coccinelle: alloc_cast: drop removed allocatorsgrafted

- pci_alloc_consistent() and pci_zalloc_consistent() were removed by
  commit 7968778914e5
  ("PCI: Remove the deprecated "pci-dma-compat.h" API")

- kmem_alloc() was removed by commit f078d4ea8276
  ("xfs: convert kmem_alloc() to kmalloc()")

- kmem_zalloc() was removed by commit 10634530f7ba
  ("xfs: convert kmem_zalloc() to kzalloc()")

- kmem_zone_alloc() and kmem_zone_zalloc() were removed by commit
  bae633a4a283 ("xfs: remove xfs_zone_{alloc,zalloc} helpers")

So drop them from the rules.

No functional change.

Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

1 files changed, 929 insertions, 0 deletions

diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
new file mode 100644
index 000000000..5a2469fb1
--- /dev/null
+++ b/mm/sparse-vmemmap.c
@@ -0,0 +1,929 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Virtual Memory Map support
+ *
+ * (C) 2007 sgi. Christoph Lameter.
+ *
+ * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
+ * virt_to_page, page_address() to be implemented as a base offset
+ * calculation without memory access.
+ *
+ * However, virtual mappings need a page table and TLBs. Many Linux
+ * architectures already map their physical space using 1-1 mappings
+ * via TLBs. For those arches the virtual memory map is essentially
+ * for free if we use the same page size as the 1-1 mappings. In that
+ * case the overhead consists of a few additional pages that are
+ * allocated to create a view of memory for vmemmap.
+ *
+ * The architecture is expected to provide a vmemmap_populate() function
+ * to instantiate the mapping.
+ */
+#include <linux/mm.h>
+#include <linux/mmzone.h>
+#include <linux/memblock.h>
+#include <linux/memremap.h>
+#include <linux/highmem.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/vmalloc.h>
+#include <linux/sched.h>
+#include <linux/pgalloc.h>
+
+#include <asm/dma.h>
+#include <asm/tlbflush.h>
+
+#include "hugetlb_vmemmap.h"
+
+/*
+ * Flags for vmemmap_populate_range and friends.
+ */
+/* Get a ref on the head page struct page, for ZONE_DEVICE compound pages */
+#define VMEMMAP_POPULATE_PAGEREF	0x0001
+
+#include "internal.h"
+#include "mm_init.h"
+#include "sparse.h"
+
+/*
+ * Allocate a block of memory to be used to back the virtual memory map
+ * or to back the page tables that are used to create the mapping.
+ * Uses the main allocators if they are available, else bootmem.
+ */
+
+static void * __ref __earlyonly_bootmem_alloc(int node,
+				unsigned long size,
+				unsigned long align,
+				unsigned long goal)
+{
+	return memmap_alloc(size, align, goal, node, false);
+}
+
+void * __meminit vmemmap_alloc_block(unsigned long size, int node)
+{
+	/* If the main allocator is up use that, fallback to bootmem. */
+	if (slab_is_available()) {
+		gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
+		int order = get_order(size);
+		static bool warned __meminitdata;
+		struct page *page;
+
+		page = alloc_pages_node(node, gfp_mask, order);
+		if (page)
+			return page_address(page);
+
+		if (!warned) {
+			warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
+				   "vmemmap alloc failure: order:%u", order);
+			warned = true;
+		}
+		return NULL;
+	} else
+		return __earlyonly_bootmem_alloc(node, size, size,
+				__pa(MAX_DMA_ADDRESS));
+}
+
+static void * __meminit altmap_alloc_block_buf(unsigned long size,
+					       struct vmem_altmap *altmap);
+
+/* need to make sure size is all the same during early stage */
+void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node,
+					 struct vmem_altmap *altmap)
+{
+	if (altmap)
