I just checked my syslog and saw a similar error as below (different CPU/PID though).  So, I cold started my box and saw the error again.  I made only two changes on the box yesterday:

 

1.  Added a new video card that will be used for a VM.

2.  Updated my Emby Server docker.

 

Possibly related to the TFTP Server docker since my OE VMs use NFS to mount the image and storage dirs?

 

Jul 14 06:13:42 unRAID kernel: ------------[ cut here ]------------
Jul 14 06:13:42 unRAID kernel: WARNING: CPU: 11 PID: 2514 at fs/nfsd/nfsproc.c:756 nfserrno+0x45/0x4c()
Jul 14 06:13:42 unRAID kernel: nfsd: non-standard errno: -38
Jul 14 06:13:42 unRAID kernel: Modules linked in: xt_CHECKSUM ipt_REJECT nf_reject_ipv4 ebtable_filter ebtables kvm_intel kvm vhost_net vhost macvtap macvlan tun iptable_mangle veth xt_nat ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_nat_ipv4 iptable_filter ip_tables nf_nat md_mod mvsas igb ahci libsas i2c_algo_bit i2c_i801 libahci scsi_transport_sas ptp pps_core ipmi_si acpi_cpufreq
Jul 14 06:13:42 unRAID kernel: CPU: 11 PID: 2514 Comm: nfsd Not tainted 4.0.4-unRAID #5
Jul 14 06:13:42 unRAID kernel: Hardware name: Supermicro X8DTH-i/6/iF/6F/X8DTH, BIOS 2.1b 05/04/12 
Jul 14 06:13:42 unRAID kernel: 0000000000000009 ffff88065682fc98 ffffffff815ff789 0000000000000000
Jul 14 06:13:42 unRAID kernel: ffff88065682fce8 ffff88065682fcd8 ffffffff810443a3 0000000000000000
Jul 14 06:13:42 unRAID kernel: ffffffff811fb7e7 ffff880662064008 ffff88058ba67d40 000000000000c000
Jul 14 06:13:42 unRAID kernel: Call Trace:
Jul 14 06:13:42 unRAID kernel: [] dump_stack+0x4c/0x6e
Jul 14 06:13:42 unRAID kernel: [] warn_slowpath_common+0x97/0xb1
Jul 14 06:13:42 unRAID kernel: [] ? nfserrno+0x45/0x4c
Jul 14 06:13:42 unRAID kernel: [] warn_slowpath_fmt+0x41/0x43
Jul 14 06:13:42 unRAID kernel: [] ? vfs_mknod+0x9e/0xd0
Jul 14 06:13:42 unRAID kernel: [] nfserrno+0x45/0x4c
Jul 14 06:13:42 unRAID kernel: [] nfsd_create+0x33c/0x35b
Jul 14 06:13:42 unRAID kernel: [] nfsd3_proc_mknod+0xef/0x14f
Jul 14 06:13:42 unRAID kernel: [] nfsd_dispatch+0x93/0x14e
Jul 14 06:13:42 unRAID kernel: [] svc_process+0x3c3/0x60f
Jul 14 06:13:42 unRAID kernel: [] nfsd+0x119/0x16b
Jul 14 06:13:42 unRAID kernel: [] ? nfsd_destroy+0x80/0x80
Jul 14 06:13:42 unRAID kernel: [] kthread+0xd6/0xde
Jul 14 06:13:42 unRAID kernel: [] ? kthread_create_on_node+0x172/0x172
Jul 14 06:13:42 unRAID kernel: [] ret_from_fork+0x58/0x90
Jul 14 06:13:42 unRAID kernel: [] ? kthread_create_on_node+0x172/0x172
Jul 14 06:13:42 unRAID kernel: ---[ end trace 46a20f78e72ff96c ]---

Definitely VM or TFTP related (I am leaning toward the latter).  I stopped/started one of my NFS netbooted OE VMs and the error popped up in the syslog again.

 

I'll try the other OE VM I have as soon as my boys go to daycare.

OK...definitely related to just the one OE VM.  I stopped/started the other one and it did not produce the error.

 

These VMs are essentially identical except for the fact that the one exhibiting the error has Retroarch and Advanced Launcher installed.  During my testing of trying to play ROMS from a network share, I did add some sources that pointed to NFS shares on my unraid box.  My guess is that they are the culprits.  I don't need them anymore so I'll remove them and see if the error ceases.

Consider this solved.  Was definitely related to that one VM.  It was also getting a "failed to start commoncache" error in Kodi.  I just rebuilt the VM and the error is gone.

 

This is what I get for trying other skins.