err.no Git - linux-2.6/blob - 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         nodemask_t *nodemask;
  99         struct zonelist *zonelist = huge_zonelist(vma, address,
 100                                         htlb_alloc_mask, &mpol, &nodemask);
 101         struct zone *zone;
 102         struct zoneref *z;
 103
 104         for_each_zone_zonelist_nodemask(zone, z, zonelist,
 105                                                 MAX_NR_ZONES - 1, nodemask) {
 106                 nid = zone_to_nid(zone);
 107                 if (cpuset_zone_allowed_softwall(zone, htlb_alloc_mask) &&
 108                     !list_empty(&hugepage_freelists[nid])) {
 109                         page = list_entry(hugepage_freelists[nid].next,
 110                                           struct page, lru);
 111                         list_del(&page->lru);
 112                         free_huge_pages--;
 113                         free_huge_pages_node[nid]--;
 114                         if (vma && vma->vm_flags & VM_MAYSHARE)
 115                                 resv_huge_pages--;
 116                         break;
 117                 }
 118         }
 119         mpol_cond_put(mpol);
 120         return page;
 121 }
 122
 123 static void update_and_free_page(struct page *page)
 124 {
 125         int i;
 126         nr_huge_pages--;
 127         nr_huge_pages_node[page_to_nid(page)]--;
 128         for (i = 0; i < (HPAGE_SIZE / PAGE_SIZE); i++) {
 129                 page[i].flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced |
 130                                 1 << PG_dirty | 1 << PG_active | 1 << PG_reserved |
 131                                 1 << PG_private | 1<< PG_writeback);
 132         }
 133         set_compound_page_dtor(page, NULL);
 134         set_page_refcounted(page);
 135         arch_release_hugepage(page);
 136         __free_pages(page, HUGETLB_PAGE_ORDER);
 137 }
 138
 139 static void free_huge_page(struct page *page)
 140 {
 141         int nid = page_to_nid(page);
 142         struct address_space *mapping;
 143
 144         mapping = (struct address_space *) page_private(page);
 145         set_page_private(page, 0);
 146         BUG_ON(page_count(page));
 147         INIT_LIST_HEAD(&page->lru);
 148
 149         spin_lock(&hugetlb_lock);
 150         if (surplus_huge_pages_node[nid]) {
 151                 update_and_free_page(page);
 152                 surplus_huge_pages--;
 153                 surplus_huge_pages_node[nid]--;
 154         } else {
 155                 enqueue_huge_page(page);
 156         }
 157         spin_unlock(&hugetlb_lock);
 158         if (mapping)
 159                 hugetlb_put_quota(mapping, 1);
 160 }
 161
 162 /*
 163  * Increment or decrement surplus_huge_pages.  Keep node-specific counters
 164  * balanced by operating on them in a round-robin fashion.
 165  * Returns 1 if an adjustment was made.
 166  */
 167 static int adjust_pool_surplus(int delta)
 168 {
 169         static int prev_nid;
 170         int nid = prev_nid;
 171         int ret = 0;
 172
 173         VM_BUG_ON(delta != -1 && delta != 1);
 174         do {
 175                 nid = next_node(nid, node_online_map);
 176                 if (nid == MAX_NUMNODES)
 177                         nid = first_node(node_online_map);
 178
 179                 /* To shrink on this node, there must be a surplus page */
 180                 if (delta < 0 && !surplus_huge_pages_node[nid])
 181                         continue;
 182                 /* Surplus cannot exceed the total number of pages */
 183                 if (delta > 0 && surplus_huge_pages_node[nid] >=
 184                                                 nr_huge_pages_node[nid])
 185                         continue;
 186
 187                 surplus_huge_pages += delta;
 188                 surplus_huge_pages_node[nid] += delta;
 189                 ret = 1;
 190                 break;
 191         } while (nid != prev_nid);
 192
 193         prev_nid = nid;
 194         return ret;
 195 }
 196
 197 static struct page *alloc_fresh_huge_page_node(int nid)
 198 {
 199         struct page *page;
 200
 201         page = alloc_pages_node(nid,
 202                 htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|__GFP_NOWARN,
 203                 HUGETLB_PAGE_ORDER);
 204         if (page) {
 205                 if (arch_prepare_hugepage(page)) {
 206                         __free_pages(page, HUGETLB_PAGE_ORDER);
 207                         return 0;
 208                 }
 209                 set_compound_page_dtor(page, free_huge_page);
 210                 spin_lock(&hugetlb_lock);
 211                 nr_huge_pages++;
 212                 nr_huge_pages_node[nid]++;
 213                 spin_unlock(&hugetlb_lock);
 214                 put_page(page); /* free it into the hugepage allocator */
 215         }
 216
 217         return page;
 218 }
 219
 220 static int alloc_fresh_huge_page(void)
 221 {
 222         struct page *page;
 223         int start_nid;
 224         int next_nid;
 225         int ret = 0;
 226
 227         start_nid = hugetlb_next_nid;
 228
 229         do {
 230                 page = alloc_fresh_huge_page_node(hugetlb_next_nid);
 231                 if (page)
 232                         ret = 1;
 233                 /*
 234                  * Use a helper variable to find the next node and then
 235                  * copy it back to hugetlb_next_nid afterwards:
 236                  * otherwise there's a window in which a racer might
 237                  * pass invalid nid MAX_NUMNODES to alloc_pages_node.
