I'd tried to advocate SIGDANGER some years ago as well, but none of
the kernel maintainers were interested.  It definitely makes sense
to have some sort of mechanism like this.  At the time I first brought
it up it was in conjunction with Netscape using too much cache on some
system, but it would be just as useful for all kinds of other memory-
hungry applications.

There is an early thread for a /proc file which you can add to your
poll() set and it will wake people when memory is low. Very elegant and
if async support is added it will also give you the signal variant for
free.

Alan