hard lockup on 2.4.20 w/ nfs over frees/wan

[Shaya Potter <spotter@cs.columbia.edu>]

I'm trying to use frees/wan 1.99 w/ NFSv3.  I've been testing it w/
large r and wsize's (32k each).  When used w/o ipsec, it seems to work
fine.  When used w/ ipsec, make dep on a kernel source tree has
consistently frozen up these IBM Netfinity boxes (2*933mhz P3s w/ smp
kernel).  One time the last thing the kernel printk'd was

pcnet32.c:	    printk(KERN_ERR "%s: Bus master arbitration failure,
status %4.4x.\n",

but didn't record the status number (well it was eth0: Bus master....,
and it's using a pcnet32 controller, so assume that's the line). 
Usually it's locked up w/o printk'ing anything, last things I see on
console are the normal ipsec printk's

Is it possible that the r/w size's are causing issues when used in
conjuction w/ ipsec?  Am I triggering some sort of race condition?  The
NFS client is running the exact same kernel on the same exact hardware
and hasn't had an issue yet.

any ideas on what I can do to debug it?

thanks,

shaya