On Fri, Apr 11, 2025 at 12:37:49AM +0530, Nilay Shroff wrote: > > > On 4/10/25 7:00 PM, Ming Lei wrote: > > Both blk_mq_map_swqueue() and blk_mq_realloc_hw_ctxs() are only called > > from queue initialization or updating nr_hw_queues code, in which > > elevator switch can't happen any more. > > > > So remove these ->elevator_lock uses. > > > But what if blk_mq_map_swqueue runs in parallel, one context from > blk_mq_init_allocated_queue and another from blk_mq_update_nr_hw_queues? > It seems this is possible due to blk_mq_map_swqueue is invoked right > after queue is added in tag-set from blk_mq_init_allocated_queue. Good catch, one simple fix is to swap blk_mq_add_queue_tag_set() with blk_mq_map_swqueue() in blk_mq_init_allocated_queue() since blk_mq_map_swqueue doesn't rely on BLK_MQ_F_TAG_QUEUE_SHARED. Thanks, Ming