 238                  * But we don't need to use a spin_lock here: it really
 239                  * doesn't matter if occasionally a racer chooses the
 240                  * same nid as we do.  Move nid forward in the mask even
 241                  * if we just successfully allocated a hugepage so that
 242                  * the next caller gets hugepages on the next node.
 243                  */
 244                 next_nid = next_node(hugetlb_next_nid, node_online_map);
 245                 if (next_nid == MAX_NUMNODES)
 246                         next_nid = first_node(node_online_map);
 247                 hugetlb_next_nid = next_nid;
 248         } while (!page && hugetlb_next_nid != start_nid);
 249
 250         if (ret)
 251                 count_vm_event(HTLB_BUDDY_PGALLOC);
 252         else
 253                 count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
 254
 255         return ret;
 256 }
 257
 258 static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma,
 259                                                 unsigned long address)
 260 {
 261         struct page *page;
 262         unsigned int nid;
 263
 264         /*
 265          * Assume we will successfully allocate the surplus page to
 266          * prevent racing processes from causing the surplus to exceed
 267          * overcommit
 268          *
 269          * This however introduces a different race, where a process B
 270          * tries to grow the static hugepage pool while alloc_pages() is
 271          * called by process A. B will only examine the per-node
 272          * counters in determining if surplus huge pages can be
 273          * converted to normal huge pages in adjust_pool_surplus(). A
 274          * won't be able to increment the per-node counter, until the
 275          * lock is dropped by B, but B doesn't drop hugetlb_lock until
 276          * no more huge pages can be converted from surplus to normal
 277          * state (and doesn't try to convert again). Thus, we have a
 278          * case where a surplus huge page exists, the pool is grown, and
 279          * the surplus huge page still exists after, even though it
 280          * should just have been converted to a normal huge page. This
 281          * does not leak memory, though, as the hugepage will be freed
 282          * once it is out of use. It also does not allow the counters to
 283          * go out of whack in adjust_pool_surplus() as we don't modify
 284          * the node values until we've gotten the hugepage and only the
 285          * per-node value is checked there.
 286          */
 287         spin_lock(&hugetlb_lock);
 288         if (surplus_huge_pages >= nr_overcommit_huge_pages) {
 289                 spin_unlock(&hugetlb_lock);
 290                 return NULL;
 291         } else {
 292                 nr_huge_pages++;
 293                 surplus_huge_pages++;
 294         }
 295         spin_unlock(&hugetlb_lock);
 296
 297         page = alloc_pages(htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN,
 298                                         HUGETLB_PAGE_ORDER);
 299
 300         spin_lock(&hugetlb_lock);
 301         if (page) {
 302                 /*
 303                  * This page is now managed by the hugetlb allocator and has
 304                  * no users -- drop the buddy allocator's reference.
 305                  */
 306                 put_page_testzero(page);
 307                 VM_BUG_ON(page_count(page));
 308                 nid = page_to_nid(page);
 309                 set_compound_page_dtor(page, free_huge_page);
 310                 /*
 311                  * We incremented the global counters already
 312                  */
 313                 nr_huge_pages_node[nid]++;
 314                 surplus_huge_pages_node[nid]++;
 315                 __count_vm_event(HTLB_BUDDY_PGALLOC);
 316         } else {
 317                 nr_huge_pages--;
 318                 surplus_huge_pages--;
 319                 __count_vm_event(HTLB_BUDDY_PGALLOC_FAIL);
 320         }
 321         spin_unlock(&hugetlb_lock);
 322
 323         return page;
 324 }
 325
 326 /*
 327  * Increase the hugetlb pool such that it can accomodate a reservation
 328  * of size 'delta'.
 329  */
 330 static int gather_surplus_pages(int delta)
 331 {
 332         struct list_head surplus_list;
 333         struct page *page, *tmp;
 334         int ret, i;
 335         int needed, allocated;
 336
 337         needed = (resv_huge_pages + delta) - free_huge_pages;
 338         if (needed <= 0) {
 339                 resv_huge_pages += delta;
 340                 return 0;
 341         }
 342
 343         allocated = 0;
 344         INIT_LIST_HEAD(&surplus_list);
 345
 346         ret = -ENOMEM;
 347 retry:
 348         spin_unlock(&hugetlb_lock);
 349         for (i = 0; i < needed; i++) {
 350                 page = alloc_buddy_huge_page(NULL, 0);
 351                 if (!page) {
 352                         /*
 353                          * We were not able to allocate enough pages to
 354                          * satisfy the entire reservation so we free what
 355                          * we've allocated so far.
 356                          */
 357                         spin_lock(&hugetlb_lock);
 358                         needed = 0;
 359                         goto free;
 360                 }
 361
 362                 list_add(&page->lru, &surplus_list);
 363         }
 364         allocated += needed;
 365
 366         /*
 367          * After retaking hugetlb_lock, we need to recalculate 'needed'
 368          * because either resv_huge_pages or free_huge_pages may have changed.
 369          */
 370         spin_lock(&hugetlb_lock);
 371         needed = (resv_huge_pages + delta) - (free_huge_pages + allocated);
 372         if (needed > 0)
 373                 goto retry;
 374
 375         /*
 376          * The surplus_list now contains _at_least_ the number of extra pages
 377          * needed to accomodate the reservation.  Add the appropriate number
 378          * of pages to the hugetlb pool and free the extras back to the buddy
 379          * allocator.  Commit the entire reservation here to prevent another
 380          * process from stealing the pages as they are added to the pool but
 381          * before they are reserved.
