Claude review: Use new dma-map IOVA alloc, link, and sync API in GPU SVM and DRM pagemap

Claude Code Review Bot
2026-04-11T23:24:50Z

Overall Series Review

Subject: Use new dma-map IOVA alloc, link, and sync API in GPU SVM and DRM pagemap
Author: Matthew Brost <matthew.brost@intel.com>
Patches: 6
Reviewed: 2026-04-12T09:24:50.817651

---

This v7 series converts GPU SVM and DRM pagemap migration paths from per-page `dma_map_page`/`dma_unmap_page` to the batched IOVA alloc/link/sync API, avoiding costly per-page IOMMU synchronizations. The performance numbers in the cover letter (33% reduction in 2M migrate CPU time) are compelling.

The series is well-structured: Patch 1 handles GPU SVM, Patches 2-3 prepare DRM pagemap by simplifying and splitting, Patch 4 adds IOVA to pagemap, and Patch 5 is a trivial doc fix. The fallback to `dma_map_page` when `dma_iova_try_alloc` fails is correctly handled in all paths.

There is one correctness issue in the GPU SVM unmap path (Patch 1) where system pages can incorrectly fall through to `device_unmap` when IOVA is active, one performance gap in the IOVA allocation trigger condition, and one documentation bug introduced in Patch 3 that Patch 5 partially addresses.

---

---
Generated by Claude Code Patch Reviewer