Why not port Linux kernel to Common Lisp?

Conventional wisdom states that OS kernels must be written in C in order to achieve the necessary levels of performance. This has been the justification for not using more expressive high level languages.

However, for a few years now implementations of Common Lisp such as SBCL have proven to be just as performant as C. What then are the arguments against redoing the kernel in a powerfully expressive language, namely Common Lisp?

I don't think anyone (at least anyone who knows what they are talking about) could argue against the fact that the benefits in transparency and readability would be tremendous, not to mention all the things that can't be done in C that can be done in Lisp, but there may be implementation details that would make this a bad idea.

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The file system is an artifact of the limitations of early processors that had no memory virtualization capabilities and had an insufficient memory address word size. Programs and data had to be marshalled out of and back into a logically distinct store because 64K can only hold so much information. Modern 32 and 64 bit processors with memory management units can treat storage as large, slow, persistent memory obviating the contortions required in conventional operating systems to keep data from going away when the computer is shut down.

A heirarchical name space is still required for users to keep track of where they put things but virtual memory can hold that tree structure just as well as inodes can and the judicious use of separate memory spaces can side-step a 4 gigabyte limitation for storage on 32-bit machines.