Same problem here on a Lenovo ideapad Y700 and Ubuntu 16.04 /dev/nvme0n1 SAMSUNG MZVLW512HMJP-000L2
I disabled APST by adding nvme_core.default_ps_max_latency_us=0 to the kernel parameters in /etc/default/grub and works ok, no blocking since then.
Same problem here on a Lenovo ideapad Y700 and Ubuntu 16.04
/dev/nvme0n1 SAMSUNG MZVLW512HMJP-000L2
I disabled APST by adding nvme_core. default_ ps_max_ latency_ us=0 to the kernel parameters in /etc/default/grub and works ok, no blocking since then.