Dear stable maintainers,
I like to indicate the oops encountered and request the below patch to
be backported to v 5.15. The fix is important to avoid recurring oops
in context of rcu detected stalls.
subject: rcu: Avoid tracing a few functions executed in stop machine
commit 48f8070f5dd8
Target kernel version v 5.15
Reason for Application: To avoid oops due to rcu_prempt detect stalls
on cpus/tasks
Environment and oops context: Issue was observed in my environment on
5.15.193 kernel (arm platform). The patch is helpful to avoid the
below oops indicated in [1] and [2]
log :
root@ls1021atwr:~# uname -r
5.15.93-rt58+ge0f69a158d5b
oops dump stack
** ID_531 main/smp_fsm.c:1884 <inrcu: INFO: rcu_preempt detected
stalls on CPUs/tasks: <<< [1]
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P116/2:b..l
(detected by 1, t=2102 jiffies, g=12741, q=1154)
task:irq/31-arm-irq1 state:D stack: 0 pid: 116 ppid: 2 flags:0x00000000
[<8064b97f>] (__schedule) from [<8064bb01>] (schedule+0x8d/0xc2)
[<8064bb01>] (schedule) from [<8064fa65>] (schedule_timeout+0x6d/0xa0)
[<8064fa65>] (schedule_timeout) from [<804ba353>]
(fsl_ifc_run_command+0x6f/0x178)
[<804ba353>] (fsl_ifc_run_command) from [<804ba72f>]
(fsl_ifc_cmdfunc+0x203/0x2b8)
[<804ba72f>] (fsl_ifc_cmdfunc) from [<804b135f>] (nand_status_op+0xaf/0xe0)
[<804b135f>] (nand_status_op) from [<804b13b3>] (nand_check_wp+0x23/0x48)
....
< snipped >
Exception stack(0x822bbfb0 to 0x822bbff8)
bfa0: 00000000 00000000 00000000 00000000
bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
bfe0: 00000000 00000000 00000000 00000000 00000013 00000000
rcu: rcu_preempt kthread timer wakeup didn't happen for 764 jiffies!
g12741 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x1000
rcu: Possible timer handling issue on cpu=0 timer-softirq=1095
rcu: rcu_preempt kthread starved for 765 jiffies! g12741 f0x0
RCU_GP_WAIT_FQS(5) ->state=0x1000 ->cpu=0 <<< [2]
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is
now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:D stack: 0 pid: 13 ppid: 2 flags:0x00000000
[<8064b97f>] (__schedule) from [<8064ba03>] (schedule_rtlock+0x1b/0x2e)
[<8064ba03>] (schedule_rtlock) from [<8064ea6f>]
(rtlock_slowlock_locked+0x93/0x108)
[<8064ea6f>] (rtlock_slowlock_locked) from [<8064eb1b>] (rt_spin_lock+0x37/0x4a)
[<8064eb1b>] (rt_spin_lock) from [<8021b723>] (__local_bh_disable_ip+0x6b/0x110)
[<8021b723>] (__local_bh_disable_ip) from [<8025a90f>]
(del_timer_sync+0x7f/0xe0)
[<8025a90f>] (del_timer_sync) from [<8064fa6b>] (schedule_timeout+0x73/0xa0)
[<8064fa6b>] (schedule_timeout) from [<80254677>] (rcu_gp_fqs_loop+0x8b/0x1bc)
[<80254677>] (rcu_gp_fqs_loop) from [<8025483f>] (rcu_gp_kthread+0x97/0xbc)
[<8025483f>] (rcu_gp_kthread) from [<8022ca67>] (kthread+0xcf/0xe4)
[<8022ca67>] (kthread) from [<80200149>] (ret_from_fork+0x11/0x28)
Exception stack(0x820fffb0 to 0x820ffff8)
ffa0: 00000000 00000000 00000000 00000000
ffc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
ffe0: 00000000 00000000 00000000 00000000 00000013 00000000
rcu: Stack dump where RCU GP kthread last ran:
<<
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
< .. >
Thank you for your time and consideration. Please let me know if you
require any additional information
Best Regards,
Ronald Monthero
