[PATCH 08/14] mm/sparse: remove sparse_decode_mem_map()

David Hildenbrand (Arm)
2026-03-17T16:57:37Z

section_deactivate() applies to CONFIG_SPARSEMEM_VMEMMAP only. So we can
just use pfn_to_page() (after making sure we have the start PFN of the
section), and remove sparse_decode_mem_map().

Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
---
include/linux/memory_hotplug.h | 2 --
mm/sparse.c | 16 +---------------
2 files changed, 1 insertion(+), 17 deletions(-)

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index e77ef3d7ff73..815e908c4135 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -308,8 +308,6 @@ extern int sparse_add_section(int nid, unsigned long pfn,
struct dev_pagemap *pgmap);
extern void sparse_remove_section(unsigned long pfn, unsigned long nr_pages,
struct vmem_altmap *altmap);
-extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
- unsigned long pnum);
extern struct zone *zone_for_pfn_range(enum mmop online_type,
int nid, struct memory_group *group, unsigned long start_pfn,
unsigned long nr_pages);
diff --git a/mm/sparse.c b/mm/sparse.c
index 636a4a0f1199..2a1f662245bc 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -274,18 +274,6 @@ static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long p
return coded_mem_map;
}

-#ifdef CONFIG_MEMORY_HOTPLUG
-/*
- * Decode mem_map from the coded memmap
- */
-struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
-{
- /* mask off the extra low bits of information */
- coded_mem_map &= SECTION_MAP_MASK;
- return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
-}
-#endif /* CONFIG_MEMORY_HOTPLUG */
-
static void __meminit sparse_init_one_section(struct mem_section *ms,
unsigned long pnum, struct page *mem_map,
struct mem_section_usage *usage, unsigned long flags)
@@ -758,8 +746,6 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,

empty = is_subsection_map_empty(ms);
if (empty) {
- unsigned long section_nr = pfn_to_section_nr(pfn);
-
/*
* Mark the section invalid so that valid_section()
* return false. This prevents code from dereferencing
@@ -778,7 +764,7 @@ static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
kfree_rcu(ms->usage, rcu);
WRITE_ONCE(ms->usage, NULL);
}
- memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
+ memmap = pfn_to_page(SECTION_ALIGN_DOWN(pfn));
}

/*
--
2.43.0