linux/mm/percpu-vm.c
<<
>>
Prefs
   1/*
   2 * mm/percpu-vm.c - vmalloc area based chunk allocation
   3 *
   4 * Copyright (C) 2010           SUSE Linux Products GmbH
   5 * Copyright (C) 2010           Tejun Heo <tj@kernel.org>
   6 *
   7 * This file is released under the GPLv2.
   8 *
   9 * Chunks are mapped into vmalloc areas and populated page by page.
  10 * This is the default chunk allocator.
  11 */
  12
  13static struct page *pcpu_chunk_page(struct pcpu_chunk *chunk,
  14                                    unsigned int cpu, int page_idx)
  15{
  16        /* must not be used on pre-mapped chunk */
  17        WARN_ON(chunk->immutable);
  18
  19        return vmalloc_to_page((void *)pcpu_chunk_addr(chunk, cpu, page_idx));
  20}
  21
  22/**
  23 * pcpu_get_pages_and_bitmap - get temp pages array and bitmap
  24 * @chunk: chunk of interest
  25 * @bitmapp: output parameter for bitmap
  26 * @may_alloc: may allocate the array
  27 *
  28 * Returns pointer to array of pointers to struct page and bitmap,
  29 * both of which can be indexed with pcpu_page_idx().  The returned
  30 * array is cleared to zero and *@bitmapp is copied from
  31 * @chunk->populated.  Note that there is only one array and bitmap
  32 * and access exclusion is the caller's responsibility.
  33 *
  34 * CONTEXT:
  35 * pcpu_alloc_mutex and does GFP_KERNEL allocation if @may_alloc.
  36 * Otherwise, don't care.
  37 *
  38 * RETURNS:
  39 * Pointer to temp pages array on success, NULL on failure.
  40 */
  41static struct page **pcpu_get_pages_and_bitmap(struct pcpu_chunk *chunk,
  42                                               unsigned long **bitmapp,
  43                                               bool may_alloc)
  44{
  45        static struct page **pages;
  46        static unsigned long *bitmap;
  47        size_t pages_size = pcpu_nr_units * pcpu_unit_pages * sizeof(pages[0]);
  48        size_t bitmap_size = BITS_TO_LONGS(pcpu_unit_pages) *
  49                             sizeof(unsigned long);
  50
  51        if (!pages || !bitmap) {
  52                if (may_alloc && !pages)
  53                        pages = pcpu_mem_alloc(pages_size);
  54                if (may_alloc && !bitmap)
  55                        bitmap = pcpu_mem_alloc(bitmap_size);
  56                if (!pages || !bitmap)
  57                        return NULL;
  58        }
  59
  60        memset(pages, 0, pages_size);
  61        bitmap_copy(bitmap, chunk->populated, pcpu_unit_pages);
  62
  63        *bitmapp = bitmap;
  64        return pages;
  65}
  66
  67/**
  68 * pcpu_free_pages - free pages which were allocated for @chunk
  69 * @chunk: chunk pages were allocated for
  70 * @pages: array of pages to be freed, indexed by pcpu_page_idx()
  71 * @populated: populated bitmap
  72 * @page_start: page index of the first page to be freed
  73 * @page_end: page index of the last page to be freed + 1
  74 *
  75 * Free pages [@page_start and @page_end) in @pages for all units.
  76 * The pages were allocated for @chunk.
  77 */
  78static void pcpu_free_pages(struct pcpu_chunk *chunk,
  79                            struct page **pages, unsigned long *populated,
  80                            int page_start, int page_end)
  81{
  82        unsigned int cpu;
  83        int i;
  84
  85        for_each_possible_cpu(cpu) {
  86                for (i = page_start; i < page_end; i++) {
  87                        struct page *page = pages[pcpu_page_idx(cpu, i)];
  88
  89                        if (page)
  90                                __free_page(page);
  91                }
  92        }
  93}
  94
  95/**
  96 * pcpu_alloc_pages - allocates pages for @chunk
  97 * @chunk: target chunk
  98 * @pages: array to put the allocated pages into, indexed by pcpu_page_idx()
  99 * @populated: populated bitmap
 100 * @page_start: page index of the first page to be allocated
 101 * @page_end: page index of the last page to be allocated + 1
 102 *
 103 * Allocate pages [@page_start,@page_end) into @pages for all units.
 104 * The allocation is for @chunk.  Percpu core doesn't care about the
 105 * content of @pages and will pass it verbatim to pcpu_map_pages().
