I'm working on my own distribution for OrangePI R1 with Allwinner sun8i SoC. I had stripped kernel_defconfig to fit my custom linux into 16M SPI NOR. After leaving the board up for few days I see such messages on my serial console.
admin@orange-pi-r1:~# [65779.614485] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[65779.620458] rcu: 3-...!: (4 GPs behind) idle=200/0/0x0 softirq=17870/17870 fqs=0 (false positive?)
[65779.629630] (detected by 2, t=2103 jiffies, g=68925, q=83)
[65779.635224] Sending NMI from CPU 2 to CPUs 3:
[65779.639605] NMI backtrace for cpu 3
[65779.639619] CPU: 3 PID: 0 Comm: swapper/3 Tainted: G O 5.15.35 #1
[65779.639636] Hardware name: Allwinner sun8i Family
[65779.639644] PC is at 0xc0106330
[65779.639651] LR is at 0xc0106340
[65779.639657] pc : [<c0106330>] lr : [<c0106340>] psr: 60000013
[65779.639669] sp : c0cadfa8 ip : 00000000 fp : c0805f90
[65779.639679] r10: c0cadfb8 r9 : 410fc075 r8 : c0805f4c
[65779.639689] r7 : c0cac000 r6 : c0cac000 r5 : 00000000 r4 : 00000000
[65779.639701] r3 : c0113ca0 r2 : 12e10204 r1 : 00000000 r0 : 12e10204
[65779.639714] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
[65779.639729] Control: 10c5387d Table: 42a7c06a DAC: 00000051
[65779.639738] CPU: 3 PID: 0 Comm: swapper/3 Tainted: G O 5.15.35 #1
[65779.639754] Hardware name: Allwinner sun8i Family
[65779.639767] Function entered at [<c010c0b8>] from [<c0108bf4>]
[65779.639779] Function entered at [<c0108bf4>] from [<c0540794>]
[65779.639791] Function entered at [<c0540794>] from [<c037e2e0>]
[65779.639803] Function entered at [<c037e2e0>] from [<c010ad00>]
[65779.639814] Function entered at [<c010ad00>] from [<c010ad50>]
[65779.639825] Function entered at [<c010ad50>] from [<c016d288>]
[65779.639837] Function entered at [<c016d288>] from [<c0167b94>]
[65779.639848] Function entered at [<c0167b94>] from [<c0168218>]
[65779.639860] Function entered at [<c0168218>] from [<c038dff0>]
[65779.639871] Function entered at [<c038dff0>] from [<c0100b7c>]
[65779.639881] Exception stack(0xc0cadf58 to 0xc0cadfa0)
[65779.639896] df40: 12e10204 00000000
[65779.639915] df60: 12e10204 c0113ca0 00000000 00000000 c0cac000 c0cac000 c0805f4c 410fc075
[65779.639934] df80: c0cadfb8 c0805f90 00000000 c0cadfa8 c0106340 c0106330 60000013 ffffffff
[65779.639946] Function entered at [<c0100b7c>] from [<c0106330>]
[65779.639957] Function entered at [<c0106330>] from [<c0546b94>]
[65779.639969] Function entered at [<c0546b94>] from [<c0148244>]
[65779.639980] Function entered at [<c0148244>] from [<c0148680>]
[65779.639991] Function entered at [<c0148680>] from [<401014d0>]
[65779.640602] rcu: rcu_sched kthread timer wakeup didn't happen for 2103 jiffies! g68925 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
[65779.845052] rcu: Possible timer handling issue on cpu=1 timer-softirq=33908
[65779.852117] rcu: rcu_sched kthread starved for 2125 jiffies! g68925 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=1
[65779.862406] rcu: Unless rcu_sched kthread gets sufficient CPU time, OOM is now expected behavior.
[65779.871383] rcu: RCU grace-period kthread stack dump:
[65779.876447] task:rcu_sched state:I stack: 0 pid: 12 ppid: 2 flags:0x00000000
[65779.884836] Function entered at [<c0543560>] from [<c0543780>]
[65779.890688] Function entered at [<c0543780>] from [<c05462f4>]
[65779.896539] Function entered at [<c05462f4>] from [<c0176720>]
[65779.902391] Function entered at [<c0176720>] from [<c01791e4>]
[65779.908241] Function entered at [<c01791e4>] from [<c013cc18>]
[65779.914093] Function entered at [<c013cc18>] from [<c0100130>]
[65779.919942] Exception stack(0xc0c71fb0 to 0xc0c71ff8)
[65779.925008] 1fa0: 00000000 00000000 00000000 00000000
[65779.933212] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[65779.941415] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
What might be causing such output? How can I debug this?