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Bug 1840989 - A warning message, "mtu: failure to set IPv6 MTU", is shown despite disabling ipv6 in the kernel boot parameter
Summary: A warning message, "mtu: failure to set IPv6 MTU", is shown despite disabling...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: NetworkManager
Version: 8.2
Hardware: x86_64
OS: Linux
unspecified
low
Target Milestone: rc
: 8.0
Assignee: Beniamino Galvani
QA Contact: Desktop QE
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2020-05-28 04:44 UTC by Ryosuke Yasuoka
Modified: 2023-10-06 20:18 UTC (History)
11 users (show)

Fixed In Version: NetworkManager-1.26.0-3.el8
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2020-11-04 01:49:42 UTC
Type: Bug
Target Upstream Version:
Embargoed:
pm-rhel: mirror+

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2020:4499 0 None None None 2020-11-04 01:50:19 UTC
freedesktop.org Gitlab NetworkManager NetworkManager-ci merge_requests 629 0 None None None 2020-09-09 10:50:01 UTC

Description Ryosuke Yasuoka 2020-05-28 04:44:02 UTC 
Description of problem:
A warning message related to ipv6, "mtu: failure to set IPv6 MTU", is shown despite disabling ipv6 in the kernel boot parameter.

Version-Release number of selected component (if applicable):
# uname -r
4.18.0-193.el8.x86_64

NetworkManager-1.22.8-4.el8.x86_64

How to Reproduce:
It only happens when we configure VLAN.

Steps to Reproduce:
1. add kernel boot parameter "ipv6.disable=1"

2. configure vlan like below
# nmcli c add type vlan ifname enp1s0.195 con-name enp1s0.195 id 195 dev enp1s0 ipv4.method manual ipv6.method ignore ipv4.address 192.168.122.195/24

3. up enp1s0.195
# date; nmcli con up enp1s0.195
Thu May 28 00:33:27 EDT 2020
Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/4)

4. the warning message is shown
# tail /var/log/messages
May 28 00:33:27 localhost NetworkManager[958]: <warn>  [1590640407.9435] device (enp1s0.195): mtu: failure to set IPv6 MTU
May 28 00:33:27 localhost NetworkManager[958]: <info>  [1590640407.9439] device (enp1s0.195): state change: ip-config -> ip-check (reason 'none', sys-iface-state: 'managed')
...

Expected results:
- We know that this warning message is NOT harmful and we can ignore it safely because the ipv6 is disabled correctly.
- I think this error message related to "ipv6" should not be shown while ipv6 is disabled in the kernel boot parameter.

Additional info:
At a glance at the source code of NetworkManager, I suspect that _commit_mtu() shows the warning message without checking the status of the kernel boot parameter, "ipv6.disable=1".
Comment 1 Beniamino Galvani 2020-07-23 15:39:38 UTC 
Upstream merge request:

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/585
Comment 2 Beniamino Galvani 2020-07-24 11:50:02 UTC 
Fixed upstream:

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/commit/9c09dcedafd51da65c04669b830bc9652000d462
Comment 8 errata-xmlrpc 2020-11-04 01:49:42 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (NetworkManager bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:4499
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