Claude review: Revert "i915: don't use a vma that didn't match the context VM"

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

Patch Review

**Correctness: OK**

The patch removes:
```c
		else
			vma = NULL;
```
from the `eb_lookup_vma()` function in `i915_gem_execbuffer.c`.

This is correct because:

1. `radix_tree_lookup()` returns `void *` and yields `NULL` when the entry is not found (declared in `include/linux/radix-tree.h`). So when the `if (likely(vma))` test falls through, `vma` is already `NULL`.

2. `i915_vma_tryget()` (defined in `i915_vma.h:194`) also returns `NULL` on failure (when `kref_get_unless_zero` fails), so even after the `if (likely(vma))` → `i915_vma_tryget(vma)` path, a failure still leaves `vma` as `NULL`.

3. After the removed `else` branch, the code proceeds to `if (likely(vma)) return vma;` — which correctly handles the `NULL` case regardless.

**Commit message: Good.** References the original commit hash, links the relevant lore discussion with Linus, and explains why the original commit was a no-op. The Cc list is appropriate — includes the original participants in the discussion.

**Style: Fine.** A straightforward revert with `git revert` formatting.

**No concerns.** This is a clean, well-justified removal of dead code.

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Generated by Claude Code Patch Reviewer