+		return altmap_alloc_block_buf(size, altmap);
+
+	return vmemmap_alloc_block(size, node);
+}
+
+static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
+{
+	return altmap->base_pfn + altmap->reserve + altmap->alloc
+		+ altmap->align;
+}
+
+static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
+{
+	unsigned long allocated = altmap->alloc + altmap->align;
+
+	if (altmap->free > allocated)
+		return altmap->free - allocated;
+	return 0;
+}
+
+static void * __meminit altmap_alloc_block_buf(unsigned long size,
+					       struct vmem_altmap *altmap)
+{
+	unsigned long pfn, nr_pfns, nr_align;
+
+	if (size & ~PAGE_MASK) {
+		pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
+				__func__, size);
+		return NULL;
+	}
+
+	pfn = vmem_altmap_next_pfn(altmap);
+	nr_pfns = size >> PAGE_SHIFT;
+	nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
+	nr_align = ALIGN(pfn, nr_align) - pfn;
+	if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
+		return NULL;
+
+	altmap->alloc += nr_pfns;
+	altmap->align += nr_align;
+	pfn += nr_align;
+
+	pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
+			__func__, pfn, altmap->alloc, altmap->align, nr_pfns);
+	return __va(__pfn_to_phys(pfn));
+}
+
+void __meminit vmemmap_verify(pte_t *pte, int node,
+				unsigned long start, unsigned long end)
+{
+	unsigned long pfn = pte_pfn(ptep_get(pte));
+	int actual_node = early_pfn_to_nid(pfn);
+
+	if (node_distance(actual_node, node) > LOCAL_DISTANCE)
+		pr_warn_once("[%lx-%lx] potential offnode page_structs\n",
+			start, end - 1);
+}
+
+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)
+{
+	pte_t *pte = pte_offset_kernel(pmd, addr);
+	if (pte_none(ptep_get(pte))) {
+		pte_t entry;
+		void *p;
+
+		if (ptpfn == (unsigned long)-1) {
+			p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
+			if (!p)
+				return NULL;
+			ptpfn = PHYS_PFN(__pa(p));
+		} else {
+			/*
+			 * When a PTE/PMD entry is freed from the init_mm
+			 * there's a free_pages() call to this page allocated
+			 * above. Thus this get_page() is paired with the
+			 * put_page_testzero() on the freeing path.
+			 * This can only called by certain ZONE_DEVICE path,
+			 * and through vmemmap_populate_compound_pages() when
+			 * slab is available.
+			 */
+			if (flags & VMEMMAP_POPULATE_PAGEREF)
+				get_page(pfn_to_page(ptpfn));
+		}
+		entry = pfn_pte(ptpfn, PAGE_KERNEL);
+		set_pte_at(&init_mm, addr, pte, entry);
+	}
+	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);
+	if (pmd_none(*pmd)) {
+		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
+		if (!p)
+			return NULL;
+		kernel_pte_init(p);
+		pmd_populate_kernel(&init_mm, pmd, p);
+	}
+	return pmd;
+}
+
+static pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
+{
+	pud_t *pud = pud_offset(p4d, addr);
+	if (pud_none(*pud)) {
+		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
+		if (!p)
+			return NULL;
+		pmd_init(p);
+		pud_populate(&init_mm, pud, p);
+	}
+	return pud;
+}
+
+static p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
+{
+	p4d_t *p4d = p4d_offset(pgd, addr);
+	if (p4d_none(*p4d)) {
+		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
+		if (!p)
+			return NULL;
+		pud_init(p);
+		p4d_populate_kernel(addr, p4d, p);
+	}
+	return p4d;
+}
+
+static pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
+{
+	pgd_t *pgd = pgd_offset_k(addr);
+	if (pgd_none(*pgd)) {
+		void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
+		if (!p)
+			return NULL;
+		pgd_populate_kernel(addr, pgd, p);
+	}
+	return pgd;
+}
+
+static pte_t * __meminit vmemmap_populate_address(unsigned long addr, int node,
+					      struct vmem_altmap *altmap,
