After several intermittent freeze-ups, an Ubuntu server refused to start, stalling when reaching kernel panic error. The following error was displayed:
kernel panic: out of memory and no killable processes
There may be several possible reasons for this error but before wrecking your noggin with the more complex causes, try a simple solution to eliminate the possibility of a hardware problem.
Before proceeding to troubleshoot the more complex causes, I suggest removing RAM down to the least possible amount (single DIMM if possible), swap DIMMs and test different banks to eliminate faulty memory controllers and corrupt DIMMs as the root cause.
The above error can be cause by faulty RAM, as was our case. A defective DIMM was the root cause of the problem. Our server had 2 x 2 GB DIMM modules for a total of 4GB. The total 4GB was being seen and reported by the motherboard to the OS however, the OS kernel was unable to access the entire 4GB memory because one of the DIMMS was defective. After removing the memory stick, the system was able to boot with only 2 GB.
As an attestation of how efficient Linux and some of its application developers are, our Ubuntu-based BBB virtual classroom server ran perfectly fine on only 2 GB RAM for several days until we were able to replace the faulty DIMMs.