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

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Overall Series Review

Subject: cgroup/dmem,drm/ttm: Improve protection in contended cases
Author: Natalie Vock <natalie.vock@gmx.de>
Patches: 12
Reviewed: 2026-03-14T07:10:15.097178

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This is v6 of a series by Natalie Vock that improves dmem cgroup protection enforcement in TTM. The core problem is well-motivated: when VRAM is filled by unprotected applications, TTM falls back to GTT for protected allocations without ever attempting eviction, defeating the purpose of cgroup protection. The series adds infrastructure (protection queries, common ancestor helpers), refactors TTM allocation flow, decouples cgroup charging from resource allocation, and then uses all of this to trigger eviction for protected allocations even when `force_space` is not set.

The series is well-structured with good incremental patches, clear commit messages, and has clearly benefited from multiple rounds of review (Tvrtko's R-b on patch 3). The overall approach is sound — it correctly models the memcg protection semantics (min vs low) and handles the subtree/sibling distinction properly.

A few issues are noted below, mostly minor.

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