 382          */
 383         needed += allocated;
 384         resv_huge_pages += delta;
 385         ret = 0;
 386 free:
 387         /* Free the needed pages to the hugetlb pool */
 388         list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
 389                 if ((--needed) < 0)
 390                         break;
 391                 list_del(&page->lru);
 392                 enqueue_huge_page(page);
 393         }
 394
 395         /* Free unnecessary surplus pages to the buddy allocator */
 396         if (!list_empty(&surplus_list)) {
 397                 spin_unlock(&hugetlb_lock);
 398                 list_for_each_entry_safe(page, tmp, &surplus_list, lru) {
 399                         list_del(&page->lru);
 400                         /*
 401                          * The page has a reference count of zero already, so
 402                          * call free_huge_page directly instead of using
 403                          * put_page.  This must be done with hugetlb_lock
 404                          * unlocked which is safe because free_huge_page takes
 405                          * hugetlb_lock before deciding how to free the page.
 406                          */
 407                         free_huge_page(page);
 408                 }
 409                 spin_lock(&hugetlb_lock);
 410         }
 411
 412         return ret;
 413 }
 414
 415 /*
 416  * When releasing a hugetlb pool reservation, any surplus pages that were
 417  * allocated to satisfy the reservation must be explicitly freed if they were
 418  * never used.
 419  */
 420 static void return_unused_surplus_pages(unsigned long unused_resv_pages)
 421 {
 422         static int nid = -1;
 423         struct page *page;
 424         unsigned long nr_pages;
 425
 426         /*
 427          * We want to release as many surplus pages as possible, spread
 428          * evenly across all nodes. Iterate across all nodes until we
 429          * can no longer free unreserved surplus pages. This occurs when
 430          * the nodes with surplus pages have no free pages.
 431          */
 432         unsigned long remaining_iterations = num_online_nodes();
 433
 434         /* Uncommit the reservation */
 435         resv_huge_pages -= unused_resv_pages;
 436
 437         nr_pages = min(unused_resv_pages, surplus_huge_pages);
 438
 439         while (remaining_iterations-- && nr_pages) {
 440                 nid = next_node(nid, node_online_map);
 441                 if (nid == MAX_NUMNODES)
 442                         nid = first_node(node_online_map);
 443
 444                 if (!surplus_huge_pages_node[nid])
 445                         continue;
 446
 447                 if (!list_empty(&hugepage_freelists[nid])) {
 448                         page = list_entry(hugepage_freelists[nid].next,
 449                                           struct page, lru);
 450                         list_del(&page->lru);
 451                         update_and_free_page(page);
 452                         free_huge_pages--;
 453                         free_huge_pages_node[nid]--;
 454                         surplus_huge_pages--;
 455                         surplus_huge_pages_node[nid]--;
 456                         nr_pages--;
 457                         remaining_iterations = num_online_nodes();
 458                 }
 459         }
 460 }
 461
 462
 463 static struct page *alloc_huge_page_shared(struct vm_area_struct *vma,
 464                                                 unsigned long addr)
 465 {
 466         struct page *page;
 467
 468         spin_lock(&hugetlb_lock);
 469         page = dequeue_huge_page_vma(vma, addr);
 470         spin_unlock(&hugetlb_lock);
 471         return page ? page : ERR_PTR(-VM_FAULT_OOM);
 472 }
 473
 474 static struct page *alloc_huge_page_private(struct vm_area_struct *vma,
 475                                                 unsigned long addr)
 476 {
 477         struct page *page = NULL;
 478
 479         if (hugetlb_get_quota(vma->vm_file->f_mapping, 1))
 480                 return ERR_PTR(-VM_FAULT_SIGBUS);
 481
 482         spin_lock(&hugetlb_lock);
 483         if (free_huge_pages > resv_huge_pages)
 484                 page = dequeue_huge_page_vma(vma, addr);
 485         spin_unlock(&hugetlb_lock);
 486         if (!page) {
 487                 page = alloc_buddy_huge_page(vma, addr);
 488                 if (!page) {
 489                         hugetlb_put_quota(vma->vm_file->f_mapping, 1);
 490                         return ERR_PTR(-VM_FAULT_OOM);
 491                 }
 492         }
 493         return page;
 494 }
 495
 496 static struct page *alloc_huge_page(struct vm_area_struct *vma,
 497                                     unsigned long addr)
 498 {
 499         struct page *page;
 500         struct address_space *mapping = vma->vm_file->f_mapping;
 501
 502         if (vma->vm_flags & VM_MAYSHARE)
 503                 page = alloc_huge_page_shared(vma, addr);
 504         else
 505                 page = alloc_huge_page_private(vma, addr);
 506
 507         if (!IS_ERR(page)) {
 508                 set_page_refcounted(page);
 509                 set_page_private(page, (unsigned long) mapping);
 510         }
 511         return page;
 512 }
 513
 514 static int __init hugetlb_init(void)
 515 {
 516         unsigned long i;
 517
 518         if (HPAGE_SHIFT == 0)
 519                 return 0;
 520
 521         for (i = 0; i < MAX_NUMNODES; ++i)
 522                 INIT_LIST_HEAD(&hugepage_freelists[i]);
 523
 524         hugetlb_next_nid = first_node(node_online_map);
 525
 526         for (i = 0; i < max_huge_pages; ++i) {
 527                 if (!alloc_fresh_huge_page())
 528                         break;
 529         }
 530         max_huge_pages = free_huge_pages = nr_huge_pages = i;
 531         printk("Total HugeTLB memory allocated, %ld\n", free_huge_pages);
 532         return 0;
 533 }
 534 module_init(hugetlb_init);
 535
 536 static int __init hugetlb_setup(char *s)
 537 {
 538         if (sscanf(s, "%lu", &max_huge_pages) <= 0)
 539                 max_huge_pages = 0;
 540         return 1;
 541 }
 542 __setup("hugepages=", hugetlb_setup);
 543
 544 static unsigned int cpuset_mems_nr(unsigned int *array)
 545 {
 546         int node;
 547         unsigned int nr = 0;
 548
 549         for_each_node_mask(node, cpuset_current_mems_allowed)
 550                 nr += array[node];
 551
 552         return nr;
 553 }
 554
 555 #ifdef CONFIG_SYSCTL
 556 #ifdef CONFIG_HIGHMEM
 557 static void try_to_free_low(unsigned long count)
 558 {
 559         int i;
 560
 561         for (i = 0; i < MAX_NUMNODES; ++i) {
 562                 struct page *page, *next;
