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 <linux/mempolicy.h>
  15 #include <linux/cpuset.h>
  16 #include <linux/mutex.h>
  17
  18 #include <asm/page.h>
  19 #include <asm/pgtable.h>
  20
  21 #include <linux/hugetlb.h>
  22 #include "internal.h"
  23
  24 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
  25 static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
  26 static unsigned long surplus_huge_pages;
  27 static unsigned long nr_overcommit_huge_pages;
  28 unsigned long max_huge_pages;
  29 unsigned long sysctl_overcommit_huge_pages;
  30 static struct list_head hugepage_freelists[MAX_NUMNODES];
  31 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
  32 static unsigned int free_huge_pages_node[MAX_NUMNODES];
  33 static unsigned int surplus_huge_pages_node[MAX_NUMNODES];
  34 static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
  35 unsigned long hugepages_treat_as_movable;
  36 static int hugetlb_next_nid;
  37
  38 /*
  39  * Protects updates to hugepage_freelists, nr_huge_pages, and free_huge_pages
  40  */
  41 static DEFINE_SPINLOCK(hugetlb_lock);
  42
  43 static void clear_huge_page(struct page *page, unsigned long addr)
  44 {
  45         int i;
  46
  47         might_sleep();
  48         for (i = 0; i < (HPAGE_SIZE/PAGE_SIZE); i++) {
  49                 cond_resched();
  50                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
  51         }
  52 }
  53
  54 static void copy_huge_page(struct page *dst, struct page *src,
  55                            unsigned long addr, struct vm_area_struct *vma)
  56 {
  57         int i;
  58
  59         might_sleep();
  60         for (i = 0; i < HPAGE_SIZE/PAGE_SIZE; i++) {
  61                 cond_resched();
  62                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
  63         }
  64 }
  65
  66 static void enqueue_huge_page(struct page *page)
  67 {
  68         int nid = page_to_nid(page);
  69         list_add(&page->lru, &hugepage_freelists[nid]);
  70         free_huge_pages++;
  71         free_huge_pages_node[nid]++;
  72 }
  73
  74 static struct page *dequeue_huge_page(void)
  75 {
  76         int nid;
  77         struct page *page = NULL;
  78
  79         for (nid = 0; nid < MAX_NUMNODES; ++nid) {
  80                 if (!list_empty(&hugepage_freelists[nid])) {
  81                         page = list_entry(hugepage_freelists[nid].next,
  82                                           struct page, lru);
  83                         list_del(&page->lru);
  84                         free_huge_pages--;
  85                         free_huge_pages_node[nid]--;
  86                         break;
  87                 }
  88         }
  89         return page;
  90 }
  91
  92 static struct page *dequeue_huge_page_vma(struct vm_area_struct *vma,
  93                                 unsigned long address)
  94 {
  95         int nid;
  96         struct page *page = NULL;
  97         struct mempolicy *mpol;
  98         struct zonelist *zonelist = huge_zonelist(vma, address,
  99                                         htlb_alloc_mask, &mpol);
 100         struct zone **z;
 101
 102         for (z = zonelist->zones; *z; z++) {
 103                 nid = zone_to_nid(*z);
 104                 if (cpuset_zone_allowed_softwall(*z, htlb_alloc_mask) &&
 105                     !list_empty(&hugepage_freelists[nid])) {
 106                         page = list_entry(hugepage_freelists[nid].next,
 107                                           struct page, lru);
 108                         list_del(&page->lru);
 109                         free_huge_pages--;
 110                         free_huge_pages_node[nid]--;
 111                         if (vma && vma->vm_flags & VM_MAYSHARE)
 112                                 resv_huge_pages--;
 113                         break;
 114                 }
 115         }
 116         mpol_free(mpol);        /* unref if mpol !NULL */
 117         return page;
 118 }
 119
 120 static void update_and_free_page(struct page *page)
 121 {
 122         int i;
 123         nr_huge_pages--;
 124         nr_huge_pages_node[page_to_nid(page)]--;
 125         for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
 126                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
 127                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
 128                                 1 << PG_private | 1<< PG_writeback);
 129         }
 130         set_compound_page_dtor(page, NULL);
 131         set_page_refcounted(page);
 132         __free_pages(page, HUGETLB_PAGE_ORDER);
 133 }
 134
 135 static void free_huge_page(struct page *page)
 136 {
 137         int nid = page_to_nid(page);
 138         struct address_space *mapping;
 139
 140         mapping = (struct address_space *) page_private(page);
 141         set_page_private(page, 0);
 142         BUG_ON(page_count(page));
 143         INIT_LIST_HEAD(&page->lru);
 144
 145         spin_lock(&hugetlb_lock);
 146         if (surplus_huge_pages_node[nid]) {
 147                 update_and_free_page(page);
 148                 surplus_huge_pages--;
 149                 surplus_huge_pages_node[nid]--;
 150         } else {
 151                 enqueue_huge_page(page);
 152         }
 153         spin_unlock(&hugetlb_lock);
 154         if (mapping)
 155                 hugetlb_put_quota(mapping, 1);
 156 }
 157
 158 /*
 159  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
 160  * balanced by operating on them in a round-robin fashion.
 161  * Returns 1 if an adjustment was made.
