Here is a 2.4.28 patch that allows core dumps to be written on
fileystems mounted with the 'intr' option.

By setting the PF_DUMPCORE bit in the current->flags (via
do_coredump()), I was able to signal the RPC and NFS code that
the current task is trying to dump a core. So the trick was to have
the rpc code (temporarily) ignore the fact  the task got signalled()
and let the write/commit path complete....

I do this by checking the PF_DUMPCORE bit in both  __rpc_execute()
and  nfs_wait_event(). One side effect is the dropping core process
becomes uninterruptable.... I combat this by only allowing the process
three retries before giving up...

Finally there are two placing in the NFS code where I don't ignore
the signal and do fail the writing of the core. One, is in 
nfs_create_request()
when there are no available pages and in nfs3_rpc_wrapper() when
the server returns EJUKEBOX. But I did place printks so it will be clear
as to why it failed....

Comments... Suggestions... Crimes against humanity that I'm committing???

steved.