Bug 198723 - data corruption with big mtu
Summary: data corruption with big mtu
Status: NEW
Alias: None
Product: Drivers
Classification: Unclassified
Component: Network (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: drivers_network@kernel-bugs.osdl.org
Depends on:
Reported: 2018-02-08 10:27 UTC by Andreas Pflug
Modified: 2018-03-25 06:12 UTC (History)
1 user (show)

See Also:
Kernel Version: 4.13 and up
Tree: Mainline
Regression: No


Description Andreas Pflug 2018-02-08 10:27:08 UTC
I've been running for quite a while two Debian9 machines with 4.9 kernel, with DRBD syncing data between them. The link is directly connected Intel X540-AT2, with default settings except for MTU bumped to 9710; driver is ixgbe V4.4.0-k.

After upgrading to Kernel 4.13 (which includes ixgbe Version 5.1.0-k), I get some dozen kernel logs from DRBD (which is the same version on 4.9 and 4.13)  stating that invalid header magics were received. tcpdump shows out-of-line data.

Testing with 4.14.7, I get the same problem. Switching MTU back to 1500 fixes the problem, so does disabling scatter-gather (which includes tso; disabling tso alone doesn't help)
Comment 1 Andreas Pflug 2018-02-12 16:04:04 UTC
Apparently, disabling scatter-gather does NOT fix the problem, seeing the same again.
large-receive-offload is off (default value), disabling gso and gro doesn't help either. So apparently only cutting mtu down to default 1500 helps.

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