 162  */
 163 static int adjust_pool_surplus(int delta)
 164 {
 165         static int prev_nid;
 166         int nid = prev_nid;
 167         int ret = 0;
 168
 169         VM_BUG_ON(delta != -1 && delta != 1);
 170         do {
 171                 nid = next_node(nid, node_online_map);
 172                 if (nid == MAX_NUMNODES)
 173                         nid = first_node(node_online_map);
 174
 175                 /* To shrink on this node, there must be a surplus page */
 176                 if (delta < 0 && !surplus_huge_pages_node[nid])
 177                         continue;
 178                 /* Surplus cannot exceed the total number of pages */
 179                 if (delta > 0 && surplus_huge_pages_node[nid] >=
 180                                                 nr_huge_pages_node[nid])
 181                         continue;
 182
 183                 surplus_huge_pages += delta;
 184                 surplus_huge_pages_node[nid] += delta;
 185                 ret = 1;
 186                 break;
 187         } while (nid != prev_nid);
 188
 189         prev_nid = nid;
 190         return ret;
 191 }
 192
 193 static struct page *alloc_fresh_huge_page_node(int nid)
 194 {
 195         struct page *page;
 196
 197         page = alloc_pages_node(nid,
 198                 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|__GFP_NOWARN,
 199                 HUGETLB_PAGE_ORDER);
 200         if (page) {
 201                 set_compound_page_dtor(page, free_huge_page);
 202                 spin_lock(&hugetlb_lock);
 203                 nr_huge_pages++;
 204                 nr_huge_pages_node[nid]++;
 205                 spin_unlock(&hugetlb_lock);
 206                 put_page(page); /* free it into the hugepage allocator */
 207         }
 208
 209         return page;
 210 }
 211
 212 static int alloc_fresh_huge_page(void)
 213 {
 214         struct page *page;
 215         int start_nid;
 216         int next_nid;
 217         int ret = 0;
 218
 219         start_nid = hugetlb_next_nid;
 220
 221         do {
 222                 page = alloc_fresh_huge_page_node(hugetlb_next_nid);
 223                 if (page)
 224                         ret = 1;
 225                 /*
 226                  * Use a helper variable to find the next node and then
 227                  * copy it back to hugetlb_next_nid afterwards:
 228                  * otherwise there's a window in which a racer might
 229                  * pass invalid nid MAX_NUMNODES to alloc_pages_node.
 230                  * But we don't need to use a spin_lock here: it really
 231                  * doesn't matter if occasionally a racer chooses the
 232                  * same nid as we do.  Move nid forward in the mask even
 233                  * if we just successfully allocated a hugepage so that
 234                  * the next caller gets hugepages on the next node.
 235                  */
 236                 next_nid = next_node(hugetlb_next_nid, node_online_map);
 237                 if (next_nid == MAX_NUMNODES)
 238                         next_nid = first_node(node_online_map);
 239                 hugetlb_next_nid = next_nid;
 240         } while (!page && hugetlb_next_nid != start_nid);
 241
 242         return ret;
 243 }
 244
 245 static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma,
 246                                                 unsigned long address)
 247 {
 248         struct page *page;
 249         unsigned int nid;
 250
 251         /*
 252          * Assume we will successfully allocate the surplus page to
 253          * prevent racing processes from causing the surplus to exceed
 254          * overcommit
 255          *
 256          * This however introduces a different race, where a process B
 257          * tries to grow the static hugepage pool while alloc_pages() is
 258          * called by process A. B will only examine the per-node
 259          * counters in determining if surplus huge pages can be
 260          * converted to normal huge pages in adjust_pool_surplus(). A
 261          * won't be able to increment the per-node counter, until the
 262          * lock is dropped by B, but B doesn't drop hugetlb_lock until
 263          * no more huge pages can be converted from surplus to normal
 264          * state (and doesn't try to convert again). Thus, we have a
 265          * case where a surplus huge page exists, the pool is grown, and
 266          * the surplus huge page still exists after, even though it
 267          * should just have been converted to a normal huge page. This
 268          * does not leak memory, though, as the hugepage will be freed
 269          * once it is out of use. It also does not allow the counters to
 270          * go out of whack in adjust_pool_surplus() as we don't modify
 271          * the node values until we've gotten the hugepage and only the
 272          * per-node value is checked there.
 273          */
 274         spin_lock(&hugetlb_lock);
 275         if (surplus_huge_pages >= nr_overcommit_huge_pages) {
 276                 spin_unlock(&hugetlb_lock);
 277                 return NULL;
 278         } else {
 279                 nr_huge_pages++;
 280                 surplus_huge_pages++;
 281         }
 282         spin_unlock(&hugetlb_lock);
 283
 284         page = alloc_pages(htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
 285                                         HUGETLB_PAGE_ORDER);
 286
 287         spin_lock(&hugetlb_lock);
 288         if (page) {
 289                 /*
 290                  * This page is now managed by the hugetlb allocator and has
 291                  * no users -- drop the buddy allocator's reference.
 292                  */
 293                 put_page_testzero(page);
 294                 VM_BUG_ON(page_count(page));
 295                 nid = page_to_nid(page);
 296                 set_compound_page_dtor(page, free_huge_page);
 297                 /*
 298                  * We incremented the global counters already
 299                  */
 300                 nr_huge_pages_node[nid]++;
 301                 surplus_huge_pages_node[nid]++;
 302         } else {
 303                 nr_huge_pages--;
 304                 surplus_huge_pages--;
 305         }
 306         spin_unlock(&hugetlb_lock);
 307
 308         return page;
 309 }
 310
 311 /*
 312  * Increase the hugetlb pool such that it can accomodate a reservation
 313  * of size 'delta'.
