Sometimes, like if you are messing with graphs pointers and malloc (because it's not yet time to refactor to introduce a memory slab system), you can get the worst of both world: you allocate slowly with malloc, but you don't know when to exactly deallocate, so you still have to retain everything until you can nuke the entire graph at once, and each element will require a slow free().
Perhaps it would be healthier for Rust to have competition?
https://www.linux.com/audience/developers/hacking-the-linux-...
https://github.com/alkhimey/Ada_Kernel_Module_Framework
Nvidia also chose Spark; a built in subset of Ada as being more cost effective for secure code than C++.
Assembly is also supported by Ada and I found it far easier to add than with C even.
C interface support is also excellent.