mm/hugetlb.c

   1 /*
   2  * Generic hugetlb support.
   3  * (C) William Irwin, April 2004
   4  */
   5 #include <linux/gfp.h>
   6 #include <linux/list.h>
   7 #include <linux/init.h>
   8 #include <linux/module.h>
   9 #include <linux/mm.h>
  10 #include <linux/sysctl.h>
  11 #include <linux/highmem.h>
  12 #include <linux/nodemask.h>
  13 #include <linux/pagemap.h>
  14 #include <asm/page.h>
  15 #include <asm/pgtable.h>
  16
  17 #include <linux/hugetlb.h>
  18
  19 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
  20 static unsigned long nr_huge_pages, free_huge_pages;
  21 unsigned long max_huge_pages;
  22 static struct list_head hugepage_freelists[MAX_NUMNODES];
  23 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
  24 static unsigned int free_huge_pages_node[MAX_NUMNODES];
  25 static DEFINE_SPINLOCK(hugetlb_lock);
  26
  27 static void enqueue_huge_page(struct page *page)
  28 {
  29         int nid = page_to_nid(page);
  30         list_add(&page->lru, &hugepage_freelists[nid]);
  31         free_huge_pages++;
  32         free_huge_pages_node[nid]++;
  33 }
  34
  35 static struct page *dequeue_huge_page(void)
  36 {
  37         int nid = numa_node_id();
  38         struct page *page = NULL;
  39
  40         if (list_empty(&hugepage_freelists[nid])) {
  41                 for (nid = 0; nid < MAX_NUMNODES; ++nid)
  42                         if (!list_empty(&hugepage_freelists[nid]))
  43                                 break;
  44         }
  45         if (nid >= 0 && nid < MAX_NUMNODES &&
  46             !list_empty(&hugepage_freelists[nid])) {
  47                 page = list_entry(hugepage_freelists[nid].next,
  48                                   struct page, lru);
  49                 list_del(&page->lru);
  50                 free_huge_pages--;
  51                 free_huge_pages_node[nid]--;
  52         }
  53         return page;
  54 }
  55
  56 static struct page *alloc_fresh_huge_page(void)
  57 {
  58         static int nid = 0;
  59         struct page *page;
  60         page = alloc_pages_node(nid, GFP_HIGHUSER|__GFP_COMP|__GFP_NOWARN,
  61                                         HUGETLB_PAGE_ORDER);
  62         nid = (nid + 1) % num_online_nodes();
  63         if (page) {
  64                 nr_huge_pages++;
  65                 nr_huge_pages_node[page_to_nid(page)]++;
  66         }
  67         return page;
  68 }
  69
  70 void free_huge_page(struct page *page)
  71 {
  72         BUG_ON(page_count(page));
  73
  74         INIT_LIST_HEAD(&page->lru);
  75         page[1].mapping = NULL;
  76
  77         spin_lock(&hugetlb_lock);
  78         enqueue_huge_page(page);
  79         spin_unlock(&hugetlb_lock);
  80 }
  81
  82 struct page *alloc_huge_page(void)
  83 {
  84         struct page *page;
  85         int i;
  86
  87         spin_lock(&hugetlb_lock);
  88         page = dequeue_huge_page();
  89         if (!page) {
  90                 spin_unlock(&hugetlb_lock);
  91                 return NULL;
  92         }
  93         spin_unlock(&hugetlb_lock);
  94         set_page_count(page, 1);
  95         page[1].mapping = (void *)free_huge_page;
  96         for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); ++i)
  97                 clear_highpage(&page[i]);
  98         return page;
  99 }
 100
 101 static int __init hugetlb_init(void)
 102 {
 103         unsigned long i;
 104         struct page *page;
 105
 106         for (i = 0; i < MAX_NUMNODES; ++i)
 107                 INIT_LIST_HEAD(&hugepage_freelists[i]);
 108
 109         for (i = 0; i < max_huge_pages; ++i) {
 110                 page = alloc_fresh_huge_page();
 111                 if (!page)
 112                         break;
 113                 spin_lock(&hugetlb_lock);
 114                 enqueue_huge_page(page);
 115                 spin_unlock(&hugetlb_lock);
 116         }
 117         max_huge_pages = free_huge_pages = nr_huge_pages = i;
 118         printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
 119         return 0;
 120 }
 121 module_init(hugetlb_init);
 122
 123 static int __init hugetlb_setup(char *s)
 124 {
 125         if (sscanf(s, "%lu", &max_huge_pages) <= 0)
 126                 max_huge_pages = 0;
 127         return 1;
 128 }
