diff --git a/src/kernel/linux/v4.19/mm/sparse.c b/src/kernel/linux/v4.19/mm/sparse.c
new file mode 100644
index 0000000..45950a0
--- /dev/null
+++ b/src/kernel/linux/v4.19/mm/sparse.c
@@ -0,0 +1,791 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * sparse memory mappings.
+ */
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/mmzone.h>
+#include <linux/bootmem.h>
+#include <linux/compiler.h>
+#include <linux/highmem.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/vmalloc.h>
+
+#include "internal.h"
+#include <asm/dma.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+
+/*
+ * Permanent SPARSEMEM data:
+ *
+ * 1) mem_section	- memory sections, mem_map's for valid memory
+ */
+#ifdef CONFIG_SPARSEMEM_EXTREME
+struct mem_section **mem_section;
+#else
+struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT]
+	____cacheline_internodealigned_in_smp;
+#endif
+EXPORT_SYMBOL(mem_section);
+
+#ifdef NODE_NOT_IN_PAGE_FLAGS
+/*
+ * If we did not store the node number in the page then we have to
+ * do a lookup in the section_to_node_table in order to find which
+ * node the page belongs to.
+ */
+#if MAX_NUMNODES <= 256
+static u8 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
+#else
+static u16 section_to_node_table[NR_MEM_SECTIONS] __cacheline_aligned;
+#endif
+
+int page_to_nid(const struct page *page)
+{
+	return section_to_node_table[page_to_section(page)];
+}
+EXPORT_SYMBOL(page_to_nid);
+
+static void set_section_nid(unsigned long section_nr, int nid)
+{
+	section_to_node_table[section_nr] = nid;
+}
+#else /* !NODE_NOT_IN_PAGE_FLAGS */
+static inline void set_section_nid(unsigned long section_nr, int nid)
+{
+}
+#endif
+
+#ifdef CONFIG_SPARSEMEM_EXTREME
+static noinline struct mem_section __ref *sparse_index_alloc(int nid)
+{
+	struct mem_section *section = NULL;
+	unsigned long array_size = SECTIONS_PER_ROOT *
+				   sizeof(struct mem_section);
+
+	if (slab_is_available())
+		section = kzalloc_node(array_size, GFP_KERNEL, nid);
+	else
+		section = memblock_virt_alloc_node(array_size, nid);
+
+	return section;
+}
+
+static int __meminit sparse_index_init(unsigned long section_nr, int nid)
+{
+	unsigned long root = SECTION_NR_TO_ROOT(section_nr);
+	struct mem_section *section;
+
+	if (mem_section[root])
+		return -EEXIST;
+
+	section = sparse_index_alloc(nid);
+	if (!section)
+		return -ENOMEM;
+
+	mem_section[root] = section;
+
+	return 0;
+}
+#else /* !SPARSEMEM_EXTREME */
+static inline int sparse_index_init(unsigned long section_nr, int nid)
+{
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_SPARSEMEM_EXTREME
+int __section_nr(struct mem_section* ms)
+{
+	unsigned long root_nr;
+	struct mem_section *root = NULL;
+
+	for (root_nr = 0; root_nr < NR_SECTION_ROOTS; root_nr++) {
+		root = __nr_to_section(root_nr * SECTIONS_PER_ROOT);
+		if (!root)
+			continue;
+
+		if ((ms >= root) && (ms < (root + SECTIONS_PER_ROOT)))
+		     break;
+	}
+
+	VM_BUG_ON(!root);
+
+	return (root_nr * SECTIONS_PER_ROOT) + (ms - root);
+}
+#else
+int __section_nr(struct mem_section* ms)
+{
+	return (int)(ms - mem_section[0]);
+}
+#endif
+
+/*
+ * During early boot, before section_mem_map is used for an actual
+ * mem_map, we use section_mem_map to store the section's NUMA
+ * node.  This keeps us from having to use another data structure.  The
+ * node information is cleared just before we store the real mem_map.
