linux/mm/mmap.c
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   1/*
   2 * mm/mmap.c
   3 *
   4 * Written by obz.
   5 *
   6 * Address space accounting code        <alan@lxorguk.ukuu.org.uk>
   7 */
   8
   9#include <linux/slab.h>
  10#include <linux/backing-dev.h>
  11#include <linux/mm.h>
  12#include <linux/shm.h>
  13#include <linux/mman.h>
  14#include <linux/pagemap.h>
  15#include <linux/swap.h>
  16#include <linux/syscalls.h>
  17#include <linux/capability.h>
  18#include <linux/init.h>
  19#include <linux/file.h>
  20#include <linux/fs.h>
  21#include <linux/personality.h>
  22#include <linux/security.h>
  23#include <linux/hugetlb.h>
  24#include <linux/profile.h>
  25#include <linux/module.h>
  26#include <linux/mount.h>
  27#include <linux/mempolicy.h>
  28#include <linux/rmap.h>
  29#include <linux/mmu_notifier.h>
  30#include <linux/perf_event.h>
  31#include <linux/audit.h>
  32#include <linux/khugepaged.h>
  33
  34#include <asm/uaccess.h>
  35#include <asm/cacheflush.h>
  36#include <asm/tlb.h>
  37#include <asm/mmu_context.h>
  38
  39#include "internal.h"
  40
  41#ifndef arch_mmap_check
  42#define arch_mmap_check(addr, len, flags)       (0)
  43#endif
  44
  45#ifndef arch_rebalance_pgtables
  46#define arch_rebalance_pgtables(addr, len)              (addr)
  47#endif
  48
  49static void unmap_region(struct mm_struct *mm,
  50                struct vm_area_struct *vma, struct vm_area_struct *prev,
  51                unsigned long start, unsigned long end);
  52
  53/*
  54 * WARNING: the debugging will use recursive algorithms so never enable this
  55 * unless you know what you are doing.
  56 */
  57#undef DEBUG_MM_RB
  58
  59/* description of effects of mapping type and prot in current implementation.
  60 * this is due to the limited x86 page protection hardware.  The expected
  61 * behavior is in parens:
  62 *
  63 * map_type     prot
  64 *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
  65 * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
  66 *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
  67 *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
  68 *              
  69 * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
  70 *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
  71 *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
  72 *
  73 */
  74pgprot_t protection_map[16] = {
  75        __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
  76        __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
  77};
  78
  79pgprot_t vm_get_page_prot(unsigned long vm_flags)
  80{
  81        return __pgprot(pgprot_val(protection_map[vm_flags &
  82                                (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
  83                        pgprot_val(arch_vm_get_page_prot(vm_flags)));
  84}
  85EXPORT_SYMBOL(vm_get_page_prot);
  86
  87int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;  /* heuristic overcommit */
  88int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
  89int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
  90/*
  91 * Make sure vm_committed_as in one cacheline and not cacheline shared with
  92 * other variables. It can be updated by several CPUs frequently.
  93 */
  94struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
  95
  96/*
  97 * Check that a process has enough memory to allocate a new virtual
  98 * mapping. 0 means there is enough memory for the allocation to
  99 * succeed and -ENOMEM implies there is not.
 100 *
 101 * We currently support three overcommit policies, which are set via the
 102 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
 103 *
 104 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
 105 * Additional code 2002 Jul 20 by Robert Love.
 106 *
 107 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
 108 *
 109 * Note this is a helper function intended to be used by LSMs which
 110 * wish to use this logic.
 111 */
 112int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
 113{
 114        unsigned long free, allowed;
 115
 116        vm_acct_memory(pages);
 117
 118        /*
 119         * Sometimes we want to use more memory than we have
 120         */
 121        if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
 122                return 0;
 123
 124        if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
 125                free = global_page_state(NR_FREE_PAGES);
 126                free += global_page_state(NR_FILE_PAGES);
 127
 128                /*
 129                 * shmem pages shouldn't be counted as free in this
 130                 * case, they can't be purged, only swapped out, and
 131                 * that won't affect the overall amount of available
 132                 * memory in the system.
 133                 */
 134                free -= global_page_state(NR_SHMEM);
 135
 136                free += nr_swap_pages;
 137
 138                /*
 139                 * Any slabs which are created with the
 140                 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
 141                 * which are reclaimable, under pressure.  The dentry
 142                 * cache and most inode caches should fall into this
 143                 */
 144                free += global_page_state(NR_SLAB_RECLAIMABLE);
 145
 146                /*
 147                 * Leave reserved pages. The pages are not for anonymous pages.
 148                 */
 149                if (free <= totalreserve_pages)
 150                        goto error;
 151                else
 152                        free -= totalreserve_pages;
 153
 154                /*
 155                 * Leave the last 3% for root
 156                 */
 157                if (!cap_sys_admin)
 158                        free -= free / 32;
 159
 160                if (free > pages)
 161                        return 0;
 162
 163                goto error;
 164        }
 165
 166        allowed = (totalram_pages - hugetlb_total_pages())
 167                * sysctl_overcommit_ratio / 100;
 168        /*
 169         * Leave the last 3% for root
 170         */
 171        if (!cap_sys_admin)
 172                allowed -= allowed / 32;
 173        allowed += total_swap_pages;
 174
 175        /* Don't let a single process grow too big:
 176           leave 3% of the size of this process for other processes */
 177        if (mm)
 178                allowed -= mm->total_vm / 32;
 179
 180        if (percpu_counter_read_positive(&vm_committed_as) < allowed)
 181                return 0;
 182error:
 183        vm_unacct_memory(pages);
 184
 185        return -ENOMEM;
 186}
 187
 188/*
 189 * Requires inode->i_mapping->i_mmap_mutex
 190 */
 191static void __remove_shared_vm_struct(struct vm_area_struct *vma,
 192                struct file *file, struct address_space *mapping)
 193{
 194        if (vma->vm_flags & VM_DENYWRITE)
 195                atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
 196        if (vma->vm_flags & VM_SHARED)
 197                mapping->i_mmap_writable--;
 198
 199        flush_dcache_mmap_lock(mapping);
 200        if (unlikely(vma->vm_flags & VM_NONLINEAR))
 201                list_del_init(&vma->shared.vm_set.list);
 202        else
 203                vma_prio_tree_remove(vma, &mapping->i_mmap);
 204        flush_dcache_mmap_unlock(mapping);
 205}
 206
 207/*
 208 * Unlink a file-based vm structure from its prio_tree, to hide
 209 * vma from rmap and vmtruncate before freeing its page tables.
 210 */
 211void unlink_file_vma(struct vm_area_struct *vma)
 212{
 213        struct file *file = vma->vm_file;
 214
 215        if (file) {
 216                struct address_space *mapping = file->f_mapping;
 217                mutex_lock(&mapping->i_mmap_mutex);
 218                __remove_shared_vm_struct(vma, file, mapping);
 219                mutex_unlock(&mapping->i_mmap_mutex);
 220        }
 221}
 222
 223/*
 224 * Close a vm structure and free it, returning the next.
 225 */
 226static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 227{
 228        struct vm_area_struct *next = vma->vm_next;
 229
 230        might_sleep();
 231        if (vma->vm_ops && vma->vm_ops->close)
 232                vma->vm_ops->close(vma);
 233        if (vma->vm_file) {
 234                fput(vma->vm_file);
 235                if (vma->vm_flags & VM_EXECUTABLE)
 236                        removed_exe_file_vma(vma->vm_mm);
 237        }
 238        mpol_put(vma_policy(vma));
 239        kmem_cache_free(vm_area_cachep, vma);
 240        return next;
 241}
 242
 243SYSCALL_DEFINE1(brk, unsigned long, brk)
 244{
 245        unsigned long rlim, retval;
 246        unsigned long newbrk, oldbrk;
 247        struct mm_struct *mm = current->mm;
 248        unsigned long min_brk;
 249
 250        down_write(&mm->mmap_sem);
 251
 252#ifdef CONFIG_COMPAT_BRK
 253        /*
 254         * CONFIG_COMPAT_BRK can still be overridden by setting
 255         * randomize_va_space to 2, which will still cause mm->start_brk
 256         * to be arbitrarily shifted
 257         */
 258        if (current->brk_randomized)
 259                min_brk = mm->start_brk;
 260        else
 261                min_brk = mm->end_data;
 262#else
 263        min_brk = mm->start_brk;
 264#endif
 265        if (brk < min_brk)
 266                goto out;
 267
 268        /*
 269         * Check against rlimit here. If this check is done later after the test
 270         * of oldbrk with newbrk then it can escape the test and let the data
 271         * segment grow beyond its set limit the in case where the limit is
 272         * not page aligned -Ram Gupta
 273         */
 274        rlim = rlimit(RLIMIT_DATA);
 275        if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
 276                        (mm->end_data - mm->start_data) > rlim)
 277                goto out;
 278
 279        newbrk = PAGE_ALIGN(brk);
 280        oldbrk = PAGE_ALIGN(mm->brk);
 281        if (oldbrk == newbrk)
 282                goto set_brk;
 283
 284        /* Always allow shrinking brk. */
 285        if (brk <= mm->brk) {
 286                if (!do_munmap(mm, newbrk, oldbrk-newbrk))
 287                        goto set_brk;
 288                goto out;
 289        }
 290
 291        /* Check against existing mmap mappings. */
 292        if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
 293                goto out;
 294
 295        /* Ok, looks good - let it rip. */
 296        if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
 297                goto out;
 298set_brk:
 299        mm->brk = brk;
 300out:
 301        retval = mm->brk;
 302        up_write(&mm->mmap_sem);
 303        return retval;
 304}
 305
 306#ifdef DEBUG_MM_RB
 307static int browse_rb(struct rb_root *root)
 308{
 309        int i = 0, j;
 310        struct rb_node *nd, *pn = NULL;
 311        unsigned long prev = 0, pend = 0;
 312
 313        for (nd = rb_first(root); nd; nd = rb_next(nd)) {
 314                struct vm_area_struct *vma;
 315                vma = rb_entry(nd, struct vm_area_struct, vm_rb);
 316                if (vma->vm_start < prev)
 317                        printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
 318                if (vma->vm_start < pend)
 319                        printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
 320                if (vma->vm_start > vma->vm_end)
 321                        printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
 322                i++;
 323                pn = nd;
 324                prev = vma->vm_start;
 325                pend = vma->vm_end;
 326        }
 327        j = 0;
 328        for (nd = pn; nd; nd = rb_prev(nd)) {
 329                j++;
 330        }
 331        if (i != j)
 332                printk("backwards %d, forwards %d\n", j, i), i = 0;
 333        return i;
 334}
 335
 336void validate_mm(struct mm_struct *mm)
 337{
 338        int bug = 0;
 339        int i = 0;
 340        struct vm_area_struct *tmp = mm->mmap;
