am335x: 5.18.x: system stalling

[Yegor Yefremov <yegorslists@googlemail.com>]

Hi Tony, all,

since kernel 5.18.x (5.17.x doesn't show this behavior), the system
stalls as soon as I invoke the following commands (initializing
USB-to-CAN converter):

slcand -o -s8 -t hw -S 3000000 /dev/ttyUSB0
ip link set slcan0 up

Have you already seen such an issue? Should I try to bisect this?

[   88.408578] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[   88.415777]  (detected by 0, t=2602 jiffies, g=2529, q=17)
[   88.422026] rcu: All QSes seen, last rcu_sched kthread activity
2602 (-21160--23762), jiffies_till_next_fqs=1, root ->qsmask 0x0
[   88.434445] rcu: rcu_sched kthread starved for 2602 jiffies! g2529
f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
[   88.445274] rcu:     Unless rcu_sched kthread gets sufficient CPU
time, OOM is now expected behavior.
[   88.454859] rcu: RCU grace-period kthread stack dump:
[   88.460446] task:rcu_sched       state:R  running task     stack:
 0 pid:   11 ppid:     2 flags:0x00000000
[   88.471840]  __schedule from schedule+0x58/0xcc
[   88.477680]  schedule from schedule_timeout+0x78/0xf8
[   88.483754]  schedule_timeout from rcu_gp_fqs_loop+0x108/0x3cc
[   88.490629]  rcu_gp_fqs_loop from rcu_gp_kthread+0xa8/0x134
[   88.497187]  rcu_gp_kthread from kthread+0xe4/0x104
[   88.503061]  kthread from ret_from_fork+0x14/0x28
[   88.508627] Exception stack(0xd0041fb0 to 0xd0041ff8)
[   88.514443] 1fa0:                                     00000000
00000000 00000000 00000000
[   88.523433] 1fc0: 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000
[   88.532374] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[   88.539639] rcu: Stack dump where RCU GP kthread last ran:
[   88.545694] NMI backtrace for cpu 0
[   88.549779] CPU: 0 PID: 58 Comm: kworker/0:8 Not tainted 5.18.0-rc5 #1
[   88.557103] Hardware name: Generic AM33XX (Flattened Device Tree)
[   88.563822] Workqueue: events dbs_work_handler
[   88.569398]  unwind_backtrace from show_stack+0x10/0x14
[   88.575662]  show_stack from dump_stack_lvl+0x58/0x70
[   88.581627]  dump_stack_lvl from nmi_cpu_backtrace+0xe0/0x128
[   88.588345]  nmi_cpu_backtrace from nmi_trigger_cpumask_backtrace+0xec/0x184
[   88.596339]  nmi_trigger_cpumask_backtrace from
trigger_single_cpu_backtrace+0x20/0x2c
[   88.605221]  trigger_single_cpu_backtrace from
rcu_check_gp_kthread_starvation+0xf4/0x148
[   88.614328]  rcu_check_gp_kthread_starvation from
rcu_sched_clock_irq+0xdf0/0xf7c
[   88.622778]  rcu_sched_clock_irq from update_process_times+0x88/0xc0
[   88.630182]  update_process_times from tick_sched_handle+0x48/0x54
[   88.637293]  tick_sched_handle from tick_sched_timer+0x48/0xac
[   88.643993]  tick_sched_timer from __hrtimer_run_queues+0x244/0x4d8
[   88.651212]  __hrtimer_run_queues from hrtimer_interrupt+0x128/0x2c8
[   88.658582]  hrtimer_interrupt from dmtimer_clockevent_interrupt+0x24/0x2c
[   88.666506]  dmtimer_clockevent_interrupt from
__handle_irq_event_percpu+0x98/0x334
[   88.675241]  __handle_irq_event_percpu from handle_irq_event+0x38/0xc0
[   88.682749]  handle_irq_event from handle_level_irq+0xb4/0x1a8
[   88.689639]  handle_level_irq from handle_irq_desc+0x1c/0x2c
[   88.696253]  handle_irq_desc from generic_handle_arch_irq+0x2c/0x64
[   88.703524]  generic_handle_arch_irq from __irq_svc+0x90/0xbc
[   88.710195] Exception stack(0xd0001f58 to 0xd0001fa0)
[   88.715947] 1f40:
    c01015c8 00000000
[   88.724939] 1f60: 0eae9000 00000000 fffffffe 60000013 ffffffff
d0385d74 00000000 c2702a80
[   88.733926] 1f80: 00000002 c2702a80 00000000 d0001fa8 c01015c8
c01015d0 60000113 ffffffff
[   88.742765]  __irq_svc from __do_softirq+0xa0/0x604
[   88.748533]  __do_softirq from __irq_exit_rcu+0x138/0x178
[   88.754961]  __irq_exit_rcu from irq_exit+0x8/0x28
[   88.760758]  irq_exit from call_with_stack+0x18/0x20
[   88.766687]  call_with_stack from __irq_svc+0x9c/0xbc
[   88.772576] Exception stack(0xd0385d40 to 0xd0385d88)
[   88.778458] 5d40: 00000005 00000488 00000000 00000000 c208c0c0
00006402 c208b800 c1874ff0
[   88.787451] 5d60: 00000000 c208c0c0 c1109210 c208c0d8 00000000
d0385d90 c06e068c c06e08a4
[   88.796305] 5d80: 60000013 ffffffff
[   88.800369]  __irq_svc from omap3_noncore_dpll_program+0x3f8/0x5ec
[   88.807588]  omap3_noncore_dpll_program from clk_change_rate+0x23c/0x4f8
[   88.815375]  clk_change_rate from clk_core_set_rate_nolock+0x1b0/0x29c
[   88.822936]  clk_core_set_rate_nolock from clk_set_rate+0x30/0x64
[   88.830056]  clk_set_rate from _set_opp+0x254/0x51c
[   88.835835]  _set_opp from dev_pm_opp_set_rate+0xec/0x228
[   88.842073]  dev_pm_opp_set_rate from __cpufreq_driver_target+0x584/0x700
[   88.849792]  __cpufreq_driver_target from od_dbs_update+0xb4/0x168
[   88.856953]  od_dbs_update from dbs_work_handler+0x2c/0x60
[   88.863441]  dbs_work_handler from process_one_work+0x284/0x72c
[   88.870411]  process_one_work from worker_thread+0x28/0x4b0
[   88.876973]  worker_thread from kthread+0xe4/0x104
[   88.882692]  kthread from ret_from_fork+0x14/0x28
[   88.888225] Exception stack(0xd0385fb0 to 0xd0385ff8)
[   88.893998] 5fa0:                                     00000000
00000000 00000000 00000000
[   88.902971] 5fc0: 00000000 00000000 00000000 00000000 00000000
00000000 00000000 00000000
[   88.911888] 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000

Regards,
Yegor