Red Hat Bugzilla – Bug 531270
TG3, kvm, ipv6 & tso data corruption bug
Last modified: 2013-01-09 06:28:53 EST
Description of problem:
Doing a large rsync-over-ssh from a RHEL 5 KVM guest (running on F12 beta) to a physical host elsewhere on my network results in a "Corrupted MAC on input." error message from ssh, which means data inside the TCP stream got corrupted.
Worse still, the packet checksum on the packet with the corrupted data is correct, because the packet did not get dropped by the receiving host. This suggests that the packet gets corrupted in-between the time the host receives the packet from the guest and the time the NIC calculates the packet's checksum.
Disabling checksum offload on the host makes the corruption go away. Possibly this is because the checksum gets calculated earlier, before the window during which packets get corrupted. Of course, I do not know the network code all that well so I may be wrong :)
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. run a RHEL 5 KVM guest on F12 beta
2. do a gigantic rsync-over-ssh from the guest to an outside system
3. wait for ssh error message
The NIC on my host is the following, which uses the tg3 driver:
05:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5761 Gigabit Ethernet PCIe (rev 10)
So far it looks like the problem only happens with ipv6 packets. I will keep running the test today to make sure of this.
OK, so far I have this info:
ipv4 => no problem
ipv6 w/ tso => data corruption
ipv6 w/o tso => no problem
It looks like either the NIC or the network driver has issues with ipv6 and TSO.
I have reported the bug upstream:
It's a long shot, but can you try this scratch build when/if it finishes? There is a fix for a TSO bug in it:
Created attachment 367852 [details]
tg3: Enable IPv6 LSO offload in hardware
This patch enables hardware IPv6 LSO offload support for the 5761
Does this patch fix the problem?
This bug appears to have been reported against 'rawhide' during the Fedora 13 development cycle.
Changing version to '13'.
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