 314  */
 315 static int gather_surplus_pages(int delta)
 316 {
 317         struct list_head surplus_list;
 318         struct page *page, *tmp;
 319         int ret, i;
 320         int needed, allocated;
 321
 322         needed = (resv_huge_pages + delta) - free_huge_pages;
 323         if (needed <= 0) {
 324                 resv_huge_pages += delta;
 325                 return 0;
 326         }
 327
 328         allocated = 0;
 329         INIT_LIST_HEAD(&surplus_list);
 330
 331         ret = -ENOMEM;
 332 retry:
 333         spin_unlock(&hugetlb_lock);
 334         for (i = 0; i < needed; i++) {
 335                 page = alloc_buddy_huge_page(NULL, 0);
 336                 if (!page) {
 337                         /*
 338                          * We were not able to allocate enough pages to
 339                          * satisfy the entire reservation so we free what
 340                          * we've allocated so far.
 341                          */
 342                         spin_lock(&hugetlb_lock);
 343                         needed = 0;
 344                         goto free;
 345                 }
 346
 347                 list_add(&page->lru, &surplus_list);
 348         }
 349         allocated += needed;
 350
 351         /*
 352          * After retaking hugetlb_lock, we need to recalculate 'needed'
 353          * because either resv_huge_pages or free_huge_pages may have changed.
 354          */
 355         spin_lock(&hugetlb_lock);
 356         needed = (resv_huge_pages + delta) - (free_huge_pages + allocated);
 357         if (needed > 0)
 358                 goto retry;
 359
 360         /*
 361          * The surplus_list now contains _at_least_ the number of extra pages
 362          * needed to accomodate the reservation.  Add the appropriate number
 363          * of pages to the hugetlb pool and free the extras back to the buddy
 364          * allocator.  Commit the entire reservation here to prevent another
 365          * process from stealing the pages as they are added to the pool but
 366          * before they are reserved.
 367          */
 368         needed += allocated;
 369         resv_huge_pages += delta;
 370         ret = 0;
 371 free:
 372         list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
 373                 list_del(&page->lru);
 374                 if ((--needed) >= 0)
 375                         enqueue_huge_page(page);
 376                 else {
 377                         /*
 378                          * The page has a reference count of zero already, so
 379                          * call free_huge_page directly instead of using
 380                          * put_page.  This must be done with hugetlb_lock
 381                          * unlocked which is safe because free_huge_page takes
 382                          * hugetlb_lock before deciding how to free the page.
 383                          */
 384                         spin_unlock(&hugetlb_lock);
 385                         free_huge_page(page);
 386                         spin_lock(&hugetlb_lock);
 387                 }
 388         }
 389
 390         return ret;
 391 }
 392
 393 /*
 394  * When releasing a hugetlb pool reservation, any surplus pages that were
 395  * allocated to satisfy the reservation must be explicitly freed if they were
 396  * never used.
 397  */
 398 static void return_unused_surplus_pages(unsigned long unused_resv_pages)
 399 {
 400         static int nid = -1;
 401         struct page *page;
 402         unsigned long nr_pages;
 403
 404         /*
 405          * We want to release as many surplus pages as possible, spread
 406          * evenly across all nodes. Iterate across all nodes until we
 407          * can no longer free unreserved surplus pages. This occurs when
 408          * the nodes with surplus pages have no free pages.
 409          */
 410         unsigned long remaining_iterations = num_online_nodes();
 411
 412         /* Uncommit the reservation */
 413         resv_huge_pages -= unused_resv_pages;
 414
 415         nr_pages = min(unused_resv_pages, surplus_huge_pages);
 416
 417         while (remaining_iterations-- && nr_pages) {
 418                 nid = next_node(nid, node_online_map);
 419                 if (nid == MAX_NUMNODES)
 420                         nid = first_node(node_online_map);
 421
 422                 if (!surplus_huge_pages_node[nid])
 423                         continue;
 424
 425                 if (!list_empty(&hugepage_freelists[nid])) {
 426                         page = list_entry(hugepage_freelists[nid].next,
 427                                           struct page, lru);
 428                         list_del(&page->lru);
 429                         update_and_free_page(page);
 430                         free_huge_pages--;
 431                         free_huge_pages_node[nid]--;
 432                         surplus_huge_pages--;
 433                         surplus_huge_pages_node[nid]--;
 434                         nr_pages--;
 435                         remaining_iterations = num_online_nodes();
 436                 }
 437         }
 438 }
 439
 440
 441 static struct page *alloc_huge_page_shared(struct vm_area_struct *vma,
 442                                                 unsigned long addr)
 443 {
 444         struct page *page;
 445
 446         spin_lock(&hugetlb_lock);
 447         page = dequeue_huge_page_vma(vma, addr);
 448         spin_unlock(&hugetlb_lock);
 449         return page ? page : ERR_PTR(-VM_FAULT_OOM);
 450 }
 451
 452 static struct page *alloc_huge_page_private(struct vm_area_struct *vma,
 453                                                 unsigned long addr)
 454 {
 455         struct page *page = NULL;
 456
 457         if (hugetlb_get_quota(vma->vm_file->f_mapping, 1))
