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