why frequent restart the dm368 linux system ,v4l2 can't get capture data

HI  everyone

my project has timetask  ,so we restart system every three minutes,

used command  reboot(LINUX_REBOOT_CMD_RESTART),

but an hour later, the app shows v4l2 can't get capture data,sensor 's VD,HD is ok.

what's the reason. 

thanks