[PATCH v5 07/17] mm/sparse-vmemmap: move helpers ahead of future callers

[Muchun Song <songmuchun@bytedance.com>]

Prepare for section-based vmemmap optimization by moving helpers that
follow-up changes will use. vmemmap_get_tail() will be called from the PTE
population path. section_nr_vmemmap_pages() will be made visible outside
the memory hotplug code and called from sparse_init_nid().

Move vmemmap_alloc_block_zero() together with vmemmap_get_tail(), since
the tail helper depends on it. Move section_nr_vmemmap_pages() earlier
into its own CONFIG_MEMORY_HOTPLUG block. That lets the later patch change
its visibility and callers without also moving the function body.

No functional change is intended.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
v5:
- Move section_nr_vmemmap_pages() earlier under its own CONFIG_MEMORY_HOTPLUG
  block to avoid code movement in the later visibility change
- Reword the subject and commit message for the helper movement
- Collect Acked-by from Mike Rapoport

v2:
- Add this new patch to move vmemmap_get_tail() before PTE
  population (suggested by Mike Rapoport)
---
 mm/sparse-vmemmap.c | 134 +++++++++++++++++++++++---------------------
 1 file changed, 69 insertions(+), 65 deletions(-)

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index b7abc5494bb9..ea3cacec0a79 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c
@@ -148,6 +148,75 @@ void __meminit vmemmap_verify(pte_t *pte, int node,
 			start, end - 1);
 }
 
+#ifdef CONFIG_MEMORY_HOTPLUG
+static int __meminit section_nr_vmemmap_pages(unsigned long pfn, unsigned long nr_pages,
+		struct vmem_altmap *altmap, struct dev_pagemap *pgmap)
+{
+	const struct mem_section *ms = __pfn_to_section(pfn);
+	const int order = pgmap ? pgmap->vmemmap_shift : section_order(ms);
+	const int vmemmap_pages = pgmap ? VMEMMAP_RESERVE_NR : VMEMMAP_OPTIMIZATION_PAGES;
+	const unsigned long pages_per_compound = 1UL << order;
+
+	VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SUBSECTION));
+	VM_WARN_ON_ONCE(nr_pages > PAGES_PER_SECTION);
+
+	if (!vmemmap_can_optimize(altmap, pgmap) && !section_vmemmap_optimizable(ms))
+		return DIV_ROUND_UP(nr_pages * sizeof(struct page), PAGE_SIZE);
+
+	if (order < PFN_SECTION_SHIFT) {
+		VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, pages_per_compound));
+		return vmemmap_pages * nr_pages / pages_per_compound;
+	}
+
+	VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION));
+
+	if (IS_ALIGNED(pfn, pages_per_compound))
+		return vmemmap_pages;
+
+	return 0;
+}
+#endif
+
+static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
+{
+	void *p = vmemmap_alloc_block(size, node);
+
+	if (!p)
+		return NULL;
+	memset(p, 0, size);
+
+	return p;
+}
+
+#ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
+static __meminit struct page *vmemmap_get_tail(unsigned int order, struct zone *zone)
+{
+	struct page *p, *tail;
+	unsigned int idx;
+	int node = zone_to_nid(zone);
+
+	if (WARN_ON_ONCE(order < VMEMMAP_OPTIMIZATION_MIN_ORDER))
+		return NULL;
+	if (WARN_ON_ONCE(order > MAX_FOLIO_ORDER))
+		return NULL;
+
+	idx = order - VMEMMAP_OPTIMIZATION_MIN_ORDER;
+	tail = zone->vmemmap_tails[idx];
+	if (tail)
+		return tail;
+	p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
+	if (!p)
+		return NULL;
+	for (int i = 0; i < PAGE_SIZE / sizeof(struct page); i++)
+		init_compound_tail(p + i, NULL, order, zone);
+
+	tail = virt_to_page(p);
+	zone->vmemmap_tails[idx] = tail;
+
+	return tail;
+}
+#endif
+
 static pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
 				       struct vmem_altmap *altmap,
 				       unsigned long ptpfn, unsigned long flags)
@@ -181,17 +250,6 @@ static pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, in
 	return pte;
 }
 
-static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
-{
-	void *p = vmemmap_alloc_block(size, node);
-
-	if (!p)
-		return NULL;
-	memset(p, 0, size);
-
-	return p;
-}
-
 static pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
 {
 	pmd_t *pmd = pmd_offset(pud, addr);
@@ -323,33 +381,6 @@ void vmemmap_wrprotect_hvo(unsigned long addr, unsigned long end,
 }
 
 #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP
-static __meminit struct page *vmemmap_get_tail(unsigned int order, struct zone *zone)
-{
-	struct page *p, *tail;
-	unsigned int idx;
-	int node = zone_to_nid(zone);
-
-	if (WARN_ON_ONCE(order < VMEMMAP_OPTIMIZATION_MIN_ORDER))
-		return NULL;
-	if (WARN_ON_ONCE(order > MAX_FOLIO_ORDER))
-		return NULL;
-
-	idx = order - VMEMMAP_OPTIMIZATION_MIN_ORDER;
-	tail = zone->vmemmap_tails[idx];
-	if (tail)
-		return tail;
-	p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
-	if (!p)
-		return NULL;
-	for (int i = 0; i < PAGE_SIZE / sizeof(struct page); i++)
-		init_compound_tail(p + i, NULL, order, zone);
-
-	tail = virt_to_page(p);
-	zone->vmemmap_tails[idx] = tail;
-
-	return tail;
-}
-
 int __meminit vmemmap_populate_hvo(unsigned long addr, unsigned long end,
 				       unsigned int order, struct zone *zone,
 				       unsigned long headsize)
@@ -646,33 +677,6 @@ void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
 	}
 }
 
-static int __meminit section_nr_vmemmap_pages(unsigned long pfn, unsigned long nr_pages,
-		struct vmem_altmap *altmap, struct dev_pagemap *pgmap)
-{
-	const struct mem_section *ms = __pfn_to_section(pfn);
-	const int order = pgmap ? pgmap->vmemmap_shift : section_order(ms);
-	const int vmemmap_pages = pgmap ? VMEMMAP_RESERVE_NR : VMEMMAP_OPTIMIZATION_PAGES;
-	const unsigned long pages_per_compound = 1UL << order;
-
-	VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SUBSECTION));
-	VM_WARN_ON_ONCE(nr_pages > PAGES_PER_SECTION);
-
-	if (!vmemmap_can_optimize(altmap, pgmap) && !section_vmemmap_optimizable(ms))
-		return DIV_ROUND_UP(nr_pages * sizeof(struct page), PAGE_SIZE);
-
-	if (order < PFN_SECTION_SHIFT) {
-		VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, pages_per_compound));
-		return vmemmap_pages * nr_pages / pages_per_compound;
-	}
-
-	VM_WARN_ON_ONCE(!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION));
-
-	if (IS_ALIGNED(pfn, pages_per_compound))
-		return vmemmap_pages;
-
-	return 0;
-}
-
 static struct page * __meminit populate_section_memmap(unsigned long pfn,
 		unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
 		struct dev_pagemap *pgmap)
-- 
2.54.0