drm/i915: Fix vma resource freeing

In some cases we use leftover kfree() instead of i915_vma_resource_free().
Fix this.

Fixes: 2f6b90da ("drm/i915: Use vma resources for async unbinding")
Reported-by: Robert Beckett <bob.beckett@collabora.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220119174734.213552-1-thomas.hellstrom@linux.intel.com

drivers/gpu/drm/i915/i915_vma.c

@@ -463,7 +463,7 @@ int i915_vma_bind(struct i915_vma *vma,
 	if (vma->resource || !vma_res) {
 		/* Rebinding with an additional I915_VMA_*_BIND */
 		GEM_WARN_ON(!vma_flags);
-		kfree(vma_res);
+		i915_vma_resource_free(vma_res);
 	} else {
 		i915_vma_resource_init_from_vma(vma_res, vma);
 		vma->resource = vma_res;
@@ -1406,7 +1406,7 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
 err_unlock:
 	mutex_unlock(&vma->vm->mutex);
 err_vma_res:
-	kfree(vma_res);
+	i915_vma_resource_free(vma_res);
 err_fence:
 	if (work)
 		dma_fence_work_commit_imm(&work->base);

drivers/gpu/drm/i915/i915_vma_resource.c

@@ -62,7 +62,8 @@ struct i915_vma_resource *i915_vma_resource_alloc(void)
  */
 void i915_vma_resource_free(struct i915_vma_resource *vma_res)
 {
-	kmem_cache_free(slab_vma_resources, vma_res);
+	if (vma_res)
+		kmem_cache_free(slab_vma_resources, vma_res);
 }
 
 static const char *get_driver_name(struct dma_fence *fence)