Followers of the linux-next integration tree may have noticed a significant
addition: initial support for writing device drivers in the Rust language.
There is some documentation in Documentation/rust,
while the code itself is in the rust
top-level directory. Appearance in linux-next generally implies readiness
for the upcoming merge window, but it is not clear if that is the case
here; this code has not seen a lot of wider review yet. It is, regardless,
an important step toward the ability to write drivers in a safer language.

Source: LWN.net – Rust support hits linux-next