linux-kernel - [PATCH v8 0/2] Live Update: File-Lifecycle-Bound (FLB) State

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Message-ID: <20251125225006.3722394-1-pasha.tatashin@soleen.com>
Date: Tue, 25 Nov 2025 17:50:04 -0500
From: Pasha Tatashin <pasha.tatashin@...een.com>
To: pratyush@...nel.org,
	pasha.tatashin@...een.com,
	rppt@...nel.org,
	dmatlack@...gle.com,
	skhawaja@...gle.com,
	rientjes@...gle.com,
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	akpm@...ux-foundation.org,
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	davidgow@...gle.com,
	pmladek@...e.com,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCH v8 0/2] Live Update: File-Lifecycle-Bound (FLB) State

This series adds support for FLB state to the Live Update Orchestrator.

This functionality was originally part of the main LUO series [1] but
has been split out to serve as a stable dependency for upcoming device
preservation series.

What is FLB?
============
FLB allows global kernel state (like IOMMU domains or HugeTLB state) to
be preserved once, shared across multiple file descriptors, and restored
when needed. It uses reference counting tied to the lifecycle of
preserved files (e.g., VFIO fds) to ensure the global state is valid
as long as any file depends on it.

Why separate?
=============
This patch does not have current user user, but multiple streams depend
on it:

1. VFIO LU preservation (ETA: Tomorrow)
2. IOMMU LU preservation (ETA: One week)
3. HugeTLB LUO preservation (ETA: A couple weeks)

Merging this into linux-next allows these dependent series to be
developed against the same API.

Github repo for this series: [2].

Dependencies
============
This series applies on top of [PATCH v8] Live Update Orchestrator [1].

[1] https://lore.kernel.org/all/20251125165850.3389713-1-pasha.tatashin@soleen.com
[2] https://github.com/soleen/linux/tree/luo/flb_v8

Pasha Tatashin (2):
  liveupdate: luo_flb: Introduce File-Lifecycle-Bound global state
  tests/liveupdate: Add in-kernel liveupdate test

 Documentation/core-api/liveupdate.rst |  11 +
 MAINTAINERS                           |   1 +
 include/linux/kho/abi/luo.h           |  81 ++++
 include/linux/liveupdate.h            | 143 ++++++
 kernel/liveupdate/Makefile            |   1 +
 kernel/liveupdate/luo_core.c          |   7 +-
 kernel/liveupdate/luo_file.c          |  32 +-
 kernel/liveupdate/luo_flb.c           | 656 ++++++++++++++++++++++++++
 kernel/liveupdate/luo_internal.h      |  15 +
 lib/Kconfig.debug                     |  23 +
 lib/tests/Makefile                    |   1 +
 lib/tests/liveupdate.c                | 158 +++++++
 12 files changed, 1125 insertions(+), 4 deletions(-)
 create mode 100644 kernel/liveupdate/luo_flb.c
 create mode 100644 lib/tests/liveupdate.c

base-commit: c26edadff67601d5bbd748ea404ca354d9d47997
-- 
2.52.0.487.g5c8c507ade-goog