 563                 list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
 564                         if (count >= nr_huge_pages)
 565                                 return;
 566                         if (PageHighMem(page))
 567                                 continue;
 568                         list_del(&page->lru);
 569                         update_and_free_page(page);
 570                         free_huge_pages--;
 571                         free_huge_pages_node[page_to_nid(page)]--;
 572                 }
 573         }
 574 }
 575 #else
 576 static inline void try_to_free_low(unsigned long count)
 577 {
 578 }
 579 #endif
 580
 581 #define persistent_huge_pages (nr_huge_pages - surplus_huge_pages)
 582 static unsigned long set_max_huge_pages(unsigned long count)
 583 {
 584         unsigned long min_count, ret;
 585
 586         /*
 587          * Increase the pool size
 588          * First take pages out of surplus state.  Then make up the
 589          * remaining difference by allocating fresh huge pages.
 590          *
 591          * We might race with alloc_buddy_huge_page() here and be unable
 592          * to convert a surplus huge page to a normal huge page. That is
 593          * not critical, though, it just means the overall size of the
 594          * pool might be one hugepage larger than it needs to be, but
 595          * within all the constraints specified by the sysctls.
 596          */
 597         spin_lock(&hugetlb_lock);
 598         while (surplus_huge_pages && count > persistent_huge_pages) {
 599                 if (!adjust_pool_surplus(-1))
 600                         break;
 601         }
 602
 603         while (count > persistent_huge_pages) {
 604                 int ret;
 605                 /*
 606                  * If this allocation races such that we no longer need the
 607                  * page, free_huge_page will handle it by freeing the page
 608                  * and reducing the surplus.
 609                  */
 610                 spin_unlock(&hugetlb_lock);
 611                 ret = alloc_fresh_huge_page();
 612                 spin_lock(&hugetlb_lock);
 613                 if (!ret)
 614                         goto out;
 615
 616         }
 617
 618         /*
 619          * Decrease the pool size
 620          * First return free pages to the buddy allocator (being careful
 621          * to keep enough around to satisfy reservations).  Then place
 622          * pages into surplus state as needed so the pool will shrink
 623          * to the desired size as pages become free.
 624          *
 625          * By placing pages into the surplus state independent of the
 626          * overcommit value, we are allowing the surplus pool size to
 627          * exceed overcommit. There are few sane options here. Since
 628          * alloc_buddy_huge_page() is checking the global counter,
 629          * though, we'll note that we're not allowed to exceed surplus
 630          * and won't grow the pool anywhere else. Not until one of the
 631          * sysctls are changed, or the surplus pages go out of use.
 632          */
 633         min_count = resv_huge_pages + nr_huge_pages - free_huge_pages;
 634         min_count = max(count, min_count);
 635         try_to_free_low(min_count);
 636         while (min_count < persistent_huge_pages) {
 637                 struct page *page = dequeue_huge_page();
 638                 if (!page)
 639                         break;
 640                 update_and_free_page(page);
 641         }
 642         while (count < persistent_huge_pages) {
 643                 if (!adjust_pool_surplus(1))
 644                         break;
 645         }
 646 out:
 647         ret = persistent_huge_pages;
 648         spin_unlock(&hugetlb_lock);
 649         return ret;
 650 }
 651
 652 int hugetlb_sysctl_handler(struct ctl_table *table, int write,
 653                            struct file *file, void __user *buffer,
 654                            size_t *length, loff_t *ppos)
 655 {
 656         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
 657         max_huge_pages = set_max_huge_pages(max_huge_pages);
 658         return 0;
 659 }
 660
 661 int hugetlb_treat_movable_handler(struct ctl_table *table, int write,
 662                         struct file *file, void __user *buffer,
 663                         size_t *length, loff_t *ppos)
 664 {
 665         proc_dointvec(table, write, file, buffer, length, ppos);
 666         if (hugepages_treat_as_movable)
 667                 htlb_alloc_mask = GFP_HIGHUSER_MOVABLE;
 668         else
 669                 htlb_alloc_mask = GFP_HIGHUSER;
 670         return 0;
 671 }
 672
 673 int hugetlb_overcommit_handler(struct ctl_table *table, int write,
 674                         struct file *file, void __user *buffer,
 675                         size_t *length, loff_t *ppos)
 676 {
 677         proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
 678         spin_lock(&hugetlb_lock);
 679         nr_overcommit_huge_pages = sysctl_overcommit_huge_pages;
 680         spin_unlock(&hugetlb_lock);
 681         return 0;
 682 }
 683
 684 #endif /* CONFIG_SYSCTL */
 685
 686 int hugetlb_report_meminfo(char *buf)
 687 {
 688         return sprintf(buf,
 689                         "HugePages_Total: %5lu\n"
 690                         "HugePages_Free:  %5lu\n"
 691                         "HugePages_Rsvd:  %5lu\n"
 692                         "HugePages_Surp:  %5lu\n"
 693                         "Hugepagesize:    %5lu kB\n",
 694                         nr_huge_pages,
 695                         free_huge_pages,
 696                         resv_huge_pages,
 697                         surplus_huge_pages,
 698                         HPAGE_SIZE/1024);
 699 }
 700
 701 int hugetlb_report_node_meminfo(int nid, char *buf)
 702 {
 703         return sprintf(buf,
 704                 "Node %d HugePages_Total: %5u\n"
 705                 "Node %d HugePages_Free:  %5u\n"
 706                 "Node %d HugePages_Surp:  %5u\n",
 707                 nid, nr_huge_pages_node[nid],
 708                 nid, free_huge_pages_node[nid],
 709                 nid, surplus_huge_pages_node[nid]);
 710 }
 711
 712 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */
 713 unsigned long hugetlb_total_pages(void)
 714 {
 715         return nr_huge_pages * (HPAGE_SIZE / PAGE_SIZE);
 716 }
 717
 718 /*
 719  * We cannot handle pagefaults against hugetlb pages at all.  They cause
 720  * handle_mm_fault() to try to instantiate regular-sized pages in the
 721  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
 722  * this far.
