[PATCH v7 03/18] memblock: introduce memmap_init_kho_scratch()

Changyuan Lyu
2025-05-01T22:55:15Z

From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>

With deferred initialization of struct page it will be necessary to
initialize memory map for KHO scratch regions early.

Add memmap_init_kho_scratch() method that will allow such initialization
in upcoming patches.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
---
include/linux/memblock.h | 2 ++
mm/internal.h | 2 ++
mm/memblock.c | 22 ++++++++++++++++++++++
mm/mm_init.c | 11 ++++++++---
4 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 993937a6b9620..bb19a25342246 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -635,9 +635,11 @@ static inline void memtest_report_meminfo(struct seq_file *m) { }
#ifdef CONFIG_MEMBLOCK_KHO_SCRATCH
void memblock_set_kho_scratch_only(void);
void memblock_clear_kho_scratch_only(void);
+void memmap_init_kho_scratch_pages(void);
#else
static inline void memblock_set_kho_scratch_only(void) { }
static inline void memblock_clear_kho_scratch_only(void) { }
+static inline void memmap_init_kho_scratch_pages(void) {}
#endif

#endif /* _LINUX_MEMBLOCK_H */
diff --git a/mm/internal.h b/mm/internal.h
index e9695baa59226..acfcefcbb6c03 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -1121,6 +1121,8 @@ DECLARE_STATIC_KEY_TRUE(deferred_pages);
bool __init deferred_grow_zone(struct zone *zone, unsigned int order);
#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */

+void init_deferred_page(unsigned long pfn, int nid);
+
enum mminit_level {
MMINIT_WARNING,
MMINIT_VERIFY,
diff --git a/mm/memblock.c b/mm/memblock.c
index 6eba0dfe87155..b9148822db7aa 100644
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -946,6 +946,28 @@ __init void memblock_clear_kho_scratch_only(void)
{
kho_scratch_only = false;
}
+
+__init void memmap_init_kho_scratch_pages(void)
+{
+ phys_addr_t start, end;
+ unsigned long pfn;
+ int nid;
+ u64 i;
+
+ if (!IS_ENABLED(CONFIG_DEFERRED_STRUCT_PAGE_INIT))
+ return;
+
+ /*
+ * Initialize struct pages for free scratch memory.
+ * The struct pages for reserved scratch memory will be set up in
+ * reserve_bootmem_region()
+ */
+ __for_each_mem_range(i, &memblock.memory, NULL, NUMA_NO_NODE,
+ MEMBLOCK_KHO_SCRATCH, &start, &end, &nid) {
+ for (pfn = PFN_UP(start); pfn < PFN_DOWN(end); pfn++)
+ init_deferred_page(pfn, nid);
+ }
+}
#endif

/**
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 9659689b8ace0..128c100fdb977 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -743,7 +743,7 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
return false;
}

-static void __meminit init_deferred_page(unsigned long pfn, int nid)
+static void __meminit __init_deferred_page(unsigned long pfn, int nid)
{
if (early_page_initialised(pfn, nid))
return;
@@ -763,11 +763,16 @@ static inline bool defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
return false;
}

-static inline void init_deferred_page(unsigned long pfn, int nid)
+static inline void __init_deferred_page(unsigned long pfn, int nid)
{
}
#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */

+void __meminit init_deferred_page(unsigned long pfn, int nid)
+{
+ __init_deferred_page(pfn, nid);
+}
+
/*
* Initialised pages do not have PageReserved set. This function is
* called for each range allocated by the bootmem allocator and
@@ -784,7 +789,7 @@ void __meminit reserve_bootmem_region(phys_addr_t start,
if (pfn_valid(start_pfn)) {
struct page *page = pfn_to_page(start_pfn);

- init_deferred_page(start_pfn, nid);
+ __init_deferred_page(start_pfn, nid);

/*
* no need for atomic set_bit because the struct
--
2.49.0.906.g1f30a19c02-goog