Re: [PATCH 0/3] blk-mq/nvme-loop: use nvme-loop's lock class for addressing lockdep false positive warning

Ming Lei
2020-11-30T02:38:13Z

On Thu, Nov 12, 2020 at 03:55:23PM +0800, Ming Lei wrote:
> Hi,
>
> Qian reported there is hang during booting when shared host tagset is
> introduced on megaraid sas. Sumit reported the whole SCSI probe takes
> about ~45min in his test.
>
> Turns out it is caused by nr_hw_queues increased, especially commit
> b3c6a5997541("block: Fix a lockdep complaint triggered by request queue flushing")
> adds synchronize_rcu() for each hctx's release handler.
>
> Address the original lockdep false positive warning by simpler way, then
> long scsi probe can be avoided with lockdep enabled.
>
> Ming Lei (3):
> blk-mq: add new API of blk_mq_hctx_set_fq_lock_class
> nvme-loop: use blk_mq_hctx_set_fq_lock_class to set loop's lock class
> Revert "block: Fix a lockdep complaint triggered by request queue
> flushing"
>
> block/blk-flush.c | 30 +++++++++++++++++++++++++-----
> block/blk.h | 1 -
> drivers/nvme/target/loop.c | 10 ++++++++++
> include/linux/blk-mq.h | 3 +++
> 4 files changed, 38 insertions(+), 6 deletions(-)
>
> Cc: Qian Cai <cai@redhat.com>
> Cc: Sumit Saxena <sumit.saxena@broadcom.com>
> Cc: John Garry <john.garry@huawei.com>
> Cc: Kashyap Desai <kashyap.desai@broadcom.com>
> Cc: Bart Van Assche <bvanassche@acm.org>
> Cc: Hannes Reinecke <hare@suse.de>

Hello Jens,

Any chance to take a look? And this issue has been reported several
times in RH internal test.

Thanks,
Ming