I had similar experience on my Cubietruck A20 (rcu_sched stalls and rejected forks)
It happened after my first reboot with kernel 4.14.15-sunxi (after some uptime with kernel 4.13.16)
I just run 'sudo cruft' at that time
Feb 2 15:58:35 localhost kernel: [102644.225181] INFO: rcu_sched detected stalls on CPUs/tasks:
Feb 2 15:58:35 localhost kernel: [102644.225228] 1-...: (1 GPs behind) idle=272/140000000000000/0 softirq=1869227/1869228 fqs=1050
Feb 2 15:58:35 localhost kernel: [102644.225232] (detected by 0, t=2102 jiffies, g=798178, c=798177, q=5594)
Feb 2 15:58:35 localhost kernel: [102644.225258] Sending NMI from CPU 0 to CPUs 1:
Feb 2 15:59:38 localhost kernel: [102707.275047] INFO: rcu_sched detected stalls on CPUs/tasks:
Feb 2 15:59:38 localhost kernel: [102707.275093] 1-...: (1 GPs behind) idle=272/140000000000000/0 softirq=1869227/1869228 fqs=3702
Feb 2 15:59:38 localhost kernel: [102707.275097] (detected by 0, t=8407 jiffies, g=798178, c=798177, q=68757)
Feb 2 15:59:38 localhost kernel: [102707.275122] Sending NMI from CPU 0 to CPUs 1:
Feb 2 15:59:51 localhost kernel: [102730.056354] cgroup: fork rejected by pids controller in /user.slice/user-1001.slice/session-222.scope
Feb 2 16:00:41 localhost kernel: [102770.324854] INFO: rcu_sched detected stalls on CPUs/tasks:
Feb 2 16:00:41 localhost kernel: [102770.324890] 1-...: (1 GPs behind) idle=272/140000000000000/0 softirq=1869227/1869228 fqs=6354
Feb 2 16:00:41 localhost kernel: [102770.324894] (detected by 0, t=14712 jiffies, g=798178, c=798177, q=89964)
Feb 2 16:00:41 localhost kernel: [102770.324918] Sending NMI from CPU 0 to CPUs 1:
Feb 2 16:01:45 localhost kernel: [102833.374711] INFO: rcu_sched detected stalls on CPUs/tasks:
Feb 2 16:01:45 localhost kernel: [102833.374751] 1-...: (1 GPs behind) idle=272/140000000000000/0 softirq=1869227/1869228 fqs=9006
Feb 2 16:01:45 localhost kernel: [102833.374756] (detected by 0, t=21017 jiffies, g=798178, c=798177, q=90505)
Feb 2 16:01:45 localhost kernel: [102833.374781] Sending NMI from CPU 0 to CPUs 1:
Feb 2 16:02:48 localhost kernel: [102896.424568] INFO: rcu_sched detected stalls on CPUs/tasks:
Feb 2 16:02:48 localhost kernel: [102896.424608] 1-...: (1 GPs behind) idle=272/140000000000000/0 softirq=1869227/1869228 fqs=11657
Feb 2 16:02:48 localhost kernel: [102896.424612] (detected by 0, t=27322 jiffies, g=798178, c=798177, q=91242)
Feb 2 16:02:48 localhost kernel: [102896.424636] Sending NMI from CPU 0 to CPUs 1:
Feb 2 16:03:51 localhost kernel: [102959.474426] INFO: rcu_sched detected stalls on CPUs/tasks:
Feb 2 16:03:51 localhost kernel: [102959.474465] 1-...: (1 GPs behind) idle=272/140000000000000/0 softirq=1869227/1869228 fqs=14307
Feb 2 16:03:51 localhost kernel: [102959.474469] (detected by 0, t=33627 jiffies, g=798178, c=798177, q=92168)
Feb 2 16:03:51 localhost kernel: [102959.474493] Sending NMI from CPU 0 to CPUs 1:
Feb 2 16:04:31 localhost kernel: [103009.885942] cgroup: fork rejected by pids controller in /user.slice/user-1001.slice/session-229.scope
Then I rebooted the board locally by its power switch, and nothing similar happened after that