[PATCH v9 0/3] kho: add support for deferred struct page init

Michal Clapinski
2026-04-23T12:25:47Z

When CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, struct page
initialization is deferred to parallel kthreads that run later in
the boot process.

Currently, KHO is incompatible with DEFERRED.
This series fixes that incompatibility.
---
v9:
- moved init_pageblock_migratetype from memmap_init_reserved_range
to __init_page_from_nid
- reduced number of ifdefs
- new commit to test this feature
v8:
- moved overriding the migratetype from init_pageblock_migratetype
to callsites
v7:
- reimplemented the initialization of kho scratch again
v6:
- reimplemented the initialization of kho scratch
v5:
- rebased
v4:
- added a new commit to fix deferred init of kho scratch
- switched to ulong when refering to pfn
v3:
- changed commit msg
- don't invoke early_pfn_to_nid if CONFIG_DEFERRED_STRUCT_PAGE_INIT=n
v2:
- updated a comment

I took Evangelos's test code:
https://git.infradead.org/?p=users/vpetrog/linux.git;a=shortlog;h=refs/heads/kho-deferred-struct-page-init
and then modified it to this monster test that does 2 allocations:
at core_initcall (early) and at module_init (late). Then kexec, then
2 more allocations at these points, then restore the original 2, then
kexec, then restore the other 2. Basically I test preservation of early
and late allocation both on cold and on warm boot.
Tested it both with and without DEFERRED.
https://github.com/mclapinski/linux/commits/deferred_test/

This patch probably doesn't apply onto anything currently.
It's based on mm-new with
"memblock: move reserve_bootmem_range() to memblock.c and make it static"
cherrypicked from rppt/memblock.

Evangelos Petrongonas (1):
kho: make preserved pages compatible with deferred struct page init

Michal Clapinski (2):
kho: fix deferred initialization of scratch areas
selftests: kho: test with deferred struct page init

include/linux/memblock.h | 21 +++++++++-
kernel/liveupdate/Kconfig | 2 -
kernel/liveupdate/kexec_handover.c | 52 ++++++++++++-------------
mm/memblock.c | 56 +++++++++++----------------
mm/mm_init.c | 30 +++++++-------
tools/testing/selftests/kho/vmtest.sh | 4 ++
6 files changed, 88 insertions(+), 77 deletions(-)

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2.54.0.rc2.533.g4f5dca5207-goog