mm/sparse: move memory hotplug bits to sparse-vmemmap.c

Let's move all memory hoptplug related code to sparse-vmemmap.c.

We only have to expose sparse_index_init().  While at it, drop the
definition of sparse_index_init() for !CONFIG_SPARSEMEM, which is unused,
and place the declaration in internal.h.

Link: https://lkml.kernel.org/r/20260320-sparsemem_cleanups-v2-15-096addc8800d@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 2 insertions, 308 deletions

diff --git a/mm/sparse.c b/mm/sparse.c
index ecd4c41c0ff0..007fd52c621e 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -79,7 +79,7 @@ static noinline struct mem_section __ref *sparse_index_alloc(int nid)
 	return section;
 }
 
-static int __meminit sparse_index_init(unsigned long section_nr, int nid)
+int __meminit sparse_index_init(unsigned long section_nr, int nid)
 {
 	unsigned long root = SECTION_NR_TO_ROOT(section_nr);
 	struct mem_section *section;
@@ -103,7 +103,7 @@ static int __meminit sparse_index_init(unsigned long section_nr, int nid)
 	return 0;
 }
 #else /* !SPARSEMEM_EXTREME */
-static inline int sparse_index_init(unsigned long section_nr, int nid)
+int sparse_index_init(unsigned long section_nr, int nid)
 {
 	return 0;
 }
@@ -167,40 +167,6 @@ static inline unsigned long first_present_section_nr(void)
 	return next_present_section_nr(-1);
 }
 