+					      unsigned long ptpfn,
+					      unsigned long flags)
+{
+	pgd_t *pgd;
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	pgd = vmemmap_pgd_populate(addr, node);
+	if (!pgd)
+		return NULL;
+	p4d = vmemmap_p4d_populate(pgd, addr, node);
+	if (!p4d)
+		return NULL;
+	pud = vmemmap_pud_populate(p4d, addr, node);
+	if (!pud)
+		return NULL;
+	pmd = vmemmap_pmd_populate(pud, addr, node);
+	if (!pmd)
+		return NULL;
+	pte = vmemmap_pte_populate(pmd, addr, node, altmap, ptpfn, flags);
+	if (!pte)
+		return NULL;
+	vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
+
+	return pte;
+}
+
+static int __meminit vmemmap_populate_range(unsigned long start,
+					    unsigned long end, int node,
+					    struct vmem_altmap *altmap,
+					    unsigned long ptpfn,
+					    unsigned long flags)
+{
+	unsigned long addr = start;
+	pte_t *pte;
+
+	for (; addr < end; addr += PAGE_SIZE) {
+		pte = vmemmap_populate_address(addr, node, altmap,
+					       ptpfn, flags);
+		if (!pte)
+			return -ENOMEM;
+	}
+
+	return 0;
+}
+
+int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
+					 int node, struct vmem_altmap *altmap)
+{
+	return vmemmap_populate_range(start, end, node, altmap, -1, 0);
+}
+
+/*
+ * Write protect the mirrored tail page structs for HVO. This will be
+ * called from the hugetlb code when gathering and initializing the
+ * memblock allocated gigantic pages. The write protect can't be
+ * done earlier, since it can't be guaranteed that the reserved
+ * page structures will not be written to during initialization,
+ * even if CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled.
+ *
+ * The PTEs are known to exist, and nothing else should be touching
+ * these pages. The caller is responsible for any TLB flushing.
+ */
+void vmemmap_wrprotect_hvo(unsigned long addr, unsigned long end,
+				    int node, unsigned long headsize)
+{
+	unsigned long maddr;
+	pte_t *pte;
+
+	for (maddr = addr + headsize; maddr < end; maddr += PAGE_SIZE) {
+		pte = virt_to_kpte(maddr);
+		ptep_set_wrprotect(&init_mm, maddr, pte);
+	}
+}
+
+#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_TAIL_MIN_ORDER))
+		return NULL;
+	if (WARN_ON_ONCE(order > MAX_FOLIO_ORDER))
+		return NULL;
+
+	idx = order - VMEMMAP_TAIL_MIN_ORDER;
+	tail = zone->vmemmap_tails[idx];
+	if (tail)
+		return tail;
+
+	/*
+	 * Only allocate the page, but do not initialize it.
+	 *
+	 * Any initialization done here will be overwritten by memmap_init().
+	 *
+	 * hugetlb_bootmem_struct_page_init() will take care of initialization
+	 * after memmap_init().
+	 */
+
+	p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
+	if (!p)
+		return NULL;
+
+	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)
+{
+	unsigned long maddr;
+	struct page *tail;
+	pte_t *pte;
+	int node = zone_to_nid(zone);
+
+	tail = vmemmap_get_tail(order, zone);
+	if (!tail)
+		return -ENOMEM;
+
+	for (maddr = addr; maddr < addr + headsize; maddr += PAGE_SIZE) {
+		pte = vmemmap_populate_address(maddr, node, NULL, -1, 0);
+		if (!pte)
+			return -ENOMEM;
+	}
+
+	/*
+	 * Reuse the last page struct page mapped above for the rest.
+	 */
+	return vmemmap_populate_range(maddr, end, node, NULL,
+				      page_to_pfn(tail), 0);
+}
+#endif
+
+void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node,
+				      unsigned long addr, unsigned long next)
+{
+	WARN_ON_ONCE(!pmd_set_huge(pmd, virt_to_phys(p), PAGE_KERNEL));
+}
+
+int __weak __meminit vmemmap_check_pmd(pmd_t *pmd, int node,
+				       unsigned long addr, unsigned long next)
+{
+	if (!pmd_leaf(pmdp_get(pmd)))
+		return 0;
+	vmemmap_verify((pte_t *)pmd, node, addr, next);
+
+	return 1;
+}
+
