Machine seems to shutdown while running hw test in M52 branch

@@@STEP_FAILURE@@@
01:52:10: ERROR: Traceback (most recent call last):
  File "/b/cbuild/shared_internal/chromite/cbuildbot/stages/generic_stages.py", line 511, in Run
    self.PerformStage()
  File "/b/cbuild/shared_internal/chromite/cbuildbot/stages/test_stages.py", line 380, in PerformStage
    debug=debug, subsystems=subsystems, skip_duts_check=skip_duts_check)
  File "/b/cbuild/shared_internal/chromite/cbuildbot/failures_lib.py", line 160, in wrapped_functor
    return functor(*args, **kwargs)
  File "/b/cbuild/shared_internal/chromite/cbuildbot/commands.py", line 899, in RunHWTestSuite
    _HWTestWait(cmd, job_id, **swarming_args)
  File "/b/cbuild/shared_internal/chromite/cbuildbot/commands.py", line 1126, in _HWTestWait
    **kwargs)
  File "/b/cbuild/shared_internal/chromite/cbuildbot/swarming_lib.py", line 142, in RunSwarmingCommandWithRetries
    return retry_util.RetryCommand(RunSwarmingCommand, max_retry, *args, **kwargs)
  File "/b/cbuild/shared_internal/chromite/lib/retry_util.py", line 180, in RetryCommand
    return GenericRetry(ShouldRetry, max_retry, functor, *args, **kwargs)
  File "/b/cbuild/shared_internal/chromite/lib/retry_util.py", line 88, in GenericRetry
    ret = functor(*args, **kwargs)
  File "/b/cbuild/shared_internal/chromite/cbuildbot/swarming_lib.py", line 87, in RunSwarmingCommand
    result = cros_build_lib.RunCommand(swarming_cmd, *args, **kwargs)
  File "/b/cbuild/shared_internal/chromite/lib/cros_build_lib.py", line 589, in RunCommand
    (cmd_result.output, cmd_result.error) = proc.communicate(input)
  File "/usr/lib/python2.7/subprocess.py", line 796, in communicate
    self.wait()
  File "/usr/lib/python2.7/subprocess.py", line 1376, in wait
    pid, sts = _eintr_retry_call(os.waitpid, self.pid, 0)
  File "/usr/lib/python2.7/subprocess.py", line 476, in _eintr_retry_call
    return func(*args)
  File "/b/cbuild/shared_internal/chromite/lib/cros_build_lib.py", line 341, in _KillChildProcess
    if not signals.RelaySignal(original_handler, signum, frame):
  File "/b/cbuild/shared_internal/chromite/lib/signals.py", line 26, in RelaySignal
    handler(signum, frame)
  File "/b/cbuild/shared_internal/chromite/lib/commandline.py", line 731, in _DefaultHandler
    signum, 'Received signal %i; shutting down' % (signum,))
_ShutDownException: (15, 'Received signal 15; shutting down')

Link to build failure log:
https://uberchromegw.corp.google.com/i/chromeos_release/builders/banjo-release%20release-R52-8350.B/builds/26/steps/HWTest%20%5Bsanity%5D/logs/stdio