reproduce:
        git remote add chrome-os https://chromium.googlesource.com/chromiumos/third_party/kernel
        git fetch --no-tags chrome-os chromeos-6.1
        git checkout 138103e8979187d309ef9bcd5645825ed9170652
        # choose either of the following two methods to reproduce the issue
        # 1. reproduce by kismet
           # install kmax per https://github.com/paulgazz/kmax/blob/master/README.md
           kismet --linux-ksrc=linux --selectees CONFIG_DRM_DISPLAY_DEBUG_DP_TUNNEL_STATE --selectors CONFIG_DRM_I915_DEBUG -a=i386
        # 2. reproduce by make
           cd linux
           # download the config file from the "config:" link in the report, and save it as .config
           make ARCH=i386 olddefconfig