Initial commit: OpenHarmony-v4.0-ReleaseOpenHarmony-v4.0-Release

1 files changed, 974 insertions, 0 deletions

diff --git a/mm/sparse.c b/mm/sparse.c
new file mode 100644
index 000000000..33406ea2e
--- /dev/null
+++ b/mm/sparse.c
@@ -0,0 +1,974 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * sparse memory mappings.
+ */
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/mmzone.h>
+#include <linux/memblock.h>
+#include <linux/compiler.h>
+#include <linux/highmem.h>
+#include <linux/export.h>
+#include <linux/spinlock.h>
+#include <linux/vmalloc.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+
+#include "internal.h"
+#include <asm/dma.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_alloc_node(array_size, SMP_CACHE_BYTES,
+                                              nid);
+                if (!section)
+                        panic("%s: Failed to allocate %lu bytes nid=%d\n",
+                              __func__, 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;
+
+        /*
+         * An existing section is possible in the sub-section hotplug
+         * case. First hot-add instantiates, follow-on hot-add reuses
+         * the existing section.
+         *
+         * The mem_hotplug_lock resolves the apparent race below.
+         */
+        if (mem_section[root])
+                return 0;
+
+        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
+unsigned long __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
+unsigned long __section_nr(struct mem_section *ms)
+{
+        return (unsigned long)(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.
+ */
+unsigned long __highest_present_section_nr;
+static void section_mark_present(struct mem_section *ms)
+{
+        unsigned long 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;
+}
+
+#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);
+}
+
+#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 subsection_map_init(unsigned long pfn, unsigned long nr_pages)
+{
+        int end_sec = pfn_to_section_nr(pfn + nr_pages - 1);
+        unsigned long nr, start_sec = pfn_to_section_nr(pfn);
+
+        if (!nr_pages)
+                return;
+
+        for (nr = start_sec; nr <= end_sec; 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;
+        }
+}
+#else
+void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
+{
+}
+#endif
+
+/* Record a memory area against a node. */
+static 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_alloc(size, align);
+                if (!mem_section)
+                        panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
+                              __func__, 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);
+                }
+        }
+}
+
+/*
+ * Mark all memblocks as present using memory_present().
+ * This is a convenience function that is useful to mark all of the systems
+ * memory as present during initialization.
+ */
+static void __init memblocks_present(void)
+{
+        unsigned long start, end;
+        int i, nid;
+
+        for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid)
+                memory_present(nid, start, end);
+}
+
+/*
+ * 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;
+}
+
+#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)
+{
+        ms->section_mem_map &= ~SECTION_MAP_MASK;
+        ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum)
+                | SECTION_HAS_MEM_MAP | flags;
+        ms->usage = usage;
+}
+
+static unsigned long usemap_size(void)
+{
+        return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long);
+}
+
+size_t mem_section_usage_size(void)
+{
+        return sizeof(struct mem_section_usage) + usemap_size();
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+static struct mem_section_usage * __init
+sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
+                                         unsigned long size)
+{
+        struct mem_section_usage *usage;
+        unsigned long goal, limit;
+        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:
+        usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, goal, limit, nid);
+        if (!usage && limit) {
+                limit = 0;
+                goto again;
+        }
+        return usage;
+}
+
+static void __init check_usemap_section_nr(int nid,
+                struct mem_section_usage *usage)
+{
+        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(usage) >> 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 struct mem_section_usage * __init
+sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
+                                         unsigned long size)
+{
+        return memblock_alloc_node(size, SMP_CACHE_BYTES, pgdat->node_id);
+}
+
+static void __init check_usemap_section_nr(int nid,
+                struct mem_section_usage *usage)
+{
+}
+#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 *__populate_section_memmap(unsigned long pfn,
+                unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
+{
+        unsigned long size = section_map_size();
+        struct page *map = sparse_buffer_alloc(size);
+        phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
+
+        if (map)
+                return map;
+
+        map = memblock_alloc_try_nid_raw(size, size, addr,
+                                          MEMBLOCK_ALLOC_ACCESSIBLE, nid);
+        if (!map)
+                panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n",
+                      __func__, size, PAGE_SIZE, nid, &addr);
+
+        return map;
+}
+#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
+
+static void *sparsemap_buf __meminitdata;
+static void *sparsemap_buf_end __meminitdata;
+
+static inline void __meminit sparse_buffer_free(unsigned long size)
+{
+        WARN_ON(!sparsemap_buf || size == 0);
+        memblock_free_early(__pa(sparsemap_buf), size);
+}
+
+static void __init sparse_buffer_init(unsigned long size, int nid)
+{
+        phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
+        WARN_ON(sparsemap_buf); /* forgot to call sparse_buffer_fini()? */
+        /*
+         * Pre-allocated buffer is mainly used by __populate_section_memmap
+         * and we want it to be properly aligned to the section size - this is
+         * especially the case for VMEMMAP which maps memmap to PMDs
+         */
+        sparsemap_buf = memblock_alloc_exact_nid_raw(size, section_map_size(),
