Bug report: ref tag error while running IO > MDTS on nvme device

[Max Gurtovoy]

Hi guys,
I would like to report a bug while running fio on local nvme device 
(SAMSUNG MZPLL1T6HEHP-00003) that was formated to use integrity:

nvme format /dev/nvme2n1 -n 1 -l 1 -i 2 -p 0 -m 0
nvme id-ns /dev/nvme2n1:

NVME Identify Namespace 1:
nsze    : 0xba4d4ab0
ncap    : 0xba4d4ab0
nuse    : 0xba4d4ab0
nsfeat  : 0
nlbaf   : 3
flbas   : 0x1
mc      : 0x3
dpc     : 0x1f
dps     : 0x2
nmic    : 0x1
rescap  : 0x7f
fpi     : 0x80
nawun   : 0
nawupf  : 0
nacwu   : 0
nabsn   : 0
nabo    : 0
nabspf  : 0
noiob   : 0
nvmcap  : 1600321314816
nguid   : 334842304a6000840025384100000002
eui64   : 002538e671000457
lbaf  0 : ms:0   lbads:9  rp:0x1
lbaf  1 : ms:8   lbads:9  rp:0x3 (in use)
lbaf  2 : ms:0   lbads:12 rp:0
lbaf  3 : ms:8   lbads:12 rp:0x2

running traffic up to IO size <= 128KB works fine but running bigger IO 
that the MDTS caused many ref tag errors (for example):

[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 324043008 
(rcvd 0)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 2929058096 
(rcvd 1241579520)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 2292844816 
(rcvd 2483027968)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 2523145472 
(rcvd 243859455)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 1177656832 
(rcvd 15400959)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 187312640 
(rcvd 243859455)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 2344798720 
(rcvd 126418943)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 2892037376 
(rcvd 126418943)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 2292845056 
(rcvd 143196159)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 1237630256 
(rcvd 1241579520)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 1237630208 
(rcvd 143196159)
[Tue Oct  3 12:34:25 2017] nvme2n1: ref tag error at location 2986034432 
(rcvd 243859455)
[Tue Oct  3 12:34:45 2017] nvme2n1: ref tag error at location 881629440 
(rcvd 15400959)
[Tue Oct  3 12:34:45 2017] nvme2n1: ref tag error at location 1889589504 
(rcvd 243859455)
[Tue Oct  3 12:34:45 2017] nvme2n1: ref tag error at location 1889589504 
(rcvd 243859455)

haven't debugged it yet, but if anyone has an idea for the root cause, 
it would be great.

Thanks,
-Max.