 723  */
 724 static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 725 {
 726         BUG();
 727         return 0;
 728 }
 729
 730 struct vm_operations_struct hugetlb_vm_ops = {
 731         .fault = hugetlb_vm_op_fault,
 732 };
 733
 734 static pte_t make_huge_pte(struct vm_area_struct *vma, struct page *page,
 735                                 int writable)
 736 {
 737         pte_t entry;
 738
 739         if (writable) {
 740                 entry =
 741                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
 742         } else {
 743                 entry = huge_pte_wrprotect(mk_pte(page, vma->vm_page_prot));
 744         }
 745         entry = pte_mkyoung(entry);
 746         entry = pte_mkhuge(entry);
 747
 748         return entry;
 749 }
 750
 751 static void set_huge_ptep_writable(struct vm_area_struct *vma,
 752                                    unsigned long address, pte_t *ptep)
 753 {
 754         pte_t entry;
 755
 756         entry = pte_mkwrite(pte_mkdirty(huge_ptep_get(ptep)));
 757         if (huge_ptep_set_access_flags(vma, address, ptep, entry, 1)) {
 758                 update_mmu_cache(vma, address, entry);
 759         }
 760 }
 761
 762
 763 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 764                             struct vm_area_struct *vma)
 765 {
 766         pte_t *src_pte, *dst_pte, entry;
 767         struct page *ptepage;
 768         unsigned long addr;
 769         int cow;
 770
 771         cow = (vma->vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
 772
 773         for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
 774                 src_pte = huge_pte_offset(src, addr);
 775                 if (!src_pte)
 776                         continue;
 777                 dst_pte = huge_pte_alloc(dst, addr);
 778                 if (!dst_pte)
 779                         goto nomem;
 780
 781                 /* If the pagetables are shared don't copy or take references */
 782                 if (dst_pte == src_pte)
 783                         continue;
 784
 785                 spin_lock(&dst->page_table_lock);
 786                 spin_lock(&src->page_table_lock);
 787                 if (!huge_pte_none(huge_ptep_get(src_pte))) {
 788                         if (cow)
 789                                 huge_ptep_set_wrprotect(src, addr, src_pte);
 790                         entry = huge_ptep_get(src_pte);
 791                         ptepage = pte_page(entry);
 792                         get_page(ptepage);
 793                         set_huge_pte_at(dst, addr, dst_pte, entry);
 794                 }
 795                 spin_unlock(&src->page_table_lock);
 796                 spin_unlock(&dst->page_table_lock);
 797         }
 798         return 0;
 799
 800 nomem:
 801         return -ENOMEM;
 802 }
 803
 804 void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
 805                             unsigned long end)
 806 {
 807         struct mm_struct *mm = vma->vm_mm;
 808         unsigned long address;
 809         pte_t *ptep;
 810         pte_t pte;
 811         struct page *page;
 812         struct page *tmp;
 813         /*
 814          * A page gathering list, protected by per file i_mmap_lock. The
 815          * lock is used to avoid list corruption from multiple unmapping
 816          * of the same page since we are using page->lru.
 817          */
 818         LIST_HEAD(page_list);
 819
 820         WARN_ON(!is_vm_hugetlb_page(vma));
 821         BUG_ON(start & ~HPAGE_MASK);
 822         BUG_ON(end & ~HPAGE_MASK);
 823
 824         spin_lock(&mm->page_table_lock);
 825         for (address = start; address < end; address += HPAGE_SIZE) {
 826                 ptep = huge_pte_offset(mm, address);
 827                 if (!ptep)
 828                         continue;
 829
 830                 if (huge_pmd_unshare(mm, &address, ptep))
 831                         continue;
 832
 833                 pte = huge_ptep_get_and_clear(mm, address, ptep);
 834                 if (huge_pte_none(pte))
 835                         continue;
 836
 837                 page = pte_page(pte);
 838                 if (pte_dirty(pte))
 839                         set_page_dirty(page);
 840                 list_add(&page->lru, &page_list);
 841         }
 842         spin_unlock(&mm->page_table_lock);
 843         flush_tlb_range(vma, start, end);
 844         list_for_each_entry_safe(page, tmp, &page_list, lru) {
 845                 list_del(&page->lru);
 846                 put_page(page);
 847         }
 848 }
 849
 850 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
 851                           unsigned long end)
 852 {
 853         /*
 854          * It is undesirable to test vma->vm_file as it should be non-null
 855          * for valid hugetlb area. However, vm_file will be NULL in the error
 856          * cleanup path of do_mmap_pgoff. When hugetlbfs ->mmap method fails,
 857          * do_mmap_pgoff() nullifies vma->vm_file before calling this function
 858          * to clean up. Since no pte has actually been setup, it is safe to
 859          * do nothing in this case.