+ */
+static inline unsigned long sparse_encode_early_nid(int nid)
+{
+	return (nid << SECTION_NID_SHIFT);
+}
+
+static inline int sparse_early_nid(struct mem_section *section)
+{
+	return (section->section_mem_map >> SECTION_NID_SHIFT);
+}
+
+/* Validate the physical addressing limitations of the model */
+void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
+						unsigned long *end_pfn)
+{
+	unsigned long max_sparsemem_pfn = 1UL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
+
+	/*
+	 * Sanity checks - do not allow an architecture to pass
+	 * in larger pfns than the maximum scope of sparsemem:
+	 */
+	if (*start_pfn > max_sparsemem_pfn) {
+		mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
+			"Start of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
+			*start_pfn, *end_pfn, max_sparsemem_pfn);
+		WARN_ON_ONCE(1);
+		*start_pfn = max_sparsemem_pfn;
+		*end_pfn = max_sparsemem_pfn;
+	} else if (*end_pfn > max_sparsemem_pfn) {
+		mminit_dprintk(MMINIT_WARNING, "pfnvalidation",
+			"End of range %lu -> %lu exceeds SPARSEMEM max %lu\n",
+			*start_pfn, *end_pfn, max_sparsemem_pfn);
+		WARN_ON_ONCE(1);
+		*end_pfn = max_sparsemem_pfn;
+	}
+}
+
+/*
+ * There are a number of times that we loop over NR_MEM_SECTIONS,
+ * looking for section_present() on each.  But, when we have very
+ * large physical address spaces, NR_MEM_SECTIONS can also be
+ * very large which makes the loops quite long.
+ *
+ * Keeping track of this gives us an easy way to break out of
+ * those loops early.
+ */
+int __highest_present_section_nr;
+static void section_mark_present(struct mem_section *ms)
+{
+	int section_nr = __section_nr(ms);
+
+	if (section_nr > __highest_present_section_nr)
+		__highest_present_section_nr = section_nr;
+
+	ms->section_mem_map |= SECTION_MARKED_PRESENT;
+}
+
+static inline int next_present_section_nr(int section_nr)
+{
+	do {
+		section_nr++;
+		if (present_section_nr(section_nr))
+			return section_nr;
+	} while ((section_nr <= __highest_present_section_nr));
+
+	return -1;
+}
+#define for_each_present_section_nr(start, section_nr)		\
+	for (section_nr = next_present_section_nr(start-1);	\
+	     ((section_nr != -1) &&				\
+	      (section_nr <= __highest_present_section_nr));	\
+	     section_nr = next_present_section_nr(section_nr))
+
+static inline unsigned long first_present_section_nr(void)
+{
+	return next_present_section_nr(-1);
+}
+
+/* Record a memory area against a node. */
+void __init memory_present(int nid, unsigned long start, unsigned long end)
+{
+	unsigned long pfn;
+
+#ifdef CONFIG_SPARSEMEM_EXTREME
+	if (unlikely(!mem_section)) {
+		unsigned long size, align;
+
+		size = sizeof(struct mem_section*) * NR_SECTION_ROOTS;
+		align = 1 << (INTERNODE_CACHE_SHIFT);
+		mem_section = memblock_virt_alloc(size, align);
+	}
+#endif
+
+	start &= PAGE_SECTION_MASK;
+	mminit_validate_memmodel_limits(&start, &end);
+	for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
+		unsigned long section = pfn_to_section_nr(pfn);
+		struct mem_section *ms;
+
+		sparse_index_init(section, nid);
+		set_section_nid(section, nid);
+
+		ms = __nr_to_section(section);
+		if (!ms->section_mem_map) {
+			ms->section_mem_map = sparse_encode_early_nid(nid) |
+							SECTION_IS_ONLINE;
+			section_mark_present(ms);
+		}
+	}
+}
+
+/*
+ * Subtle, we encode the real pfn into the mem_map such that
+ * the identity pfn - section_mem_map will return the actual
+ * physical page frame number.
