Same problem here:
Banana PI M1 - ARMBIAN 5.38 stable Debian GNU/Linux 9 (stretch) 4.14.18-sunxi
It makes a daily reboot and runs for a couple of days, maybe 3 to 5.
Then the system partial stops to work.
SSH login works, but my cronjobs don't run.
And it seems that the system is just using one of the two cpu cores.
When I try to restart the system with "reboot", it doesn't come up again.
I have to use the reset-button.
Here is my log:
Aug 12 21:51:26 pi-router kernel: [82260.470855] INFO: rcu_sched detected stalls on CPUs/tasks:
Aug 12 21:51:26 pi-router kernel: [82260.470892] 1-...: (1 GPs behind) idle=fe6/140000000000000/0 softirq=172179/172185 fqs=639049
Aug 12 21:51:26 pi-router kernel: [82260.470897] (detected by 0, t=1578352 jiffies, g=83018, c=83017, q=198500)
Aug 12 21:51:26 pi-router kernel: [82260.470922] Sending NMI from CPU 0 to CPUs 1:
Aug 12 21:51:27 pi-router kernel: [82271.651723] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:29 pi-router kernel: [82273.811868] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:31 pi-router kernel: [82275.972016] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:34 pi-router kernel: [82278.132167] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:36 pi-router kernel: [82280.292319] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:38 pi-router kernel: [82282.452471] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:40 pi-router kernel: [82284.612622] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:42 pi-router kernel: [82286.772783] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:44 pi-router kernel: [82288.932919] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:46 pi-router kernel: [82291.093111] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:49 pi-router kernel: [82293.253221] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:51 pi-router kernel: [82295.413375] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:53 pi-router kernel: [82297.573525] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:55 pi-router kernel: [82299.733682] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:57 pi-router kernel: [82301.893902] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:51:59 pi-router kernel: [82304.053975] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:02 pi-router kernel: [82306.214126] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:04 pi-router kernel: [82308.374273] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:06 pi-router kernel: [82310.534438] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:08 pi-router kernel: [82312.694576] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:10 pi-router kernel: [82314.854736] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:12 pi-router kernel: [82317.015819] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:15 pi-router kernel: [82319.175042] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:17 pi-router kernel: [82321.335187] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:19 pi-router kernel: [82323.495331] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:29 pi-router kernel: [82323.525252] INFO: rcu_sched detected stalls on CPUs/tasks:
Aug 12 21:52:29 pi-router kernel: [82323.525290] 1-...: (1 GPs behind) idle=fe6/140000000000000/0 softirq=172179/172185 fqs=641602
Aug 12 21:52:29 pi-router kernel: [82323.525295] (detected by 0, t=1584657 jiffies, g=83018, c=83017, q=199148)
Aug 12 21:52:29 pi-router kernel: [82323.525319] Sending NMI from CPU 0 to CPUs 1:
Aug 12 21:52:30 pi-router kernel: [82334.696137] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:32 pi-router kernel: [82336.856262] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:34 pi-router kernel: [82339.016434] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:37 pi-router kernel: [82341.176561] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:39 pi-router kernel: [82343.336713] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:41 pi-router kernel: [82345.496864] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:43 pi-router kernel: [82347.657017] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:45 pi-router kernel: [82349.817192] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:47 pi-router kernel: [82351.977312] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:50 pi-router kernel: [82354.137477] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:52 pi-router kernel: [82356.297613] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:54 pi-router kernel: [82358.457766] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:56 pi-router kernel: [82360.617913] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:52:58 pi-router kernel: [82362.778074] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:00 pi-router kernel: [82364.938289] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:02 pi-router kernel: [82367.098371] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:05 pi-router kernel: [82369.258521] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:07 pi-router kernel: [82371.418683] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:09 pi-router kernel: [82373.578825] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:11 pi-router kernel: [82375.738982] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:13 pi-router kernel: [82377.899121] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:15 pi-router kernel: [82380.060167] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:18 pi-router kernel: [82382.219429] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:20 pi-router kernel: [82384.379579] thermal thermal_zone0: failed to read out thermal zone (-110)
Aug 12 21:53:22 pi-router kernel: [82386.539739] thermal thermal_zone0: failed to read out thermal zone (-110)