GNOME Bugzilla – Bug 752508
NetworkManager 1.0.4 minimizes MTU
Last modified: 2015-08-04 11:45:42 UTC
I'm seeing this in the journal: <warn> (wlp3s0): Lowering IPv6 MTU (1472) to match device MTU (0) <warn> (wlp3s0): IPv6 MTU (0) smaller than 1280, adjusting <warn> (wlp3s0): Raising device MTU (0) to match IPv6 MTU (1280) <error> [1437068831.306733] [platform/nm-linux-platform.c:2440] sysctl_set(): platform-linux: sysctl: failed to set '/proc/sys/net/ipv6/conf/wlp3s0/mtu' to '1472': (22) Invalid argument The MTU of my wireless device should be set to 1472, but is actually set to 1280. Writing to /proc/sys/net/ipv6/conf/wlp3s0/mtu reproduces the "Invalid argument" error. "ip l set dev wlp3s0 mtu 1472" works as expected and also updates the ipv6 MTU. Linux 4.1.2 Network controller: Intel Corporation Wireless 7260 (rev 73)
Created attachment 307772 [details] Suggested fix
(In reply to Lubomir Rintel from comment #1) > Created attachment 307772 [details] > Suggested fix does this also decrease the number of logging message? Maybe also lower the severity, is it really an issue worth to warn?
Created attachment 308205 [details] Lower logging serverity (In reply to Thomas Haller from comment #2) > (In reply to Lubomir Rintel from comment #1) > > Created attachment 307772 [details] > > Suggested fix > > does this also decrease the number of logging message? Maybe also lower the > severity, is it really an issue worth to warn? I believe that belongs to a separate patch (attached).
(In reply to Lubomir Rintel from comment #3) > Created attachment 308205 [details] > Lower logging serverity > > (In reply to Thomas Haller from comment #2) > > (In reply to Lubomir Rintel from comment #1) > > > Created attachment 307772 [details] > > > Suggested fix > > > > does this also decrease the number of logging message? Maybe also lower the > > severity, is it really an issue worth to warn? > > I believe that belongs to a separate patch (attached). I agree with "separate patch" and lowering the logging severity. But can we not combine the 3 logging statements? I used to see all three lines about lowering, raising and setting MTU. That seems far too many lines. Let's just log one concise message.
Both commits LGTM. I agree with Thomas about combining the log messages into one if we can, I don't think we have that many cases here to work with. I tried for 5 minutes to come up with some short code for this but failed, but maybe it just takes a bit longer.
(In reply to Thomas Haller from comment #4) > But can we not combine the 3 logging statements? I used to see all three > lines about lowering, raising and setting MTU. That seems far too many > lines. Let's just log one concise message. Yeah, but that was due to the bug that's reported here. With the patches applied you'll just get the log lines in exceptional cases (RA trying to lower the MTU too much).
f7f9e73 device: lower serverity of MTU adjustment logging a92d8b0 device: don't modify the device MTU if it's unset