+ */
+static unsigned long sparse_encode_mem_map(struct page *mem_map, unsigned long pnum)
+{
+	unsigned long coded_mem_map =
+		(unsigned long)(mem_map - (section_nr_to_pfn(pnum)));
+	BUILD_BUG_ON(SECTION_MAP_LAST_BIT > (1UL<<PFN_SECTION_SHIFT));
+	BUG_ON(coded_mem_map & ~SECTION_MAP_MASK);
+	return coded_mem_map;
+}
+
+/*
+ * 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);
+}
+
+static void __meminit sparse_init_one_section(struct mem_section *ms,
+		unsigned long pnum, struct page *mem_map,
+		unsigned long *pageblock_bitmap)
+{
+	ms->section_mem_map &= ~SECTION_MAP_MASK;
+	ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum) |
+							SECTION_HAS_MEM_MAP;
+ 	ms->pageblock_flags = pageblock_bitmap;
+}
+
+unsigned long usemap_size(void)
+{
+	return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+static unsigned long *__kmalloc_section_usemap(void)
+{
+	return kmalloc(usemap_size(), GFP_KERNEL);
+}
+#endif /* CONFIG_MEMORY_HOTPLUG */
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static unsigned long * __init
+sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
+					 unsigned long size)
+{
+	unsigned long goal, limit;
+	unsigned long *p;
+	int nid;
+	/*
+	 * A page may contain usemaps for other sections preventing the
+	 * page being freed and making a section unremovable while
+	 * other sections referencing the usemap remain active. Similarly,
+	 * a pgdat can prevent a section being removed. If section A
+	 * contains a pgdat and section B contains the usemap, both
+	 * sections become inter-dependent. This allocates usemaps
+	 * from the same section as the pgdat where possible to avoid
+	 * this problem.
+	 */
+	goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
+	limit = goal + (1UL << PA_SECTION_SHIFT);
+	nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
+again:
+	p = memblock_virt_alloc_try_nid_nopanic(size,
+						SMP_CACHE_BYTES, goal, limit,
+						nid);
+	if (!p && limit) {
+		limit = 0;
+		goto again;
+	}
+	return p;
+}
+
+static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
+{
+	unsigned long usemap_snr, pgdat_snr;
+	static unsigned long old_usemap_snr;
+	static unsigned long old_pgdat_snr;
+	struct pglist_data *pgdat = NODE_DATA(nid);
+	int usemap_nid;
+
+	/* First call */
+	if (!old_usemap_snr) {
+		old_usemap_snr = NR_MEM_SECTIONS;
+		old_pgdat_snr = NR_MEM_SECTIONS;
+	}
+
+	usemap_snr = pfn_to_section_nr(__pa(usemap) >> PAGE_SHIFT);
+	pgdat_snr = pfn_to_section_nr(__pa(pgdat) >> PAGE_SHIFT);
+	if (usemap_snr == pgdat_snr)
+		return;
+
+	if (old_usemap_snr == usemap_snr && old_pgdat_snr == pgdat_snr)
+		/* skip redundant message */
+		return;
+
+	old_usemap_snr = usemap_snr;
+	old_pgdat_snr = pgdat_snr;
+
+	usemap_nid = sparse_early_nid(__nr_to_section(usemap_snr));
+	if (usemap_nid != nid) {
+		pr_info("node %d must be removed before remove section %ld\n",
+			nid, usemap_snr);
+		return;
+	}
+	/*
+	 * There is a circular dependency.
+	 * Some platforms allow un-removable section because they will just
+	 * gather other removable sections for dynamic partitioning.
+	 * Just notify un-removable section's number here.