 458                 return ERR_PTR(-VM_FAULT_SIGBUS);
 459
 460         spin_lock(&hugetlb_lock);
 461         if (free_huge_pages > resv_huge_pages)
 462                 page = dequeue_huge_page_vma(vma, addr);
 463         spin_unlock(&hugetlb_lock);
 464         if (!page) {
 465                 page = alloc_buddy_huge_page(vma, addr);
 466                 if (!page) {
 467                         hugetlb_put_quota(vma->vm_file->f_mapping, 1);
 468                         return ERR_PTR(-VM_FAULT_OOM);
 469                 }
 470         }
 471         return page;
 472 }
 473
 474 static struct page *alloc_huge_page(struct vm_area_struct *vma,
 475                                     unsigned long addr)
 476 {
 477         struct page *page;
 478         struct address_space *mapping = vma->vm_file->f_mapping;
 479
 480         if (vma->vm_flags & VM_MAYSHARE)
 481                 page = alloc_huge_page_shared(vma, addr);
 482         else
 483                 page = alloc_huge_page_private(vma, addr);
 484
 485         if (!IS_ERR(page)) {
 486                 set_page_refcounted(page);
 487                 set_page_private(page, (unsigned long) mapping);
 488         }
 489         return page;
 490 }
 491
 492 static int __init hugetlb_init(void)
 493 {
 494         unsigned long i;
 495
 496         if (HPAGE_SHIFT == 0)
 497                 return 0;
 498
 499         for (i = 0; i < MAX_NUMNODES; ++i)
 500                 INIT_LIST_HEAD(&hugepage_freelists[i]);
 501
 502         hugetlb_next_nid = first_node(node_online_map);
 503
 504         for (i = 0; i < max_huge_pages; ++i) {
 505                 if (!alloc_fresh_huge_page())
 506                         break;
 507         }
 508         max_huge_pages = free_huge_pages = nr_huge_pages = i;
 509         printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
 510         return 0;
 511 }
 512 module_init(hugetlb_init);
 513
 514 static int __init hugetlb_setup(char *s)
 515 {
 516         if (sscanf(s, "%lu", &max_huge_pages) <= 0)
 517                 max_huge_pages = 0;
 518         return 1;
 519 }
 520 __setup("hugepages=", hugetlb_setup);
 521
 522 static unsigned int cpuset_mems_nr(unsigned int *array)
 523 {
 524         int node;
 525         unsigned int nr = 0;
 526
 527         for_each_node_mask(node, cpuset_current_mems_allowed)
 528                 nr += array[node];
 529
 530         return nr;
 531 }
 532
 533 #ifdef CONFIG_SYSCTL
 534 #ifdef CONFIG_HIGHMEM
 535 static void try_to_free_low(unsigned long count)
 536 {
 537         int i;
 538
 539         for (i = 0; i < MAX_NUMNODES; ++i) {
 540                 struct page *page, *next;
 541                 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
 542                         if (count >= nr_huge_pages)
 543                                 return;
 544                         if (PageHighMem(page))
 545                                 continue;
 546                         list_del(&page->lru);
 547                         update_and_free_page(page);
 548                         free_huge_pages--;
 549                         free_huge_pages_node[page_to_nid(page)]--;
 550                 }
 551         }
 552 }
 553 #else
 554 static inline void try_to_free_low(unsigned long count)
 555 {
 556 }
 557 #endif
 558
 559 #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
 560 static unsigned long set_max_huge_pages(unsigned long count)
 561 {
 562         unsigned long min_count, ret;
 563
 564         /*
 565          * Increase the pool size
 566          * First take pages out of surplus state.  Then make up the
 567          * remaining difference by allocating fresh huge pages.
 568          *
 569          * We might race with alloc_buddy_huge_page() here and be unable
 570          * to convert a surplus huge page to a normal huge page. That is
 571          * not critical, though, it just means the overall size of the
 572          * pool might be one hugepage larger than it needs to be, but
 573          * within all the constraints specified by the sysctls.
 574          */
 575         spin_lock(&hugetlb_lock);
 576         while (surplus_huge_pages && count > persistent_huge_pages) {
 577                 if (!adjust_pool_surplus(-1))
 578                         break;
 579         }
 580
 581         while (count > persistent_huge_pages) {
 582                 int ret;
 583                 /*
 584                  * If this allocation races such that we no longer need the
 585                  * page, free_huge_page will handle it by freeing the page
 586                  * and reducing the surplus.
 587                  */
 588                 spin_unlock(&hugetlb_lock);
 589                 ret = alloc_fresh_huge_page();
 590                 spin_lock(&hugetlb_lock);
 591                 if (!ret)
 592                         goto out;
 593
 594         }
 595
 596         /*
 597          * Decrease the pool size
 598          * First return free pages to the buddy allocator (being careful
 599          * to keep enough around to satisfy reservations).  Then place
 600          * pages into surplus state as needed so the pool will shrink
 601          * to the desired size as pages become free.
 602          *
 603          * By placing pages into the surplus state independent of the
 604          * overcommit value, we are allowing the surplus pool size to
 605          * exceed overcommit. There are few sane options here. Since
 606          * alloc_buddy_huge_page() is checking the global counter,
 607          * though, we'll note that we're not allowed to exceed surplus
 608          * and won't grow the pool anywhere else. Not until one of the
 609          * sysctls are changed, or the surplus pages go out of use.