 341        while (tmp) {
 342                tmp = tmp->vm_next;
 343                i++;
 344        }
 345        if (i != mm->map_count)
 346                printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
 347        i = browse_rb(&mm->mm_rb);
 348        if (i != mm->map_count)
 349                printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
 350        BUG_ON(bug);
 351}
 352#else
 353#define validate_mm(mm) do { } while (0)
 354#endif
 355
 356static struct vm_area_struct *
 357find_vma_prepare(struct mm_struct *mm, unsigned long addr,
 358                struct vm_area_struct **pprev, struct rb_node ***rb_link,
 359                struct rb_node ** rb_parent)
 360{
 361        struct vm_area_struct * vma;
 362        struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
 363
 364        __rb_link = &mm->mm_rb.rb_node;
 365        rb_prev = __rb_parent = NULL;
 366        vma = NULL;
 367
 368        while (*__rb_link) {
 369                struct vm_area_struct *vma_tmp;
 370
 371                __rb_parent = *__rb_link;
 372                vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
 373
 374                if (vma_tmp->vm_end > addr) {
 375                        vma = vma_tmp;
 376                        if (vma_tmp->vm_start <= addr)
 377                                break;
 378                        __rb_link = &__rb_parent->rb_left;
 379                } else {
 380                        rb_prev = __rb_parent;
 381                        __rb_link = &__rb_parent->rb_right;
 382                }
 383        }
 384
 385        *pprev = NULL;
 386        if (rb_prev)
 387                *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 388        *rb_link = __rb_link;
 389        *rb_parent = __rb_parent;
 390        return vma;
 391}
 392
 393void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
 394                struct rb_node **rb_link, struct rb_node *rb_parent)
 395{
 396        rb_link_node(&vma->vm_rb, rb_parent, rb_link);
 397        rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 398}
 399
 400static void __vma_link_file(struct vm_area_struct *vma)
 401{
 402        struct file *file;
 403
 404        file = vma->vm_file;
 405        if (file) {
 406                struct address_space *mapping = file->f_mapping;
 407
 408                if (vma->vm_flags & VM_DENYWRITE)
 409                        atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
 410                if (vma->vm_flags & VM_SHARED)
 411                        mapping->i_mmap_writable++;
 412
 413                flush_dcache_mmap_lock(mapping);
 414                if (unlikely(vma->vm_flags & VM_NONLINEAR))
 415                        vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
 416                else
 417                        vma_prio_tree_insert(vma, &mapping->i_mmap);
 418                flush_dcache_mmap_unlock(mapping);
 419        }
 420}
 421
 422static void
 423__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 424        struct vm_area_struct *prev, struct rb_node **rb_link,
 425        struct rb_node *rb_parent)
 426{
 427        __vma_link_list(mm, vma, prev, rb_parent);
 428        __vma_link_rb(mm, vma, rb_link, rb_parent);
 429}
 430
 431static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 432                        struct vm_area_struct *prev, struct rb_node **rb_link,
 433                        struct rb_node *rb_parent)
 434{
 435        struct address_space *mapping = NULL;
 436
 437        if (vma->vm_file)
 438                mapping = vma->vm_file->f_mapping;
 439
 440        if (mapping)
 441                mutex_lock(&mapping->i_mmap_mutex);
 442
 443        __vma_link(mm, vma, prev, rb_link, rb_parent);
 444        __vma_link_file(vma);
 445
 446        if (mapping)
 447                mutex_unlock(&mapping->i_mmap_mutex);
 448
 449        mm->map_count++;
 450        validate_mm(mm);
 451}
 452
 453/*
 454 * Helper for vma_adjust in the split_vma insert case:
 455 * insert vm structure into list and rbtree and anon_vma,
 456 * but it has already been inserted into prio_tree earlier.
 457 */
 458static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
 459{
 460        struct vm_area_struct *__vma, *prev;
 461        struct rb_node **rb_link, *rb_parent;
 462
 463        __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
 464        BUG_ON(__vma && __vma->vm_start < vma->vm_end);
 465        __vma_link(mm, vma, prev, rb_link, rb_parent);
 466        mm->map_count++;
 467}
 468
 469static inline void
 470__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
 471                struct vm_area_struct *prev)
 472{
 473        struct vm_area_struct *next = vma->vm_next;
 474
 475        prev->vm_next = next;
 476        if (next)
 477                next->vm_prev = prev;
 478        rb_erase(&vma->vm_rb, &mm->mm_rb);
 479        if (mm->mmap_cache == vma)
 480                mm->mmap_cache = prev;
 481}
 482
 483/*
 484 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
 485 * is already present in an i_mmap tree without adjusting the tree.
 486 * The following helper function should be used when such adjustments
 487 * are necessary.  The "insert" vma (if any) is to be inserted
 488 * before we drop the necessary locks.
 489 */
 490int vma_adjust(struct vm_area_struct *vma, unsigned long start,
 491        unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
 492{
 493        struct mm_struct *mm = vma->vm_mm;
 494        struct vm_area_struct *next = vma->vm_next;
 495        struct vm_area_struct *importer = NULL;
 496        struct address_space *mapping = NULL;
 497        struct prio_tree_root *root = NULL;
 498        struct anon_vma *anon_vma = NULL;
 499        struct file *file = vma->vm_file;
 500        long adjust_next = 0;
 501        int remove_next = 0;
 502
 503        if (next && !insert) {
 504                struct vm_area_struct *exporter = NULL;
 505
 506                if (end >= next->vm_end) {
 507                        /*
 508                         * vma expands, overlapping all the next, and
 509                         * perhaps the one after too (mprotect case 6).
 510                         */
 511again:                  remove_next = 1 + (end > next->vm_end);
 512                        end = next->vm_end;
 513                        exporter = next;
 514                        importer = vma;
 515                } else if (end > next->vm_start) {
 516                        /*
 517                         * vma expands, overlapping part of the next:
 518                         * mprotect case 5 shifting the boundary up.
 519                         */
 520                        adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
 521                        exporter = next;
 522                        importer = vma;
 523                } else if (end < vma->vm_end) {
 524                        /*
 525                         * vma shrinks, and !insert tells it's not
 526                         * split_vma inserting another: so it must be
 527                         * mprotect case 4 shifting the boundary down.
 528                         */
 529                        adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
 530                        exporter = vma;
 531                        importer = next;
 532                }
 533
 534                /*
 535                 * Easily overlooked: when mprotect shifts the boundary,
 536                 * make sure the expanding vma has anon_vma set if the
 537                 * shrinking vma had, to cover any anon pages imported.
 538                 */
 539                if (exporter && exporter->anon_vma && !importer->anon_vma) {
 540                        if (anon_vma_clone(importer, exporter))
 541                                return -ENOMEM;
 542                        importer->anon_vma = exporter->anon_vma;
 543                }
 544        }
 545
 546        if (file) {
 547                mapping = file->f_mapping;
 548                if (!(vma->vm_flags & VM_NONLINEAR))
 549                        root = &mapping->i_mmap;
 550                mutex_lock(&mapping->i_mmap_mutex);
 551                if (insert) {
 552                        /*
 553                         * Put into prio_tree now, so instantiated pages
 554                         * are visible to arm/parisc __flush_dcache_page
 555                         * throughout; but we cannot insert into address
 556                         * space until vma start or end is updated.
 557                         */
 558                        __vma_link_file(insert);
 559                }
 560        }
 561
 562        vma_adjust_trans_huge(vma, start, end, adjust_next);
 563
 564        /*
 565         * When changing only vma->vm_end, we don't really need anon_vma
 566         * lock. This is a fairly rare case by itself, but the anon_vma
 567         * lock may be shared between many sibling processes.  Skipping
 568         * the lock for brk adjustments makes a difference sometimes.
 569         */
 570        if (vma->anon_vma && (importer || start != vma->vm_start)) {
 571                anon_vma = vma->anon_vma;
 572                anon_vma_lock(anon_vma);
 573        }
 574
 575        if (root) {
 576                flush_dcache_mmap_lock(mapping);
 577                vma_prio_tree_remove(vma, root);
 578                if (adjust_next)
 579                        vma_prio_tree_remove(next, root);
 580        }
 581
 582        vma->vm_start = start;
 583        vma->vm_end = end;
 584        vma->vm_pgoff = pgoff;
 585        if (adjust_next) {
 586                next->vm_start += adjust_next << PAGE_SHIFT;
 587                next->vm_pgoff += adjust_next;
 588        }
 589
 590        if (root) {
 591                if (adjust_next)
 592                        vma_prio_tree_insert(next, root);
 593                vma_prio_tree_insert(vma, root);
 594                flush_dcache_mmap_unlock(mapping);
 595        }
 596
 597        if (remove_next) {
 598                /*
 599                 * vma_merge has merged next into vma, and needs
 600                 * us to remove next before dropping the locks.
 601                 */
 602                __vma_unlink(mm, next, vma);
 603                if (file)
 604                        __remove_shared_vm_struct(next, file, mapping);
 605        } else if (insert) {
 606                /*
 607                 * split_vma has split insert from vma, and needs
 608                 * us to insert it before dropping the locks
 609                 * (it may either follow vma or precede it).
 610                 */
 611                __insert_vm_struct(mm, insert);
 612        }
 613
 614        if (anon_vma)
 615                anon_vma_unlock(anon_vma);
 616        if (mapping)
 617                mutex_unlock(&mapping->i_mmap_mutex);
 618
 619        if (remove_next) {
 620                if (file) {
 621                        fput(file);
 622                        if (next->vm_flags & VM_EXECUTABLE)
 623                                removed_exe_file_vma(mm);
 624                }
 625                if (next->anon_vma)
 626                        anon_vma_merge(vma, next);
 627                mm->map_count--;
 628                mpol_put(vma_policy(next));
 629                kmem_cache_free(vm_area_cachep, next);
 630                /*
 631                 * In mprotect's case 6 (see comments on vma_merge),
 632                 * we must remove another next too. It would clutter
 633                 * up the code too much to do both in one go.
 634                 */
 635                if (remove_next == 2) {
 636                        next = vma->vm_next;
 637                        goto again;
 638                }
 639        }
 640
 641        validate_mm(mm);
 642
 643        return 0;
 644}
 645
 646/*
 647 * If the vma has a ->close operation then the driver probably needs to release
 648 * per-vma resources, so we don't attempt to merge those.
