Comment 11 for bug 845158

The reason why this bug happens are that some process, currently unknown to us which one, have locked and keeps on holding the kernel &mm->mmap_sem lock without releasing it.

When java hits a pagefault then the Linux kernel needs to aquire this lock in order to serve the pagefault, it waits, and wait for this lock to become available again, unfortunally in this case the kernel waits forever...

note that this bug also prevents other tools from operating like
ps ax

http://www.kernel.org/doc/Documentation/vm/locking