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 #ifdef CONFIG_DEBUG_VM
 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         if (unlikely(!base))
 117                 return NULL;
 118 #endif
 119         offset = pfn - round_down(node_start_pfn(page_to_nid(page)),
 120                                         MAX_ORDER_NR_PAGES);
 121         return base + offset;
 122 }
 123
 124 static int __init alloc_node_page_ext(int nid)
 125 {
 126         struct page_ext *base;
 127         unsigned long table_size;
 128         unsigned long nr_pages;
 129
 130         nr_pages = NODE_DATA(nid)->node_spanned_pages;
 131         if (!nr_pages)
 132                 return 0;
 133
 134         /*
 135          * Need extra space if node range is not aligned with
 136          * MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
 137          * checks buddy's status, range could be out of exact node range.
 138          */
 139         if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
 140                 !IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
 141                 nr_pages += MAX_ORDER_NR_PAGES;
 142
 143         table_size = sizeof(struct page_ext) * nr_pages;
 144
 145         base = memblock_virt_alloc_try_nid_nopanic(
 146                         table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
 147                         BOOTMEM_ALLOC_ACCESSIBLE, nid);
 148         if (!base)
 149                 return -ENOMEM;
 150         NODE_DATA(nid)->node_page_ext = base;
 151         total_usage += table_size;
 152         return 0;
 153 }
 154
 155 void __init page_ext_init_flatmem(void)
 156 {
 157
 158         int nid, fail;
 159
 160         if (!invoke_need_callbacks())
 161                 return;
 162
 163         for_each_online_node(nid)  {
 164                 fail = alloc_node_page_ext(nid);
 165                 if (fail)
 166                         goto fail;
 167         }
 168         pr_info("allocated %ld bytes of page_ext\n", total_usage);
 169         invoke_init_callbacks();
 170         return;
 171
 172 fail:
 173         pr_crit("allocation of page_ext failed.\n");
 174         panic("Out of memory");
 175 }
 176
 177 #else /* CONFIG_FLAT_NODE_MEM_MAP */
 178
 179 struct page_ext *lookup_page_ext(struct page *page)
 180 {
 181         unsigned long pfn = page_to_pfn(page);
 182         struct mem_section *section = __pfn_to_section(pfn);
 183 #ifdef CONFIG_DEBUG_VM
 184         /*
 185          * The sanity checks the page allocator does upon freeing a
 186          * page can reach here before the page_ext arrays are
 187          * allocated when feeding a range of pages to the allocator
 188          * for the first time during bootup or memory hotplug.
 189          */
 190         if (!section->page_ext)
 191                 return NULL;
 192 #endif
 193         return section->page_ext + pfn;
 194 }
 195
 196 static void *__meminit alloc_page_ext(size_t size, int nid)
 197 {
 198         gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
 199         void *addr = NULL;
 200
 201         addr = alloc_pages_exact_nid(nid, size, flags);
 202         if (addr) {
 203                 kmemleak_alloc(addr, size, 1, flags);
 204                 return addr;
 205         }
 206
 207         if (node_state(nid, N_HIGH_MEMORY))
 208                 addr = vzalloc_node(size, nid);
 209         else
 210                 addr = vzalloc(size);
 211
 212         return addr;
 213 }
 214
 215 static int __meminit init_section_page_ext(unsigned long pfn, int nid)
 216 {
 217         struct mem_section *section;
 218         struct page_ext *base;
 219         unsigned long table_size;
 220
 221         section = __pfn_to_section(pfn);
 222
 223         if (section->page_ext)
 224                 return 0;
 225
 226         table_size = sizeof(struct page_ext) * PAGES_PER_SECTION;
 227         base = alloc_page_ext(table_size, nid);
 228
 229         /*
 230          * The value stored in section->page_ext is (base - pfn)
 231          * and it does not point to the memory block allocated above,
 232          * causing kmemleak false positives.
 233          */
 234         kmemleak_not_leak(base);
 235
 236         if (!base) {
 237                 pr_err("page ext allocation failure\n");
 238                 return -ENOMEM;
 239         }
 240
 241         /*
 242          * The passed "pfn" may not be aligned to SECTION.  For the calculation
 243          * we need to apply a mask.
