Hi Grant,

On Thu, Jun 04, 2015 at 09:35:04AM -0700, Grant Zhang wrote:

Hi Neal,

Unfortunately with the patch we still see the same stack trace.
Attached is the TcpExtTCPSACKReneging with the patch, captured with
60 seconds interval. Its value is incremented at an similar speed as
before, about 30/minute.

If you want to collect any other data, please feel free to let me know.

We are also seeing similar WARN_ON stack in our kernel 4.0 testing.

What is your net.ipv4.tcp_mtu_probing setting?  I am currently testing some
code changes and waiting for some more data.  If it is 1 or 2,
can you help to check whether turning it off (by setting it to 0) will stop the
WARN_ON or not in your environment?  Note that after setting it to 0, you
may need to wait for a while (like a few mins) for the existing probing
activities to quiet down before observing the WARN_ON output.

Thanks,
--Martin