 129 __setup("hugepages=", hugetlb_setup);
 130
 131 #ifdef CONFIG_SYSCTL
 132 static void update_and_free_page(struct page *page)
 133 {
 134         int i;
 135         nr_huge_pages--;
 136         nr_huge_pages_node[page_zone(page)->zone_pgdat->node_id]--;
 137         for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
 138                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
 139                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
 140                                 1 << PG_private | 1<< PG_writeback);
 141                 set_page_count(&page[i], 0);
 142         }
 143         set_page_count(page, 1);
 144         __free_pages(page, HUGETLB_PAGE_ORDER);
 145 }
 146
 147 #ifdef CONFIG_HIGHMEM
 148 static void try_to_free_low(unsigned long count)
 149 {
 150         int i, nid;
 151         for (i = 0; i < MAX_NUMNODES; ++i) {
 152                 struct page *page, *next;
 153                 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
 154                         if (PageHighMem(page))
 155                                 continue;
 156                         list_del(&page->lru);
 157                         update_and_free_page(page);
 158                         nid = page_zone(page)->zone_pgdat->node_id;
 159                         free_huge_pages--;
 160                         free_huge_pages_node[nid]--;
 161                         if (count >= nr_huge_pages)
 162                                 return;
 163                 }
 164         }
 165 }
 166 #else
 167 static inline void try_to_free_low(unsigned long count)
 168 {
 169 }
 170 #endif
 171
 172 static unsigned long set_max_huge_pages(unsigned long count)
 173 {
 174         while (count > nr_huge_pages) {
 175                 struct page *page = alloc_fresh_huge_page();
 176                 if (!page)
 177                         return nr_huge_pages;
 178                 spin_lock(&hugetlb_lock);
 179                 enqueue_huge_page(page);
 180                 spin_unlock(&hugetlb_lock);
 181         }
 182         if (count >= nr_huge_pages)
 183                 return nr_huge_pages;
 184
 185         spin_lock(&hugetlb_lock);
 186         try_to_free_low(count);
 187         while (count < nr_huge_pages) {
 188                 struct page *page = dequeue_huge_page();
 189                 if (!page)
 190                         break;
 191                 update_and_free_page(page);
 192         }
 193         spin_unlock(&hugetlb_lock);
 194         return nr_huge_pages;
 195 }
 196
 197 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
 198                            struct file *file, void __user *buffer,
 199                            size_t *length, loff_t *ppos)
 200 {
 201         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
 202         max_huge_pages = set_max_huge_pages(max_huge_pages);
 203         return 0;
 204 }
 205 #endif /* CONFIG_SYSCTL */
 206
 207 int hugetlb_report_meminfo(char *buf)
 208 {
 209         return sprintf(buf,
 210                         "HugePages_Total: %5lu\n"
 211                         "HugePages_Free:  %5lu\n"
 212                         "Hugepagesize:    %5lu kB\n",
 213                         nr_huge_pages,
 214                         free_huge_pages,
 215                         HPAGE_SIZE/1024);
 216 }
 217
 218 int hugetlb_report_node_meminfo(int nid, char *buf)
 219 {
 220         return sprintf(buf,
 221                 "Node %d HugePages_Total: %5u\n"
 222                 "Node %d HugePages_Free:  %5u\n",
 223                 nid, nr_huge_pages_node[nid],
 224                 nid, free_huge_pages_node[nid]);
 225 }
 226
 227 int is_hugepage_mem_enough(size_t size)
 228 {
 229         return (size + ~HPAGE_MASK)/HPAGE_SIZE <= free_huge_pages;
 230 }
 231
 232 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
 233 unsigned long hugetlb_total_pages(void)
 234 {
 235         return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
 236 }
 237 EXPORT_SYMBOL(hugetlb_total_pages);
 238
 239 /*
 240  * We cannot handle pagefaults against hugetlb pages at all.  They cause
 241  * handle_mm_fault() to try to instantiate regular-sized pages in the
 242  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
 243  * this far.