 649 */
 650static inline int is_mergeable_vma(struct vm_area_struct *vma,
 651                        struct file *file, unsigned long vm_flags)
 652{
 653        /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
 654        if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
 655                return 0;
 656        if (vma->vm_file != file)
 657                return 0;
 658        if (vma->vm_ops && vma->vm_ops->close)
 659                return 0;
 660        return 1;
 661}
 662
 663static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
 664                                        struct anon_vma *anon_vma2,
 665                                        struct vm_area_struct *vma)
 666{
 667        /*
 668         * The list_is_singular() test is to avoid merging VMA cloned from
 669         * parents. This can improve scalability caused by anon_vma lock.
 670         */
 671        if ((!anon_vma1 || !anon_vma2) && (!vma ||
 672                list_is_singular(&vma->anon_vma_chain)))
 673                return 1;
 674        return anon_vma1 == anon_vma2;
 675}
 676
 677/*
 678 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 679 * in front of (at a lower virtual address and file offset than) the vma.
 680 *
 681 * We cannot merge two vmas if they have differently assigned (non-NULL)
 682 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 683 *
 684 * We don't check here for the merged mmap wrapping around the end of pagecache
 685 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
 686 * wrap, nor mmaps which cover the final page at index -1UL.
 687 */
 688static int
 689can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
 690        struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
 691{
 692        if (is_mergeable_vma(vma, file, vm_flags) &&
 693            is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 694                if (vma->vm_pgoff == vm_pgoff)
 695                        return 1;
 696        }
 697        return 0;
 698}
 699
 700/*
 701 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 702 * beyond (at a higher virtual address and file offset than) the vma.
 703 *
 704 * We cannot merge two vmas if they have differently assigned (non-NULL)
 705 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 706 */
 707static int
 708can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
 709        struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
 710{
 711        if (is_mergeable_vma(vma, file, vm_flags) &&
 712            is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 713                pgoff_t vm_pglen;
 714                vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 715                if (vma->vm_pgoff + vm_pglen == vm_pgoff)
 716                        return 1;
 717        }
 718        return 0;
 719}
 720
 721/*
 722 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
 723 * whether that can be merged with its predecessor or its successor.
 724 * Or both (it neatly fills a hole).
 725 *
 726 * In most cases - when called for mmap, brk or mremap - [addr,end) is
 727 * certain not to be mapped by the time vma_merge is called; but when
 728 * called for mprotect, it is certain to be already mapped (either at
 729 * an offset within prev, or at the start of next), and the flags of
 730 * this area are about to be changed to vm_flags - and the no-change
 731 * case has already been eliminated.
 732 *
 733 * The following mprotect cases have to be considered, where AAAA is
 734 * the area passed down from mprotect_fixup, never extending beyond one
 735 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
 736 *
 737 *     AAAA             AAAA                AAAA          AAAA
 738 *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
 739 *    cannot merge    might become    might become    might become
 740 *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
 741 *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
 742 *    mremap move:                                    PPPPNNNNNNNN 8
 743 *        AAAA
 744 *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
 745 *    might become    case 1 below    case 2 below    case 3 below
 746 *
 747 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
 748 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
 749 */
 750struct vm_area_struct *vma_merge(struct mm_struct *mm,
 751                        struct vm_area_struct *prev, unsigned long addr,
 752                        unsigned long end, unsigned long vm_flags,
 753                        struct anon_vma *anon_vma, struct file *file,
 754                        pgoff_t pgoff, struct mempolicy *policy)
 755{
 756        pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
 757        struct vm_area_struct *area, *next;
 758        int err;
 759
 760        /*
 761         * We later require that vma->vm_flags == vm_flags,
 762         * so this tests vma->vm_flags & VM_SPECIAL, too.
 763         */
 764        if (vm_flags & VM_SPECIAL)
 765                return NULL;
 766
 767        if (prev)
 768                next = prev->vm_next;
 769        else
 770                next = mm->mmap;
 771        area = next;
 772        if (next && next->vm_end == end)                /* cases 6, 7, 8 */
 773                next = next->vm_next;
 774
 775        /*
 776         * Can it merge with the predecessor?
 777         */
 778        if (prev && prev->vm_end == addr &&
 779                        mpol_equal(vma_policy(prev), policy) &&
 780                        can_vma_merge_after(prev, vm_flags,
 781                                                anon_vma, file, pgoff)) {
 782                /*
 783                 * OK, it can.  Can we now merge in the successor as well?
 784                 */
 785                if (next && end == next->vm_start &&
 786                                mpol_equal(policy, vma_policy(next)) &&
 787                                can_vma_merge_before(next, vm_flags,
 788                                        anon_vma, file, pgoff+pglen) &&
 789                                is_mergeable_anon_vma(prev->anon_vma,
 790                                                      next->anon_vma, NULL)) {
 791                                                        /* cases 1, 6 */
 792                        err = vma_adjust(prev, prev->vm_start,
 793                                next->vm_end, prev->vm_pgoff, NULL);
 794                } else                                  /* cases 2, 5, 7 */
 795                        err = vma_adjust(prev, prev->vm_start,
 796                                end, prev->vm_pgoff, NULL);
 797                if (err)
 798                        return NULL;
 799                khugepaged_enter_vma_merge(prev);
 800                return prev;
 801        }
 802
 803        /*
 804         * Can this new request be merged in front of next?
 805         */
 806        if (next && end == next->vm_start &&
 807                        mpol_equal(policy, vma_policy(next)) &&
 808                        can_vma_merge_before(next, vm_flags,
 809                                        anon_vma, file, pgoff+pglen)) {
 810                if (prev && addr < prev->vm_end)        /* case 4 */
 811                        err = vma_adjust(prev, prev->vm_start,
 812                                addr, prev->vm_pgoff, NULL);
 813                else                                    /* cases 3, 8 */
 814                        err = vma_adjust(area, addr, next->vm_end,
 815                                next->vm_pgoff - pglen, NULL);
 816                if (err)
 817                        return NULL;
 818                khugepaged_enter_vma_merge(area);
 819                return area;
 820        }
 821
 822        return NULL;
 823}
 824
 825/*
 826 * Rough compatbility check to quickly see if it's even worth looking
 827 * at sharing an anon_vma.
 828 *
 829 * They need to have the same vm_file, and the flags can only differ
 830 * in things that mprotect may change.
 831 *
 832 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
 833 * we can merge the two vma's. For example, we refuse to merge a vma if
 834 * there is a vm_ops->close() function, because that indicates that the
 835 * driver is doing some kind of reference counting. But that doesn't
 836 * really matter for the anon_vma sharing case.
 837 */
 838static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
 839{
 840        return a->vm_end == b->vm_start &&
 841                mpol_equal(vma_policy(a), vma_policy(b)) &&
 842                a->vm_file == b->vm_file &&
 843                !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
 844                b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
 845}
 846
 847/*
 848 * Do some basic sanity checking to see if we can re-use the anon_vma
 849 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
 850 * the same as 'old', the other will be the new one that is trying
 851 * to share the anon_vma.
 852 *
 853 * NOTE! This runs with mm_sem held for reading, so it is possible that
 854 * the anon_vma of 'old' is concurrently in the process of being set up
 855 * by another page fault trying to merge _that_. But that's ok: if it
 856 * is being set up, that automatically means that it will be a singleton
 857 * acceptable for merging, so we can do all of this optimistically. But
 858 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
 859 *
 860 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
 861 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
 862 * is to return an anon_vma that is "complex" due to having gone through
 863 * a fork).
 864 *
 865 * We also make sure that the two vma's are compatible (adjacent,
 866 * and with the same memory policies). That's all stable, even with just
 867 * a read lock on the mm_sem.
 868 */
 869static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
 870{
 871        if (anon_vma_compatible(a, b)) {
 872                struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
 873
 874                if (anon_vma && list_is_singular(&old->anon_vma_chain))
 875                        return anon_vma;
 876        }
 877        return NULL;
 878}
 879
 880/*
 881 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
 882 * neighbouring vmas for a suitable anon_vma, before it goes off
 883 * to allocate a new anon_vma.  It checks because a repetitive
 884 * sequence of mprotects and faults may otherwise lead to distinct
 885 * anon_vmas being allocated, preventing vma merge in subsequent
 886 * mprotect.
 887 */
 888struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
 889{
 890        struct anon_vma *anon_vma;
 891        struct vm_area_struct *near;
 892
 893        near = vma->vm_next;
 894        if (!near)
 895                goto try_prev;
 896
 897        anon_vma = reusable_anon_vma(near, vma, near);
 898        if (anon_vma)
 899                return anon_vma;
 900try_prev:
 901        near = vma->vm_prev;
 902        if (!near)
 903                goto none;
 904
 905        anon_vma = reusable_anon_vma(near, near, vma);
 906        if (anon_vma)
 907                return anon_vma;
 908none:
 909        /*
 910         * There's no absolute need to look only at touching neighbours:
 911         * we could search further afield for "compatible" anon_vmas.
 912         * But it would probably just be a waste of time searching,
 913         * or lead to too many vmas hanging off the same anon_vma.
 914         * We're trying to allow mprotect remerging later on,
 915         * not trying to minimize memory used for anon_vmas.
 916         */
 917        return NULL;
 918}
 919
 920#ifdef CONFIG_PROC_FS
 921void vm_stat_account(struct mm_struct *mm, unsigned long flags,
 922                                                struct file *file, long pages)
 923{
 924        const unsigned long stack_flags
 925                = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
 926
 927        if (file) {
 928                mm->shared_vm += pages;
 929                if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
 930                        mm->exec_vm += pages;
 931        } else if (flags & stack_flags)
 932                mm->stack_vm += pages;
 933        if (flags & (VM_RESERVED|VM_IO))
 934                mm->reserved_vm += pages;
 935}
 936#endif /* CONFIG_PROC_FS */
 937
 938/*
 939 * The caller must hold down_write(&current->mm->mmap_sem).
 940 */
 941
 942unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
 943                        unsigned long len, unsigned long prot,
 944                        unsigned long flags, unsigned long pgoff)
 945{
 946        struct mm_struct * mm = current->mm;
 947        struct inode *inode;
 948        vm_flags_t vm_flags;
 949        int error;
 950        unsigned long reqprot = prot;
 951
 952        /*
 953         * Does the application expect PROT_READ to imply PROT_EXEC?
 954         *
 955         * (the exception is when the underlying filesystem is noexec
 956         *  mounted, in which case we dont add PROT_EXEC.)
 957         */
 958        if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
 959                if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
 960                        prot |= PROT_EXEC;
 961
 962        if (!len)
 963                return -EINVAL;
 964
 965        if (!(flags & MAP_FIXED))
 966                addr = round_hint_to_min(addr);
 967
 968        /* Careful about overflows.. */
 969        len = PAGE_ALIGN(len);
 970        if (!len)
 971                return -ENOMEM;
 972
 973        /* offset overflow? */
 974        if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
 975               return -EOVERFLOW;
 976
 977        /* Too many mappings? */
 978        if (mm->map_count > sysctl_max_map_count)
 979                return -ENOMEM;
 980
 981        /* Obtain the address to map to. we verify (or select) it and ensure
 982         * that it represents a valid section of the address space.
