New: Enabling 802.1q vlan causes some packets to be received with a vlan id of 64

https://bugzilla.kernel.org/show_bug.cgi?id=37172

Summary: Enabling 802.1q vlan causes some packets to be
received with a vlan id of 64
Product: Networking
Version: 2.5
Kernel Version: 2.6.39
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: normal
Priority: P1
Component: Other
AssignedTo: [email protected]
ReportedBy: [email protected]
Regression: Yes

From which kernel version did we regress? Was 2.6.38 OK?

Created an attachment (id=61502)
--> (https://bugzilla.kernel.org/attachment.cgi?id=61502)
Packet capture of problem

I added a vlan to my main network card by doing :

vconfig add eth0 6

Then I got huge packet loss when pinging e.g google (around 70% packet loss).

After checking a packet capture it seems that some packets come in with a vlan tag even though they shouldn't. In my capture I see them with a vlan id of 64 where they shouldn't even be 802.1q tagged.

Kernel version is 2.6.39 and I am using the forcedeth driver so I don't know if it is related to the network stack or the forcedeth driver.

Attached is the relevant capture. Note how packet with seq 2 for instance is tagged and packet with seq 5 isn't.

I'll test this with the latest 3.0 rc and update the bug report if the problem is fixed in there.

From which kernel version did we regress?  Was 2.6.38 OK?

Quoted 2 lines · Andrew Morton

From which kernel version did we regress?  Was 2.6.38 OK?

I can confirm this bug is present in 2.6.38.6

I'll try and see if I can reproduce it on a 2.6.37

I've tested 2.6.37.6 and 3.0.0-rc2 and the bug is still reproducible in both kernels. I'll try a 2.6.36 to see if it was present in it too.

Has this been tested on other hardware ? I'm still unsure if it's a driver issue or if it's something else.