 860          */
 861         if (vma->vm_file) {
 862                 spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
 863                 __unmap_hugepage_range(vma, start, end);
 864                 spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
 865         }
 866 }
 867
 868 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
 869                         unsigned long address, pte_t *ptep, pte_t pte)
 870 {
 871         struct page *old_page, *new_page;
 872         int avoidcopy;
 873
 874         old_page = pte_page(pte);
 875
 876         /* If no-one else is actually using this page, avoid the copy
 877          * and just make the page writable */
 878         avoidcopy = (page_count(old_page) == 1);
 879         if (avoidcopy) {
 880                 set_huge_ptep_writable(vma, address, ptep);
 881                 return 0;
 882         }
 883
 884         page_cache_get(old_page);
 885         new_page = alloc_huge_page(vma, address);
 886
 887         if (IS_ERR(new_page)) {
 888                 page_cache_release(old_page);
 889                 return -PTR_ERR(new_page);
 890         }
 891
 892         spin_unlock(&mm->page_table_lock);
 893         copy_huge_page(new_page, old_page, address, vma);
 894         __SetPageUptodate(new_page);
 895         spin_lock(&mm->page_table_lock);
 896
 897         ptep = huge_pte_offset(mm, address & HPAGE_MASK);
 898         if (likely(pte_same(huge_ptep_get(ptep), pte))) {
 899                 /* Break COW */
 900                 huge_ptep_clear_flush(vma, address, ptep);
 901                 set_huge_pte_at(mm, address, ptep,
 902                                 make_huge_pte(vma, new_page, 1));
 903                 /* Make the old page be freed below */
 904                 new_page = old_page;
 905         }
 906         page_cache_release(new_page);
 907         page_cache_release(old_page);
 908         return 0;
 909 }
 910
 911 static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
 912                         unsigned long address, pte_t *ptep, int write_access)
 913 {
 914         int ret = VM_FAULT_SIGBUS;
 915         unsigned long idx;
 916         unsigned long size;
 917         struct page *page;
 918         struct address_space *mapping;
 919         pte_t new_pte;
 920
 921         mapping = vma->vm_file->f_mapping;
 922         idx = ((address - vma->vm_start) >> HPAGE_SHIFT)
 923                 + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
 924
 925         /*
 926          * Use page lock to guard against racing truncation
 927          * before we get page_table_lock.
 928          */
 929 retry:
 930         page = find_lock_page(mapping, idx);
 931         if (!page) {
 932                 size = i_size_read(mapping->host) >> HPAGE_SHIFT;
 933                 if (idx >= size)
 934                         goto out;
 935                 page = alloc_huge_page(vma, address);
 936                 if (IS_ERR(page)) {
 937                         ret = -PTR_ERR(page);
 938                         goto out;
 939                 }
 940                 clear_huge_page(page, address);
 941                 __SetPageUptodate(page);
 942
 943                 if (vma->vm_flags & VM_SHARED) {
 944                         int err;
 945                         struct inode *inode = mapping->host;
 946
 947                         err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
 948                         if (err) {
 949                                 put_page(page);
 950                                 if (err == -EEXIST)
 951                                         goto retry;
 952                                 goto out;
 953                         }
 954
 955                         spin_lock(&inode->i_lock);
 956                         inode->i_blocks += BLOCKS_PER_HUGEPAGE;
 957                         spin_unlock(&inode->i_lock);
 958                 } else
 959                         lock_page(page);
 960         }
 961
 962         spin_lock(&mm->page_table_lock);
 963         size = i_size_read(mapping->host) >> HPAGE_SHIFT;
 964         if (idx >= size)
 965                 goto backout;
 966
 967         ret = 0;
 968         if (!huge_pte_none(huge_ptep_get(ptep)))
 969                 goto backout;
 970
 971         new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
 972                                 && (vma->vm_flags & VM_SHARED)));
 973         set_huge_pte_at(mm, address, ptep, new_pte);
 974
 975         if (write_access && !(vma->vm_flags & VM_SHARED)) {
 976                 /* Optimization, do the COW without a second fault */
 977                 ret = hugetlb_cow(mm, vma, address, ptep, new_pte);
 978         }
 979
 980         spin_unlock(&mm->page_table_lock);
 981         unlock_page(page);
 982 out:
 983         return ret;
 984
 985 backout:
 986         spin_unlock(&mm->page_table_lock);
 987         unlock_page(page);
 988         put_page(page);
 989         goto out;
 990 }
 991
 992 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 993                         unsigned long address, int write_access)
 994 {
 995         pte_t *ptep;
 996         pte_t entry;
 997         int ret;
 998         static DEFINE_MUTEX(hugetlb_instantiation_mutex);
 999
1000         ptep = huge_pte_alloc(mm, address);
1001         if (!ptep)
1002                 return VM_FAULT_OOM;
1003
1004         /*
1005          * Serialize hugepage allocation and instantiation, so that we don't
1006          * get spurious allocation failures if two CPUs race to instantiate
1007          * the same page in the page cache.