-#ifdef CONFIG_SPARSEMEM_VMEMMAP
-static void subsection_mask_set(unsigned long *map, unsigned long pfn,
-		unsigned long nr_pages)
-{
-	int idx = subsection_map_index(pfn);
-	int end = subsection_map_index(pfn + nr_pages - 1);
-
-	bitmap_set(map, idx, end - idx + 1);
-}
-
-void __init sparse_init_subsection_map(unsigned long pfn, unsigned long nr_pages)
-{
-	int end_sec_nr = pfn_to_section_nr(pfn + nr_pages - 1);
-	unsigned long nr, start_sec_nr = pfn_to_section_nr(pfn);
-
-	for (nr = start_sec_nr; nr <= end_sec_nr; nr++) {
-		struct mem_section *ms;
-		unsigned long pfns;
-
-		pfns = min(nr_pages, PAGES_PER_SECTION
-				- (pfn & ~PAGE_SECTION_MASK));
-		ms = __nr_to_section(nr);
-		subsection_mask_set(ms->usage->subsection_map, pfn, pfns);
-
-		pr_debug("%s: sec: %lu pfns: %lu set(%d, %d)\n", __func__, nr,
-				pfns, subsection_map_index(pfn),
-				subsection_map_index(pfn + pfns - 1));
-
-		pfn += pfns;
-		nr_pages -= pfns;
-	}
-}
-#endif
-
 /* Record a memory area against a node. */
 static void __init memory_present(int nid, unsigned long start, unsigned long end)
 {
@@ -482,275 +448,3 @@ void __init sparse_init(void)
 	sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
 	vmemmap_populate_print_last();
 }
-
-#ifdef CONFIG_MEMORY_HOTPLUG
-
-/* Mark all memory sections within the pfn range as online */
-void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
-{
-	unsigned long pfn;
-
-	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
-		unsigned long section_nr = pfn_to_section_nr(pfn);
-		struct mem_section *ms = __nr_to_section(section_nr);
-
-		ms->section_mem_map |= SECTION_IS_ONLINE;
-	}
-}
-
-/* Mark all memory sections within the pfn range as offline */
-void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
-{
-	unsigned long pfn;
-
-	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
-		unsigned long section_nr = pfn_to_section_nr(pfn);
-		struct mem_section *ms = __nr_to_section(section_nr);
-
-		ms->section_mem_map &= ~SECTION_IS_ONLINE;
-	}
-}
-
-static struct page * __meminit populate_section_memmap(unsigned long pfn,
-		unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
-		struct dev_pagemap *pgmap)
-{
-	return __populate_section_memmap(pfn, nr_pages, nid, altmap, pgmap);
-}
-
-static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
-		struct vmem_altmap *altmap)
-{
-	unsigned long start = (unsigned long) pfn_to_page(pfn);
-	unsigned long end = start + nr_pages * sizeof(struct page);
-
-	vmemmap_free(start, end, altmap);
-}
-static void free_map_bootmem(struct page *memmap)
-{
-	unsigned long start = (unsigned long)memmap;
-	unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
-
-	vmemmap_free(start, end, NULL);
-}
-
-static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
-{
-	DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
-	DECLARE_BITMAP(tmp, SUBSECTIONS_PER_SECTION) = { 0 };
-	struct mem_section *ms = __pfn_to_section(pfn);
-	unsigned long *subsection_map = ms->usage
-		? &ms->usage->subsection_map[0] : NULL;
-
-	subsection_mask_set(map, pfn, nr_pages);
-	if (subsection_map)
-		bitmap_and(tmp, map, subsection_map, SUBSECTIONS_PER_SECTION);
-
-	if (WARN(!subsection_map || !bitmap_equal(tmp, map, SUBSECTIONS_PER_SECTION),
-				"section already deactivated (%#lx + %ld)\n",
-				pfn, nr_pages))
-		return -EINVAL;
-
-	bitmap_xor(subsection_map, map, subsection_map, SUBSECTIONS_PER_SECTION);
-	return 0;
-}
-
-static bool is_subsection_map_empty(struct mem_section *ms)
-{
-	return bitmap_empty(&ms->usage->subsection_map[0],
-			    SUBSECTIONS_PER_SECTION);
-}
-
-static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
-{
-	struct mem_section *ms = __pfn_to_section(pfn);
-	DECLARE_BITMAP(map, SUBSECTIONS_PER_SECTION) = { 0 };
-	unsigned long *subsection_map;
-	int rc = 0;
-
-	subsection_mask_set(map, pfn, nr_pages);
-
-	subsection_map = &ms->usage->subsection_map[0];
-
-	if (bitmap_empty(map, SUBSECTIONS_PER_SECTION))
-		rc = -EINVAL;
-	else if (bitmap_intersects(map, subsection_map, SUBSECTIONS_PER_SECTION))
-		rc = -EEXIST;
-	else
-		bitmap_or(subsection_map, map, subsection_map,
-				SUBSECTIONS_PER_SECTION);
-
-	return rc;
-}
-
-/*
- * To deactivate a memory region, there are 3 cases to handle:
- *
- * 1. deactivation of a partial hot-added section:
- *      a) section was present at memory init.
- *      b) section was hot-added post memory init.
- * 2. deactivation of a complete hot-added section.
- * 3. deactivation of a complete section from memory init.
- *
- * For 1, when subsection_map does not empty we will not be freeing the
- * usage map, but still need to free the vmemmap range.
- */
