Comment 29 for bug 582264

I've upgraded to kernel 2.6.37-12-generic, and the problem seems to be much harder to trigger, but it was still possible. It seems to be triggered by low-memory conditions:

1) I used the KDE file manager and navigated to a directory containing a lot of images, so that it started to create thumbnails
2) I started Python and had it create an endless list of junk:

a = list()
while(True):
 a.append(1)

As memory ran out, the entire system started grinding to a halt, ignoring keyboard and mouse input, dropping network traffic and using the disk for some mysterious purpose as before (as mentioned, I don't use swap, so it's not that).

I was able to get to the console eventually and run "top", and top showed two things:
1) A high "wa" value, which seems to mean that the CPU is waiting for I/O? But that value is at around 13% now, and everything's running smoothly.
2) Python was taking up a great deal of memory.

Killing Python resolved the problem immediately, and nothing else crashed, unlike with the previous kernel. But that still means that an unprivileged user running Python can stall the entire system by creating a list.