 983         */
 984        addr = get_unmapped_area(file, addr, len, pgoff, flags);
 985        if (addr & ~PAGE_MASK)
 986                return addr;
 987
 988        /* Do simple checking here so the lower-level routines won't have
 989         * to. we assume access permissions have been handled by the open
 990         * of the memory object, so we don't do any here.
 991         */
 992        vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
 993                        mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 994
 995        if (flags & MAP_LOCKED)
 996                if (!can_do_mlock())
 997                        return -EPERM;
 998
 999        /* mlock MCL_FUTURE? */
1000        if (vm_flags & VM_LOCKED) {
1001                unsigned long locked, lock_limit;
1002                locked = len >> PAGE_SHIFT;
1003                locked += mm->locked_vm;
1004                lock_limit = rlimit(RLIMIT_MEMLOCK);
1005                lock_limit >>= PAGE_SHIFT;
1006                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1007                        return -EAGAIN;
1008        }
1009
1010        inode = file ? file->f_path.dentry->d_inode : NULL;
1011
1012        if (file) {
1013                switch (flags & MAP_TYPE) {
1014                case MAP_SHARED:
1015                        if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1016                                return -EACCES;
1017
1018                        /*
1019                         * Make sure we don't allow writing to an append-only
1020                         * file..
1021                         */
1022                        if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1023                                return -EACCES;
1024
1025                        /*
1026                         * Make sure there are no mandatory locks on the file.
1027                         */
1028                        if (locks_verify_locked(inode))
1029                                return -EAGAIN;
1030
1031                        vm_flags |= VM_SHARED | VM_MAYSHARE;
1032                        if (!(file->f_mode & FMODE_WRITE))
1033                                vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1034
1035                        /* fall through */
1036                case MAP_PRIVATE:
1037                        if (!(file->f_mode & FMODE_READ))
1038                                return -EACCES;
1039                        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1040                                if (vm_flags & VM_EXEC)
1041                                        return -EPERM;
1042                                vm_flags &= ~VM_MAYEXEC;
1043                        }
1044
1045                        if (!file->f_op || !file->f_op->mmap)
1046                                return -ENODEV;
1047                        break;
1048
1049                default:
1050                        return -EINVAL;
1051                }
1052        } else {
1053                switch (flags & MAP_TYPE) {
1054                case MAP_SHARED:
1055                        /*
1056                         * Ignore pgoff.
1057                         */
1058                        pgoff = 0;
1059                        vm_flags |= VM_SHARED | VM_MAYSHARE;
1060                        break;
1061                case MAP_PRIVATE:
1062                        /*
1063                         * Set pgoff according to addr for anon_vma.
1064                         */
1065                        pgoff = addr >> PAGE_SHIFT;
1066                        break;
1067                default:
1068                        return -EINVAL;
1069                }
1070        }
1071
1072        error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1073        if (error)
1074                return error;
1075
1076        return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1077}
1078EXPORT_SYMBOL(do_mmap_pgoff);
1079
1080SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1081                unsigned long, prot, unsigned long, flags,
1082                unsigned long, fd, unsigned long, pgoff)
1083{
1084        struct file *file = NULL;
1085        unsigned long retval = -EBADF;
1086
1087        if (!(flags & MAP_ANONYMOUS)) {
1088                audit_mmap_fd(fd, flags);
1089                if (unlikely(flags & MAP_HUGETLB))
1090                        return -EINVAL;
1091                file = fget(fd);
1092                if (!file)
1093                        goto out;
1094        } else if (flags & MAP_HUGETLB) {
1095                struct user_struct *user = NULL;
1096                /*
1097                 * VM_NORESERVE is used because the reservations will be
1098                 * taken when vm_ops->mmap() is called
1099                 * A dummy user value is used because we are not locking
1100                 * memory so no accounting is necessary
1101                 */
1102                len = ALIGN(len, huge_page_size(&default_hstate));
1103                file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
1104                                                &user, HUGETLB_ANONHUGE_INODE);
1105                if (IS_ERR(file))
1106                        return PTR_ERR(file);
1107        }
1108
1109        flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1110
1111        down_write(&current->mm->mmap_sem);
1112        retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1113        up_write(&current->mm->mmap_sem);
1114
1115        if (file)
1116                fput(file);
1117out:
1118        return retval;
1119}
1120
1121#ifdef __ARCH_WANT_SYS_OLD_MMAP
1122struct mmap_arg_struct {
1123        unsigned long addr;
1124        unsigned long len;
1125        unsigned long prot;
1126        unsigned long flags;
1127        unsigned long fd;
1128        unsigned long offset;
1129};
1130
1131SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1132{
1133        struct mmap_arg_struct a;
1134
1135        if (copy_from_user(&a, arg, sizeof(a)))
1136                return -EFAULT;
1137        if (a.offset & ~PAGE_MASK)
1138                return -EINVAL;
1139
1140        return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1141                              a.offset >> PAGE_SHIFT);
1142}
1143#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1144
1145/*
1146 * Some shared mappigns will want the pages marked read-only
1147 * to track write events. If so, we'll downgrade vm_page_prot
1148 * to the private version (using protection_map[] without the
1149 * VM_SHARED bit).
1150 */
1151int vma_wants_writenotify(struct vm_area_struct *vma)
1152{
1153        vm_flags_t vm_flags = vma->vm_flags;
1154
1155        /* If it was private or non-writable, the write bit is already clear */
1156        if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1157                return 0;
1158
1159        /* The backer wishes to know when pages are first written to? */
1160        if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1161                return 1;
1162
1163        /* The open routine did something to the protections already? */
1164        if (pgprot_val(vma->vm_page_prot) !=
1165            pgprot_val(vm_get_page_prot(vm_flags)))
1166                return 0;
1167
1168        /* Specialty mapping? */
1169        if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1170                return 0;
1171
1172        /* Can the mapping track the dirty pages? */
1173        return vma->vm_file && vma->vm_file->f_mapping &&
1174                mapping_cap_account_dirty(vma->vm_file->f_mapping);
1175}
1176
1177/*
1178 * We account for memory if it's a private writeable mapping,
1179 * not hugepages and VM_NORESERVE wasn't set.
1180 */
1181static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1182{
1183        /*
1184         * hugetlb has its own accounting separate from the core VM
1185         * VM_HUGETLB may not be set yet so we cannot check for that flag.
1186         */
1187        if (file && is_file_hugepages(file))
1188                return 0;
1189
1190        return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1191}
1192
1193unsigned long mmap_region(struct file *file, unsigned long addr,
1194                          unsigned long len, unsigned long flags,
1195                          vm_flags_t vm_flags, unsigned long pgoff)
1196{
1197        struct mm_struct *mm = current->mm;
1198        struct vm_area_struct *vma, *prev;
1199        int correct_wcount = 0;
1200        int error;
1201        struct rb_node **rb_link, *rb_parent;
1202        unsigned long charged = 0;
1203        struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;
1204
1205        /* Clear old maps */
1206        error = -ENOMEM;
1207munmap_back:
1208        vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1209        if (vma && vma->vm_start < addr + len) {
1210                if (do_munmap(mm, addr, len))
1211                        return -ENOMEM;
1212                goto munmap_back;
1213        }
1214
1215        /* Check against address space limit. */
1216        if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1217                return -ENOMEM;
1218
1219        /*
1220         * Set 'VM_NORESERVE' if we should not account for the
1221         * memory use of this mapping.
1222         */
1223        if ((flags & MAP_NORESERVE)) {
1224                /* We honor MAP_NORESERVE if allowed to overcommit */
1225                if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1226                        vm_flags |= VM_NORESERVE;
1227
1228                /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1229                if (file && is_file_hugepages(file))
1230                        vm_flags |= VM_NORESERVE;
1231        }
1232
1233        /*
1234         * Private writable mapping: check memory availability
1235         */
1236        if (accountable_mapping(file, vm_flags)) {
1237                charged = len >> PAGE_SHIFT;
1238                if (security_vm_enough_memory(charged))
1239                        return -ENOMEM;
1240                vm_flags |= VM_ACCOUNT;
1241        }
1242
1243        /*
1244         * Can we just expand an old mapping?
1245         */
1246        vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1247        if (vma)
1248                goto out;
1249
1250        /*
1251         * Determine the object being mapped and call the appropriate
1252         * specific mapper. the address has already been validated, but
1253         * not unmapped, but the maps are removed from the list.
1254         */
1255        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1256        if (!vma) {
1257                error = -ENOMEM;
1258                goto unacct_error;
1259        }
1260
1261        vma->vm_mm = mm;
1262        vma->vm_start = addr;
1263        vma->vm_end = addr + len;
1264        vma->vm_flags = vm_flags;
1265        vma->vm_page_prot = vm_get_page_prot(vm_flags);
1266        vma->vm_pgoff = pgoff;
1267        INIT_LIST_HEAD(&vma->anon_vma_chain);
1268
1269        if (file) {
1270                error = -EINVAL;
1271                if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1272                        goto free_vma;
1273                if (vm_flags & VM_DENYWRITE) {
1274                        error = deny_write_access(file);
1275                        if (error)
1276                                goto free_vma;
1277                        correct_wcount = 1;
1278                }
1279                vma->vm_file = file;
1280                get_file(file);
1281                error = file->f_op->mmap(file, vma);
1282                if (error)
1283                        goto unmap_and_free_vma;
1284                if (vm_flags & VM_EXECUTABLE)
1285                        added_exe_file_vma(mm);
1286
1287                /* Can addr have changed??
1288                 *
1289                 * Answer: Yes, several device drivers can do it in their
1290                 *         f_op->mmap method. -DaveM
1291                 */
1292                addr = vma->vm_start;
1293                pgoff = vma->vm_pgoff;
1294                vm_flags = vma->vm_flags;
1295        } else if (vm_flags & VM_SHARED) {
1296                error = shmem_zero_setup(vma);
1297                if (error)
1298                        goto free_vma;
1299        }
1300
1301        if (vma_wants_writenotify(vma)) {
1302                pgprot_t pprot = vma->vm_page_prot;
1303
1304                /* Can vma->vm_page_prot have changed??
1305                 *
1306                 * Answer: Yes, drivers may have changed it in their
1307                 *         f_op->mmap method.
1308                 *
1309                 * Ensures that vmas marked as uncached stay that way.
