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: 10
Reviewed: 2026-04-01T07:50:36.145257

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This is a well-structured series by Maxime Ripard (v4) that enables the CMA and system dma-buf heaps to be built as loadable modules. The approach is sound: invert the dependency so that `kernel/dma/contiguous.c` stores the CMA areas and provides an iterator, rather than calling into the heap code. The series is logically ordered, with each patch building on the previous one, and the individual changes are small and easy to follow.

The key concern is around **duplicate registration of the default CMA area**, which I detail below. Otherwise, the series looks good and the progression from inverting the logic, to de-inlining, to making static, to exporting, and finally to tristate is clean.

One note from the mbox: patches 3 and 4 appear in the mbox in the **wrong order** relative to the cover letter (the mbox has patch 3 "Make dma_contiguous_default_area static" before patch 4 "Export dev_get_cma_area()", but the message numbering is correct). The logical dependency is fine either way since patch 3 makes the variable static and patch 4 exports the function, and they touch independent lines.

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