Enable CONFIG_USERFAULTFD in Talos kernel builds

[boddumanohar]

Summary

Please enable the CONFIG_USERFAULTFD kernel configuration option in Talos Linux kernel builds.

This option is required for workloads and tools that rely on lazy memory migration or user-space page fault handling, such as advanced live migration systems and certain container runtime features.

Background / Motivation

We are testing a feature that performs lazy migration of memory contents using userfaultfd.
This feature requires that the kernel is built with:

CONFIG_USERFAULTFD=y

However, as of Talos v1.11.3, /dev/userfaultfd is not present, and inspection suggests that CONFIG_USERFAULTFD is not enabled in the current Talos kernel configuration.

Benefits

Enables support for user-space memory fault handling (used by CRIU, QEMU live migration, Kata Containers, etc.). Aligns Talos kernel capabilities with mainstream Linux distributions and cloud OSes.

References

Kernel documentation: https://www.kernel.org/doc/html/latest/admin-guide/mm/userfaultfd.html
Example use cases: QEMU live migration, container lazy memory migration, and CRIU.

Talos Version

v1.11.3

[smira]

We will consider this, it is disabled due to being against best security practices.