1310                 */
1311                vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1312                if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1313                        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1314        }
1315
1316        vma_link(mm, vma, prev, rb_link, rb_parent);
1317        file = vma->vm_file;
1318
1319        /* Once vma denies write, undo our temporary denial count */
1320        if (correct_wcount)
1321                atomic_inc(&inode->i_writecount);
1322out:
1323        perf_event_mmap(vma);
1324
1325        mm->total_vm += len >> PAGE_SHIFT;
1326        vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1327        if (vm_flags & VM_LOCKED) {
1328                if (!mlock_vma_pages_range(vma, addr, addr + len))
1329                        mm->locked_vm += (len >> PAGE_SHIFT);
1330        } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1331                make_pages_present(addr, addr + len);
1332        return addr;
1333
1334unmap_and_free_vma:
1335        if (correct_wcount)
1336                atomic_inc(&inode->i_writecount);
1337        vma->vm_file = NULL;
1338        fput(file);
1339
1340        /* Undo any partial mapping done by a device driver. */
1341        unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1342        charged = 0;
1343free_vma:
1344        kmem_cache_free(vm_area_cachep, vma);
1345unacct_error:
1346        if (charged)
1347                vm_unacct_memory(charged);
1348        return error;
1349}
1350
1351/* Get an address range which is currently unmapped.
1352 * For shmat() with addr=0.
1353 *
1354 * Ugly calling convention alert:
1355 * Return value with the low bits set means error value,
1356 * ie
1357 *      if (ret & ~PAGE_MASK)
1358 *              error = ret;
1359 *
1360 * This function "knows" that -ENOMEM has the bits set.
1361 */
1362#ifndef HAVE_ARCH_UNMAPPED_AREA
1363unsigned long
1364arch_get_unmapped_area(struct file *filp, unsigned long addr,
1365                unsigned long len, unsigned long pgoff, unsigned long flags)
1366{
1367        struct mm_struct *mm = current->mm;
1368        struct vm_area_struct *vma;
1369        unsigned long start_addr;
1370
1371        if (len > TASK_SIZE)
1372                return -ENOMEM;
1373
1374        if (flags & MAP_FIXED)
1375                return addr;
1376
1377        if (addr) {
1378                addr = PAGE_ALIGN(addr);
1379                vma = find_vma(mm, addr);
1380                if (TASK_SIZE - len >= addr &&
1381                    (!vma || addr + len <= vma->vm_start))
1382                        return addr;
1383        }
1384        if (len > mm->cached_hole_size) {
1385                start_addr = addr = mm->free_area_cache;
1386        } else {
1387                start_addr = addr = TASK_UNMAPPED_BASE;
1388                mm->cached_hole_size = 0;
1389        }
1390
1391full_search:
1392        for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1393                /* At this point:  (!vma || addr < vma->vm_end). */
1394                if (TASK_SIZE - len < addr) {
1395                        /*
1396                         * Start a new search - just in case we missed
1397                         * some holes.
1398                         */
1399                        if (start_addr != TASK_UNMAPPED_BASE) {
1400                                addr = TASK_UNMAPPED_BASE;
1401                                start_addr = addr;
1402                                mm->cached_hole_size = 0;
1403                                goto full_search;
1404                        }
1405                        return -ENOMEM;
1406                }
1407                if (!vma || addr + len <= vma->vm_start) {
1408                        /*
1409                         * Remember the place where we stopped the search:
1410                         */
1411                        mm->free_area_cache = addr + len;
1412                        return addr;
1413                }
1414                if (addr + mm->cached_hole_size < vma->vm_start)
1415                        mm->cached_hole_size = vma->vm_start - addr;
1416                addr = vma->vm_end;
1417        }
1418}
1419#endif  
1420
1421void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1422{
1423        /*
1424         * Is this a new hole at the lowest possible address?
1425         */
1426        if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1427                mm->free_area_cache = addr;
1428                mm->cached_hole_size = ~0UL;
1429        }
1430}
1431
1432/*
1433 * This mmap-allocator allocates new areas top-down from below the
1434 * stack's low limit (the base):
1435 */
1436#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1437unsigned long
1438arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1439                          const unsigned long len, const unsigned long pgoff,
1440                          const unsigned long flags)
1441{
1442        struct vm_area_struct *vma;
1443        struct mm_struct *mm = current->mm;
1444        unsigned long addr = addr0;
1445
1446        /* requested length too big for entire address space */
1447        if (len > TASK_SIZE)
1448                return -ENOMEM;
1449
1450        if (flags & MAP_FIXED)
1451                return addr;
1452
1453        /* requesting a specific address */
1454        if (addr) {
1455                addr = PAGE_ALIGN(addr);
1456                vma = find_vma(mm, addr);
1457                if (TASK_SIZE - len >= addr &&
1458                                (!vma || addr + len <= vma->vm_start))
1459                        return addr;
1460        }
1461
1462        /* check if free_area_cache is useful for us */
1463        if (len <= mm->cached_hole_size) {
1464                mm->cached_hole_size = 0;
1465                mm->free_area_cache = mm->mmap_base;
1466        }
1467
1468        /* either no address requested or can't fit in requested address hole */
1469        addr = mm->free_area_cache;
1470
1471        /* make sure it can fit in the remaining address space */
1472        if (addr > len) {
1473                vma = find_vma(mm, addr-len);
1474                if (!vma || addr <= vma->vm_start)
1475                        /* remember the address as a hint for next time */
1476                        return (mm->free_area_cache = addr-len);
1477        }
1478
1479        if (mm->mmap_base < len)
1480                goto bottomup;
1481
1482        addr = mm->mmap_base-len;
1483
1484        do {
1485                /*
1486                 * Lookup failure means no vma is above this address,
1487                 * else if new region fits below vma->vm_start,
1488                 * return with success:
1489                 */
1490                vma = find_vma(mm, addr);
1491                if (!vma || addr+len <= vma->vm_start)
1492                        /* remember the address as a hint for next time */
1493                        return (mm->free_area_cache = addr);
1494
1495                /* remember the largest hole we saw so far */
1496                if (addr + mm->cached_hole_size < vma->vm_start)
1497                        mm->cached_hole_size = vma->vm_start - addr;
1498
1499                /* try just below the current vma->vm_start */
1500                addr = vma->vm_start-len;
1501        } while (len < vma->vm_start);
1502
1503bottomup:
1504        /*
1505         * A failed mmap() very likely causes application failure,
1506         * so fall back to the bottom-up function here. This scenario
1507         * can happen with large stack limits and large mmap()
1508         * allocations.
1509         */
1510        mm->cached_hole_size = ~0UL;
1511        mm->free_area_cache = TASK_UNMAPPED_BASE;
1512        addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1513        /*
1514         * Restore the topdown base:
1515         */
1516        mm->free_area_cache = mm->mmap_base;
1517        mm->cached_hole_size = ~0UL;
1518
1519        return addr;
1520}
1521#endif
1522
1523void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1524{
1525        /*
1526         * Is this a new hole at the highest possible address?
1527         */
1528        if (addr > mm->free_area_cache)
1529                mm->free_area_cache = addr;
1530
1531        /* dont allow allocations above current base */
1532        if (mm->free_area_cache > mm->mmap_base)
1533                mm->free_area_cache = mm->mmap_base;
1534}
1535
1536unsigned long
1537get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1538                unsigned long pgoff, unsigned long flags)
1539{
1540        unsigned long (*get_area)(struct file *, unsigned long,
1541                                  unsigned long, unsigned long, unsigned long);
1542
1543        unsigned long error = arch_mmap_check(addr, len, flags);
1544        if (error)
1545                return error;
1546
1547        /* Careful about overflows.. */
1548        if (len > TASK_SIZE)
1549                return -ENOMEM;
1550
1551        get_area = current->mm->get_unmapped_area;
1552        if (file && file->f_op && file->f_op->get_unmapped_area)
1553                get_area = file->f_op->get_unmapped_area;
1554        addr = get_area(file, addr, len, pgoff, flags);
1555        if (IS_ERR_VALUE(addr))
1556                return addr;
1557
1558        if (addr > TASK_SIZE - len)
1559                return -ENOMEM;
1560        if (addr & ~PAGE_MASK)
1561                return -EINVAL;
1562
1563        return arch_rebalance_pgtables(addr, len);
1564}
1565
1566EXPORT_SYMBOL(get_unmapped_area);
1567
1568/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1569struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1570{
1571        struct vm_area_struct *vma = NULL;
1572
1573        if (mm) {
1574                /* Check the cache first. */
1575                /* (Cache hit rate is typically around 35%.) */
1576                vma = mm->mmap_cache;
1577                if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1578                        struct rb_node * rb_node;
1579
1580                        rb_node = mm->mm_rb.rb_node;
1581                        vma = NULL;
1582
1583                        while (rb_node) {
1584                                struct vm_area_struct * vma_tmp;
1585
1586                                vma_tmp = rb_entry(rb_node,
1587                                                struct vm_area_struct, vm_rb);
1588
1589                                if (vma_tmp->vm_end > addr) {
1590                                        vma = vma_tmp;
1591                                        if (vma_tmp->vm_start <= addr)
1592                                                break;
1593                                        rb_node = rb_node->rb_left;
1594                                } else
1595                                        rb_node = rb_node->rb_right;
1596                        }
1597                        if (vma)
1598                                mm->mmap_cache = vma;
1599                }
1600        }
1601        return vma;
1602}
1603
1604EXPORT_SYMBOL(find_vma);
1605
1606/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1607struct vm_area_struct *
1608find_vma_prev(struct mm_struct *mm, unsigned long addr,
1609                        struct vm_area_struct **pprev)
1610{
1611        struct vm_area_struct *vma = NULL, *prev = NULL;
1612        struct rb_node *rb_node;
1613        if (!mm)
1614                goto out;
1615
1616        /* Guard against addr being lower than the first VMA */
1617        vma = mm->mmap;
1618
1619        /* Go through the RB tree quickly. */
1620        rb_node = mm->mm_rb.rb_node;
1621
1622        while (rb_node) {
1623                struct vm_area_struct *vma_tmp;
1624                vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1625
1626                if (addr < vma_tmp->vm_end) {
1627                        rb_node = rb_node->rb_left;
1628                } else {
1629                        prev = vma_tmp;
1630                        if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1631                                break;
1632                        rb_node = rb_node->rb_right;
1633                }
1634        }
1635
1636out:
1637        *pprev = prev;
1638        return prev ? prev->vm_next : vma;
1639}
1640
1641/*
1642 * Verify that the stack growth is acceptable and
1643 * update accounting. This is shared with both the
1644 * grow-up and grow-down cases.