1008          */
1009         mutex_lock(&hugetlb_instantiation_mutex);
1010         entry = huge_ptep_get(ptep);
1011         if (huge_pte_none(entry)) {
1012                 ret = hugetlb_no_page(mm, vma, address, ptep, write_access);
1013                 mutex_unlock(&hugetlb_instantiation_mutex);
1014                 return ret;
1015         }
1016
1017         ret = 0;
1018
1019         spin_lock(&mm->page_table_lock);
1020         /* Check for a racing update before calling hugetlb_cow */
1021         if (likely(pte_same(entry, huge_ptep_get(ptep))))
1022                 if (write_access && !pte_write(entry))
1023                         ret = hugetlb_cow(mm, vma, address, ptep, entry);
1024         spin_unlock(&mm->page_table_lock);
1025         mutex_unlock(&hugetlb_instantiation_mutex);
1026
1027         return ret;
1028 }
1029
1030 int follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
1031                         struct page **pages, struct vm_area_struct **vmas,
1032                         unsigned long *position, int *length, int i,
1033                         int write)
1034 {
1035         unsigned long pfn_offset;
1036         unsigned long vaddr = *position;
1037         int remainder = *length;
1038
1039         spin_lock(&mm->page_table_lock);
1040         while (vaddr < vma->vm_end && remainder) {
1041                 pte_t *pte;
1042                 struct page *page;
1043
1044                 /*
1045                  * Some archs (sparc64, sh*) have multiple pte_ts to
1046                  * each hugepage.  We have to make * sure we get the
1047                  * first, for the page indexing below to work.
1048                  */
1049                 pte = huge_pte_offset(mm, vaddr & HPAGE_MASK);
1050
1051                 if (!pte || huge_pte_none(huge_ptep_get(pte)) ||
1052                     (write && !pte_write(huge_ptep_get(pte)))) {
1053                         int ret;
1054
1055                         spin_unlock(&mm->page_table_lock);
1056                         ret = hugetlb_fault(mm, vma, vaddr, write);
1057                         spin_lock(&mm->page_table_lock);
1058                         if (!(ret & VM_FAULT_ERROR))
1059                                 continue;
1060
1061                         remainder = 0;
1062                         if (!i)
1063                                 i = -EFAULT;
1064                         break;
1065                 }
1066
1067                 pfn_offset = (vaddr & ~HPAGE_MASK) >> PAGE_SHIFT;
1068                 page = pte_page(huge_ptep_get(pte));
1069 same_page:
1070                 if (pages) {
1071                         get_page(page);
1072                         pages[i] = page + pfn_offset;
1073                 }
1074
1075                 if (vmas)
1076                         vmas[i] = vma;
1077
1078                 vaddr += PAGE_SIZE;
1079                 ++pfn_offset;
1080                 --remainder;
1081                 ++i;
1082                 if (vaddr < vma->vm_end && remainder &&
1083                                 pfn_offset < HPAGE_SIZE/PAGE_SIZE) {
1084                         /*
1085                          * We use pfn_offset to avoid touching the pageframes
1086                          * of this compound page.
1087                          */
1088                         goto same_page;
1089                 }
1090         }
1091         spin_unlock(&mm->page_table_lock);
1092         *length = remainder;
1093         *position = vaddr;
1094
1095         return i;
1096 }
1097
1098 void hugetlb_change_protection(struct vm_area_struct *vma,
1099                 unsigned long address, unsigned long end, pgprot_t newprot)
1100 {
1101         struct mm_struct *mm = vma->vm_mm;
1102         unsigned long start = address;
1103         pte_t *ptep;
1104         pte_t pte;
1105
1106         BUG_ON(address >= end);
1107         flush_cache_range(vma, address, end);
1108
1109         spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
1110         spin_lock(&mm->page_table_lock);
1111         for (; address < end; address += HPAGE_SIZE) {
1112                 ptep = huge_pte_offset(mm, address);
1113                 if (!ptep)
1114                         continue;
1115                 if (huge_pmd_unshare(mm, &address, ptep))
1116                         continue;
1117                 if (!huge_pte_none(huge_ptep_get(ptep))) {
1118                         pte = huge_ptep_get_and_clear(mm, address, ptep);
1119                         pte = pte_mkhuge(pte_modify(pte, newprot));
1120                         set_huge_pte_at(mm, address, ptep, pte);
1121                 }
1122         }
1123         spin_unlock(&mm->page_table_lock);
1124         spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
1125
1126         flush_tlb_range(vma, start, end);
1127 }
1128
1129 struct file_region {
1130         struct list_head link;
1131         long from;
1132         long to;
1133 };
1134
1135 static long region_add(struct list_head *head, long f, long t)
1136 {
1137         struct file_region *rg, *nrg, *trg;
1138
1139         /* Locate the region we are either in or before. */
1140         list_for_each_entry(rg, head, link)
1141                 if (f <= rg->to)
1142                         break;
1143
1144         /* Round our left edge to the current segment if it encloses us. */
1145         if (f > rg->from)
1146                 f = rg->from;
1147
1148         /* Check for and consume any regions we now overlap with. */
1149         nrg = rg;
1150         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
1151                 if (&rg->link == head)
1152                         break;
1153                 if (rg->from > t)
1154                         break;
1155
1156                 /* If this area reaches higher then extend our area to
1157                  * include it completely.  If this is not the first area
1158                  * which we intend to reuse, free it. */
1159                 if (rg->to > t)
1160                         t = rg->to;
1161                 if (rg != nrg) {
1162                         list_del(&rg->link);
1163                         kfree(rg);
1164                 }
1165         }
1166         nrg->from = f;
1167         nrg->to = t;
1168         return 0;
1169 }
1170
1171 static long region_chg(struct list_head *head, long f, long t)
1172 {
1173         struct file_region *rg, *nrg;
1174         long chg = 0;
1175
1176         /* Locate the region we are before or in. */
1177         list_for_each_entry(rg, head, link)
1178                 if (f <= rg->to)
1179                         break;
1180
1181         /* If we are below the current region then a new region is required.