+int __meminit vmemmap_populate_hugepages(unsigned long start, unsigned long end,
+					 int node, struct vmem_altmap *altmap)
+{
+	unsigned long addr;
+	unsigned long next;
+	pgd_t *pgd;
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd;
+
+	for (addr = start; addr < end; addr = next) {
+		next = pmd_addr_end(addr, end);
+
+		pgd = vmemmap_pgd_populate(addr, node);
+		if (!pgd)
+			return -ENOMEM;
+
+		p4d = vmemmap_p4d_populate(pgd, addr, node);
+		if (!p4d)
+			return -ENOMEM;
+
+		pud = vmemmap_pud_populate(p4d, addr, node);
+		if (!pud)
+			return -ENOMEM;
+
+		pmd = pmd_offset(pud, addr);
+		if (pmd_none(pmdp_get(pmd))) {
+			void *p;
+
+			p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
+			if (p) {
+				vmemmap_set_pmd(pmd, p, node, addr, next);
+				continue;
+			} else if (altmap) {
+				/*
+				 * No fallback: In any case we care about, the
+				 * altmap should be reasonably sized and aligned
+				 * such that vmemmap_alloc_block_buf() will always
+				 * succeed. For consistency with the PTE case,
+				 * return an error here as failure could indicate
+				 * a configuration issue with the size of the altmap.
+				 */
+				return -ENOMEM;
+			}
+		} else if (vmemmap_check_pmd(pmd, node, addr, next))
+			continue;
+		if (vmemmap_populate_basepages(addr, next, node, altmap))
+			return -ENOMEM;
+	}
+	return 0;
+}
+
+#ifndef vmemmap_populate_compound_pages
+/*
+ * For compound pages bigger than section size (e.g. x86 1G compound
+ * pages with 2M subsection size) fill the rest of sections as tail
+ * pages.
+ *
+ * Note that memremap_pages() resets @nr_range value and will increment
+ * it after each range successful onlining. Thus the value or @nr_range
+ * at section memmap populate corresponds to the in-progress range
+ * being onlined here.
+ */
+static bool __meminit reuse_compound_section(unsigned long start_pfn,
+					     struct dev_pagemap *pgmap)
+{
+	unsigned long nr_pages = pgmap_vmemmap_nr(pgmap);
+	unsigned long offset = start_pfn -
+		PHYS_PFN(pgmap->ranges[pgmap->nr_range].start);
+
+	return !IS_ALIGNED(offset, nr_pages) && nr_pages > PAGES_PER_SUBSECTION;
+}
+
+static pte_t * __meminit compound_section_tail_page(unsigned long addr)
+{
+	pte_t *pte;
+
+	addr -= PAGE_SIZE;
+
+	/*
+	 * Assuming sections are populated sequentially, the previous section's
+	 * page data can be reused.
+	 */
+	pte = pte_offset_kernel(pmd_off_k(addr), addr);
+	if (!pte)
+		return NULL;
+
+	return pte;
+}
+
+static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
+						     unsigned long start,
+						     unsigned long end, int node,
+						     struct dev_pagemap *pgmap)
+{
+	unsigned long size, addr;
+	pte_t *pte;
+	int rc;
+
+	if (reuse_compound_section(start_pfn, pgmap)) {
+		pte = compound_section_tail_page(start);
+		if (!pte)
+			return -ENOMEM;
+
+		/*
+		 * Reuse the page that was populated in the prior iteration
+		 * with just tail struct pages.
+		 */
+		return vmemmap_populate_range(start, end, node, NULL,
+					      pte_pfn(ptep_get(pte)),
+					      VMEMMAP_POPULATE_PAGEREF);
+	}
+
+	size = min(end - start, pgmap_vmemmap_nr(pgmap) * sizeof(struct page));
+	for (addr = start; addr < end; addr += size) {
+		unsigned long next, last = addr + size;
+
+		/* Populate the head page vmemmap page */
+		pte = vmemmap_populate_address(addr, node, NULL, -1, 0);
+		if (!pte)
+			return -ENOMEM;
+
+		/* Populate the tail pages vmemmap page */
+		next = addr + PAGE_SIZE;
+		pte = vmemmap_populate_address(next, node, NULL, -1, 0);
+		if (!pte)
+			return -ENOMEM;
+
+		/*
+		 * Reuse the previous page for the rest of tail pages
+		 * See layout diagram in Documentation/mm/vmemmap_dedup.rst
