I have changed governor to performance and since it seems to be better, can somebody also try it?
echo "performance" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
But I have still strange behavior, It freeze for some time but after several minutes the problems dissapear and BPI is running well again. No logs, no messages, nothing. Probably some ghosts in the kernel.
BPI M2U is really not good choose for stable server until stable version will be released.