+                                        addr, MEMBLOCK_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)
+                sparse_buffer_free(size);
+        sparsemap_buf = NULL;
+}
+
+void * __meminit sparse_buffer_alloc(unsigned long size)
+{
+        void *ptr = NULL;
+
+        if (sparsemap_buf) {
+                ptr = (void *) roundup((unsigned long)sparsemap_buf, size);
+                if (ptr + size > sparsemap_buf_end)
+                        ptr = NULL;
+                else {
+                        /* Free redundant aligned space */
+                        if ((unsigned long)(ptr - sparsemap_buf) > 0)
+                                sparse_buffer_free((unsigned long)(ptr - sparsemap_buf));
+                        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)
+{
+        struct mem_section_usage *usage;
+        unsigned long pnum;
+        struct page *map;
+
+        usage = sparse_early_usemaps_alloc_pgdat_section(NODE_DATA(nid),
+                        mem_section_usage_size() * map_count);
+        if (!usage) {
+                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) {
+                unsigned long pfn = section_nr_to_pfn(pnum);
+
+                if (pnum >= pnum_end)
+                        break;
+
+                map = __populate_section_memmap(pfn, PAGES_PER_SECTION,
+                                nid, NULL);
+                if (!map) {
+                        pr_err("%s: node[%d] memory map backing failed. Some memory will not be available.",
+                               __func__, nid);
+                        pnum_begin = pnum;
+                        sparse_buffer_fini();
+                        goto failed;
+                }
+                check_usemap_section_nr(nid, usage);
+                sparse_init_one_section(__nr_to_section(pnum), pnum, map, usage,
+                                SECTION_IS_EARLY);
+                usage = (void *) usage + mem_section_usage_size();
+        }
+        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_end, pnum_begin, map_count = 1;
+        int nid_begin;
+
+        memblocks_present();
+
+        pnum_begin = first_present_section_nr();
+        nid_begin = sparse_early_nid(__nr_to_section(pnum_begin));
+
+        /* 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 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;
+
+                /*
+                 * 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 struct page * __meminit populate_section_memmap(unsigned long pfn,
+                unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
+{
+        return __populate_section_memmap(pfn, nr_pages, nid, altmap);
+}
+
+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;
+}
+#else
+struct page * __meminit populate_section_memmap(unsigned long pfn,
+                unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
+{
+        return kvmalloc_node(array_size(sizeof(struct page),
+                                        PAGES_PER_SECTION), GFP_KERNEL, nid);
+}
+
+static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,
+                struct vmem_altmap *altmap)
+{
+        kvfree(pfn_to_page(pfn));
+}
+
+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);
+        }
+}
+
+static int clear_subsection_map(unsigned long pfn, unsigned long nr_pages)
+{
+        return 0;
+}
+
+static bool is_subsection_map_empty(struct mem_section *ms)
+{
+        return true;
+}
+
+static int fill_subsection_map(unsigned long pfn, unsigned long nr_pages)
+{
+        return 0;
+}
+#endif /* CONFIG_SPARSEMEM_VMEMMAP */
+
+/*
+ * To deactivate a memory region, there are 3 cases to handle across
+ * two configurations (SPARSEMEM_VMEMMAP={y,n}):
+ *
+ * 1. deactivation of a partial hot-added section (only possible in
+ *    the SPARSEMEM_VMEMMAP=y case).
+ *      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.
+ *
+ * For 2 and 3, the SPARSEMEM_VMEMMAP={y,n} cases are unified
+ */
+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) {
+                unsigned long section_nr = pfn_to_section_nr(pfn);
+
+                /*
+                 * 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(ms->usage);
+                        ms->usage = NULL;
+                }
+                memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
+                /*
+                 * 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;
+        }
+
+        /*
+         * 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);
+        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 mem_section *ms = __pfn_to_section(pfn);
+        struct mem_section_usage *usage = NULL;
+        struct page *memmap;
+        int rc = 0;
+
+        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);
+        if (!memmap) {
+                section_deactivate(pfn, nr_pages, altmap);
+                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: device page map
+ *
+ * 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)
+{
+        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);
+        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);
+        set_section_nid(section_nr, nid);
+        section_mark_present(ms);
+
+        /* 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;
+}
+
+#ifdef CONFIG_MEMORY_FAILURE
+static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
+{
+        int i;
+
+        /*
+         * A further optimization is to have per section refcounted
+         * num_poisoned_pages.  But that would need more space per memmap, so
+         * for now just do a quick global check to speed up this routine in the
+         * absence of bad pages.
+         */
+        if (atomic_long_read(&num_poisoned_pages) == 0)
+                return;
+
+        for (i = 0; i < nr_pages; i++) {
+                if (PageHWPoison(&memmap[i])) {
+                        num_poisoned_pages_dec();
+                        ClearPageHWPoison(&memmap[i]);
+                }
+        }
+}
+#else
+static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
+{
+}
+#endif
+
+void sparse_remove_section(struct mem_section *ms, unsigned long pfn,
+                unsigned long nr_pages, unsigned long map_offset,
+                struct vmem_altmap *altmap)
+{
+        clear_hwpoisoned_pages(pfn_to_page(pfn) + map_offset,
+                        nr_pages - map_offset);
+        section_deactivate(pfn, nr_pages, altmap);
+}
+#endif /* CONFIG_MEMORY_HOTPLUG */