cooperating with the VM when memory pressure increases
notify user applications of virtual memory events via real-time signals
http://www.cs.umass.edu/~emery/pubs/bookmarking-collector/, and discussion at http://lambda-the-ultimate.org/node/2391 and http://marc.info/?t=113269321800003&r=1&w=2.
Found this via http://lambda-the-ultimate.org/node/4094#comment-62100, which was linked from LWN.
From a quick glance, this sounds to me quite a bit like mechanisms also found in (originating in?) Mach's external pager mechanism. May be worth having a look at it.