These patches are taken from the LUOv4 series [1] and address recent comments from Pratyush.
They apply onto mm/mm-nonmm-unstable.
This series refactors the KHO framework to better support in-kernel users like the upcoming LUO. The current design, which relies on a notifier chain and debugfs for control, is too restrictive for direct programmatic use.
The core of this rework is the removal of the notifier chain in favor of a direct registration API. This decouples clients from the shutdown-time finalization sequence, allowing them to manage their preserved state more flexibly and at any time.
In support of this new model, this series also: - Exports kho_finalize() and kho_abort() for programmatic control. - Makes the debugfs interface optional. - Introduces APIs to unpreserve memory and fixes a bug in the abort path where client state was being incorrectly discarded. Note that this is an interim step, as a more comprehensive fix is planned as part of the stateless KHO work [2]. - Moves all KHO code into a new kernel/liveupdate/ directory to consolidate live update components.
[1] https://lore.kernel.org/all/20250929010321.3462457-1-pasha.tatashin@soleen.c... [2] https://lore.kernel.org/all/20251001011941.1513050-1-jasonmiu@google.com
Mike Rapoport (Microsoft) (1): kho: drop notifiers
Pasha Tatashin (6): kho: allow to drive kho from within kernel kho: make debugfs interface optional kho: add interfaces to unpreserve folios and page ranges kho: don't unpreserve memory during abort liveupdate: kho: move to kernel/liveupdate liveupdate: kho: move kho debugfs directory to liveupdate
Documentation/core-api/kho/concepts.rst | 2 +- MAINTAINERS | 3 +- include/linux/kexec_handover.h | 53 +- init/Kconfig | 2 + kernel/Kconfig.kexec | 24 - kernel/Makefile | 3 +- kernel/kexec_handover_internal.h | 16 - kernel/liveupdate/Kconfig | 39 ++ kernel/liveupdate/Makefile | 5 + kernel/{ => liveupdate}/kexec_handover.c | 513 +++++++----------- .../{ => liveupdate}/kexec_handover_debug.c | 0 kernel/liveupdate/kexec_handover_debugfs.c | 219 ++++++++ kernel/liveupdate/kexec_handover_internal.h | 56 ++ lib/test_kho.c | 30 +- mm/memblock.c | 62 +-- tools/testing/selftests/kho/init.c | 2 +- tools/testing/selftests/kho/vmtest.sh | 1 + 17 files changed, 576 insertions(+), 454 deletions(-) delete mode 100644 kernel/kexec_handover_internal.h create mode 100644 kernel/liveupdate/Kconfig create mode 100644 kernel/liveupdate/Makefile rename kernel/{ => liveupdate}/kexec_handover.c (80%) rename kernel/{ => liveupdate}/kexec_handover_debug.c (100%) create mode 100644 kernel/liveupdate/kexec_handover_debugfs.c create mode 100644 kernel/liveupdate/kexec_handover_internal.h
base-commit: 4d90027271cfa0d89473d1e288af52fda9a74935