+	 */
+	pr_info("Section %ld and %ld (node %d) have a circular dependency on usemap and pgdat allocations\n",
+		usemap_snr, pgdat_snr, nid);
+}
+#else
+static unsigned long * __init
+sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
+					 unsigned long size)
+{
+	return memblock_virt_alloc_node_nopanic(size, pgdat->node_id);
+}
+
+static void __init check_usemap_section_nr(int nid, unsigned long *usemap)
+{
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+static unsigned long __init section_map_size(void)
+{
+	return ALIGN(sizeof(struct page) * PAGES_PER_SECTION, PMD_SIZE);
+}
+
+#else
+static unsigned long __init section_map_size(void)
+{
+	return PAGE_ALIGN(sizeof(struct page) * PAGES_PER_SECTION);
+}
+
+struct page __init *sparse_mem_map_populate(unsigned long pnum, int nid,
+		struct vmem_altmap *altmap)
+{
+	unsigned long size = section_map_size();
+	struct page *map = sparse_buffer_alloc(size);
+
+	if (map)
+		return map;
+
+	map = memblock_virt_alloc_try_nid(size,
+					  PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
+					  BOOTMEM_ALLOC_ACCESSIBLE, nid);
+	return map;
+}
+#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
+
+static void *sparsemap_buf __meminitdata;
+static void *sparsemap_buf_end __meminitdata;
+
+static void __init sparse_buffer_init(unsigned long size, int nid)
+{
+	WARN_ON(sparsemap_buf);	/* forgot to call sparse_buffer_fini()? */
+	sparsemap_buf =
+		memblock_virt_alloc_try_nid_raw(size, PAGE_SIZE,
+						__pa(MAX_DMA_ADDRESS),
+						BOOTMEM_ALLOC_ACCESSIBLE, nid);
+	sparsemap_buf_end = sparsemap_buf + size;
+}
+
+static void __init sparse_buffer_fini(void)
+{
+	unsigned long size = sparsemap_buf_end - sparsemap_buf;
+
+	if (sparsemap_buf && size > 0)
+		memblock_free_early(__pa(sparsemap_buf), size);
+	sparsemap_buf = NULL;
+}
+
+void * __meminit sparse_buffer_alloc(unsigned long size)
+{
+	void *ptr = NULL;
+
+	if (sparsemap_buf) {
+		ptr = PTR_ALIGN(sparsemap_buf, size);
+		if (ptr + size > sparsemap_buf_end)
+			ptr = NULL;
+		else
+			sparsemap_buf = ptr + size;
+	}
+	return ptr;
+}
+
+void __weak __meminit vmemmap_populate_print_last(void)
+{
+}
+
+/*
+ * Initialize sparse on a specific node. The node spans [pnum_begin, pnum_end)
+ * And number of present sections in this node is map_count.
+ */
+static void __init sparse_init_nid(int nid, unsigned long pnum_begin,
+				   unsigned long pnum_end,
+				   unsigned long map_count)
+{
+	unsigned long pnum, usemap_longs, *usemap;
+	struct page *map;
+
+	usemap_longs = BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS);
+	usemap = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nid),
+							  usemap_size() *
+							  map_count);
+	if (!usemap) {
+		pr_err("%s: node[%d] usemap allocation failed", __func__, nid);
+		goto failed;
+	}
+	sparse_buffer_init(map_count * section_map_size(), nid);
+	for_each_present_section_nr(pnum_begin, pnum) {
+		if (pnum >= pnum_end)
+			break;
+
+		map = sparse_mem_map_populate(pnum, nid, NULL);
+		if (!map) {
+			pr_err("%s: node[%d] memory map backing failed. Some memory will not be available.",
+			       __func__, nid);
+			pnum_begin = pnum;
+			goto failed;
+		}
+		check_usemap_section_nr(nid, usemap);
+		sparse_init_one_section(__nr_to_section(pnum), pnum, map, usemap);
+		usemap += usemap_longs;
+	}
+	sparse_buffer_fini();
+	return;
+failed:
+	/* We failed to allocate, mark all the following pnums as not present */
+	for_each_present_section_nr(pnum_begin, pnum) {
+		struct mem_section *ms;
+
+		if (pnum >= pnum_end)
+			break;
+		ms = __nr_to_section(pnum);
+		ms->section_mem_map = 0;
+	}
+}
+
+/*
+ * Allocate the accumulated non-linear sections, allocate a mem_map
+ * for each and record the physical to section mapping.