-static void section_deactivate(unsigned long pfn, unsigned long nr_pages,
-		struct vmem_altmap *altmap)
-{
-	struct mem_section *ms = __pfn_to_section(pfn);
-	bool section_is_early = early_section(ms);
-	struct page *memmap = NULL;
-	bool empty;
-
-	if (clear_subsection_map(pfn, nr_pages))
-		return;
-
-	empty = is_subsection_map_empty(ms);
-	if (empty) {
-		/*
-		 * Mark the section invalid so that valid_section()
-		 * return false. This prevents code from dereferencing
-		 * ms->usage array.
-		 */
-		ms->section_mem_map &= ~SECTION_HAS_MEM_MAP;
-
-		/*
-		 * When removing an early section, the usage map is kept (as the
-		 * usage maps of other sections fall into the same page). It
-		 * will be re-used when re-adding the section - which is then no
-		 * longer an early section. If the usage map is PageReserved, it
-		 * was allocated during boot.
-		 */
-		if (!PageReserved(virt_to_page(ms->usage))) {
-			kfree_rcu(ms->usage, rcu);
-			WRITE_ONCE(ms->usage, NULL);
-		}
-		memmap = pfn_to_page(SECTION_ALIGN_DOWN(pfn));
-	}
-
-	/*
-	 * The memmap of early sections is always fully populated. See
-	 * section_activate() and pfn_valid() .
-	 */
-	if (!section_is_early) {
-		memmap_pages_add(-1L * (DIV_ROUND_UP(nr_pages * sizeof(struct page), PAGE_SIZE)));
-		depopulate_section_memmap(pfn, nr_pages, altmap);
-	} else if (memmap) {
-		memmap_boot_pages_add(-1L * (DIV_ROUND_UP(nr_pages * sizeof(struct page),
-							  PAGE_SIZE)));
-		free_map_bootmem(memmap);
-	}
-
-	if (empty)
-		ms->section_mem_map = (unsigned long)NULL;
-}
-
-static struct page * __meminit section_activate(int nid, unsigned long pfn,
-		unsigned long nr_pages, struct vmem_altmap *altmap,
-		struct dev_pagemap *pgmap)
-{
-	struct mem_section *ms = __pfn_to_section(pfn);
-	struct mem_section_usage *usage = NULL;
-	struct page *memmap;
-	int rc;
-
-	if (!ms->usage) {
-		usage = kzalloc(mem_section_usage_size(), GFP_KERNEL);
-		if (!usage)
-			return ERR_PTR(-ENOMEM);
-		ms->usage = usage;
-	}
-
-	rc = fill_subsection_map(pfn, nr_pages);
-	if (rc) {
-		if (usage)
-			ms->usage = NULL;
-		kfree(usage);
-		return ERR_PTR(rc);
-	}
-
-	/*
-	 * The early init code does not consider partially populated
-	 * initial sections, it simply assumes that memory will never be
-	 * referenced.  If we hot-add memory into such a section then we
-	 * do not need to populate the memmap and can simply reuse what
-	 * is already there.
-	 */
-	if (nr_pages < PAGES_PER_SECTION && early_section(ms))
-		return pfn_to_page(pfn);
-
-	memmap = populate_section_memmap(pfn, nr_pages, nid, altmap, pgmap);
-	if (!memmap) {
-		section_deactivate(pfn, nr_pages, altmap);
-		return ERR_PTR(-ENOMEM);
-	}
-	memmap_pages_add(DIV_ROUND_UP(nr_pages * sizeof(struct page), PAGE_SIZE));
-
-	return memmap;
-}
-
-/**
- * sparse_add_section - add a memory section, or populate an existing one
- * @nid: The node to add section on
- * @start_pfn: start pfn of the memory range
- * @nr_pages: number of pfns to add in the section
- * @altmap: alternate pfns to allocate the memmap backing store
- * @pgmap: alternate compound page geometry for devmap mappings
- *
- * This is only intended for hotplug.
- *
- * Note that only VMEMMAP supports sub-section aligned hotplug,
- * the proper alignment and size are gated by check_pfn_span().
- *
- *
- * Return:
- * * 0		- On success.
- * * -EEXIST	- Section has been present.
- * * -ENOMEM	- Out of memory.
- */
-int __meminit sparse_add_section(int nid, unsigned long start_pfn,
-		unsigned long nr_pages, struct vmem_altmap *altmap,
-		struct dev_pagemap *pgmap)
-{
-	unsigned long section_nr = pfn_to_section_nr(start_pfn);
-	struct mem_section *ms;
-	struct page *memmap;
-	int ret;
-
-	ret = sparse_index_init(section_nr, nid);
-	if (ret < 0)
-		return ret;
-
-	memmap = section_activate(nid, start_pfn, nr_pages, altmap, pgmap);
-	if (IS_ERR(memmap))
-		return PTR_ERR(memmap);
-
-	/*
-	 * Poison uninitialized struct pages in order to catch invalid flags
-	 * combinations.
-	 */
-	page_init_poison(memmap, sizeof(struct page) * nr_pages);
-
-	ms = __nr_to_section(section_nr);
-	__section_mark_present(ms, section_nr);
-
-	/* Align memmap to section boundary in the subsection case */
-	if (section_nr_to_pfn(section_nr) != start_pfn)
-		memmap = pfn_to_page(section_nr_to_pfn(section_nr));
-	sparse_init_one_section(ms, section_nr, memmap, ms->usage, 0);
-
-	return 0;
-}
-
-void sparse_remove_section(unsigned long pfn, unsigned long nr_pages,
-			   struct vmem_altmap *altmap)
-{
-	struct mem_section *ms = __pfn_to_section(pfn);
-
-	if (WARN_ON_ONCE(!valid_section(ms)))
-		return;
-
-	section_deactivate(pfn, nr_pages, altmap);
-}
-#endif /* CONFIG_MEMORY_HOTPLUG */