1645 */
1646static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1647{
1648        struct mm_struct *mm = vma->vm_mm;
1649        struct rlimit *rlim = current->signal->rlim;
1650        unsigned long new_start;
1651
1652        /* address space limit tests */
1653        if (!may_expand_vm(mm, grow))
1654                return -ENOMEM;
1655
1656        /* Stack limit test */
1657        if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1658                return -ENOMEM;
1659
1660        /* mlock limit tests */
1661        if (vma->vm_flags & VM_LOCKED) {
1662                unsigned long locked;
1663                unsigned long limit;
1664                locked = mm->locked_vm + grow;
1665                limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1666                limit >>= PAGE_SHIFT;
1667                if (locked > limit && !capable(CAP_IPC_LOCK))
1668                        return -ENOMEM;
1669        }
1670
1671        /* Check to ensure the stack will not grow into a hugetlb-only region */
1672        new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1673                        vma->vm_end - size;
1674        if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1675                return -EFAULT;
1676
1677        /*
1678         * Overcommit..  This must be the final test, as it will
1679         * update security statistics.
1680         */
1681        if (security_vm_enough_memory_mm(mm, grow))
1682                return -ENOMEM;
1683
1684        /* Ok, everything looks good - let it rip */
1685        mm->total_vm += grow;
1686        if (vma->vm_flags & VM_LOCKED)
1687                mm->locked_vm += grow;
1688        vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1689        return 0;
1690}
1691
1692#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1693/*
1694 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1695 * vma is the last one with address > vma->vm_end.  Have to extend vma.
1696 */
1697int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1698{
1699        int error;
1700
1701        if (!(vma->vm_flags & VM_GROWSUP))
1702                return -EFAULT;
1703
1704        /*
1705         * We must make sure the anon_vma is allocated
1706         * so that the anon_vma locking is not a noop.
1707         */
1708        if (unlikely(anon_vma_prepare(vma)))
1709                return -ENOMEM;
1710        vma_lock_anon_vma(vma);
1711
1712        /*
1713         * vma->vm_start/vm_end cannot change under us because the caller
1714         * is required to hold the mmap_sem in read mode.  We need the
1715         * anon_vma lock to serialize against concurrent expand_stacks.
1716         * Also guard against wrapping around to address 0.
1717         */
1718        if (address < PAGE_ALIGN(address+4))
1719                address = PAGE_ALIGN(address+4);
1720        else {
1721                vma_unlock_anon_vma(vma);
1722                return -ENOMEM;
1723        }
1724        error = 0;
1725
1726        /* Somebody else might have raced and expanded it already */
1727        if (address > vma->vm_end) {
1728                unsigned long size, grow;
1729
1730                size = address - vma->vm_start;
1731                grow = (address - vma->vm_end) >> PAGE_SHIFT;
1732
1733                error = -ENOMEM;
1734                if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
1735                        error = acct_stack_growth(vma, size, grow);
1736                        if (!error) {
1737                                vma->vm_end = address;
1738                                perf_event_mmap(vma);
1739                        }
1740                }
1741        }
1742        vma_unlock_anon_vma(vma);
1743        khugepaged_enter_vma_merge(vma);
1744        return error;
1745}
1746#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1747
1748/*
1749 * vma is the first one with address < vma->vm_start.  Have to extend vma.
1750 */
1751int expand_downwards(struct vm_area_struct *vma,
1752                                   unsigned long address)
1753{
1754        int error;
1755
1756        /*
1757         * We must make sure the anon_vma is allocated
1758         * so that the anon_vma locking is not a noop.
1759         */
1760        if (unlikely(anon_vma_prepare(vma)))
1761                return -ENOMEM;
1762
1763        address &= PAGE_MASK;
1764        error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1765        if (error)
1766                return error;
1767
1768        vma_lock_anon_vma(vma);
1769
1770        /*
1771         * vma->vm_start/vm_end cannot change under us because the caller
1772         * is required to hold the mmap_sem in read mode.  We need the
1773         * anon_vma lock to serialize against concurrent expand_stacks.
1774         */
1775
1776        /* Somebody else might have raced and expanded it already */
1777        if (address < vma->vm_start) {
1778                unsigned long size, grow;
1779
1780                size = vma->vm_end - address;
1781                grow = (vma->vm_start - address) >> PAGE_SHIFT;
1782
1783                error = -ENOMEM;
1784                if (grow <= vma->vm_pgoff) {
1785                        error = acct_stack_growth(vma, size, grow);
1786                        if (!error) {
1787                                vma->vm_start = address;
1788                                vma->vm_pgoff -= grow;
1789                                perf_event_mmap(vma);
1790                        }
1791                }
1792        }
1793        vma_unlock_anon_vma(vma);
1794        khugepaged_enter_vma_merge(vma);
1795        return error;
1796}
1797
1798#ifdef CONFIG_STACK_GROWSUP
1799int expand_stack(struct vm_area_struct *vma, unsigned long address)
1800{
1801        return expand_upwards(vma, address);
1802}
1803
1804struct vm_area_struct *
1805find_extend_vma(struct mm_struct *mm, unsigned long addr)
1806{
1807        struct vm_area_struct *vma, *prev;
1808
1809        addr &= PAGE_MASK;
1810        vma = find_vma_prev(mm, addr, &prev);
1811        if (vma && (vma->vm_start <= addr))
1812                return vma;
1813        if (!prev || expand_stack(prev, addr))
1814                return NULL;
1815        if (prev->vm_flags & VM_LOCKED) {
1816                mlock_vma_pages_range(prev, addr, prev->vm_end);
1817        }
1818        return prev;
1819}
1820#else
1821int expand_stack(struct vm_area_struct *vma, unsigned long address)
1822{
1823        return expand_downwards(vma, address);
1824}
1825
1826struct vm_area_struct *
1827find_extend_vma(struct mm_struct * mm, unsigned long addr)
1828{
1829        struct vm_area_struct * vma;
1830        unsigned long start;
1831
1832        addr &= PAGE_MASK;
1833        vma = find_vma(mm,addr);
1834        if (!vma)
1835                return NULL;
1836        if (vma->vm_start <= addr)
1837                return vma;
1838        if (!(vma->vm_flags & VM_GROWSDOWN))
1839                return NULL;
1840        start = vma->vm_start;
1841        if (expand_stack(vma, addr))
1842                return NULL;
1843        if (vma->vm_flags & VM_LOCKED) {
1844                mlock_vma_pages_range(vma, addr, start);
1845        }
1846        return vma;
1847}
1848#endif
1849
1850/*
1851 * Ok - we have the memory areas we should free on the vma list,
1852 * so release them, and do the vma updates.
1853 *
1854 * Called with the mm semaphore held.
1855 */
1856static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1857{
1858        /* Update high watermark before we lower total_vm */
1859        update_hiwater_vm(mm);
1860        do {
1861                long nrpages = vma_pages(vma);
1862
1863                mm->total_vm -= nrpages;
1864                vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1865                vma = remove_vma(vma);
1866        } while (vma);
1867        validate_mm(mm);
1868}
1869
1870/*
1871 * Get rid of page table information in the indicated region.
1872 *
1873 * Called with the mm semaphore held.
1874 */
1875static void unmap_region(struct mm_struct *mm,
1876                struct vm_area_struct *vma, struct vm_area_struct *prev,
1877                unsigned long start, unsigned long end)
1878{
1879        struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1880        struct mmu_gather tlb;
1881        unsigned long nr_accounted = 0;
1882
1883        lru_add_drain();
1884        tlb_gather_mmu(&tlb, mm, 0);
1885        update_hiwater_rss(mm);
1886        unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1887        vm_unacct_memory(nr_accounted);
1888        free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
1889                                 next ? next->vm_start : 0);
1890        tlb_finish_mmu(&tlb, start, end);
1891}
1892
1893/*
1894 * Create a list of vma's touched by the unmap, removing them from the mm's
1895 * vma list as we go..
1896 */
1897static void
1898detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1899        struct vm_area_struct *prev, unsigned long end)
1900{
1901        struct vm_area_struct **insertion_point;
1902        struct vm_area_struct *tail_vma = NULL;
1903        unsigned long addr;
1904
1905        insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1906        vma->vm_prev = NULL;
1907        do {
1908                rb_erase(&vma->vm_rb, &mm->mm_rb);
1909                mm->map_count--;
1910                tail_vma = vma;
1911                vma = vma->vm_next;
1912        } while (vma && vma->vm_start < end);
1913        *insertion_point = vma;
1914        if (vma)
1915                vma->vm_prev = prev;
1916        tail_vma->vm_next = NULL;
1917        if (mm->unmap_area == arch_unmap_area)
1918                addr = prev ? prev->vm_end : mm->mmap_base;
1919        else
1920                addr = vma ?  vma->vm_start : mm->mmap_base;
1921        mm->unmap_area(mm, addr);
1922        mm->mmap_cache = NULL;          /* Kill the cache. */
1923}
1924
1925/*
1926 * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
1927 * munmap path where it doesn't make sense to fail.
1928 */
1929static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1930              unsigned long addr, int new_below)
1931{
1932        struct mempolicy *pol;
1933        struct vm_area_struct *new;
1934        int err = -ENOMEM;
1935
1936        if (is_vm_hugetlb_page(vma) && (addr &
1937                                        ~(huge_page_mask(hstate_vma(vma)))))
1938                return -EINVAL;
1939
1940        new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1941        if (!new)
1942                goto out_err;
1943
1944        /* most fields are the same, copy all, and then fixup */
1945        *new = *vma;
1946
1947        INIT_LIST_HEAD(&new->anon_vma_chain);
1948
1949        if (new_below)
1950                new->vm_end = addr;
1951        else {
1952                new->vm_start = addr;
1953                new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1954        }
1955
1956        pol = mpol_dup(vma_policy(vma));
1957        if (IS_ERR(pol)) {
1958                err = PTR_ERR(pol);
1959                goto out_free_vma;
1960        }
1961        vma_set_policy(new, pol);
1962
1963        if (anon_vma_clone(new, vma))
1964                goto out_free_mpol;
1965
1966        if (new->vm_file) {
1967                get_file(new->vm_file);
1968                if (vma->vm_flags & VM_EXECUTABLE)
1969                        added_exe_file_vma(mm);
1970        }
1971
1972        if (new->vm_ops && new->vm_ops->open)
1973                new->vm_ops->open(new);
1974
1975        if (new_below)
1976                err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1977                        ((addr - new->vm_start) >> PAGE_SHIFT), new);
1978        else
1979                err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1980
1981        /* Success. */
1982        if (!err)
1983                return 0;
1984
1985        /* Clean everything up if vma_adjust failed. */
1986        if (new->vm_ops && new->vm_ops->close)
1987                new->vm_ops->close(new);
1988        if (new->vm_file) {
1989                if (vma->vm_flags & VM_EXECUTABLE)
1990                        removed_exe_file_vma(mm);
1991                fput(new->vm_file);
1992        }
1993        unlink_anon_vmas(new);
1994 out_free_mpol:
1995        mpol_put(pol);
1996 out_free_vma:
1997        kmem_cache_free(vm_area_cachep, new);
1998 out_err:
1999        return err;
2000}
2001
2002/*
2003 * Split a vma into two pieces at address 'addr', a new vma is allocated
2004 * either for the first part or the tail.