+ */
+void __init sparse_init(void)
+{
+	unsigned long pnum_begin = first_present_section_nr();
+	int nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
+	unsigned long pnum_end, map_count = 1;
+
+	/* Setup pageblock_order for HUGETLB_PAGE_SIZE_VARIABLE */
+	set_pageblock_order();
+
+	for_each_present_section_nr(pnum_begin + 1, pnum_end) {
+		int nid = sparse_early_nid(__nr_to_section(pnum_end));
+
+		if (nid == nid_begin) {
+			map_count++;
+			continue;
+		}
+		/* Init node with sections in range [pnum_begin, pnum_end) */
+		sparse_init_nid(nid_begin, pnum_begin, pnum_end, map_count);
+		nid_begin = nid;
+		pnum_begin = pnum_end;
+		map_count = 1;
+	}
+	/* cover the last node */
+	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;
+
+		/* onlining code should never touch invalid ranges */
+		if (WARN_ON(!valid_section_nr(section_nr)))
+			continue;
+
+		ms = __nr_to_section(section_nr);
+		ms->section_mem_map |= SECTION_IS_ONLINE;
+	}
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/* Mark all memory sections within the pfn range as online */
+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;
+
+		/*
+		 * TODO this needs some double checking. Offlining code makes
+		 * sure to check pfn_valid but those checks might be just bogus
+		 */
+		if (WARN_ON(!valid_section_nr(section_nr)))
+			continue;
+
+		ms = __nr_to_section(section_nr);
+		ms->section_mem_map &= ~SECTION_IS_ONLINE;
+	}
+}
+#endif
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
+		struct vmem_altmap *altmap)
+{
+	/* This will make the necessary allocations eventually. */
+	return sparse_mem_map_populate(pnum, nid, altmap);
+}
+static void __kfree_section_memmap(struct page *memmap,
+		struct vmem_altmap *altmap)
+{
+	unsigned long start = (unsigned long)memmap;
+	unsigned long end = (unsigned long)(memmap + PAGES_PER_SECTION);
+
+	vmemmap_free(start, end, altmap);
+}
+#ifdef CONFIG_MEMORY_HOTREMOVE
+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);
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+#else
+static struct page *__kmalloc_section_memmap(void)
+{
+	struct page *page, *ret;
+	unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION;
+
+	page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
+	if (page)
+		goto got_map_page;
+
+	ret = vmalloc(memmap_size);
+	if (ret)
+		goto got_map_ptr;
+
+	return NULL;
+got_map_page:
+	ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));
+got_map_ptr:
+
+	return ret;
+}
+
+static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
+		struct vmem_altmap *altmap)
+{
+	return __kmalloc_section_memmap();
+}
+
+static void __kfree_section_memmap(struct page *memmap,
+		struct vmem_altmap *altmap)
+{
+	if (is_vmalloc_addr(memmap))
+		vfree(memmap);
+	else
+		free_pages((unsigned long)memmap,
+			   get_order(sizeof(struct page) * PAGES_PER_SECTION));
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static void free_map_bootmem(struct page *memmap)
+{
+	unsigned long maps_section_nr, removing_section_nr, i;
+	unsigned long magic, nr_pages;
+	struct page *page = virt_to_page(memmap);
+
+	nr_pages = PAGE_ALIGN(PAGES_PER_SECTION * sizeof(struct page))
+		>> PAGE_SHIFT;
+
+	for (i = 0; i < nr_pages; i++, page++) {
+		magic = (unsigned long) page->freelist;
+
+		BUG_ON(magic == NODE_INFO);
+
+		maps_section_nr = pfn_to_section_nr(page_to_pfn(page));
+		removing_section_nr = page_private(page);
+
+		/*
+		 * When this function is called, the removing section is
+		 * logical offlined state. This means all pages are isolated
+		 * from page allocator. If removing section's memmap is placed
+		 * on the same section, it must not be freed.
+		 * If it is freed, page allocator may allocate it which will
+		 * be removed physically soon.
+		 */
+		if (maps_section_nr != removing_section_nr)
+			put_page_bootmem(page);
+	}
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+#endif /* CONFIG_SPARSEMEM_VMEMMAP */
+
+/*
+ * returns the number of sections whose mem_maps were properly
+ * set.  If this is <=0, then that means that the passed-in
+ * map was not consumed and must be freed.