+		 */
+		next += PAGE_SIZE;
+		rc = vmemmap_populate_range(next, last, node, NULL,
+					    pte_pfn(ptep_get(pte)),
+					    VMEMMAP_POPULATE_PAGEREF);
+		if (rc)
+			return -ENOMEM;
+	}
+
+	return 0;
+}
+
+#endif
+
+struct page * __meminit __populate_section_memmap(unsigned long pfn,
+		unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
+		struct dev_pagemap *pgmap)
+{
+	unsigned long start = (unsigned long) pfn_to_page(pfn);
+	unsigned long end = start + nr_pages * sizeof(struct page);
+	int r;
+
+	if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
+		!IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
+		return NULL;
+
+	if (vmemmap_can_optimize(altmap, pgmap))
+		r = vmemmap_populate_compound_pages(pfn, start, end, nid, pgmap);
+	else
+		r = vmemmap_populate(start, end, nid, altmap);
+
+	if (r < 0)
+		return NULL;
+
+	flush_cache_vmap(start, end);
+
+	return pfn_to_page(pfn);
+}
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP_PREINIT
+/*
+ * This is called just before initializing sections for a NUMA node.
+ * Any special initialization that needs to be done before the
+ * generic initialization can be done from here. Sections that
+ * are initialized in hooks called from here will be skipped by
+ * the generic initialization.
+ */
+void __init sparse_vmemmap_init_nid_early(int nid)
+{
+	hugetlb_vmemmap_init_early(nid);
+}
+#endif
+
+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);
+}
+
+static void __init sparse_init_subsection_map_range(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;
+	}
+}
+
+void __init sparse_init_subsection_map(void)
+{
+	int i, nid;
+	unsigned long start, end;
+
+	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid)
+		sparse_init_subsection_map_range(start, end - start);
+}
+
+#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 int __meminit section_nr_vmemmap_pages(unsigned long pfn, unsigned long nr_pages,
+		struct vmem_altmap *altmap, struct dev_pagemap *pgmap)
+{
+	const unsigned int order = pgmap ? pgmap->vmemmap_shift : 0;
+	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))
+		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_RESERVE_NR * 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_RESERVE_NR;
+
+	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)
+{
+	struct page *page = __populate_section_memmap(pfn, nr_pages, nid, altmap,
+						      pgmap);
+
+	memmap_pages_add(section_nr_vmemmap_pages(pfn, nr_pages, altmap, pgmap));
+
+	return page;
+}
+
+static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
+		struct vmem_altmap *altmap, struct dev_pagemap *pgmap)
+{
+	unsigned long start = (unsigned long) pfn_to_page(pfn);
+	unsigned long end = start + nr_pages * sizeof(struct page);
+
+	memmap_pages_add(-section_nr_vmemmap_pages(pfn, nr_pages, altmap, pgmap));
+	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);
+	unsigned long pfn = page_to_pfn(memmap);
+
+	memmap_boot_pages_add(-section_nr_vmemmap_pages(pfn, PAGES_PER_SECTION,
+							NULL, NULL));
+	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 dev_pagemap *pgmap)
+{
+	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)
+		depopulate_section_memmap(pfn, nr_pages, altmap, pgmap);
+	else if (memmap)
+		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, pgmap);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	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 dev_pagemap *pgmap)
+{
+	struct mem_section *ms = __pfn_to_section(pfn);
+
+	if (WARN_ON_ONCE(!valid_section(ms)))
+		return;
+
+	section_deactivate(pfn, nr_pages, altmap, pgmap);
+}
+#endif /* CONFIG_MEMORY_HOTPLUG */