 244          */
 245         pfn &= PAGE_SECTION_MASK;
 246         section->page_ext = base - pfn;
 247         total_usage += table_size;
 248         return 0;
 249 }
 250 #ifdef CONFIG_MEMORY_HOTPLUG
 251 static void free_page_ext(void *addr)
 252 {
 253         if (is_vmalloc_addr(addr)) {
 254                 vfree(addr);
 255         } else {
 256                 struct page *page = virt_to_page(addr);
 257                 size_t table_size;
 258
 259                 table_size = sizeof(struct page_ext) * PAGES_PER_SECTION;
 260
 261                 BUG_ON(PageReserved(page));
 262                 free_pages_exact(addr, table_size);
 263         }
 264 }
 265
 266 static void __free_page_ext(unsigned long pfn)
 267 {
 268         struct mem_section *ms;
 269         struct page_ext *base;
 270
 271         ms = __pfn_to_section(pfn);
 272         if (!ms || !ms->page_ext)
 273                 return;
 274         base = ms->page_ext + pfn;
 275         free_page_ext(base);
 276         ms->page_ext = NULL;
 277 }
 278
 279 static int __meminit online_page_ext(unsigned long start_pfn,
 280                                 unsigned long nr_pages,
 281                                 int nid)
 282 {
 283         unsigned long start, end, pfn;
 284         int fail = 0;
 285
 286         start = SECTION_ALIGN_DOWN(start_pfn);
 287         end = SECTION_ALIGN_UP(start_pfn + nr_pages);
 288
 289         if (nid == -1) {
 290                 /*
 291                  * In this case, "nid" already exists and contains valid memory.
 292                  * "start_pfn" passed to us is a pfn which is an arg for
 293                  * online__pages(), and start_pfn should exist.
 294                  */
 295                 nid = pfn_to_nid(start_pfn);
 296                 VM_BUG_ON(!node_state(nid, N_ONLINE));
 297         }
 298
 299         for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
 300                 if (!pfn_present(pfn))
 301                         continue;
 302                 fail = init_section_page_ext(pfn, nid);
 303         }
 304         if (!fail)
 305                 return 0;
 306
 307         /* rollback */
 308         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
 309                 __free_page_ext(pfn);
 310
 311         return -ENOMEM;
 312 }
 313
 314 static int __meminit offline_page_ext(unsigned long start_pfn,
 315                                 unsigned long nr_pages, int nid)
 316 {
 317         unsigned long start, end, pfn;
 318
 319         start = SECTION_ALIGN_DOWN(start_pfn);
 320         end = SECTION_ALIGN_UP(start_pfn + nr_pages);
 321
 322         for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
 323                 __free_page_ext(pfn);
 324         return 0;
 325
 326 }
 327
 328 static int __meminit page_ext_callback(struct notifier_block *self,
 329                                unsigned long action, void *arg)
 330 {
 331         struct memory_notify *mn = arg;
 332         int ret = 0;
 333
 334         switch (action) {
 335         case MEM_GOING_ONLINE:
 336                 ret = online_page_ext(mn->start_pfn,
 337                                    mn->nr_pages, mn->status_change_nid);
 338                 break;
 339         case MEM_OFFLINE:
 340                 offline_page_ext(mn->start_pfn,
 341                                 mn->nr_pages, mn->status_change_nid);
 342                 break;
 343         case MEM_CANCEL_ONLINE:
 344                 offline_page_ext(mn->start_pfn,
 345                                 mn->nr_pages, mn->status_change_nid);
 346                 break;
 347         case MEM_GOING_OFFLINE:
 348                 break;
 349         case MEM_ONLINE:
 350         case MEM_CANCEL_OFFLINE:
 351                 break;
 352         }
 353
 354         return notifier_from_errno(ret);
 355 }
 356
 357 #endif
 358
 359 void __init page_ext_init(void)
 360 {
 361         unsigned long pfn;
 362         int nid;
 363
 364         if (!invoke_need_callbacks())
 365                 return;
 366
 367         for_each_node_state(nid, N_MEMORY) {
 368                 unsigned long start_pfn, end_pfn;
 369
 370                 start_pfn = node_start_pfn(nid);
 371                 end_pfn = node_end_pfn(nid);
 372                 /*
 373                  * start_pfn and end_pfn may not be aligned to SECTION and the
 374                  * page->flags of out of node pages are not initialized.  So we
 375                  * scan [start_pfn, the biggest section's pfn < end_pfn) here.
 376                  */
 377                 for (pfn = start_pfn; pfn < end_pfn;
 378                         pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
 379
 380                         if (!pfn_valid(pfn))
 381                                 continue;
 382                         /*
 383                          * Nodes's pfns can be overlapping.
 384                          * We know some arch can have a nodes layout such as
 385                          * -------------pfn-------------->
 386                          * N0 | N1 | N2 | N0 | N1 | N2|....
 387                          */
 388                         if (pfn_to_nid(pfn) != nid)
 389                                 continue;
 390                         if (init_section_page_ext(pfn, nid))
 391                                 goto oom;
 392                 }
 393         }
 394         hotplug_memory_notifier(page_ext_callback, 0);
 395         pr_info("allocated %ld bytes of page_ext\n", total_usage);
 396         invoke_init_callbacks();
 397         return;
 398
 399 oom:
 400         panic("Out of memory");
 401 }
 402
 403 void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
 404 {
 405 }
 406
 407 #endif