 106 */
 107static int pcpu_alloc_pages(struct pcpu_chunk *chunk,
 108                            struct page **pages, unsigned long *populated,
 109                            int page_start, int page_end)
 110{
 111        const gfp_t gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_COLD;
 112        unsigned int cpu;
 113        int i;
 114
 115        for_each_possible_cpu(cpu) {
 116                for (i = page_start; i < page_end; i++) {
 117                        struct page **pagep = &pages[pcpu_page_idx(cpu, i)];
 118
 119                        *pagep = alloc_pages_node(cpu_to_node(cpu), gfp, 0);
 120                        if (!*pagep) {
 121                                pcpu_free_pages(chunk, pages, populated,
 122                                                page_start, page_end);
 123                                return -ENOMEM;
 124                        }
 125                }
 126        }
 127        return 0;
 128}
 129
 130/**
 131 * pcpu_pre_unmap_flush - flush cache prior to unmapping
 132 * @chunk: chunk the regions to be flushed belongs to
 133 * @page_start: page index of the first page to be flushed
 134 * @page_end: page index of the last page to be flushed + 1
 135 *
 136 * Pages in [@page_start,@page_end) of @chunk are about to be
 137 * unmapped.  Flush cache.  As each flushing trial can be very
 138 * expensive, issue flush on the whole region at once rather than
 139 * doing it for each cpu.  This could be an overkill but is more
 140 * scalable.
 141 */
 142static void pcpu_pre_unmap_flush(struct pcpu_chunk *chunk,
 143                                 int page_start, int page_end)
 144{
 145        flush_cache_vunmap(
 146                pcpu_chunk_addr(chunk, pcpu_first_unit_cpu, page_start),
 147                pcpu_chunk_addr(chunk, pcpu_last_unit_cpu, page_end));
 148}
 149
 150static void __pcpu_unmap_pages(unsigned long addr, int nr_pages)
 151{
 152        unmap_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT);
 153}
 154
 155/**
 156 * pcpu_unmap_pages - unmap pages out of a pcpu_chunk
 157 * @chunk: chunk of interest
 158 * @pages: pages array which can be used to pass information to free
 159 * @populated: populated bitmap
 160 * @page_start: page index of the first page to unmap
 161 * @page_end: page index of the last page to unmap + 1
 162 *
 163 * For each cpu, unmap pages [@page_start,@page_end) out of @chunk.
 164 * Corresponding elements in @pages were cleared by the caller and can
 165 * be used to carry information to pcpu_free_pages() which will be
 166 * called after all unmaps are finished.  The caller should call
 167 * proper pre/post flush functions.
 168 */
 169static void pcpu_unmap_pages(struct pcpu_chunk *chunk,
 170                             struct page **pages, unsigned long *populated,
 171                             int page_start, int page_end)
 172{
 173        unsigned int cpu;
 174        int i;
 175
 176        for_each_possible_cpu(cpu) {
 177                for (i = page_start; i < page_end; i++) {
 178                        struct page *page;
 179
 180                        page = pcpu_chunk_page(chunk, cpu, i);
 181                        WARN_ON(!page);
 182                        pages[pcpu_page_idx(cpu, i)] = page;
 183                }
 184                __pcpu_unmap_pages(pcpu_chunk_addr(chunk, cpu, page_start),
 185                                   page_end - page_start);
 186        }
 187
 188        for (i = page_start; i < page_end; i++)
 189                __clear_bit(i, populated);
 190}
 191
 192/**
 193 * pcpu_post_unmap_tlb_flush - flush TLB after unmapping
 194 * @chunk: pcpu_chunk the regions to be flushed belong to
 195 * @page_start: page index of the first page to be flushed
 196 * @page_end: page index of the last page to be flushed + 1
 197 *
 198 * Pages [@page_start,@page_end) of @chunk have been unmapped.  Flush
 199 * TLB for the regions.  This can be skipped if the area is to be
 200 * returned to vmalloc as vmalloc will handle TLB flushing lazily.
 201 *
 202 * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
 203 * for the whole region.
