Comment 31 for bug 1294283

As a way to validate if equivalent patches have been submitted, the Linux-Next kernel from April 15, 2015 was built and installed on a 14.10 Gen 2 VM. After rebooting into the Linux-Next kernel (version 4.0.0-next-20150415), ballooning worked.
Tested dynamic memory configuration:
    Minimum Memory: 1024MB
    Startup Memory : 2048MB
    Maximum Memory: 4096MB
    Memory buffer: 20%
    Memory Weight: 50

Two minutes after booting, memory was ballooned down from 2048MB to 1024MB
Ran stressapptest to generate 600MB of memory demand
Memory was ballooned up to 1762MB
After memory demand was removed, memory was ballooned down to 1024MB

Ballooning does work with the upstream kernel on a Ubuntu 14.10 Gen 2 VM.