 610          */
 611         min_count = resv_huge_pages + nr_huge_pages - free_huge_pages;
 612         min_count = max(count, min_count);
 613         try_to_free_low(min_count);
 614         while (min_count < persistent_huge_pages) {
 615                 struct page *page = dequeue_huge_page();
 616                 if (!page)
 617                         break;
 618                 update_and_free_page(page);
 619         }
 620         while (count < persistent_huge_pages) {
 621                 if (!adjust_pool_surplus(1))
 622                         break;
 623         }
 624 out:
 625         ret = persistent_huge_pages;
 626         spin_unlock(&hugetlb_lock);
 627         return ret;
 628 }
 629
 630 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
 631                            struct file *file, void __user *buffer,
 632                            size_t *length, loff_t *ppos)
 633 {
 634         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
 635         max_huge_pages = set_max_huge_pages(max_huge_pages);
 636         return 0;
 637 }
 638
 639 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
 640                         struct file *file, void __user *buffer,
 641                         size_t *length, loff_t *ppos)
 642 {
 643         proc_dointvec(table, write, file, buffer, length, ppos);
 644         if (hugepages_treat_as_movable)
 645                 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
 646         else
 647                 htlb_alloc_mask = GFP_HIGHUSER;
 648         return 0;
 649 }
 650
 651 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
 652                         struct file *file, void __user *buffer,
 653                         size_t *length, loff_t *ppos)
 654 {
 655         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
 656         spin_lock(&hugetlb_lock);
 657         nr_overcommit_huge_pages = sysctl_overcommit_huge_pages;
 658         spin_unlock(&hugetlb_lock);
 659         return 0;
 660 }
 661
 662 #endif /* CONFIG_SYSCTL */
 663
 664 int hugetlb_report_meminfo(char *buf)
 665 {
 666         return sprintf(buf,
 667                         "HugePages_Total: %5lu\n"
 668                         "HugePages_Free:  %5lu\n"
 669                         "HugePages_Rsvd:  %5lu\n"
 670                         "HugePages_Surp:  %5lu\n"
 671                         "Hugepagesize:    %5lu kB\n",
 672                         nr_huge_pages,
 673                         free_huge_pages,
 674                         resv_huge_pages,
 675                         surplus_huge_pages,
 676                         HPAGE_SIZE/1024);
 677 }
 678
 679 int hugetlb_report_node_meminfo(int nid, char *buf)
 680 {
 681         return sprintf(buf,
 682                 "Node %d HugePages_Total: %5u\n"
 683                 "Node %d HugePages_Free:  %5u\n"
 684                 "Node %d HugePages_Surp:  %5u\n",
 685                 nid, nr_huge_pages_node[nid],
 686                 nid, free_huge_pages_node[nid],
 687                 nid, surplus_huge_pages_node[nid]);
 688 }
 689
 690 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
 691 unsigned long hugetlb_total_pages(void)
 692 {
 693         return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
 694 }
 695
 696 /*
 697  * We cannot handle pagefaults against hugetlb pages at all.  They cause
 698  * handle_mm_fault() to try to instantiate regular-sized pages in the
 699  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
 700  * this far.
 701  */
 702 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 703 {
 704         BUG();
 705         return 0;
 706 }
 707
 708 struct vm_operations_struct hugetlb_vm_ops = {
 709         .fault = hugetlb_vm_op_fault,
 710 };
 711
 712 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
 713                                 int writable)
 714 {
 715         pte_t entry;
 716
 717         if (writable) {
 718                 entry =
 719                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
 720         } else {
 721                 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
 722         }
 723         entry = pte_mkyoung(entry);
 724         entry = pte_mkhuge(entry);
 725
 726         return entry;
 727 }
 728
 729 static void set_huge_ptep_writable(struct vm_area_struct *vma,
 730                                    unsigned long address, pte_t *ptep)
 731 {
 732         pte_t entry;
 733
 734         entry = pte_mkwrite(pte_mkdirty(*ptep));
 735         if (ptep_set_access_flags(vma, address, ptep, entry, 1)) {
 736                 update_mmu_cache(vma, address, entry);
 737         }
 738 }
 739
 740
 741 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 742                             struct vm_area_struct *vma)
 743 {
 744         pte_t *src_pte, *dst_pte, entry;
 745         struct page *ptepage;
 746         unsigned long addr;
 747         int cow;
 748
 749         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 750
 751         for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
 752                 src_pte = huge_pte_offset(src, addr);
 753                 if (!src_pte)
 754                         continue;
 755                 dst_pte = huge_pte_alloc(dst, addr);
 756                 if (!dst_pte)
 757                         goto nomem;
 758
 759                 /* If the pagetables are shared don't copy or take references */
 760                 if (dst_pte == src_pte)
 761                         continue;
 762
 763                 spin_lock(&dst->page_table_lock);
 764                 spin_lock(&src->page_table_lock);
 765                 if (!pte_none(*src_pte)) {
 766                         if (cow)
 767                                 ptep_set_wrprotect(src, addr, src_pte);
 768                         entry = *src_pte;
 769                         ptepage = pte_page(entry);
 770                         get_page(ptepage);
 771                         set_huge_pte_at(dst, addr, dst_pte, entry);
 772                 }
 773                 spin_unlock(&src->page_table_lock);
 774                 spin_unlock(&dst->page_table_lock);
 775         }
 776         return 0;
 777
 778 nomem:
 779         return -ENOMEM;
 780 }
 781
 782 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
 783                             unsigned long end)
 784 {
 785         struct mm_struct *mm = vma->vm_mm;
 786         unsigned long address;
 787         pte_t *ptep;
 788         pte_t pte;
 789         struct page *page;
 790         struct page *tmp;
 791         /*
 792          * A page gathering list, protected by per file i_mmap_lock. The
 793          * lock is used to avoid list corruption from multiple unmapping
 794          * of the same page since we are using page->lru.
