mm/page_ext.c

   1 #include <linux/mm.h>
   2 #include <linux/mmzone.h>
   3 #include <linux/bootmem.h>
   4 #include <linux/page_ext.h>
   5 #include <linux/memory.h>
   6 #include <linux/vmalloc.h>
   7 #include <linux/kmemleak.h>
   8 #include <linux/page_owner.h>
   9 #include <linux/page_idle.h>
  10
  11 /*
  12  * struct page extension
  13  *
  14  * This is the feature to manage memory for extended data per page.
  15  *
  16  * Until now, we must modify struct page itself to store extra data per page.
  17  * This requires rebuilding the kernel and it is really time consuming process.
  18  * And, sometimes, rebuild is impossible due to third party module dependency.
  19  * At last, enlarging struct page could cause un-wanted system behaviour change.
  20  *
  21  * This feature is intended to overcome above mentioned problems. This feature
  22  * allocates memory for extended data per page in certain place rather than
  23  * the struct page itself. This memory can be accessed by the accessor
  24  * functions provided by this code. During the boot process, it checks whether
  25  * allocation of huge chunk of memory is needed or not. If not, it avoids
  26  * allocating memory at all. With this advantage, we can include this feature
  27  * into the kernel in default and can avoid rebuild and solve related problems.
  28  *
  29  * To help these things to work well, there are two callbacks for clients. One
  30  * is the need callback which is mandatory if user wants to avoid useless
  31  * memory allocation at boot-time. The other is optional, init callback, which
  32  * is used to do proper initialization after memory is allocated.
  33  *
  34  * The need callback is used to decide whether extended memory allocation is
  35  * needed or not. Sometimes users want to deactivate some features in this
  36  * boot and extra memory would be unneccessary. In this case, to avoid
  37  * allocating huge chunk of memory, each clients represent their need of
  38  * extra memory through the need callback. If one of the need callbacks
  39  * returns true, it means that someone needs extra memory so that
  40  * page extension core should allocates memory for page extension. If
  41  * none of need callbacks return true, memory isn't needed at all in this boot
  42  * and page extension core can skip to allocate memory. As result,
  43  * none of memory is wasted.
  44  *
  45  * The init callback is used to do proper initialization after page extension
  46  * is completely initialized. In sparse memory system, extra memory is
  47  * allocated some time later than memmap is allocated. In other words, lifetime
  48  * of memory for page extension isn't same with memmap for struct page.
  49  * Therefore, clients can't store extra data until page extension is
  50  * initialized, even if pages are allocated and used freely. This could
  51  * cause inadequate state of extra data per page, so, to prevent it, client
  52  * can utilize this callback to initialize the state of it correctly.
  53  */
  54
  55 static struct page_ext_operations *page_ext_ops[] = {
  56         &debug_guardpage_ops,
  57 #ifdef CONFIG_PAGE_POISONING
  58         &page_poisoning_ops,
  59 #endif
  60 #ifdef CONFIG_PAGE_OWNER
  61         &page_owner_ops,
  62 #endif
  63 #if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
  64         &page_idle_ops,
  65 #endif
  66 };
  67
  68 static unsigned long total_usage;
  69
  70 static bool __init invoke_need_callbacks(void)
  71 {
  72         int i;
  73         int entries = ARRAY_SIZE(page_ext_ops);
  74
  75         for (i = 0; i < entries; i++) {
  76                 if (page_ext_ops[i]->need && page_ext_ops[i]->need())
  77                         return true;
  78         }
  79
  80         return false;
  81 }
  82
  83 static void __init invoke_init_callbacks(void)
  84 {
  85         int i;
  86         int entries = ARRAY_SIZE(page_ext_ops);
  87
  88         for (i = 0; i < entries; i++) {
  89                 if (page_ext_ops[i]->init)
  90                         page_ext_ops[i]->init();
  91         }
  92 }
  93
  94 #if !defined(CONFIG_SPARSEMEM)
  95
  96
  97 void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
  98 {
  99         pgdat->node_page_ext = NULL;
 100 }
 101
 102 struct page_ext *lookup_page_ext(struct page *page)
 103 {
 104         unsigned long pfn = page_to_pfn(page);
 105         unsigned long offset;
 106         struct page_ext *base;
 107
 108         base = NODE_DATA(page_to_nid(page))->node_page_ext;
 109 #if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING)
 110         /*
 111          * The sanity checks the page allocator does upon freeing a
 112          * page can reach here before the page_ext arrays are
 113          * allocated when feeding a range of pages to the allocator
 114          * for the first time during bootup or memory hotplug.