2005 */
2006int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2007              unsigned long addr, int new_below)
2008{
2009        if (mm->map_count >= sysctl_max_map_count)
2010                return -ENOMEM;
2011
2012        return __split_vma(mm, vma, addr, new_below);
2013}
2014
2015/* Munmap is split into 2 main parts -- this part which finds
2016 * what needs doing, and the areas themselves, which do the
2017 * work.  This now handles partial unmappings.
2018 * Jeremy Fitzhardinge <jeremy@goop.org>
2019 */
2020int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2021{
2022        unsigned long end;
2023        struct vm_area_struct *vma, *prev, *last;
2024
2025        if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2026                return -EINVAL;
2027
2028        if ((len = PAGE_ALIGN(len)) == 0)
2029                return -EINVAL;
2030
2031        /* Find the first overlapping VMA */
2032        vma = find_vma(mm, start);
2033        if (!vma)
2034                return 0;
2035        prev = vma->vm_prev;
2036        /* we have  start < vma->vm_end  */
2037
2038        /* if it doesn't overlap, we have nothing.. */
2039        end = start + len;
2040        if (vma->vm_start >= end)
2041                return 0;
2042
2043        /*
2044         * If we need to split any vma, do it now to save pain later.
2045         *
2046         * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2047         * unmapped vm_area_struct will remain in use: so lower split_vma
2048         * places tmp vma above, and higher split_vma places tmp vma below.
2049         */
2050        if (start > vma->vm_start) {
2051                int error;
2052
2053                /*
2054                 * Make sure that map_count on return from munmap() will
2055                 * not exceed its limit; but let map_count go just above
2056                 * its limit temporarily, to help free resources as expected.
2057                 */
2058                if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2059                        return -ENOMEM;
2060
2061                error = __split_vma(mm, vma, start, 0);
2062                if (error)
2063                        return error;
2064                prev = vma;
2065        }
2066
2067        /* Does it split the last one? */
2068        last = find_vma(mm, end);
2069        if (last && end > last->vm_start) {
2070                int error = __split_vma(mm, last, end, 1);
2071                if (error)
2072                        return error;
2073        }
2074        vma = prev? prev->vm_next: mm->mmap;
2075
2076        /*
2077         * unlock any mlock()ed ranges before detaching vmas
2078         */
2079        if (mm->locked_vm) {
2080                struct vm_area_struct *tmp = vma;
2081                while (tmp && tmp->vm_start < end) {
2082                        if (tmp->vm_flags & VM_LOCKED) {
2083                                mm->locked_vm -= vma_pages(tmp);
2084                                munlock_vma_pages_all(tmp);
2085                        }
2086                        tmp = tmp->vm_next;
2087                }
2088        }
2089
2090        /*
2091         * Remove the vma's, and unmap the actual pages
2092         */
2093        detach_vmas_to_be_unmapped(mm, vma, prev, end);
2094        unmap_region(mm, vma, prev, start, end);
2095
2096        /* Fix up all other VM information */
2097        remove_vma_list(mm, vma);
2098
2099        return 0;
2100}
2101
2102EXPORT_SYMBOL(do_munmap);
2103
2104SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2105{
2106        int ret;
2107        struct mm_struct *mm = current->mm;
2108
2109        profile_munmap(addr);
2110
2111        down_write(&mm->mmap_sem);
2112        ret = do_munmap(mm, addr, len);
2113        up_write(&mm->mmap_sem);
2114        return ret;
2115}
2116
2117static inline void verify_mm_writelocked(struct mm_struct *mm)
2118{
2119#ifdef CONFIG_DEBUG_VM
2120        if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2121                WARN_ON(1);
2122                up_read(&mm->mmap_sem);
2123        }
2124#endif
2125}
2126
2127/*
2128 *  this is really a simplified "do_mmap".  it only handles
2129 *  anonymous maps.  eventually we may be able to do some
2130 *  brk-specific accounting here.
2131 */
2132unsigned long do_brk(unsigned long addr, unsigned long len)
2133{
2134        struct mm_struct * mm = current->mm;
2135        struct vm_area_struct * vma, * prev;
2136        unsigned long flags;
2137        struct rb_node ** rb_link, * rb_parent;
2138        pgoff_t pgoff = addr >> PAGE_SHIFT;
2139        int error;
2140
2141        len = PAGE_ALIGN(len);
2142        if (!len)
2143                return addr;
2144
2145        error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2146        if (error)
2147                return error;
2148
2149        flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2150
2151        error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2152        if (error & ~PAGE_MASK)
2153                return error;
2154
2155        /*
2156         * mlock MCL_FUTURE?
2157         */
2158        if (mm->def_flags & VM_LOCKED) {
2159                unsigned long locked, lock_limit;
2160                locked = len >> PAGE_SHIFT;
2161                locked += mm->locked_vm;
2162                lock_limit = rlimit(RLIMIT_MEMLOCK);
2163                lock_limit >>= PAGE_SHIFT;
2164                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2165                        return -EAGAIN;
2166        }
2167
2168        /*
2169         * mm->mmap_sem is required to protect against another thread
2170         * changing the mappings in case we sleep.
2171         */
2172        verify_mm_writelocked(mm);
2173
2174        /*
2175         * Clear old maps.  this also does some error checking for us
2176         */
2177 munmap_back:
2178        vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2179        if (vma && vma->vm_start < addr + len) {
2180                if (do_munmap(mm, addr, len))
2181                        return -ENOMEM;
2182                goto munmap_back;
2183        }
2184
2185        /* Check against address space limits *after* clearing old maps... */
2186        if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2187                return -ENOMEM;
2188
2189        if (mm->map_count > sysctl_max_map_count)
2190                return -ENOMEM;
2191
2192        if (security_vm_enough_memory(len >> PAGE_SHIFT))
2193                return -ENOMEM;
2194
2195        /* Can we just expand an old private anonymous mapping? */
2196        vma = vma_merge(mm, prev, addr, addr + len, flags,
2197                                        NULL, NULL, pgoff, NULL);
2198        if (vma)
2199                goto out;
2200
2201        /*
2202         * create a vma struct for an anonymous mapping
2203         */
2204        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2205        if (!vma) {
2206                vm_unacct_memory(len >> PAGE_SHIFT);
2207                return -ENOMEM;
2208        }
2209
2210        INIT_LIST_HEAD(&vma->anon_vma_chain);
2211        vma->vm_mm = mm;
2212        vma->vm_start = addr;
2213        vma->vm_end = addr + len;
2214        vma->vm_pgoff = pgoff;
2215        vma->vm_flags = flags;
2216        vma->vm_page_prot = vm_get_page_prot(flags);
2217        vma_link(mm, vma, prev, rb_link, rb_parent);
2218out:
2219        perf_event_mmap(vma);
2220        mm->total_vm += len >> PAGE_SHIFT;
2221        if (flags & VM_LOCKED) {
2222                if (!mlock_vma_pages_range(vma, addr, addr + len))
2223                        mm->locked_vm += (len >> PAGE_SHIFT);
2224        }
2225        return addr;
2226}
2227
2228EXPORT_SYMBOL(do_brk);
2229
2230/* Release all mmaps. */
2231void exit_mmap(struct mm_struct *mm)
2232{
2233        struct mmu_gather tlb;
2234        struct vm_area_struct *vma;
2235        unsigned long nr_accounted = 0;
2236        unsigned long end;
2237
2238        /* mm's last user has gone, and its about to be pulled down */
2239        mmu_notifier_release(mm);
2240
2241        if (mm->locked_vm) {
2242                vma = mm->mmap;
2243                while (vma) {
2244                        if (vma->vm_flags & VM_LOCKED)
2245                                munlock_vma_pages_all(vma);
2246                        vma = vma->vm_next;
2247                }
2248        }
2249
2250        arch_exit_mmap(mm);
2251
2252        vma = mm->mmap;
2253        if (!vma)       /* Can happen if dup_mmap() received an OOM */
2254                return;
2255
2256        lru_add_drain();
2257        flush_cache_mm(mm);
2258        tlb_gather_mmu(&tlb, mm, 1);
2259        /* update_hiwater_rss(mm) here? but nobody should be looking */
2260        /* Use -1 here to ensure all VMAs in the mm are unmapped */
2261        end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2262        vm_unacct_memory(nr_accounted);
2263
2264        free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
2265        tlb_finish_mmu(&tlb, 0, end);
2266
2267        /*
2268         * Walk the list again, actually closing and freeing it,
2269         * with preemption enabled, without holding any MM locks.
2270         */
2271        while (vma)
2272                vma = remove_vma(vma);
2273
2274        BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2275}
2276
2277/* Insert vm structure into process list sorted by address
2278 * and into the inode's i_mmap tree.  If vm_file is non-NULL
2279 * then i_mmap_mutex is taken here.
2280 */
2281int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2282{
2283        struct vm_area_struct * __vma, * prev;
2284        struct rb_node ** rb_link, * rb_parent;
2285
2286        /*
2287         * The vm_pgoff of a purely anonymous vma should be irrelevant
2288         * until its first write fault, when page's anon_vma and index
2289         * are set.  But now set the vm_pgoff it will almost certainly
2290         * end up with (unless mremap moves it elsewhere before that
2291         * first wfault), so /proc/pid/maps tells a consistent story.
2292         *
2293         * By setting it to reflect the virtual start address of the
2294         * vma, merges and splits can happen in a seamless way, just
2295         * using the existing file pgoff checks and manipulations.
2296         * Similarly in do_mmap_pgoff and in do_brk.
2297         */
2298        if (!vma->vm_file) {
2299                BUG_ON(vma->anon_vma);
2300                vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2301        }
2302        __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2303        if (__vma && __vma->vm_start < vma->vm_end)
2304                return -ENOMEM;
2305        if ((vma->vm_flags & VM_ACCOUNT) &&
2306             security_vm_enough_memory_mm(mm, vma_pages(vma)))
2307                return -ENOMEM;
2308        vma_link(mm, vma, prev, rb_link, rb_parent);
2309        return 0;
2310}
2311
2312/*
2313 * Copy the vma structure to a new location in the same mm,
2314 * prior to moving page table entries, to effect an mremap move.
2315 */
2316struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2317        unsigned long addr, unsigned long len, pgoff_t pgoff)
2318{
2319        struct vm_area_struct *vma = *vmap;
2320        unsigned long vma_start = vma->vm_start;
2321        struct mm_struct *mm = vma->vm_mm;
2322        struct vm_area_struct *new_vma, *prev;
2323        struct rb_node **rb_link, *rb_parent;
2324        struct mempolicy *pol;
2325
2326        /*
2327         * If anonymous vma has not yet been faulted, update new pgoff
2328         * to match new location, to increase its chance of merging.
