On Fri, May 21, 2021 at 12:33:53AM +0200, Jan Kara wrote: > Lockdep complains about lock inversion between ioc->lock and bfqd->lock: > > bfqd -> ioc: > put_io_context+0x33/0x90 -> ioc->lock grabbed > blk_mq_free_request+0x51/0x140 > blk_put_request+0xe/0x10 > blk_attempt_req_merge+0x1d/0x30 > elv_attempt_insert_merge+0x56/0xa0 > blk_mq_sched_try_insert_merge+0x4b/0x60 > bfq_insert_requests+0x9e/0x18c0 -> bfqd->lock grabbed We could move blk_put_request() into scheduler code, then the lock inversion is avoided. So far only mq-deadline and bfq calls into blk_mq_sched_try_insert_merge(), and this change should be small. Thanks, Ming
