexity. He described this approach as akin to “cancer” and expressed concerns that future maintainers would be overwhelmed as a result.

Hellwig pointed out that there are significant semantic differences between C and Rust, and that a large amount of “glue code” or binding layers would be required for interoperability. Once this binding layer spreads across different subsystems, it could lead to multiple rewrites of core infrastructure, increasing system complexity.

Nevertheless, the Rust for Linux project continues to push for the use of Rust code and has released what is referred to as the “Rust Kernel Policy.” However, this policy has not yet been formally incorporated into the kernel code tree, raising questions about its effectiveness within the community.

2. Supporters’ Voices: Rust is the Future

In contrast to the opponents, another core developer, Greg Kroah-Hartman (Greg K-H), supports the introduction of Rust. He believes that Rust can address common issues in C, such as memory overflows, error handling cleanup, and the use of freed resources, which are major sources of vulnerabilities in the current Linux kernel.

Greg K-H noted that while improvements to C are ongoing, using Rust for new code and drivers can significantly reduce such errors, allowing developers to focus on higher-level issues like logical errors and race conditions. He sees Rust as the direction of the future and stated, “When good new ideas emerge, we must move forward.”

3. Challenges in the Open Source Community: Maintainer Burnout

Another issue worth noting in this debate is the “maintainer burnout” within the open-source community. Hector Martin, the former lead of the Asahi Linux project, resigned from his maintainer position due to dissatisfaction with the community governance model. He pointed out that some subsystem maintainers in the Linux community deliberately obstruct contributors’ work, which severely undermines developer motivation.

Additionally, Martin mentioned that open-source maintainers often face high levels of work pressure without sufficient recognition and support. Rust engineer Jynn Nelson has also stated that the number of developers leaving the Rust project due to burnout is alarming.

Brian Fox, co-founder of Sonatype, mentioned in an interview, “The issue of burnout among open-source developers is rising at an astonishing rate, posing a threat to software supply chain security.” He called for a healthy software ecosystem that requires positive community operation, which cannot be achieved without financial support.

The Future of Rust and the Linux Kernel

Despite the heated debate, Linus Torvalds, the founder of the Linux kernel, seems determined to continue pushing for the integration of Rust code. Hellwig revealed in an email that Linus privately stated he would merge Rust code regardless of maintainers’ opposition.

This means that future Linux developers will have to face the reality of a mixed language codebase. However, whether this decision will truly advance the Linux kernel remains to be seen.

Conclusion

The introduction of Rust brings new possibilities to the Linux kernel, but it also comes with significant controversy. Supporters believe that Rust can enhance the kernel’s security, while opponents worry that the complexity of a mixed language codebase will lead to long-term maintenance issues.

Regardless, this debate over Rust and the Linux kernel reveals deep-seated contradictions within the open-source community regarding technical choices and governance models. Perhaps this is also a challenge that the open-source ecosystem must face as it continues to evolve.

We hope this article helps you better understand the current state and future of Rust and the Linux kernel. If you are interested in Rust or Linux development, consider delving deeper into the relevant technologies and becoming a part of the progress in the open-source community!