Hi Jens Two fixes for updating nr_hw_queues. The first patch fixes the following scenario: io scheduler (kyber) depends on the mapping between ctx and hctx. When update nr_hw_queues, io scheduler's init_hctx will be invoked before the mapping is adapted correctly, this would cause panic in kyber. The second patch fixes the following scenario: part_in_flight/rw will invoke blk_mq_in_flight/rw to account the inflight requests. It will access the queue_hw_ctx and nr_hw_queues w/o any protection. When updating nr_hw_queues and blk_mq_in_flight /rw occur concurrently, panic comes up. V3: - move the rcu and q_usage_counter checking into blk_mq_queue_tag_busy_iter as suggestion of Ming. - Add more comment about the __module_get in 1st patch. - Add Ming's Reviewd-by on 1st patch. V2: - remove blk_mq_sched_init/exit_hctx in patch 1. - use q_usage_counter instead of adding new member suggested by Ming in patch 2. - comment modification. Jianchao Wang(2) blk-mq: init hctx sched after update ctx and hctx blk-mq: sync the update nr_hw_queues with block/blk-mq-sched.c | 44 -------------------------------------------- block/blk-mq-sched.h | 5 ----- block/blk-mq-tag.c | 14 +++++++++++++- block/blk-mq.c | 43 +++++++++++++++++++++++++++++++++++-------- block/blk.h | 2 ++ block/elevator.c | 20 ++++++++++++-------- include/linux/blkdev.h | 3 +++ 7 files changed, 65 insertions(+), 66 deletions(-) Thanks Jianchao
