Linux VM error on Azure: kernel: serial8250: too much work for irq4

Question

_{Thursday, October 4, 2018 8:36 AM}

Hi,

Just having this error below on my new deployed Linux CentOS VM.

Apparently it is a known issue with virtualization platforms, and I have found on stackexchange this info: "The problem is that the UART hardware that is emulated by various brands of virtual machine behaves impossibly, sending characters at an impossibly fast line speed." (https://unix.stackexchange.com/questions/387600/understanding-serial8250-too-much-work-for-irq4-kernel-message)

**kernel: serial8250: too much work for irq4

ANY IDEA HOW TO WORK THIS AROUND?**

My Linux version below:

CentOS Linux release 7.5.1804 (Core)

Linux XXX 3.10.0-862.11.6.el7.x86_64

All replies (10)

_{Thursday, October 4, 2018 6:09 PM}

Can you tell me what image you used when deploying from the portal? You mention CentOS and the version but I do not see that specific one listed

_{Monday, October 8, 2018 7:22 AM}

Hi,

I have chosen that VM Image from the drop down list on the page "Create a virtual machine", written as: "CentOS-based 7.5".

I couldn't upload the screenshot as apparently my account needs to be somehow verified.

Cheers :-)

_{Monday, October 8, 2018 7:57 AM}

Hi,

I get this error on my console every 3 minutes or so, it is appearing after I deployed docker.

Apparently it is related to NIC card.

My Linux version below:

CentOS Linux release 7.5.1804 (Core)

Linux XXX 3.10.0-862.11.6.el7.x86_64

Any idea on what it is?, thanks.

21.397762 INFO ExtHandler Updated NIC state: [{ "name": "lo", "link": "<LOOPBACK,UP,LOWER_UP> mtu 65536qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000\   link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 promiscuity 0 addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 " }, { "name": "docker0", "link": "<NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN mode DEFAULT group default \   link/ether 02:42:45:34:a2:90 brd ff:ff:ff:ff:ff:ff promiscuity 0 \   bridge forward_delay 1500 hello_time 200 max_age 2000 ageing_time 30000 stp_state 0 priority 32768 vlan_filtering 0 vlan_protocol 802.1Q bridge_id 8000.2:42:45:34:a2:90 designated_root 8000.2:42:45:34:a2:90 root_port 0 root_path_cost 0 topology_change 0 topology_change_detected 0 hello_timer    0.00 tcn_timer    0.00 topology_change_timer    0.00 gc_timer  251.65 vlan_default_pvid 1 vlan_stats_enabled 0 group_fwd_mask 0 group_address 01:80:c2:00:00:00 mcast_snooping 1 mcast_router 1 mcast_query_use_ifaddr 0 mcast_querier 0 mcast_hash_elasticity 4 mcast_hash_max 512 mcast_last_member_count 2 mcast_startup_query_count 2 mcast_last_member_interval 100 mcast_membership_interval 26000 mcast_querier_interval 25500 mcast_query_interval 12500 mcast_query_response_interval 1000 mcast_startup_query_interval 3125 mcast_stats_enabled 0 mcast_igmp_version 2 mcast_mld_version 1 nf_call_iptables 0 nf_call_ip6tables 0 nf_call_arptables 0 addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 " }, { "name": "eth0", "link": "<BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen1000\   link/ether 00:0d:3a:46:0e:bc brd ff:ff:ff:ff:ff:ff promiscuity 0 addrgenmode eui64 numtxqueues 64 numrxqueues 64 gso_max_size 62780 gso_max_segs 65535 " }]

_{Monday, October 8, 2018 5:44 PM}

What size Virtual machine are you trying with? 

I created a VM from that same image under a DS2_V3 and was able to deploy and connect without any error. 

Also, when do you see this error? When connecting via SSH? 

_{Tuesday, October 9, 2018 7:41 AM}

Hi,

Regarding size:

Standard D2s v3 (2 vcpus, 8 GB memory)

OS HDD: 30GB

Is there a connection with deploying docker and this "NIC state error"?.

All I did was to execute this docker installation script: curl -sSL https://get.docker.com/ | sh

How do I connect?:

I connect to the VM only via serial console, but If I check the /var/log/messages, it is totally full with entries like: "INFO ExtHandler Updated NIC state", and still see this one too: "kernel: serial8250: too much work for irq4".

I'm not a master user of Azure as a cloud solution, but before I have deployed VM's on AWS and Google Cloud and I didn't have any issues. 

I have just installed 2 more VM's and I get the same issue with error "INFO ExtHandler Updated NIC state".

So far I'm clueless, hoping that someone knows what it is, cheers.

_{Tuesday, October 9, 2018 7:37 PM}

Thanks for the extra details. I have not been able to repro this issue. 

Do you have the ability to open a technical support ticket? If not, you can email me at [email protected] and provide me with your subscriptionID and link to this thread. 

I can enable one for you. 

This will allow us to get you in contact with a Linux engineer to have this looked into further. 

_{Wednesday, October 10, 2018 12:20 PM}

Hi,

Unfortunately I cannot raise support tickets as I'm using the Free Trial.

I'm going to email you and provide all the requested information.

Thanks a lot for the time you put on this issue :-)

_{Wednesday, October 17, 2018 3:18 PM}

Hi, Did you found the solution for this ? I got it also.

_{Monday, October 22, 2018 12:42 PM}

I get this "ExtHandler Updated NIC state", too. What seems to be happening is the "gc_timer" on the docker0 and docker_gwbridge interfaces is changing each time the WA Linux agent looks at it. This is with Ubuntu Server 18.04, walinuxagent 2.2.21+really2.2.20-0ubuntu3, WALinuxAgent-2.2.32.2-py2.7.egg.

I opened a ticket in Azure.

_{Tuesday, November 6, 2018 2:07 AM}

***UPDATE FOR ALL****

It seems the problem was coming from the Azure Linux Agent. It was causing these messages to spam. We disabled the Linux Agent and it corrected the issue. However, generally you want to have the linux agent installed as it helps with managing your VM. 

I am following up to see what a long term fix will be and will update when I have something.