 244  */
 245 static struct page *hugetlb_nopage(struct vm_area_struct *vma,
 246                                 unsigned long address, int *unused)
 247 {
 248         BUG();
 249         return NULL;
 250 }
 251
 252 struct vm_operations_struct hugetlb_vm_ops = {
 253         .nopage = hugetlb_nopage,
 254 };
 255
 256 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page)
 257 {
 258         pte_t entry;
 259
 260         if (vma->vm_flags & VM_WRITE) {
 261                 entry =
 262                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
 263         } else {
 264                 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
 265         }
 266         entry = pte_mkyoung(entry);
 267         entry = pte_mkhuge(entry);
 268
 269         return entry;
 270 }
 271
 272 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 273                             struct vm_area_struct *vma)
 274 {
 275         pte_t *src_pte, *dst_pte, entry;
 276         struct page *ptepage;
 277         unsigned long addr;
 278
 279         for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
 280                 src_pte = huge_pte_offset(src, addr);
 281                 if (!src_pte)
 282                         continue;
 283                 dst_pte = huge_pte_alloc(dst, addr);
 284                 if (!dst_pte)
 285                         goto nomem;
 286                 spin_lock(&dst->page_table_lock);
 287                 spin_lock(&src->page_table_lock);
 288                 if (!pte_none(*src_pte)) {
 289                         entry = *src_pte;
 290                         ptepage = pte_page(entry);
 291                         get_page(ptepage);
 292                         add_mm_counter(dst, file_rss, HPAGE_SIZE / PAGE_SIZE);
 293                         set_huge_pte_at(dst, addr, dst_pte, entry);
 294                 }
 295                 spin_unlock(&src->page_table_lock);
 296                 spin_unlock(&dst->page_table_lock);
 297         }
 298         return 0;
 299
 300 nomem:
 301         return -ENOMEM;
 302 }
 303
 304 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
 305                           unsigned long end)
 306 {
 307         struct mm_struct *mm = vma->vm_mm;
 308         unsigned long address;
 309         pte_t *ptep;
 310         pte_t pte;
 311         struct page *page;
 312
 313         WARN_ON(!is_vm_hugetlb_page(vma));
 314         BUG_ON(start & ~HPAGE_MASK);
 315         BUG_ON(end & ~HPAGE_MASK);
 316
 317         spin_lock(&mm->page_table_lock);
 318
 319         /* Update high watermark before we lower rss */
 320         update_hiwater_rss(mm);
 321
 322         for (address = start; address < end; address += HPAGE_SIZE) {
 323                 ptep = huge_pte_offset(mm, address);
 324                 if (!ptep)
 325                         continue;
 326
 327                 pte = huge_ptep_get_and_clear(mm, address, ptep);
 328                 if (pte_none(pte))
 329                         continue;
 330
 331                 page = pte_page(pte);
 332                 put_page(page);
 333                 add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE));
 334         }
 335
 336         spin_unlock(&mm->page_table_lock);
 337         flush_tlb_range(vma, start, end);
 338 }
 339
 340 static struct page *find_lock_huge_page(struct address_space *mapping,
 341                         unsigned long idx)
 342 {
 343         struct page *page;
 344         int err;
 345         struct inode *inode = mapping->host;
 346         unsigned long size;
 347
 348 retry:
 349         page = find_lock_page(mapping, idx);
 350         if (page)
 351                 goto out;
 352
 353         /* Check to make sure the mapping hasn't been truncated */
 354         size = i_size_read(inode) >> HPAGE_SHIFT;
 355         if (idx >= size)
 356                 goto out;
 357
 358         if (hugetlb_get_quota(mapping))
 359                 goto out;
 360         page = alloc_huge_page();
 361         if (!page) {
 362                 hugetlb_put_quota(mapping);
 363                 goto out;