 115          *
 116          * This check is also necessary for ensuring page poisoning
 117          * works as expected when enabled
 118          */
 119         if (unlikely(!base))
 120                 return NULL;
 121 #endif
 122         offset = pfn - round_down(node_start_pfn(page_to_nid(page)),
 123                                         MAX_ORDER_NR_PAGES);
 124         return base + offset;
 125 }
 126
 127 static int __init alloc_node_page_ext(int nid)
 128 {
 129         struct page_ext *base;
 130         unsigned long table_size;
 131         unsigned long nr_pages;
 132
 133         nr_pages = NODE_DATA(nid)->node_spanned_pages;
 134         if (!nr_pages)
 135                 return 0;
 136
 137         /*
 138          * Need extra space if node range is not aligned with
 139          * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
 140          * checks buddy's status, range could be out of exact node range.
 141          */
 142         if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
 143                 !IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
 144                 nr_pages += MAX_ORDER_NR_PAGES;
 145
 146         table_size = sizeof(struct page_ext) * nr_pages;
 147
 148         base = memblock_virt_alloc_try_nid_nopanic(
 149                         table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
 150                         BOOTMEM_ALLOC_ACCESSIBLE, nid);
 151         if (!base)
 152                 return -ENOMEM;
 153         NODE_DATA(nid)->node_page_ext = base;
 154         total_usage += table_size;
 155         return 0;
 156 }
 157
 158 void __init page_ext_init_flatmem(void)
 159 {
 160
 161         int nid, fail;
 162
 163         if (!invoke_need_callbacks())
 164                 return;
 165
 166         for_each_online_node(nid)  {
 167                 fail = alloc_node_page_ext(nid);
 168                 if (fail)
 169                         goto fail;
 170         }
 171         pr_info("allocated %ld bytes of page_ext\n", total_usage);
 172         invoke_init_callbacks();
 173         return;
 174
 175 fail:
 176         pr_crit("allocation of page_ext failed.\n");
 177         panic("Out of memory");
 178 }
 179
 180 #else /* CONFIG_FLAT_NODE_MEM_MAP */
 181
 182 struct page_ext *lookup_page_ext(struct page *page)
 183 {
 184         unsigned long pfn = page_to_pfn(page);
 185         struct mem_section *section = __pfn_to_section(pfn);
 186 #if defined(CONFIG_DEBUG_VM) || defined(CONFIG_PAGE_POISONING)
 187         /*
 188          * The sanity checks the page allocator does upon freeing a
 189          * page can reach here before the page_ext arrays are
 190          * allocated when feeding a range of pages to the allocator
 191          * for the first time during bootup or memory hotplug.
 192          *
 193          * This check is also necessary for ensuring page poisoning
 194          * works as expected when enabled
 195          */
 196         if (!section->page_ext)
 197                 return NULL;
 198 #endif
 199         return section->page_ext + pfn;
 200 }
 201
 202 static void *__meminit alloc_page_ext(size_t size, int nid)
 203 {
 204         gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
 205         void *addr = NULL;
 206
 207         addr = alloc_pages_exact_nid(nid, size, flags);
 208         if (addr) {
 209                 kmemleak_alloc(addr, size, 1, flags);
 210                 return addr;
 211         }
 212
 213         if (node_state(nid, N_HIGH_MEMORY))
 214                 addr = vzalloc_node(size, nid);
 215         else
 216                 addr = vzalloc(size);
 217
 218         return addr;
 219 }
 220
 221 static int __meminit init_section_page_ext(unsigned long pfn, int nid)
 222 {
 223         struct mem_section *section;
 224         struct page_ext *base;
 225         unsigned long table_size;
 226
 227         section = __pfn_to_section(pfn);
 228
 229         if (section->page_ext)
 230                 return 0;
 231
 232         table_size = sizeof(struct page_ext) * PAGES_PER_SECTION;
 233         base = alloc_page_ext(table_size, nid);
 234
 235         /*
 236          * The value stored in section->page_ext is (base - pfn)
 237          * and it does not point to the memory block allocated above,
 238          * causing kmemleak false positives.
 239          */
 240         kmemleak_not_leak(base);
 241
 242         if (!base) {
 243                 pr_err("page ext allocation failure\n");
 244                 return -ENOMEM;
 245         }
 246
 247         /*
 248          * The passed "pfn" may not be aligned to SECTION.  For the calculation
 249          * we need to apply a mask.
