Claude review: dma-buf: heaps: Turn heaps into modules

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Overall Series Review

Subject: dma-buf: heaps: Turn heaps into modules
Author: Maxime Ripard <mripard@kernel.org>
Patches: 22
Reviewed: 2026-02-27T13:12:02.708329

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This series by Maxime Ripard converts the CMA and system dma-buf heaps from built-in-only to tristate (module-capable) Kconfig symbols. The approach is straightforward: (1) reverse the dependency so the kernel core stores reserved CMA regions and the heap module iterates over them, (2) export the necessary CMA and dma-buf symbols, and (3) add the standard `MODULE_*` macros.

The series is generally well-structured and the design decision to invert the registration flow (kernel stores CMA regions, heap module queries them) is sound and cleanly resolves the built-in-to-module dependency.

There are a few issues worth raising, most notably: neither heap has a `module_exit` function, and the `__init` annotations on the CMA heap functions are fine for built-in but become effectively no-ops for modules (which is safe but worth a note). One ordering concern exists with `rmem_cma_areas` not being `__initdata` while the old `dma_areas` was.

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