Public bug reported:
Since August 19th we have been struggling with irregular crashes on our
NFS server.
Our experiences with NFS server crashes are:
- We were able to reproduce the crashes in our production and test environments
with NFS4.2. Rarely after minutes, sometimes after hours or days, but sometimes
not at all,
as we often stopped the experiments after 12 to 24 hours.
- We have not yet been able to reproduce a crash between a bare metal NFS
server and a bare metal NFS client, but between a bare metal NFS server and a
virtualized client with NFS4.2.
- we could not reproduce a crash with NFS vers=4.0 up to now
- we now running NFS vers=4.1 since some hours to see if this helps to get the
system stable
- the crashs happens with or without GSSPROXY
- before Sept 15 the kernel back on the NFS server trace allways started with:
watchdog: BUG: soft lockup - CPU#23 stuck for 26s! [kworker/u483:0:8805]
and after Sept 15 with:
rcu: INFO: rcu_sched self-detected stall on CPU
- changing the kernel on the client from 6.8.0-40-generic to the unofficial
6.5.0-46-generic from Mehmet Basaran (mehmetbasaran) only removed the
backchannel error from the client,
but the server still hangs with "rcu: INFO: rcu_sched self-detected stall on
CPU"
- changing the client kernel from 6.8.0-40-generic back to 6.5.0-44-generic
does not solved the problem that user can not login after the crash:
client:
kernel: [29361.795714] INFO: task python3:107226 blocked for
more than 120 seconds.
- changing also the server kernel back from 5.15.0-122-generic to
5.15.0-112-generic only changed the error message but not the stability:
server:
kernel: [82884.774039] INFO: task split:8351 blocked for more
than 120 seconds.
Our setup:
- virtualized NFS 4.2 server with Ubuntu 22.04.5 LTS and kernel
5.15.0-122-generic
- virtualized NFS clients with Ubuntu 22.04.5 LTS and kernel 6.8.0-40-generic
or kernel 6.8.0-45-generic
- /etc/exports : /mnt/home
nfsclient(sec=krb5,rw,root_squash,sync,no_subtree_check)
- /etc/fstab : nfsserver:/mnt/home /home nfs
vers=4.2,rw,soft,sec=krb5,proto=tcp 0 0
- apt info nfs-common : Version: 1:2.6.1-1ubuntu1.2
# NFS Server error message with mainline kernel 5.15.0-122-generic :
Sep 30 01:15:51 export2.iap-kborn.de kernel: rcu: INFO: rcu_sched self-detected
stall on CPU
Sep 30 01:15:51 export2.iap-kborn.de kernel: rcu: 54-....: (14998 ticks
this GP) idle=2db/1/0x4000000000000000 softirq=32173387/32173387 fqs=7449
Sep 30 01:15:51 export2.iap-kborn.de kernel: (t=15000 jiffies
g=144775177 q=49782)
Sep 30 01:15:51 export2.iap-kborn.de kernel: NMI backtrace for cpu 54
Sep 30 01:15:51 export2.iap-kborn.de kernel: CPU: 54 PID: 153154 Comm:
kworker/u480:36 Not tainted 5.15.0-122-generic #132-Ubuntu
Sep 30 01:15:51 export2.iap-kborn.de kernel: Hardware name: Microsoft
Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v4.0
12/17/2019
Sep 30 01:15:51 export2.iap-kborn.de kernel: Workqueue: rpciod
rpc_async_schedule [sunrpc]
Sep 30 01:15:51 export2.iap-kborn.de kernel: Call Trace:
Sep 30 01:15:51 export2.iap-kborn.de kernel: <IRQ>
Sep 30 01:15:51 export2.iap-kborn.de kernel: show_stack+0x52/0x5c
Sep 30 01:15:51 export2.iap-kborn.de kernel: dump_stack_lvl+0x4a/0x63
Sep 30 01:15:51 export2.iap-kborn.de kernel: dump_stack+0x10/0x16
Sep 30 01:15:51 export2.iap-kborn.de kernel: nmi_cpu_backtrace.cold+0x4d/0x93
Sep 30 01:15:51 export2.iap-kborn.de kernel: ? lapic_can_unplug_cpu+0x90/0x90
Sep 30 01:15:51 export2.iap-kborn.de kernel:
nmi_trigger_cpumask_backtrace+0xec/0x100
Sep 30 01:15:51 export2.iap-kborn.de kernel:
arch_trigger_cpumask_backtrace+0x19/0x20
Sep 30 01:15:51 export2.iap-kborn.de kernel:
trigger_single_cpu_backtrace+0x44/0x4f
Sep 30 01:15:51 export2.iap-kborn.de kernel: rcu_dump_cpu_stacks+0x102/0x149
Sep 30 01:15:51 export2.iap-kborn.de kernel: print_cpu_stall.cold+0x2f/0xe2
Sep 30 01:15:51 export2.iap-kborn.de kernel: check_cpu_stall+0x1d8/0x270
Sep 30 01:15:51 export2.iap-kborn.de kernel: rcu_sched_clock_irq+0x9a/0x250
Sep 30 01:15:51 export2.iap-kborn.de kernel: update_process_times+0x94/0xd0
Sep 30 01:15:51 export2.iap-kborn.de kernel: tick_sched_handle+0x29/0x70
Sep 30 01:15:51 export2.iap-kborn.de kernel: tick_sched_timer+0x6f/0x90
Sep 30 01:15:51 export2.iap-kborn.de kernel: ? tick_sched_do_timer+0xa0/0xa0
Sep 30 01:15:51 export2.iap-kborn.de kernel: __hrtimer_run_queues+0x104/0x230
Sep 30 01:15:51 export2.iap-kborn.de kernel: ? read_hv_clock_tsc_cs+0x9/0x30
Sep 30 01:15:51 export2.iap-kborn.de kernel: hrtimer_interrupt+0x101/0x220
Sep 30 01:15:51 export2.iap-kborn.de kernel: hv_stimer0_isr+0x1d/0x30
Sep 30 01:15:51 export2.iap-kborn.de kernel: __sysvec_hyperv_stimer0+0x2f/0x70
Sep 30 01:15:51 export2.iap-kborn.de kernel: sysvec_hyperv_stimer0+0x7b/0x90
Sep 30 01:15:51 export2.iap-kborn.de kernel: </IRQ>
Sep 30 01:15:51 export2.iap-kborn.de kernel: <TASK>
Sep 30 01:15:51 export2.iap-kborn.de kernel:
asm_sysvec_hyperv_stimer0+0x1b/0x20
Sep 30 01:15:51 export2.iap-kborn.de kernel: RIP:
0010:read_hv_clock_tsc+0x1b/0x60
** Affects: ubuntu
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2083502
Title:
NFS4.2 crashes with high IO load after some hours
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