Claude review: drm/panthor: Fix a race in the shrinker logic

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

Overall Series Review

Subject: drm/panthor: Fix a race in the shrinker logic
Author: Boris Brezillon <boris.brezillon@collabora.com>
Patches: 9
Reviewed: 2026-05-07T13:31:55.806526

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This is a well-analyzed and cleanly structured 3-patch series from Boris Brezillon fixing a real race condition between `drm_gem_lru_remove()` and `drm_gem_lru_scan()` in the DRM GEM LRU/shrinker infrastructure. The core problem: `drm_gem_lru_remove()` reads `obj->lru` without the LRU lock, but `drm_gem_lru_scan()` temporarily moves objects to a stack-allocated `still_in_lru` LRU — if the timing is wrong, `drm_gem_lru_remove()` dereferences a stale pointer to a stack object that no longer exists (UAF).

The series is logically ordered: (1) fix the panthor driver to stop using the racy API, (2) fix a second race in the core `drm_gem_lru_scan()`, (3) remove the racy `drm_gem_lru_remove()` entirely. All three patches have Reviewed-by from the reporter (Chia-I Wu). The approach is sound — rather than trying to make `drm_gem_lru_remove()` safe (which would require external locking that defeats its purpose), the series eliminates the problematic API.

The series looks good to me and ready to merge. One minor concern noted below in Patch 2.

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