 204 */
 205static void pcpu_post_unmap_tlb_flush(struct pcpu_chunk *chunk,
 206                                      int page_start, int page_end)
 207{
 208        flush_tlb_kernel_range(
 209                pcpu_chunk_addr(chunk, pcpu_first_unit_cpu, page_start),
 210                pcpu_chunk_addr(chunk, pcpu_last_unit_cpu, page_end));
 211}
 212
 213static int __pcpu_map_pages(unsigned long addr, struct page **pages,
 214                            int nr_pages)
 215{
 216        return map_kernel_range_noflush(addr, nr_pages << PAGE_SHIFT,
 217                                        PAGE_KERNEL, pages);
 218}
 219
 220/**
 221 * pcpu_map_pages - map pages into a pcpu_chunk
 222 * @chunk: chunk of interest
 223 * @pages: pages array containing pages to be mapped
 224 * @populated: populated bitmap
 225 * @page_start: page index of the first page to map
 226 * @page_end: page index of the last page to map + 1
 227 *
 228 * For each cpu, map pages [@page_start,@page_end) into @chunk.  The
 229 * caller is responsible for calling pcpu_post_map_flush() after all
 230 * mappings are complete.
 231 *
 232 * This function is responsible for setting corresponding bits in
 233 * @chunk->populated bitmap and whatever is necessary for reverse
 234 * lookup (addr -> chunk).
 235 */
 236static int pcpu_map_pages(struct pcpu_chunk *chunk,
 237                          struct page **pages, unsigned long *populated,
 238                          int page_start, int page_end)
 239{
 240        unsigned int cpu, tcpu;
 241        int i, err;
 242
 243        for_each_possible_cpu(cpu) {
 244                err = __pcpu_map_pages(pcpu_chunk_addr(chunk, cpu, page_start),
 245                                       &pages[pcpu_page_idx(cpu, page_start)],
 246                                       page_end - page_start);
 247                if (err < 0)
 248                        goto err;
 249        }
 250
 251        /* mapping successful, link chunk and mark populated */
 252        for (i = page_start; i < page_end; i++) {
 253                for_each_possible_cpu(cpu)
 254                        pcpu_set_page_chunk(pages[pcpu_page_idx(cpu, i)],
 255                                            chunk);
 256                __set_bit(i, populated);
 257        }
 258
 259        return 0;
 260
 261err:
 262        for_each_possible_cpu(tcpu) {
 263                if (tcpu == cpu)
 264                        break;
 265                __pcpu_unmap_pages(pcpu_chunk_addr(chunk, tcpu, page_start),
 266                                   page_end - page_start);
 267        }
 268        return err;
 269}
 270
 271/**
 272 * pcpu_post_map_flush - flush cache after mapping
 273 * @chunk: pcpu_chunk the regions to be flushed belong to
 274 * @page_start: page index of the first page to be flushed
 275 * @page_end: page index of the last page to be flushed + 1
 276 *
 277 * Pages [@page_start,@page_end) of @chunk have been mapped.  Flush
 278 * cache.
 279 *
 280 * As with pcpu_pre_unmap_flush(), TLB flushing also is done at once
 281 * for the whole region.
 282 */
 283static void pcpu_post_map_flush(struct pcpu_chunk *chunk,
 284                                int page_start, int page_end)
 285{
 286        flush_cache_vmap(
 287                pcpu_chunk_addr(chunk, pcpu_first_unit_cpu, page_start),
 288                pcpu_chunk_addr(chunk, pcpu_last_unit_cpu, page_end));
 289}
 290
 291/**
 292 * pcpu_populate_chunk - populate and map an area of a pcpu_chunk
 293 * @chunk: chunk of interest
 294 * @off: offset to the area to populate
 295 * @size: size of the area to populate in bytes
 296 *
 297 * For each cpu, populate and map pages [@page_start,@page_end) into
 298 * @chunk.  The area is cleared on return.
 299 *
 300 * CONTEXT:
 301 * pcpu_alloc_mutex, does GFP_KERNEL allocation.
