Public bug reported:

uname -a
Linux Laptop 2.6.24-19-generic #1 SMP Wed Aug 20 22:56:21 UTC 2008 i686 
GNU/Linux

java -version
java version "1.6.0_06"
Java(TM) SE Runtime Environment (build 1.6.0_06-b02)
Java HotSpot(TM) Server VM (build 10.0-b22, mixed mode)

sysctl vm.overcommit_memory=2
(if you're unlucky fork will fail right from there on! so don't try this when 
you got importand files open)

then start java (or anything else..)

java
Error occurred during initialization of VM
Could not reserve enough space for object heap
#
# An unexpected error has been detected by Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0xb7dee4da, pid=7477, tid=3084225424
#
# Java VM: Java HotSpot(TM) Server VM (10.0-b22 mixed mode linux-x86)
# Problematic frame:
# C  [libc.so.6+0x6f4da]  cfree+0x7a
#
# An error report file with more information is saved as:
# /home/john/hs_err_pid7477.log
#
# If you would like to submit a bug report, please visit:
#   http://java.sun.com/webapps/bugreport/crash.jsp
#
Aborted

This is just a java example. Other applications segfault. The problem
itself is the kernel memory overcommitment and the resulting oom. To
disable it or to trying out a workaround.. just makes things worse.
Maybe the vm.overcommit_memory was a bad advice i read somewhere.

There is a lot of memory free. So this error is just.. i see no reason
for this. Is the kernel memory management so dependent on the bad
behavior of overcommiting memory?

To return to the default:

sysctl vm.overcommit_memory=0

and java works again.


Further reading to show that this seems to be a well known problem for years - 
still not fixed. There they just ask for the 'kernel version' but it's there 
since all those versions.
http://www.redhat.com/archives/rhl-devel-list/2005-February/msg00671.html

I got enabled swap. I got enough RAM. So all those factors are allright.
Still the kernel faults with crappy memory management from time to time.

Some more information rich reading about kernel memory:
http://www.win.tue.nl/~aeb/linux/lk/lk-9.html

** Affects: ubuntu
     Importance: Undecided
         Status: New

-- 
Kernel memory disable overcommitment - java and other things dysfunctional
https://bugs.launchpad.net/bugs/267100
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