 795          */
 796         LIST_HEAD(page_list);
 797
 798         WARN_ON(!is_vm_hugetlb_page(vma));
 799         BUG_ON(start & ~HPAGE_MASK);
 800         BUG_ON(end & ~HPAGE_MASK);
 801
 802         spin_lock(&mm->page_table_lock);
 803         for (address = start; address < end; address += HPAGE_SIZE) {
 804                 ptep = huge_pte_offset(mm, address);
 805                 if (!ptep)
 806                         continue;
 807
 808                 if (huge_pmd_unshare(mm, &address, ptep))
 809                         continue;
 810
 811                 pte = huge_ptep_get_and_clear(mm, address, ptep);
 812                 if (pte_none(pte))
 813                         continue;
 814
 815                 page = pte_page(pte);
 816                 if (pte_dirty(pte))
 817                         set_page_dirty(page);
 818                 list_add(&page->lru, &page_list);
 819         }
 820         spin_unlock(&mm->page_table_lock);
 821         flush_tlb_range(vma, start, end);
 822         list_for_each_entry_safe(page, tmp, &page_list, lru) {
 823                 list_del(&page->lru);
 824                 put_page(page);
 825         }
 826 }
 827
 828 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
 829                           unsigned long end)
 830 {
 831         /*
 832          * It is undesirable to test vma->vm_file as it should be non-null
 833          * for valid hugetlb area. However, vm_file will be NULL in the error
 834          * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
 835          * do_mmap_pgoff() nullifies vma->vm_file before calling this function
 836          * to clean up. Since no pte has actually been setup, it is safe to
 837          * do nothing in this case.
 838          */
 839         if (vma->vm_file) {
 840                 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
 841                 __unmap_hugepage_range(vma, start, end);
 842                 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
 843         }
 844 }
 845
 846 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
 847                         unsigned long address, pte_t *ptep, pte_t pte)
 848 {
 849         struct page *old_page, *new_page;
 850         int avoidcopy;
 851
 852         old_page = pte_page(pte);
 853
 854         /* If no-one else is actually using this page, avoid the copy
 855          * and just make the page writable */
 856         avoidcopy = (page_count(old_page) == 1);
 857         if (avoidcopy) {
 858                 set_huge_ptep_writable(vma, address, ptep);
 859                 return 0;
 860         }
 861
 862         page_cache_get(old_page);
 863         new_page = alloc_huge_page(vma, address);
 864
 865         if (IS_ERR(new_page)) {
 866                 page_cache_release(old_page);
 867                 return -PTR_ERR(new_page);
 868         }
 869
 870         spin_unlock(&mm->page_table_lock);
 871         copy_huge_page(new_page, old_page, address, vma);
 872         __SetPageUptodate(new_page);
 873         spin_lock(&mm->page_table_lock);
 874
 875         ptep = huge_pte_offset(mm, address & HPAGE_MASK);
 876         if (likely(pte_same(*ptep, pte))) {
 877                 /* Break COW */
 878                 set_huge_pte_at(mm, address, ptep,
 879                                 make_huge_pte(vma, new_page, 1));
 880                 /* Make the old page be freed below */
 881                 new_page = old_page;
 882         }
 883         page_cache_release(new_page);
 884         page_cache_release(old_page);
 885         return 0;
 886 }
 887
 888 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
 889                         unsigned long address, pte_t *ptep, int write_access)
 890 {
 891         int ret = VM_FAULT_SIGBUS;
 892         unsigned long idx;
 893         unsigned long size;
 894         struct page *page;
 895         struct address_space *mapping;
 896         pte_t new_pte;
 897
 898         mapping = vma->vm_file->f_mapping;
 899         idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
 900                 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
 901
 902         /*
 903          * Use page lock to guard against racing truncation
 904          * before we get page_table_lock.
 905          */
 906 retry:
 907         page = find_lock_page(mapping, idx);
 908         if (!page) {
 909                 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
 910                 if (idx >= size)
 911                         goto out;
 912                 page = alloc_huge_page(vma, address);
 913                 if (IS_ERR(page)) {
 914                         ret = -PTR_ERR(page);
 915                         goto out;
 916                 }
 917                 clear_huge_page(page, address);
 918                 __SetPageUptodate(page);
 919
 920                 if (vma->vm_flags & VM_SHARED) {
 921                         int err;
 922                         struct inode *inode = mapping->host;
 923
 924                         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
 925                         if (err) {
 926                                 put_page(page);
 927                                 if (err == -EEXIST)
 928                                         goto retry;
 929                                 goto out;
 930                         }
 931
 932                         spin_lock(&inode->i_lock);
 933                         inode->i_blocks += BLOCKS_PER_HUGEPAGE;
 934                         spin_unlock(&inode->i_lock);
 935                 } else
 936                         lock_page(page);
 937         }
 938
 939         spin_lock(&mm->page_table_lock);
 940         size = i_size_read(mapping->host) >> HPAGE_SHIFT;
 941         if (idx >= size)
 942                 goto backout;
 943
 944         ret = 0;
 945         if (!pte_none(*ptep))
 946                 goto backout;
 947
 948         new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
 949                                 && (vma->vm_flags & VM_SHARED)));
 950         set_huge_pte_at(mm, address, ptep, new_pte);
 951
 952         if (write_access && !(vma->vm_flags & VM_SHARED)) {
 953                 /* Optimization, do the COW without a second fault */
 954                 ret = hugetlb_cow(mm, vma, address, ptep, new_pte);
 955         }
 956
 957         spin_unlock(&mm->page_table_lock);
 958         unlock_page(page);
 959 out:
 960         return ret;
 961
 962 backout:
 963         spin_unlock(&mm->page_table_lock);
 964         unlock_page(page);
 965         put_page(page);
 966         goto out;
 967 }
 968
 969 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 970                         unsigned long address, int write_access)
 971 {
 972         pte_t *ptep;
 973         pte_t entry;
 974         int ret;
 975         static DEFINE_MUTEX(hugetlb_instantiation_mutex);
 976
 977         ptep = huge_pte_alloc(mm, address);
 978         if (!ptep)
 979                 return VM_FAULT_OOM;
 980
 981         /*
 982          * Serialize hugepage allocation and instantiation, so that we don't
 983          * get spurious allocation failures if two CPUs race to instantiate
 984          * the same page in the page cache.
