On my specific data it always crashes on geo searching using:
db.points.find({ loc : { $near : [50, 50] }}) - crash
db.points.find({ loc : { $near : [50, 50] }}).limit(26) - works
db.points.find({ loc : { $near : [70, 70] }}) - works

Typical data is: { "_id" : ObjectId("4b9a36c3a5ff9d0cb900c20c"), "loc" :

}
The problem is that I can't see which exactly data causes the problem.

Let me know if you need actual data and which method do you prefer to get it.