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Diffstat (limited to '')
| -rw-r--r-- | mm/sparse.c | 935 |
1 files changed, 935 insertions, 0 deletions
diff --git a/mm/sparse.c b/mm/sparse.c new file mode 100644 index 0000000000..338cf946de --- /dev/null +++ b/mm/sparse.c @@ -0,0 +1,935 @@ +// 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 <linux/bootmem_info.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 + +/* + * 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 ((unsigned long)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 */ +static 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) +{ + 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 = 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, section); + } + } +} + +/* + * 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 > 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 inline phys_addr_t pgdat_to_phys(struct pglist_data *pgdat) +{ +#ifndef CONFIG_NUMA + VM_BUG_ON(pgdat != &contig_page_data); + return __pa_symbol(&contig_page_data); +#else + return __pa(pgdat); +#endif +} + +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 = pgdat_to_phys(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(pgdat_to_phys(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, + struct dev_pagemap *pgmap) +{ + 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 = memmap_alloc(size, size, addr, nid, false); + 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(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 = memmap_alloc(size, section_map_size(), addr, nid, true); + 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, 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; + } +} + +/* 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; + } +} + +#ifdef CONFIG_SPARSEMEM_VMEMMAP +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; +} +#else +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 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 = page->index; + + 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); + + /* + * 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 = sparse_decode_mem_map(ms->section_mem_map, section_nr); + } + + /* + * 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 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); + } + + 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); + set_section_nid(section_nr, nid); + __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 */ |