Hello, Tao. On Thu, 15 Oct 2026 20:00:20 +0800, Tao Cui wrote: > When you have a chance, could you take a look at this series? I'd > appreciate your thoughts on whether the implementation still matches > what we discussed, or whether it has drifted somewhere along the way.
The behavior matches what was discussed, but the implementation needs a lot of cleanup, and there are bugs in the detach path and the iocg_init()/iocg_free() pairing. Details are in the replies to the patches. > Sashiko flagged a possible ABBA between the BPF paths and > ioc_cost_model_write(): attach/detach take the queue freeze before > q->rq_qos_mutex, while the cost-model write holds rq_qos_mutex across > its freeze. That is indeed the current ordering, but I don't think this > can deadlock because the queue freeze is a depth counter The attach and detach order matches ioc_qos_write(). The reverse order in ioc_cost_model_write() predates this series and is better fixed separately. An earlier attempt to convert it ran into blk_iocost_init()'s percpu allocation under the freeze: https://lore.kernel.org/all/aV5OwAvw1sRF1IW1@fedora/ Thanks. -- tejun
