[Observium] Incorrect memory graph for large RAM amount

Hi,

Just discovered a weirdness when I added a server that has 3TB of RAM : the ucd_memory graph is totally messed up. It only displays negative amount of Cache/Shared buffers.

The legend shows that it didn't handle the 3TB correctly.  But it seems to be fine for the health/memory view where the correct amount is displayed everywhere.

I have attached the debug output of the poller for this device. Best regards, Louis