Re: ipv6 UNH-IOL Intact test cases failure on kernel 4.4.178

On Fri, Oct 11, 2019 at 05:00:32PM +0800, Lei Chen wrote:

Hi David,
Thanks in advance for reading my message.

We are running UNH-IOL test on our product which is based on kernel
4.4.178. The INTACT test cases failed on ipv6 verification. The same test
cases just got pass on 4.4.153. (Sorry, the INTACT suite does not look to
be open sourced. Hence I don't really know what the cases were indeed
doing.)

Our verification engineer also mentioned: "The pattern of failures look
eerily similar to a regression we recently discovered in SLES 12. I.e.,
Failures related to “Parameter Problems”, as well as “Fragmentation“." We
have tried to back out the defragment related patch:

commit 5f2d68b6b5a439c3223d8fa6ba20736f91fc58d8
Author: Florian Westphal
Date:   Wed Oct 10 12:30:10 2018 -0700

    ipv6: defrag: drop non-last frags smaller than min mtu

    commit 0ed4229b08c13c84a3c301a08defdc9e7f4467e6 upstream.

    don't bother with pathological cases, they only waste cycles.
    IPv6 requires a minimum MTU of 1280 so we should never see fragments
    smaller than this (except last frag).


But it doesn't help. Could you please shed a light on which patch between
4.4.153 and 4.4.178 could have caused such a regression? Thanks again.

As you can run the test, why can't you run 'git bisect' to find the
offending patch?

thanks,

greg k-h