 364         }
 365
 366         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
 367         if (err) {
 368                 put_page(page);
 369                 hugetlb_put_quota(mapping);
 370                 if (err == -EEXIST)
 371                         goto retry;
 372                 page = NULL;
 373         }
 374 out:
 375         return page;
 376 }
 377
 378 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 379                         unsigned long address, int write_access)
 380 {
 381         int ret = VM_FAULT_SIGBUS;
 382         unsigned long idx;
 383         unsigned long size;
 384         pte_t *pte;
 385         struct page *page;
 386         struct address_space *mapping;
 387
 388         pte = huge_pte_alloc(mm, address);
 389         if (!pte)
 390                 goto out;
 391
 392         mapping = vma->vm_file->f_mapping;
 393         idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
 394                 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
 395
 396         /*
 397          * Use page lock to guard against racing truncation
 398          * before we get page_table_lock.
 399          */
 400         page = find_lock_huge_page(mapping, idx);
 401         if (!page)
 402                 goto out;
 403
 404         spin_lock(&mm->page_table_lock);
 405         size = i_size_read(mapping->host) >> HPAGE_SHIFT;
 406         if (idx >= size)
 407                 goto backout;
 408
 409         ret = VM_FAULT_MINOR;
 410         if (!pte_none(*pte))
 411                 goto backout;
 412
 413         add_mm_counter(mm, file_rss, HPAGE_SIZE / PAGE_SIZE);
 414         set_huge_pte_at(mm, address, pte, make_huge_pte(vma, page));
 415         spin_unlock(&mm->page_table_lock);
 416         unlock_page(page);
 417 out:
 418         return ret;
 419
 420 backout:
 421         spin_unlock(&mm->page_table_lock);
 422         hugetlb_put_quota(mapping);
 423         unlock_page(page);
 424         put_page(page);
 425         goto out;
 426 }
 427
 428 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 429                         struct page **pages, struct vm_area_struct **vmas,
 430                         unsigned long *position, int *length, int i)
 431 {
 432         unsigned long vpfn, vaddr = *position;
 433         int remainder = *length;
 434
 435         vpfn = vaddr/PAGE_SIZE;
 436         spin_lock(&mm->page_table_lock);
 437         while (vaddr < vma->vm_end && remainder) {
 438                 pte_t *pte;
 439                 struct page *page;
 440
 441                 /*
 442                  * Some archs (sparc64, sh*) have multiple pte_ts to
 443                  * each hugepage.  We have to make * sure we get the
 444                  * first, for the page indexing below to work.
 445                  */
 446                 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
 447
 448                 if (!pte || pte_none(*pte)) {
 449                         int ret;
 450
 451                         spin_unlock(&mm->page_table_lock);
 452                         ret = hugetlb_fault(mm, vma, vaddr, 0);
 453                         spin_lock(&mm->page_table_lock);
 454                         if (ret == VM_FAULT_MINOR)
 455                                 continue;
 456
 457                         remainder = 0;
 458                         if (!i)
 459                                 i = -EFAULT;
 460                         break;
 461                 }
 462
 463                 if (pages) {
 464                         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
 465                         get_page(page);
 466                         pages[i] = page;
 467                 }
 468
 469                 if (vmas)
 470                         vmas[i] = vma;
 471
 472                 vaddr += PAGE_SIZE;
 473                 ++vpfn;
 474                 --remainder;
 475                 ++i;
 476         }
 477         spin_unlock(&mm->page_table_lock);
 478         *length = remainder;
 479         *position = vaddr;
 480
 481         return i;
 482 }