pg_upgrade: out of memory

Hi!

While running pg_upgrade, on one instance, it ran out of memory during the
final stages of upgrade
(just before it starts to "link" old database files to new ones).

We are using Postgres 9.1.1, and I see that there were some fixes to
pg_upgrade in 9.1.2, though
it doesn't mention anything about memory issues as such.

Wondering if anyone has run into a similar type of situation, and if so,
how to solve it?

Also, is it possible to recover the database once pg_upgrade aborts in this
manner?

Here's an excerpt from the log while running pg_upgrade:
...
"bin/pg_ctl" -w -D "data" stop
waiting for server to shut down....LOG: received smart shutdown request
LOG: shutting down
.......LOG: database system is shut down
. done
server stopped
Restoring user relation files
Restoring user relation files
pg_upgrade: out of memory

pg_upgrade: out of memory

Thanks for any pointers,

Deepak