 302 */
 303static int pcpu_populate_chunk(struct pcpu_chunk *chunk, int off, int size)
 304{
 305        int page_start = PFN_DOWN(off);
 306        int page_end = PFN_UP(off + size);
 307        int free_end = page_start, unmap_end = page_start;
 308        struct page **pages;
 309        unsigned long *populated;
 310        unsigned int cpu;
 311        int rs, re, rc;
 312
 313        /* quick path, check whether all pages are already there */
 314        rs = page_start;
 315        pcpu_next_pop(chunk, &rs, &re, page_end);
 316        if (rs == page_start && re == page_end)
 317                goto clear;
 318
 319        /* need to allocate and map pages, this chunk can't be immutable */
 320        WARN_ON(chunk->immutable);
 321
 322        pages = pcpu_get_pages_and_bitmap(chunk, &populated, true);
 323        if (!pages)
 324                return -ENOMEM;
 325
 326        /* alloc and map */
 327        pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
 328                rc = pcpu_alloc_pages(chunk, pages, populated, rs, re);
 329                if (rc)
 330                        goto err_free;
 331                free_end = re;
 332        }
 333
 334        pcpu_for_each_unpop_region(chunk, rs, re, page_start, page_end) {
 335                rc = pcpu_map_pages(chunk, pages, populated, rs, re);
 336                if (rc)
 337                        goto err_unmap;
 338                unmap_end = re;
 339        }
 340        pcpu_post_map_flush(chunk, page_start, page_end);
 341
 342        /* commit new bitmap */
 343        bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
 344clear:
 345        for_each_possible_cpu(cpu)
 346                memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
 347        return 0;
 348
 349err_unmap:
 350        pcpu_pre_unmap_flush(chunk, page_start, unmap_end);
 351        pcpu_for_each_unpop_region(chunk, rs, re, page_start, unmap_end)
 352                pcpu_unmap_pages(chunk, pages, populated, rs, re);
 353        pcpu_post_unmap_tlb_flush(chunk, page_start, unmap_end);
 354err_free:
 355        pcpu_for_each_unpop_region(chunk, rs, re, page_start, free_end)
 356                pcpu_free_pages(chunk, pages, populated, rs, re);
 357        return rc;
 358}
 359
 360/**
 361 * pcpu_depopulate_chunk - depopulate and unmap an area of a pcpu_chunk
 362 * @chunk: chunk to depopulate
 363 * @off: offset to the area to depopulate
 364 * @size: size of the area to depopulate in bytes
 365 * @flush: whether to flush cache and tlb or not
 366 *
 367 * For each cpu, depopulate and unmap pages [@page_start,@page_end)
 368 * from @chunk.  If @flush is true, vcache is flushed before unmapping
 369 * and tlb after.
 370 *
 371 * CONTEXT:
 372 * pcpu_alloc_mutex.
 373 */
 374static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk, int off, int size)
 375{
 376        int page_start = PFN_DOWN(off);
 377        int page_end = PFN_UP(off + size);
 378        struct page **pages;
 379        unsigned long *populated;
 380        int rs, re;
 381
 382        /* quick path, check whether it's empty already */
 383        rs = page_start;
 384        pcpu_next_unpop(chunk, &rs, &re, page_end);
 385        if (rs == page_start && re == page_end)
 386                return;
 387
 388        /* immutable chunks can't be depopulated */
 389        WARN_ON(chunk->immutable);
 390
 391        /*
 392         * If control reaches here, there must have been at least one
 393         * successful population attempt so the temp pages array must
 394         * be available now.
 395         */
 396        pages = pcpu_get_pages_and_bitmap(chunk, &populated, false);
 397        BUG_ON(!pages);
 398
 399        /* unmap and free */
 400        pcpu_pre_unmap_flush(chunk, page_start, page_end);
 401
 402        pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
 403                pcpu_unmap_pages(chunk, pages, populated, rs, re);
 404
 405        /* no need to flush tlb, vmalloc will handle it lazily */
 406
 407        pcpu_for_each_pop_region(chunk, rs, re, page_start, page_end)
 408                pcpu_free_pages(chunk, pages, populated, rs, re);
 409
 410        /* commit new bitmap */
 411        bitmap_copy(chunk->populated, populated, pcpu_unit_pages);
 412}
 413
 414static struct pcpu_chunk *pcpu_create_chunk(void)
 415{
 416        struct pcpu_chunk *chunk;
 417        struct vm_struct **vms;
 418
 419        chunk = pcpu_alloc_chunk();
 420        if (!chunk)
 421                return NULL;
 422
 423        vms = pcpu_get_vm_areas(pcpu_group_offsets, pcpu_group_sizes,
 424                                pcpu_nr_groups, pcpu_atom_size);
 425        if (!vms) {
 426                pcpu_free_chunk(chunk);
 427                return NULL;
 428        }
 429
 430        chunk->data = vms;
 431        chunk->base_addr = vms[0]->addr - pcpu_group_offsets[0];
 432        return chunk;
 433}
 434
 435static void pcpu_destroy_chunk(struct pcpu_chunk *chunk)
 436{
 437        if (chunk && chunk->data)
 438                pcpu_free_vm_areas(chunk->data, pcpu_nr_groups);
 439        pcpu_free_chunk(chunk);
 440}
 441
 442static struct page *pcpu_addr_to_page(void *addr)
 443{
 444        return vmalloc_to_page(addr);
 445}
 446
 447static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai)
 448{
 449        /* no extra restriction */
 450        return 0;
 451}
 452
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.