uberAgent determines and reports the GPU memory usage. This happens if the GpuUsage configuration option is enabled (default: yes). GPU memory and compute usage are determined for every process that is using the GPU as part of the ProcessDetail sourcetype.
In rare occasions we have observed that the reported GPU memory usage is far too high. In those cases the ProcGpuMemMB field would reach values as high as 17592178311168.
In the observed cases the cause of the high values was a broken Citrix XenDesktop graphics driver that would cause display issues, too. The issue could be fixed by uninstalling and reinstalling the Citrix XenDesktop VDA (including a reboot after uninstall and reinstall).