RCU stall/SOFT-Lockup on 4.11.3/4.13.11 after multiple days uptime

[Bruno PrÃmont]

Hi,

On a single-CPU KVM-based virtual machine I'm suffering from RCU stall
and soft-lockup. 4.10.x kernels run fine (4.10.12) but starting with
4.11.x (4.11.3, 4.13.11) I'm getting system freezes for no apparent
reason.

All info I have is following console dump (from 4.13.11):
[526415.290012] INFO: rcu_sched self-detected stall on CPU
[526415.290012] o0-...: (745847 ticks this GP) idle=ba2/2/0 softirq=37393463/37393463 fqs=0
[526415.290012] o (t=745854 jiffies g=23779976 c=23779975 q=32)
[526415.290012] rcu_sched kthread starved for 745854 jiffies! g23779976 c23779975 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0
[526440.020015] watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:0]
[526468.020005] watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:0]
[526478.320009] INFO: rcu_sched self-detected stall on CPU
[526478.320009] o0-...: (752143 ticks this GP) idle=ba2/2/0 softirq=37393463/37393463 fqs=0
[526478.320009] o (t=752157 jiffies g=23779976 c=23779975 q=32)
[526478.320009] rcu_sched kthread starved for 752157 jiffies! g23779976 c23779975 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0
[526504.020016] watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:0]
[526532.020007] watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:0]
...

Attached is kernel config (4.13.11).


The output obtained with 4.11.3 was:
[  280.680010] INFO: rcu_sched self-detected stall on CPU
[  280.680021] o0-...: (27312 ticks this GP) dile=b11/2/0 softirq=6119/6119 fqs=0
[  280.680021] o (t=27312 jiffies g=441 c=440 q=0)
[  280.680021] rcu_sched_kthread starved for 27312 jiffies! g441 c440 f0x0 RCU_GP_WAIT_FQS(3) ->state=0x0
...


As it's a remote VM for which I don't have access to the host I have little
options for further digging (can't trigger sysrq's).


Same kernel (4.13.11) seems to be running just fine on another KVM-base VM that
has two CPUs.


Does it ring a bell or is there some info that might be of any use,
assuming I can obtain it?

Bruno

Attachment: kvm-guest.config
Description: Binary data