drm/amdgpu: fix gtt available page num accounting

Signed-off-by: Flora Cui <[e-mail]>
Reviewed-by: Hawking Zhang <[e-mail]>
Reviewed-by: Christian König <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c

···
 	spin_unlock(&mgr->lock);
 
 	node = kzalloc(sizeof(*node), GFP_KERNEL);
-	if (!node)
-		return -ENOMEM;
+	if (!node) {
+		r = -ENOMEM;
+		goto err_out;
+	}
 
 	node->start = AMDGPU_BO_INVALID_OFFSET;
 	node->size = mem->num_pages;
···
 		if (unlikely(r)) {
 			kfree(node);
 			mem->mm_node = NULL;
+			r = 0;
+			goto err_out;
 		}
 	} else {
 		mem->start = node->start;
 	}
 
 	return 0;
+err_out:
+	spin_lock(&mgr->lock);
+	mgr->available += mem->num_pages;
+	spin_unlock(&mgr->lock);
+
+	return r;
 }
 
 /**