1182          * Subtle, allocate a new region at the position but make it zero
1183          * size such that we can guarantee to record the reservation. */
1184         if (&rg->link == head || t < rg->from) {
1185                 nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
1186                 if (!nrg)
1187                         return -ENOMEM;
1188                 nrg->from = f;
1189                 nrg->to   = f;
1190                 INIT_LIST_HEAD(&nrg->link);
1191                 list_add(&nrg->link, rg->link.prev);
1192
1193                 return t - f;
1194         }
1195
1196         /* Round our left edge to the current segment if it encloses us. */
1197         if (f > rg->from)
1198                 f = rg->from;
1199         chg = t - f;
1200
1201         /* Check for and consume any regions we now overlap with. */
1202         list_for_each_entry(rg, rg->link.prev, link) {
1203                 if (&rg->link == head)
1204                         break;
1205                 if (rg->from > t)
1206                         return chg;
1207
1208                 /* We overlap with this area, if it extends futher than
1209                  * us then we must extend ourselves.  Account for its
1210                  * existing reservation. */
1211                 if (rg->to > t) {
1212                         chg += rg->to - t;
1213                         t = rg->to;
1214                 }
1215                 chg -= rg->to - rg->from;
1216         }
1217         return chg;
1218 }
1219
1220 static long region_truncate(struct list_head *head, long end)
1221 {
1222         struct file_region *rg, *trg;
1223         long chg = 0;
1224
1225         /* Locate the region we are either in or before. */
1226         list_for_each_entry(rg, head, link)
1227                 if (end <= rg->to)
1228                         break;
1229         if (&rg->link == head)
1230                 return 0;
1231
1232         /* If we are in the middle of a region then adjust it. */
1233         if (end > rg->from) {
1234                 chg = rg->to - end;
1235                 rg->to = end;
1236                 rg = list_entry(rg->link.next, typeof(*rg), link);
1237         }
1238
1239         /* Drop any remaining regions. */
1240         list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
1241                 if (&rg->link == head)
1242                         break;
1243                 chg += rg->to - rg->from;
1244                 list_del(&rg->link);
1245                 kfree(rg);
1246         }
1247         return chg;
1248 }
1249
1250 static int hugetlb_acct_memory(long delta)
1251 {
1252         int ret = -ENOMEM;
1253
1254         spin_lock(&hugetlb_lock);
1255         /*
1256          * When cpuset is configured, it breaks the strict hugetlb page
1257          * reservation as the accounting is done on a global variable. Such
1258          * reservation is completely rubbish in the presence of cpuset because
1259          * the reservation is not checked against page availability for the
1260          * current cpuset. Application can still potentially OOM'ed by kernel
1261          * with lack of free htlb page in cpuset that the task is in.
1262          * Attempt to enforce strict accounting with cpuset is almost
1263          * impossible (or too ugly) because cpuset is too fluid that
1264          * task or memory node can be dynamically moved between cpusets.
1265          *
1266          * The change of semantics for shared hugetlb mapping with cpuset is
1267          * undesirable. However, in order to preserve some of the semantics,
1268          * we fall back to check against current free page availability as
1269          * a best attempt and hopefully to minimize the impact of changing
1270          * semantics that cpuset has.
1271          */
1272         if (delta > 0) {
1273                 if (gather_surplus_pages(delta) < 0)
1274                         goto out;
1275
1276                 if (delta > cpuset_mems_nr(free_huge_pages_node)) {
1277                         return_unused_surplus_pages(delta);
1278                         goto out;
1279                 }
1280         }
1281
1282         ret = 0;
1283         if (delta < 0)
1284                 return_unused_surplus_pages((unsigned long) -delta);
1285
1286 out:
1287         spin_unlock(&hugetlb_lock);
1288         return ret;
1289 }
1290
1291 int hugetlb_reserve_pages(struct inode *inode, long from, long to)
1292 {
1293         long ret, chg;
1294
1295         chg = region_chg(&inode->i_mapping->private_list, from, to);
1296         if (chg < 0)
1297                 return chg;
1298
1299         if (hugetlb_get_quota(inode->i_mapping, chg))
1300                 return -ENOSPC;
1301         ret = hugetlb_acct_memory(chg);
1302         if (ret < 0) {
1303                 hugetlb_put_quota(inode->i_mapping, chg);
1304                 return ret;
1305         }
1306         region_add(&inode->i_mapping->private_list, from, to);
1307         return 0;
1308 }
1309
1310 void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
1311 {
1312         long chg = region_truncate(&inode->i_mapping->private_list, offset);
1313
1314         spin_lock(&inode->i_lock);
1315         inode->i_blocks -= BLOCKS_PER_HUGEPAGE * freed;
1316         spin_unlock(&inode->i_lock);
1317
1318         hugetlb_put_quota(inode->i_mapping, (chg - freed));
1319         hugetlb_acct_memory(-(chg - freed));
1320 }