This series addresses comments and combines into one the two series [1] and [2], and adds review-bys.
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. Also, this series fixes a memory corruption bug in KHO that occurs when KFENCE is enabled. The root cause is that KHO metadata, allocated via kzalloc(), can be randomly serviced by kfence_alloc(). When a kernel boots via KHO, the early memblock allocator is restricted to a "scratch area". This forces the KFENCE pool to be allocated within this scratch area, creating a conflict. If KHO metadata is subsequently placed in this pool, it gets corrupted during the next kexec operation. [1] https://lore.kernel.org/all/[email protected] [2] https://lore.kernel.org/all/[email protected] Mike Rapoport (Microsoft) (1): kho: drop notifiers Pasha Tatashin (9): kho: allow to drive kho from within kernel kho: make debugfs interface optional kho: add interfaces to unpreserve folios and page ranes kho: don't unpreserve memory during abort liveupdate: kho: move to kernel/liveupdate kho: move kho debugfs directory to liveupdate liveupdate: kho: warn and fail on metadata or preserved memory in scratch area liveupdate: kho: Increase metadata bitmap size to PAGE_SIZE liveupdate: kho: allocate metadata directly from the buddy allocator Documentation/core-api/kho/concepts.rst | 2 +- MAINTAINERS | 3 +- include/linux/kexec_handover.h | 53 +- init/Kconfig | 2 + kernel/Kconfig.kexec | 15 - kernel/Makefile | 2 +- kernel/liveupdate/Kconfig | 38 ++ kernel/liveupdate/Makefile | 5 + kernel/{ => liveupdate}/kexec_handover.c | 588 +++++++++----------- kernel/liveupdate/kexec_handover_debug.c | 25 + kernel/liveupdate/kexec_handover_debugfs.c | 216 +++++++ 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 + 16 files changed, 645 insertions(+), 455 deletions(-) create mode 100644 kernel/liveupdate/Kconfig create mode 100644 kernel/liveupdate/Makefile rename kernel/{ => liveupdate}/kexec_handover.c (78%) create mode 100644 kernel/liveupdate/kexec_handover_debug.c create mode 100644 kernel/liveupdate/kexec_handover_debugfs.c create mode 100644 kernel/liveupdate/kexec_handover_internal.h base-commit: f406055cb18c6e299c4a783fc1effeb16be41803 -- 2.51.0.915.g61a8936c21-goog
