In the Debian 9 (EOL) operating system, there is a probability that the kernel kworker process occupies nearly 100% of the CPU even under low-load conditions.

Problem description:

When I use the top command to view the CPU usage of the instance, the kernel kworker process occupies 100% of the CPU.

Causes

This issue occurs because when the server runs workloads with a large number of bursty fragmented packets, it may get stuck in a state where the rht_shrink() function returns -EEXIST. This triggers continuous rescheduling of the delayed work of the hash table, thereby occupying the CPU core.

Learn more.

Fix Patch

Solutions

Solution 1: Replace the operating system

We recommend that you replace the operating system of the server with a non-EOL distribution, such as Debian 12.

Solution 2: Install a newer version of the kernel

In the Backports repository of Debian 9, this issue has been fixed in the kernel version 4.19+105+deb10u4~bpo9+1. You can upgrade the kernel version based on your needs. Learn more.

Last updated: 2026.06.18 17:49:50

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