 250          */
 251         pfn &= PAGE_SECTION_MASK;
 252         section->page_ext = base - pfn;
 253         total_usage += table_size;
 254         return 0;
 255 }
 256 #ifdef CONFIG_MEMORY_HOTPLUG
 257 static void free_page_ext(void *addr)
 258 {
 259         if (is_vmalloc_addr(addr)) {
 260                 vfree(addr);
 261         } else {
 262                 struct page *page = virt_to_page(addr);
 263                 size_t table_size;
 264
 265                 table_size = sizeof(struct page_ext) * PAGES_PER_SECTION;
 266
 267                 BUG_ON(PageReserved(page));
 268                 free_pages_exact(addr, table_size);
 269         }
 270 }
 271
 272 static void __free_page_ext(unsigned long pfn)
 273 {
 274         struct mem_section *ms;
 275         struct page_ext *base;
 276
 277         ms = __pfn_to_section(pfn);
 278         if (!ms || !ms->page_ext)
 279                 return;
 280         base = ms->page_ext + pfn;
 281         free_page_ext(base);
 282         ms->page_ext = NULL;
 283 }
 284
 285 static int __meminit online_page_ext(unsigned long start_pfn,
 286                                 unsigned long nr_pages,
 287                                 int nid)
 288 {
 289         unsigned long start, end, pfn;
 290         int fail = 0;
 291
 292         start = SECTION_ALIGN_DOWN(start_pfn);
 293         end = SECTION_ALIGN_UP(start_pfn + nr_pages);
 294
 295         if (nid == -1) {
 296                 /*
 297                  * In this case, "nid" already exists and contains valid memory.
 298                  * "start_pfn" passed to us is a pfn which is an arg for
 299                  * online__pages(), and start_pfn should exist.
 300                  */
 301                 nid = pfn_to_nid(start_pfn);
 302                 VM_BUG_ON(!node_state(nid, N_ONLINE));
 303         }
 304
 305         for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
 306                 if (!pfn_present(pfn))
 307                         continue;
 308                 fail = init_section_page_ext(pfn, nid);
 309         }
 310         if (!fail)
 311                 return 0;
 312
 313         /* rollback */
 314         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
 315                 __free_page_ext(pfn);
 316
 317         return -ENOMEM;
 318 }
 319
 320 static int __meminit offline_page_ext(unsigned long start_pfn,
 321                                 unsigned long nr_pages, int nid)
 322 {
 323         unsigned long start, end, pfn;
 324
 325         start = SECTION_ALIGN_DOWN(start_pfn);
 326         end = SECTION_ALIGN_UP(start_pfn + nr_pages);
 327
 328         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
 329                 __free_page_ext(pfn);
 330         return 0;
 331
 332 }
 333
 334 static int __meminit page_ext_callback(struct notifier_block *self,
 335                                unsigned long action, void *arg)
 336 {
 337         struct memory_notify *mn = arg;
 338         int ret = 0;
 339
 340         switch (action) {
 341         case MEM_GOING_ONLINE:
 342                 ret = online_page_ext(mn->start_pfn,
 343                                    mn->nr_pages, mn->status_change_nid);
 344                 break;
 345         case MEM_OFFLINE:
 346                 offline_page_ext(mn->start_pfn,
 347                                 mn->nr_pages, mn->status_change_nid);
 348                 break;
 349         case MEM_CANCEL_ONLINE:
 350                 offline_page_ext(mn->start_pfn,
 351                                 mn->nr_pages, mn->status_change_nid);
 352                 break;
 353         case MEM_GOING_OFFLINE:
 354                 break;
 355         case MEM_ONLINE:
 356         case MEM_CANCEL_OFFLINE:
 357                 break;
 358         }
 359
 360         return notifier_from_errno(ret);
 361 }
 362
 363 #endif
 364
 365 void __init page_ext_init(void)
 366 {
 367         unsigned long pfn;
 368         int nid;
 369
 370         if (!invoke_need_callbacks())
 371                 return;
 372
 373         for_each_node_state(nid, N_MEMORY) {
 374                 unsigned long start_pfn, end_pfn;
 375
 376                 start_pfn = node_start_pfn(nid);
 377                 end_pfn = node_end_pfn(nid);
 378                 /*
 379                  * start_pfn and end_pfn may not be aligned to SECTION and the
 380                  * page->flags of out of node pages are not initialized.  So we
 381                  * scan [start_pfn, the biggest section's pfn < end_pfn) here.
 382                  */
 383                 for (pfn = start_pfn; pfn < end_pfn;
 384                         pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
 385
 386                         if (!pfn_valid(pfn))
 387                                 continue;
 388                         /*
 389                          * Nodes's pfns can be overlapping.
 390                          * We know some arch can have a nodes layout such as
 391                          * -------------pfn-------------->
 392                          * N0 | N1 | N2 | N0 | N1 | N2|....
 393                          *
 394                          * Take into account DEFERRED_STRUCT_PAGE_INIT.
 395                          */
 396                         if (early_pfn_to_nid(pfn) != nid)
 397                                 continue;
 398                         if (init_section_page_ext(pfn, nid))
 399                                 goto oom;
 400                 }
 401         }
 402         hotplug_memory_notifier(page_ext_callback, 0);
 403         pr_info("allocated %ld bytes of page_ext\n", total_usage);
 404         invoke_init_callbacks();
 405         return;
 406
 407 oom:
 408         panic("Out of memory");
 409 }
 410
 411 void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
 412 {
 413 }
 414
 415 #endif