This was originally reported by a partner

It seems that CrOS low mem notifications are broken on 4.14
I ran platform_CompressedSwap on a Samus running 4.14 and it consistently fails

17:51:23 INFO | Writing results to /usr/local/autotest/results/default
17:51:23 INFO | START   ----    ----    timestamp=1531356683    localtime=Jul 11 17:51:23
17:51:23 INFO | File /var/lib/cleanup_logs_paused was already present
17:51:23 INFO |         START   platform_CompressedSwap platform_CompressedSwap timestamp=1531356683    localtime=Jul 11 17:51:23  
17:51:23 INFO | Starting before_hook for platform_CompressedSwap
17:51:23 INFO | before_hook completed
17:51:23 INFO | ChromeOS BOARD = samus_2.7GHz_2GB
17:51:23 INFO | Swap enable (nonexistent), requested 2987683, total 2917656
17:53:21 INFO | Finished creating 58 hogs, SwapFree 0, MemFree 121824, low mem at 0, oom at 0
17:53:26 INFO | SwapFree was 0 before cleanup, 2442236 after.
17:53:26 WARNI| The test failed with the following exception
Traceback (most recent call last):
  File "/usr/local/autotest/common_lib/test.py", line 631, in _exec
    _call_test_function(self.execute, *p_args, **p_dargs)
  File "/usr/local/autotest/common_lib/test.py", line 831, in _call_test_function
    return func(*args, **dargs)
  File "/usr/local/autotest/common_lib/test.py", line 495, in execute
    dargs)
  File "/usr/local/autotest/common_lib/test.py", line 362, in _call_run_once_with_retry
    postprocess_profiled_run, args, dargs)
  File "/usr/local/autotest/common_lib/test.py", line 400, in _call_run_once
    self.run_once(*args, **dargs)
  File "/usr/local/autotest/tests/platform_CompressedSwap/platform_CompressedSwap.py", line 162, in run_once
    raise error.TestFail('We did not get low memory notification!')
TestFail: We did not get low memory notification!
17:53:26 INFO | Starting after_hook for platform_CompressedSwap

The system is running with only 2GB of memory and the margin was set to 101 
I tried raising it to 200 and 400 and the test was still failing

I had originally thought the notifications were working because platform_MemoryPressure was reporting discards but it may have actually been hitting OOMs.