[dm-devel] split scsi passthrough fields out of struct request V2

[Bart Van Assche]

On Thu, 2017-01-26 at 16:26 -0700, Jens Axboe wrote:
> What device is stuck? Is it running with an mq scheduler attached, or
> with "none"?
> 
> Would also be great to see the output of /sys/block/*/mq/*/tags and
> sched_tags so we can see if they have anything pending.
> 
> From a quick look at the below, it looks like a request leak. Bisection
> would most likely be very helpful.

Hello Jens,

This happens with and without scheduler attached. The most recent test I ran
was with the deadline scheduler configured as default scheduler for all blk-mq
devices (CONFIG_DEFAULT_SQ_IOSCHED="mq-deadline" and
CONFIG_DEFAULT_MQ_IOSCHED="mq-deadline"). The block devices that hang are
/dev/dm-0 and /dev/dm-1. The tags and sched_tags data is as follows:

# (cd /sys/class/block && grep -aH '' dm*/mq/*/tags)
dm-0/mq/0/tags:nr_tags=2048, reserved_tags=0, bits_per_word=64
dm-0/mq/0/tags:nr_free=1795, nr_reserved=0
dm-0/mq/0/tags:active_queues=0
dm-1/mq/0/tags:nr_tags=2048, reserved_tags=0, bits_per_word=64
dm-1/mq/0/tags:nr_free=2047, nr_reserved=0
dm-1/mq/0/tags:active_queues=0
# (cd /sys/class/block && grep -aH '' dm*/mq/*/sched_tags)
dm-0/mq/0/sched_tags:nr_tags=256, reserved_tags=0, bits_per_word=64
dm-0/mq/0/sched_tags:nr_free=0, nr_reserved=0
dm-0/mq/0/sched_tags:active_queues=0
dm-1/mq/0/sched_tags:nr_tags=256, reserved_tags=0, bits_per_word=64
dm-1/mq/0/sched_tags:nr_free=254, nr_reserved=0
dm-1/mq/0/sched_tags:active_queues=0

Bart.