Claude review: drm/pagemap: Use dma-map IOVA alloc, link, and sync API for DRM pagemap

[Claude Code Review Bot <claude-review@example.com>]

Patch Review

The `struct drm_pagemap_iova_state` wrapper is well-designed, combining `dma_iova_state` with a tracking `offset` that serves as the iterator for packing IOVA addresses contiguously.

The `try_alloc` flag pattern in `drm_pagemap_migrate_map_system_pages` (`drm_pagemap.c:348-355`) is better than Patch 1's `!i` approach -- it correctly handles leading NULL pages by triggering on the first valid page.

The alignment hint logic is reasonable:
```c
(npages - i) * PAGE_SIZE >= HPAGE_PMD_SIZE ? HPAGE_PMD_SIZE : 0
```
This passes an alignment hint only when there are enough remaining pages to benefit from huge page IOMMU mappings.

The unmap path in `drm_pagemap_migrate_unmap_pages` (`drm_pagemap.c:413-416`) correctly does an early return after `dma_iova_destroy` when IOVA is active. This is safe because this function is only called from paths that map system pages (not device-private pages), so the loop below for device pages is not needed.

The `state` re-initialization in `drm_pagemap_evict_to_ram` on retry (`drm_pagemap.c:1189`) is correct and necessary.

No issues beyond what's noted above.

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Generated by Claude Code Patch Reviewer