2329         */
2330        if (!vma->vm_file && !vma->anon_vma)
2331                pgoff = addr >> PAGE_SHIFT;
2332
2333        find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2334        new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2335                        vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2336        if (new_vma) {
2337                /*
2338                 * Source vma may have been merged into new_vma
2339                 */
2340                if (vma_start >= new_vma->vm_start &&
2341                    vma_start < new_vma->vm_end)
2342                        *vmap = new_vma;
2343        } else {
2344                new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2345                if (new_vma) {
2346                        *new_vma = *vma;
2347                        pol = mpol_dup(vma_policy(vma));
2348                        if (IS_ERR(pol))
2349                                goto out_free_vma;
2350                        INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2351                        if (anon_vma_clone(new_vma, vma))
2352                                goto out_free_mempol;
2353                        vma_set_policy(new_vma, pol);
2354                        new_vma->vm_start = addr;
2355                        new_vma->vm_end = addr + len;
2356                        new_vma->vm_pgoff = pgoff;
2357                        if (new_vma->vm_file) {
2358                                get_file(new_vma->vm_file);
2359                                if (vma->vm_flags & VM_EXECUTABLE)
2360                                        added_exe_file_vma(mm);
2361                        }
2362                        if (new_vma->vm_ops && new_vma->vm_ops->open)
2363                                new_vma->vm_ops->open(new_vma);
2364                        vma_link(mm, new_vma, prev, rb_link, rb_parent);
2365                }
2366        }
2367        return new_vma;
2368
2369 out_free_mempol:
2370        mpol_put(pol);
2371 out_free_vma:
2372        kmem_cache_free(vm_area_cachep, new_vma);
2373        return NULL;
2374}
2375
2376/*
2377 * Return true if the calling process may expand its vm space by the passed
2378 * number of pages
2379 */
2380int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2381{
2382        unsigned long cur = mm->total_vm;       /* pages */
2383        unsigned long lim;
2384
2385        lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2386
2387        if (cur + npages > lim)
2388                return 0;
2389        return 1;
2390}
2391
2392
2393static int special_mapping_fault(struct vm_area_struct *vma,
2394                                struct vm_fault *vmf)
2395{
2396        pgoff_t pgoff;
2397        struct page **pages;
2398
2399        /*
2400         * special mappings have no vm_file, and in that case, the mm
2401         * uses vm_pgoff internally. So we have to subtract it from here.
2402         * We are allowed to do this because we are the mm; do not copy
2403         * this code into drivers!
2404         */
2405        pgoff = vmf->pgoff - vma->vm_pgoff;
2406
2407        for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2408                pgoff--;
2409
2410        if (*pages) {
2411                struct page *page = *pages;
2412                get_page(page);
2413                vmf->page = page;
2414                return 0;
2415        }
2416
2417        return VM_FAULT_SIGBUS;
2418}
2419
2420/*
2421 * Having a close hook prevents vma merging regardless of flags.
2422 */
2423static void special_mapping_close(struct vm_area_struct *vma)
2424{
2425}
2426
2427static const struct vm_operations_struct special_mapping_vmops = {
2428        .close = special_mapping_close,
2429        .fault = special_mapping_fault,
2430};
2431
2432/*
2433 * Called with mm->mmap_sem held for writing.
2434 * Insert a new vma covering the given region, with the given flags.
2435 * Its pages are supplied by the given array of struct page *.
2436 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2437 * The region past the last page supplied will always produce SIGBUS.
2438 * The array pointer and the pages it points to are assumed to stay alive
2439 * for as long as this mapping might exist.
2440 */
2441int install_special_mapping(struct mm_struct *mm,
2442                            unsigned long addr, unsigned long len,
2443                            unsigned long vm_flags, struct page **pages)
2444{
2445        int ret;
2446        struct vm_area_struct *vma;
2447
2448        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2449        if (unlikely(vma == NULL))
2450                return -ENOMEM;
2451
2452        INIT_LIST_HEAD(&vma->anon_vma_chain);
2453        vma->vm_mm = mm;
2454        vma->vm_start = addr;
2455        vma->vm_end = addr + len;
2456
2457        vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2458        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2459
2460        vma->vm_ops = &special_mapping_vmops;
2461        vma->vm_private_data = pages;
2462
2463        ret = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
2464        if (ret)
2465                goto out;
2466
2467        ret = insert_vm_struct(mm, vma);
2468        if (ret)
2469                goto out;
2470
2471        mm->total_vm += len >> PAGE_SHIFT;
2472
2473        perf_event_mmap(vma);
2474
2475        return 0;
2476
2477out:
2478        kmem_cache_free(vm_area_cachep, vma);
2479        return ret;
2480}
2481
2482static DEFINE_MUTEX(mm_all_locks_mutex);
2483
2484static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2485{
2486        if (!test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2487                /*
2488                 * The LSB of head.next can't change from under us
2489                 * because we hold the mm_all_locks_mutex.
2490                 */
2491                mutex_lock_nest_lock(&anon_vma->root->mutex, &mm->mmap_sem);
2492                /*
2493                 * We can safely modify head.next after taking the
2494                 * anon_vma->root->mutex. If some other vma in this mm shares
2495                 * the same anon_vma we won't take it again.
2496                 *
2497                 * No need of atomic instructions here, head.next
2498                 * can't change from under us thanks to the
2499                 * anon_vma->root->mutex.
2500                 */
2501                if (__test_and_set_bit(0, (unsigned long *)
2502                                       &anon_vma->root->head.next))
2503                        BUG();
2504        }
2505}
2506
2507static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2508{
2509        if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2510                /*
2511                 * AS_MM_ALL_LOCKS can't change from under us because
2512                 * we hold the mm_all_locks_mutex.
2513                 *
2514                 * Operations on ->flags have to be atomic because
2515                 * even if AS_MM_ALL_LOCKS is stable thanks to the
2516                 * mm_all_locks_mutex, there may be other cpus
2517                 * changing other bitflags in parallel to us.
2518                 */
2519                if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2520                        BUG();
2521                mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
2522        }
2523}
2524
2525/*
2526 * This operation locks against the VM for all pte/vma/mm related
2527 * operations that could ever happen on a certain mm. This includes
2528 * vmtruncate, try_to_unmap, and all page faults.
2529 *
2530 * The caller must take the mmap_sem in write mode before calling
2531 * mm_take_all_locks(). The caller isn't allowed to release the
2532 * mmap_sem until mm_drop_all_locks() returns.
2533 *
2534 * mmap_sem in write mode is required in order to block all operations
2535 * that could modify pagetables and free pages without need of
2536 * altering the vma layout (for example populate_range() with
2537 * nonlinear vmas). It's also needed in write mode to avoid new
2538 * anon_vmas to be associated with existing vmas.
2539 *
2540 * A single task can't take more than one mm_take_all_locks() in a row
2541 * or it would deadlock.
2542 *
2543 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2544 * mapping->flags avoid to take the same lock twice, if more than one
2545 * vma in this mm is backed by the same anon_vma or address_space.
2546 *
2547 * We can take all the locks in random order because the VM code
2548 * taking i_mmap_mutex or anon_vma->mutex outside the mmap_sem never
2549 * takes more than one of them in a row. Secondly we're protected
2550 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2551 *
2552 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2553 * that may have to take thousand of locks.
2554 *
2555 * mm_take_all_locks() can fail if it's interrupted by signals.
2556 */
2557int mm_take_all_locks(struct mm_struct *mm)
2558{
2559        struct vm_area_struct *vma;
2560        struct anon_vma_chain *avc;
2561        int ret = -EINTR;
2562
2563        BUG_ON(down_read_trylock(&mm->mmap_sem));
2564
2565        mutex_lock(&mm_all_locks_mutex);
2566
2567        for (vma = mm->mmap; vma; vma = vma->vm_next) {
2568                if (signal_pending(current))
2569                        goto out_unlock;
2570                if (vma->vm_file && vma->vm_file->f_mapping)
2571                        vm_lock_mapping(mm, vma->vm_file->f_mapping);
2572        }
2573
2574        for (vma = mm->mmap; vma; vma = vma->vm_next) {
2575                if (signal_pending(current))
2576                        goto out_unlock;
2577                if (vma->anon_vma)
2578                        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2579                                vm_lock_anon_vma(mm, avc->anon_vma);
2580        }
2581
2582        ret = 0;
2583
2584out_unlock:
2585        if (ret)
2586                mm_drop_all_locks(mm);
2587
2588        return ret;
2589}
2590
2591static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2592{
2593        if (test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2594                /*
2595                 * The LSB of head.next can't change to 0 from under
2596                 * us because we hold the mm_all_locks_mutex.
2597                 *
2598                 * We must however clear the bitflag before unlocking
2599                 * the vma so the users using the anon_vma->head will
2600                 * never see our bitflag.
2601                 *
2602                 * No need of atomic instructions here, head.next
2603                 * can't change from under us until we release the
2604                 * anon_vma->root->mutex.
2605                 */
2606                if (!__test_and_clear_bit(0, (unsigned long *)
2607                                          &anon_vma->root->head.next))
2608                        BUG();
2609                anon_vma_unlock(anon_vma);
2610        }
2611}
2612
2613static void vm_unlock_mapping(struct address_space *mapping)
2614{
2615        if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2616                /*
2617                 * AS_MM_ALL_LOCKS can't change to 0 from under us
2618                 * because we hold the mm_all_locks_mutex.
2619                 */
2620                mutex_unlock(&mapping->i_mmap_mutex);
2621                if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2622                                        &mapping->flags))
2623                        BUG();
2624        }
2625}
2626
2627/*
2628 * The mmap_sem cannot be released by the caller until
2629 * mm_drop_all_locks() returns.
2630 */
2631void mm_drop_all_locks(struct mm_struct *mm)
2632{
2633        struct vm_area_struct *vma;
2634        struct anon_vma_chain *avc;
2635
2636        BUG_ON(down_read_trylock(&mm->mmap_sem));
2637        BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2638
2639        for (vma = mm->mmap; vma; vma = vma->vm_next) {
2640                if (vma->anon_vma)
2641                        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2642                                vm_unlock_anon_vma(avc->anon_vma);
2643                if (vma->vm_file && vma->vm_file->f_mapping)
2644                        vm_unlock_mapping(vma->vm_file->f_mapping);
2645        }
2646
2647        mutex_unlock(&mm_all_locks_mutex);
2648}
2649
2650/*
2651 * initialise the VMA slab
2652 */
2653void __init mmap_init(void)
2654{
2655        int ret;
2656
2657        ret = percpu_counter_init(&vm_committed_as, 0);
2658        VM_BUG_ON(ret);
2659}
2660
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