When Graydon Hoare of Mozilla (and later others) designed Rust, they wanted a fast, concurrent, memory-safe language without garbage collection because web browsers need to be fast and resistant to malware. Their decision was to create Rust, which provides these features by forcing restrictions on the developer. Now that the language has reached a decent level of maturity, third parties are looking into it.
One group is apparently the Linux Kernel developers.
Josh Triplett (Principal Engineer at Intel) talked with Greg Kroah-Hartman (Linux kernel maintainer for the -stable branch) about Rust. According to posts on LWN.net, they are willing to investigate a framework for the Linux kernel to load drivers that are written in Rust. For now, Rust must not be required to build Linux, but they are willing to accept a (for now) optional component to handle Rust. While this does not fundamentally change how the Linux kernel is designed, it should allow more developers to write drivers that are more stable.