 985          */
 986         mutex_lock(&hugetlb_instantiation_mutex);
 987         entry = *ptep;
 988         if (pte_none(entry)) {
 989                 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
 990                 mutex_unlock(&hugetlb_instantiation_mutex);
 991                 return ret;
 992         }
 993
 994         ret = 0;
 995
 996         spin_lock(&mm->page_table_lock);
 997         /* Check for a racing update before calling hugetlb_cow */
 998         if (likely(pte_same(entry, *ptep)))
 999                 if (write_access && !pte_write(entry))
1000                         ret = hugetlb_cow(mm, vma, address, ptep, entry);
1001         spin_unlock(&mm->page_table_lock);
1002         mutex_unlock(&hugetlb_instantiation_mutex);
1003
1004         return ret;
1005 }
1006
1007 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
1008                         struct page **pages, struct vm_area_struct **vmas,
1009                         unsigned long *position, int *length, int i,
1010                         int write)
1011 {
1012         unsigned long pfn_offset;
1013         unsigned long vaddr = *position;
1014         int remainder = *length;
1015
1016         spin_lock(&mm->page_table_lock);
1017         while (vaddr < vma->vm_end && remainder) {
1018                 pte_t *pte;
1019                 struct page *page;
1020
1021                 /*
1022                  * Some archs (sparc64, sh*) have multiple pte_ts to
1023                  * each hugepage.  We have to make * sure we get the
1024                  * first, for the page indexing below to work.
1025                  */
1026                 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
1027
1028                 if (!pte || pte_none(*pte) || (write && !pte_write(*pte))) {
1029                         int ret;
1030
1031                         spin_unlock(&mm->page_table_lock);
1032                         ret = hugetlb_fault(mm, vma, vaddr, write);
1033                         spin_lock(&mm->page_table_lock);
1034                         if (!(ret & VM_FAULT_ERROR))
1035                                 continue;
1036
1037                         remainder = 0;
1038                         if (!i)
1039                                 i = -EFAULT;
1040                         break;
1041                 }
1042
1043                 pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
1044                 page = pte_page(*pte);
1045 same_page:
1046                 if (pages) {
1047                         get_page(page);
1048                         pages[i] = page + pfn_offset;
1049                 }
1050
1051                 if (vmas)
1052                         vmas[i] = vma;
1053
1054                 vaddr += PAGE_SIZE;
1055                 ++pfn_offset;
1056                 --remainder;
1057                 ++i;
1058                 if (vaddr < vma->vm_end && remainder &&
1059                                 pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
1060                         /*
1061                          * We use pfn_offset to avoid touching the pageframes
1062                          * of this compound page.
1063                          */
1064                         goto same_page;
1065                 }
1066         }
1067         spin_unlock(&mm->page_table_lock);
1068         *length = remainder;
1069         *position = vaddr;
1070
1071         return i;
1072 }
1073
1074 void hugetlb_change_protection(struct vm_area_struct *vma,
1075                 unsigned long address, unsigned long end, pgprot_t newprot)
1076 {
1077         struct mm_struct *mm = vma->vm_mm;
1078         unsigned long start = address;
1079         pte_t *ptep;
1080         pte_t pte;
1081
1082         BUG_ON(address >= end);
1083         flush_cache_range(vma, address, end);
1084
1085         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1086         spin_lock(&mm->page_table_lock);
1087         for (; address < end; address += HPAGE_SIZE) {
1088                 ptep = huge_pte_offset(mm, address);
1089                 if (!ptep)
1090                         continue;
1091                 if (huge_pmd_unshare(mm, &address, ptep))
1092                         continue;
1093                 if (!pte_none(*ptep)) {
1094                         pte = huge_ptep_get_and_clear(mm, address, ptep);
1095                         pte = pte_mkhuge(pte_modify(pte, newprot));
1096                         set_huge_pte_at(mm, address, ptep, pte);
1097                 }
1098         }
1099         spin_unlock(&mm->page_table_lock);
1100         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1101
1102         flush_tlb_range(vma, start, end);
1103 }
1104
1105 struct file_region {
1106         struct list_head link;
1107         long from;
1108         long to;
1109 };
1110
1111 static long region_add(struct list_head *head, long f, long t)
1112 {
1113         struct file_region *rg, *nrg, *trg;
1114
1115         /* Locate the region we are either in or before. */
1116         list_for_each_entry(rg, head, link)
1117                 if (f <= rg->to)
1118                         break;
1119
1120         /* Round our left edge to the current segment if it encloses us. */
1121         if (f > rg->from)
1122                 f = rg->from;
1123
1124         /* Check for and consume any regions we now overlap with. */
1125         nrg = rg;
1126         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
1127                 if (&rg->link == head)
1128                         break;
1129                 if (rg->from > t)
1130                         break;
1131
1132                 /* If this area reaches higher then extend our area to
1133                  * include it completely.  If this is not the first area
1134                  * which we intend to reuse, free it. */
1135                 if (rg->to > t)
1136                         t = rg->to;
1137                 if (rg != nrg) {
1138                         list_del(&rg->link);
1139                         kfree(rg);
1140                 }
1141         }
1142         nrg->from = f;
1143         nrg->to = t;
1144         return 0;
1145 }
1146
1147 static long region_chg(struct list_head *head, long f, long t)
1148 {
1149         struct file_region *rg, *nrg;
1150         long chg = 0;
1151
1152         /* Locate the region we are before or in. */
1153         list_for_each_entry(rg, head, link)
1154                 if (f <= rg->to)
1155                         break;
1156
1157         /* If we are below the current region then a new region is required.
