mbuf_jumbo_9k & iSCSI failing

[Ryan Stone]

Is this setup using the mlx4_en driver?  If so, recent versions of that
driver has a regression when using MTUs greater than the page size (4096 on
i386/amd64).  The bug will cause the card to drop packets when the system
is under memory pressure, and in certain causes the card can get into a
state when it is no longer able to receive packets.  I am working on a fix;
I can post a patch when it's complete.