nvme-tcp request timeouts

[Seth Forshee]

Hi,

I'm seeing timeouts like the following from nvme-tcp:

[ 6369.513269] nvme nvme5: queue 102: timeout request 0x73 type 4
[ 6369.513283] nvme nvme5: starting error recovery
[ 6369.514379] block nvme5n1: no usable path - requeuing I/O
[ 6369.514385] block nvme5n1: no usable path - requeuing I/O
[ 6369.514392] block nvme5n1: no usable path - requeuing I/O
[ 6369.514393] block nvme5n1: no usable path - requeuing I/O
[ 6369.514401] block nvme5n1: no usable path - requeuing I/O
[ 6369.514414] block nvme5n1: no usable path - requeuing I/O
[ 6369.514420] block nvme5n1: no usable path - requeuing I/O
[ 6369.514427] block nvme5n1: no usable path - requeuing I/O
[ 6369.514430] block nvme5n1: no usable path - requeuing I/O
[ 6369.514432] block nvme5n1: no usable path - requeuing I/O
[ 6369.514926] nvme nvme5: Reconnecting in 10 seconds...
[ 6379.761015] nvme nvme5: creating 128 I/O queues.
[ 6379.944389] nvme nvme5: mapped 128/0/0 default/read/poll queues.
[ 6379.947922] nvme nvme5: Successfully reconnected (1 attempt)

This is with 6.0, using nvmet-tcp on a different machine as the target.
I've seen this sporadically with several test cases. The fio fio-rand-RW
example test is a pretty good reproducer when numjobs in increased (I'm
setting it equal to the number of CPUs in the system).

Let me know what I can do to help debug this. I'm currently adding some
tracing to the driver to see if I can get an idea of the sequence of
events that leads to this problem.

Thanks,
Seth