+ */
+int __meminit sparse_add_one_section(struct pglist_data *pgdat,
+		unsigned long start_pfn, struct vmem_altmap *altmap)
+{
+	unsigned long section_nr = pfn_to_section_nr(start_pfn);
+	struct mem_section *ms;
+	struct page *memmap;
+	unsigned long *usemap;
+	unsigned long flags;
+	int ret;
+
+	/*
+	 * no locking for this, because it does its own
+	 * plus, it does a kmalloc
+	 */
+	ret = sparse_index_init(section_nr, pgdat->node_id);
+	if (ret < 0 && ret != -EEXIST)
+		return ret;
+	ret = 0;
+	memmap = kmalloc_section_memmap(section_nr, pgdat->node_id, altmap);
+	if (!memmap)
+		return -ENOMEM;
+	usemap = __kmalloc_section_usemap();
+	if (!usemap) {
+		__kfree_section_memmap(memmap, altmap);
+		return -ENOMEM;
+	}
+
+	pgdat_resize_lock(pgdat, &flags);
+
+	ms = __pfn_to_section(start_pfn);
+	if (ms->section_mem_map & SECTION_MARKED_PRESENT) {
+		ret = -EEXIST;
+		goto out;
+	}
+
+#ifdef CONFIG_DEBUG_VM
+	/*
+	 * Poison uninitialized struct pages in order to catch invalid flags
+	 * combinations.
+	 */
+	memset(memmap, PAGE_POISON_PATTERN, sizeof(struct page) * PAGES_PER_SECTION);
+#endif
+
+	section_mark_present(ms);
+	sparse_init_one_section(ms, section_nr, memmap, usemap);
+
+out:
+	pgdat_resize_unlock(pgdat, &flags);
+	if (ret < 0) {
+		kfree(usemap);
+		__kfree_section_memmap(memmap, altmap);
+	}
+	return ret;
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+#ifdef CONFIG_MEMORY_FAILURE
+static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
+{
+	int i;
+
+	if (!memmap)
+		return;
+
+	for (i = 0; i < nr_pages; i++) {
+		if (PageHWPoison(&memmap[i])) {
+			atomic_long_sub(1, &num_poisoned_pages);
+			ClearPageHWPoison(&memmap[i]);
+		}
+	}
+}
+#else
+static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
+{
+}
+#endif
+
+static void free_section_usemap(struct page *memmap, unsigned long *usemap,
+		struct vmem_altmap *altmap)
+{
+	struct page *usemap_page;
+
+	if (!usemap)
+		return;
+
+	usemap_page = virt_to_page(usemap);
+	/*
+	 * Check to see if allocation came from hot-plug-add
+	 */
+	if (PageSlab(usemap_page) || PageCompound(usemap_page)) {
+		kfree(usemap);
+		if (memmap)
+			__kfree_section_memmap(memmap, altmap);
+		return;
+	}
+
+	/*
+	 * The usemap came from bootmem. This is packed with other usemaps
+	 * on the section which has pgdat at boot time. Just keep it as is now.
+	 */
+
+	if (memmap)
+		free_map_bootmem(memmap);
+}
+
+void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
+		unsigned long map_offset, struct vmem_altmap *altmap)
+{
+	struct page *memmap = NULL;
+	unsigned long *usemap = NULL, flags;
+	struct pglist_data *pgdat = zone->zone_pgdat;
+
+	pgdat_resize_lock(pgdat, &flags);
+	if (ms->section_mem_map) {
+		usemap = ms->pageblock_flags;
+		memmap = sparse_decode_mem_map(ms->section_mem_map,
+						__section_nr(ms));
+		ms->section_mem_map = 0;
+		ms->pageblock_flags = NULL;
+	}
+	pgdat_resize_unlock(pgdat, &flags);
+
+	clear_hwpoisoned_pages(memmap + map_offset,
+			PAGES_PER_SECTION - map_offset);
+	free_section_usemap(memmap, usemap, altmap);
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+#endif /* CONFIG_MEMORY_HOTPLUG */