extreme behavior of nfsubfields()

[Igor Schein <igor@txc.com>]

Hi,

I need to find a degree-27 subfield of a non-Galois degree-81
polynomial.  When I run nfsubfields(), it returns "too many blocks".
So I increased the value of oldllist inside choose_prime() from 10^6
to 5*10^7, and ran gp with 2048MB stack on 32bit Linux.  In a few
seconds, I saw the screen filled with "***   bug in  ***   bug in  ***
bug in  *** bug in  ***   bug in  ***   bug in  ***".   If I reduce
stack size to 1900MB, I'm getting a nicer "not enough memory".  When I
tried the same on 32bit Solaris with 2048MB stack, the session just
died with SEGV.  I'll see what happens with 64bit binary, but I'm
skeptical.

Thanks

Igor