Find processes which have a file open without lsof or fuser

I'm working on a Linux (Scientific Linux CERN SLC release 6.9 (Carbon)) machine on which I am unable to install programs and on which the lsof or fuser commands are not available. I'm trying to remove an NFS dotfile on this machine but I keep getting the Device or resource busy error so I'd like to find out which process (I suspect it might be one I have previously started with nohup) still has a file descriptor to this file. How can I achieve this?