Claude review: cgroup/dmem,drm/ttm: Improve protection in contended cases

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

Overall Series Review

Subject: cgroup/dmem,drm/ttm: Improve protection in contended cases
Author: Natalie Vock <natalie.vock@gmx.de>
Patches: 13
Reviewed: 2026-02-27T13:36:27.560367

---

This is a well-structured v4 series from Natalie Vock that addresses a real and important problem: when VRAM is scarce, cgroup-protected allocations can end up in GTT because unprotected applications filled VRAM first, and TTM backs off to GTT before ever attempting eviction. The series correctly fixes this by making TTM more aggressive about evicting unprotected buffers when the allocating cgroup is within its min/low protection limits.

The series decomposes nicely into:
- **Patches 1-2**: cgroup/dmem infrastructure (protection queries, common ancestor)
- **Patch 3**: TTM refactoring to prepare for the behavioral changes
- **Patch 4**: Decoupling cgroup charge from resource allocation (correctness fix)
- **Patches 5-6**: The actual behavioral improvements (aggressive eviction + correct protection semantics)

The overall design is sound. The min vs low priority hierarchy is correctly implemented: below-min triggers full eviction (even low-protected buffers), while below-low only evicts genuinely unprotected buffers. Patch 6's common-ancestor approach correctly handles recursive protection semantics for sibling cgroup competition.

The v4 changes in response to Tvrtko's review (splitting charge decoupling, errno handling, documentation) are well-incorporated.

**Minor issues**: a doc typo in patch 2, a commit message typo in patch 4, and a comment style nit in patch 5. Nothing blocking.

---

---
Generated by Claude Code Patch Reviewer