insert_augmented_cached() open-codes the descent that the generic rb_add_augmented_cached() helper provides. Use the helper instead, so that rbtree_test covers it: it is what sched/eevdf relies on and nothing in lib/ exercises it today. Signed-off-by: Yiwei Lin <s921975628@gmail.com> Assisted-by: LLM Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://patch.msgid.link/20261005093236.62702-5-s921975628@gmail.com