[PATCH v2 0/5] Handle update hardware queues and queue freeze more carefully

From: Daniel Wagner
Date: Thu Jul 08 2021 - 05:28:13 EST


Hi,

I've tested this on top of Ming's patches 'blk-mq: fix
blk_mq_alloc_request_hctx'[1] which fixes all problems (including the
hanger in nvme_wait_freeze()).

Thanks,
Danie

[1] https://lore.kernel.org/linux-nvme/20210629074951.1981284-1-ming.lei@xxxxxxxxxx/

v1:
- https://lore.kernel.org/linux-nvme/20210625101649.49296-1-dwagner@xxxxxxx/
v2:
- reviewed tags collected
- added 'update hardware queues' for all transport
- added fix for fc hanger in nvme_wait_freeze_timeout


Initial cover letter:

this is a followup on the crash I reported in

https://lore.kernel.org/linux-block/20210608183339.70609-1-dwagner@xxxxxxx/

By moving the hardware check up the crash was gone. Unfortuntatly, I
don't understand why this fixes the crash. The per-cpu access is
crashing but I can't see why the blk_mq_update_nr_hw_queues() is
fixing this problem.

Even though I can't explain why it fixes it, I think it makes sense to
update the hardware queue mapping bevore we recreate the IO
queues. Thus I avoided in the commit message to say it fixes
something.

Also during testing I observed the we hang indivinetly in
blk_mq_freeze_queue_wait(). Again I can't explain why we get stuck
there but given a common pattern for the nvme_wait_freeze() is to use
it with a timeout I think the timeout should be used too :)

Anyway, someone with more undertanding of the stack can explain the
problems.


Daniel Wagner (4):
nvme-fc: Update hardware queues before using them
nvme-rdma: Update number of hardware queues before using them
nvme-fc: Wait with a timeout for queue to freeze
nvme-fc: Freeze queues before destroying them

Hannes Reinecke (1):
nvme-tcp: Update number of hardware queues before using them

drivers/nvme/host/fc.c | 26 +++++++++++++++++---------
drivers/nvme/host/rdma.c | 13 ++++++-------
drivers/nvme/host/tcp.c | 14 ++++++--------
3 files changed, 29 insertions(+), 24 deletions(-)

--
2.29.2