1158          * Subtle, allocate a new region at the position but make it zero
1159          * size such that we can guarantee to record the reservation. */
1160         if (&rg->link == head || t < rg->from) {
1161                 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
1162                 if (!nrg)
1163                         return -ENOMEM;
1164                 nrg->from = f;
1165                 nrg->to   = f;
1166                 INIT_LIST_HEAD(&nrg->link);
1167                 list_add(&nrg->link, rg->link.prev);
1168
1169                 return t - f;
1170         }
1171
1172         /* Round our left edge to the current segment if it encloses us. */
1173         if (f > rg->from)
1174                 f = rg->from;
1175         chg = t - f;
1176
1177         /* Check for and consume any regions we now overlap with. */
1178         list_for_each_entry(rg, rg->link.prev, link) {
1179                 if (&rg->link == head)
1180                         break;
1181                 if (rg->from > t)
1182                         return chg;
1183
1184                 /* We overlap with this area, if it extends futher than
1185                  * us then we must extend ourselves.  Account for its
1186                  * existing reservation. */
1187                 if (rg->to > t) {
1188                         chg += rg->to - t;
1189                         t = rg->to;
1190                 }
1191                 chg -= rg->to - rg->from;
1192         }
1193         return chg;
1194 }
1195
1196 static long region_truncate(struct list_head *head, long end)
1197 {
1198         struct file_region *rg, *trg;
1199         long chg = 0;
1200
1201         /* Locate the region we are either in or before. */
1202         list_for_each_entry(rg, head, link)
1203                 if (end <= rg->to)
1204                         break;
1205         if (&rg->link == head)
1206                 return 0;
1207
1208         /* If we are in the middle of a region then adjust it. */
1209         if (end > rg->from) {
1210                 chg = rg->to - end;
1211                 rg->to = end;
1212                 rg = list_entry(rg->link.next, typeof(*rg), link);
1213         }
1214
1215         /* Drop any remaining regions. */
1216         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
1217                 if (&rg->link == head)
1218                         break;
1219                 chg += rg->to - rg->from;
1220                 list_del(&rg->link);
1221                 kfree(rg);
1222         }
1223         return chg;
1224 }
1225
1226 static int hugetlb_acct_memory(long delta)
1227 {
1228         int ret = -ENOMEM;
1229
1230         spin_lock(&hugetlb_lock);
1231         /*
1232          * When cpuset is configured, it breaks the strict hugetlb page
1233          * reservation as the accounting is done on a global variable. Such
1234          * reservation is completely rubbish in the presence of cpuset because
1235          * the reservation is not checked against page availability for the
1236          * current cpuset. Application can still potentially OOM'ed by kernel
1237          * with lack of free htlb page in cpuset that the task is in.
1238          * Attempt to enforce strict accounting with cpuset is almost
1239          * impossible (or too ugly) because cpuset is too fluid that
1240          * task or memory node can be dynamically moved between cpusets.
1241          *
1242          * The change of semantics for shared hugetlb mapping with cpuset is
1243          * undesirable. However, in order to preserve some of the semantics,
1244          * we fall back to check against current free page availability as
1245          * a best attempt and hopefully to minimize the impact of changing
1246          * semantics that cpuset has.
1247          */
1248         if (delta > 0) {
1249                 if (gather_surplus_pages(delta) < 0)
1250                         goto out;
1251
1252                 if (delta > cpuset_mems_nr(free_huge_pages_node)) {
1253                         return_unused_surplus_pages(delta);
1254                         goto out;
1255                 }
1256         }
1257
1258         ret = 0;
1259         if (delta < 0)
1260                 return_unused_surplus_pages((unsigned long) -delta);
1261
1262 out:
1263         spin_unlock(&hugetlb_lock);
1264         return ret;
1265 }
1266
1267 int hugetlb_reserve_pages(struct inode *inode, long from, long to)
1268 {
1269         long ret, chg;
1270
1271         chg = region_chg(&inode->i_mapping->private_list, from, to);
1272         if (chg < 0)
1273                 return chg;
1274
1275         if (hugetlb_get_quota(inode->i_mapping, chg))
1276                 return -ENOSPC;
1277         ret = hugetlb_acct_memory(chg);
1278         if (ret < 0) {
1279                 hugetlb_put_quota(inode->i_mapping, chg);
1280                 return ret;
1281         }
1282         region_add(&inode->i_mapping->private_list, from, to);
1283         return 0;
1284 }
1285
1286 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
1287 {
1288         long chg = region_truncate(&inode->i_mapping->private_list, offset);
1289
1290         spin_lock(&inode->i_lock);
1291         inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed;
1292         spin_unlock(&inode->i_lock);
1293
1294         hugetlb_put_quota(inode->i_mapping, (chg - freed));
1295         hugetlb_acct_memory(-(chg - freed));
1296 }