Claude review: Fix leaking of cached Host1x buffer objects

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Overall Series Review

Subject: Fix leaking of cached Host1x buffer objects
Author: Mikko Perttunen <mperttunen@nvidia.com>
Patches: 3
Reviewed: 2026-05-16T10:12:28.032839

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This is a well-reasoned 2-patch series from Mikko Perttunen fixing a real memory leak in the Host1x buffer object cache. The core problem is a classic circular reference: cached mappings hold a refcount on the BO, but the only way to release a cached mapping is through the BO's free path — which never runs because the cache keeps the BO alive.

The fix is clean: centralize BO refcounting in the common `host1x_bo_pin()`/`host1x_bo_unpin()` functions rather than in each driver's `.pin`/`.unpin` callbacks, and make the cache's reference to the BO "weak" (no refcount bump). The BO free path is then responsible for tearing down cached mappings via a new `host1x_bo_clear_cached_mappings()` helper.

The series is correct and the approach is sound. I have one concern about the direct invocation of `__host1x_bo_unpin` bypassing `kref_put` in the teardown path, and a minor locking observation, but nothing blocking.

**Verdict: Looks good overall. Two minor observations below, neither blocking.**

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