Excessive swapping under Linux 4.14.91 (no issues in 4.14.90).

From: Hussam Al-Tayeb
Date: Thu Jan 03 2019 - 14:49:27 EST

Hello. My system has 16GB of ram. Before kernel 4.14.91, it would use about 700KBytes to 1MB of the swap if the memory usage was 4 to 5GB in use out of 16GB (15.6 actually).

After upgrading to 4.14.91, I am seeing 500 to 700MB of swap usage even under low memory pressure situations. For example, 3.5GB used out of 16GB.

I downgraded to 4.14.90 and the excessive swapping stopped. I upgraded to 4.14.91 and the heavy swapping came back.

Any idea how I can gather information to tell what is happening?

The machine always has the same services and applications running so I am sure this is a kernel issue. It hasn't received any non-kernel updates in months. This narrows the issue down to the kernel.

Thank you.