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 = OVERCOMMIT_GUESS;  /* heuristic overcommit */
  88int sysctl_overcommit_ratio = 50;       /* default is 50% */
  89int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
  90struct percpu_counter vm_committed_as;
  91
  92/*
  93 * Check that a process has enough memory to allocate a new virtual
  94 * mapping. 0 means there is enough memory for the allocation to
  95 * succeed and -ENOMEM implies there is not.
  96 *
  97 * We currently support three overcommit policies, which are set via the
  98 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
  99 *
 100 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
 101 * Additional code 2002 Jul 20 by Robert Love.
 102 *
 103 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
 104 *
 105 * Note this is a helper function intended to be used by LSMs which
 106 * wish to use this logic.
 107 */
 108int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
 109{
 110        unsigned long free, allowed;
 111
 112        vm_acct_memory(pages);
 113
 114        /*
 115         * Sometimes we want to use more memory than we have
 116         */
 117        if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
 118                return 0;
 119
 120        if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
 121                unsigned long n;
 122
 123                free = global_page_state(NR_FILE_PAGES);
 124                free += nr_swap_pages;
 125
 126                /*
 127                 * Any slabs which are created with the
 128                 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
 129                 * which are reclaimable, under pressure.  The dentry
 130                 * cache and most inode caches should fall into this
 131                 */
 132                free += global_page_state(NR_SLAB_RECLAIMABLE);
 133
 134                /*
 135                 * Leave the last 3% for root
 136                 */
 137                if (!cap_sys_admin)
 138                        free -= free / 32;
 139
 140                if (free > pages)
 141                        return 0;
 142
 143                /*
 144                 * nr_free_pages() is very expensive on large systems,
 145                 * only call if we're about to fail.
 146                 */
 147                n = nr_free_pages();
 148
 149                /*
 150                 * Leave reserved pages. The pages are not for anonymous pages.
 151                 */
 152                if (n <= totalreserve_pages)
 153                        goto error;
 154                else
 155                        n -= totalreserve_pages;
 156
 157                /*
 158                 * Leave the last 3% for root
 159                 */
 160                if (!cap_sys_admin)
 161                        n -= n / 32;
 162                free += n;
 163
 164                if (free > pages)
 165                        return 0;
 166
 167                goto error;
 168        }
 169
 170        allowed = (totalram_pages - hugetlb_total_pages())
 171                * sysctl_overcommit_ratio / 100;
 172        /*
 173         * Leave the last 3% for root
 174         */
 175        if (!cap_sys_admin)
 176                allowed -= allowed / 32;
 177        allowed += total_swap_pages;
 178
 179        /* Don't let a single process grow too big:
 180           leave 3% of the size of this process for other processes */
 181        if (mm)
 182                allowed -= mm->total_vm / 32;
 183
 184        if (percpu_counter_read_positive(&vm_committed_as) < allowed)
 185                return 0;
 186error:
 187        vm_unacct_memory(pages);
 188
 189        return -ENOMEM;
 190}
 191
 192/*
 193 * Requires inode->i_mapping->i_mmap_lock
 194 */
 195static void __remove_shared_vm_struct(struct vm_area_struct *vma,
 196                struct file *file, struct address_space *mapping)
 197{
 198        if (vma->vm_flags & VM_DENYWRITE)
 199                atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
 200        if (vma->vm_flags & VM_SHARED)
 201                mapping->i_mmap_writable--;
 202
 203        flush_dcache_mmap_lock(mapping);
 204        if (unlikely(vma->vm_flags & VM_NONLINEAR))
 205                list_del_init(&vma->shared.vm_set.list);
 206        else
 207                vma_prio_tree_remove(vma, &mapping->i_mmap);
 208        flush_dcache_mmap_unlock(mapping);
 209}
 210
 211/*
 212 * Unlink a file-based vm structure from its prio_tree, to hide
 213 * vma from rmap and vmtruncate before freeing its page tables.
 214 */
 215void unlink_file_vma(struct vm_area_struct *vma)
 216{
 217        struct file *file = vma->vm_file;
 218
 219        if (file) {
 220                struct address_space *mapping = file->f_mapping;
 221                spin_lock(&mapping->i_mmap_lock);
 222                __remove_shared_vm_struct(vma, file, mapping);
 223                spin_unlock(&mapping->i_mmap_lock);
 224        }
 225}
 226
 227/*
 228 * Close a vm structure and free it, returning the next.
 229 */
 230static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 231{
 232        struct vm_area_struct *next = vma->vm_next;
 233
 234        might_sleep();
 235        if (vma->vm_ops && vma->vm_ops->close)
 236                vma->vm_ops->close(vma);
 237        if (vma->vm_file) {
 238                fput(vma->vm_file);
 239                if (vma->vm_flags & VM_EXECUTABLE)
 240                        removed_exe_file_vma(vma->vm_mm);
 241        }
 242        mpol_put(vma_policy(vma));
 243        kmem_cache_free(vm_area_cachep, vma);
 244        return next;
 245}
 246
 247SYSCALL_DEFINE1(brk, unsigned long, brk)
 248{
 249        unsigned long rlim, retval;
 250        unsigned long newbrk, oldbrk;
 251        struct mm_struct *mm = current->mm;
 252        unsigned long min_brk;
 253
 254        down_write(&mm->mmap_sem);
 255
 256#ifdef CONFIG_COMPAT_BRK
 257        /*
 258         * CONFIG_COMPAT_BRK can still be overridden by setting
 259         * randomize_va_space to 2, which will still cause mm->start_brk
 260         * to be arbitrarily shifted
 261         */
 262        if (current->brk_randomized)
 263                min_brk = mm->start_brk;
 264        else
 265                min_brk = mm->end_data;
 266#else
 267        min_brk = mm->start_brk;
 268#endif
 269        if (brk < min_brk)
 270                goto out;
 271
 272        /*
 273         * Check against rlimit here. If this check is done later after the test
 274         * of oldbrk with newbrk then it can escape the test and let the data
 275         * segment grow beyond its set limit the in case where the limit is
 276         * not page aligned -Ram Gupta
 277         */
 278        rlim = rlimit(RLIMIT_DATA);
 279        if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
 280                        (mm->end_data - mm->start_data) > rlim)
 281                goto out;
 282
 283        newbrk = PAGE_ALIGN(brk);
 284        oldbrk = PAGE_ALIGN(mm->brk);
 285        if (oldbrk == newbrk)
 286                goto set_brk;
 287
 288        /* Always allow shrinking brk. */
 289        if (brk <= mm->brk) {
 290                if (!do_munmap(mm, newbrk, oldbrk-newbrk))
 291                        goto set_brk;
 292                goto out;
 293        }
 294
 295        /* Check against existing mmap mappings. */
 296        if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
 297                goto out;
 298
 299        /* Ok, looks good - let it rip. */
 300        if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
 301                goto out;
 302set_brk:
 303        mm->brk = brk;
 304out:
 305        retval = mm->brk;
 306        up_write(&mm->mmap_sem);
 307        return retval;
 308}
 309
 310#ifdef DEBUG_MM_RB
 311static int browse_rb(struct rb_root *root)
 312{
 313        int i = 0, j;
 314        struct rb_node *nd, *pn = NULL;
 315        unsigned long prev = 0, pend = 0;
 316
 317        for (nd = rb_first(root); nd; nd = rb_next(nd)) {
 318                struct vm_area_struct *vma;
 319                vma = rb_entry(nd, struct vm_area_struct, vm_rb);
 320                if (vma->vm_start < prev)
 321                        printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
 322                if (vma->vm_start < pend)
 323                        printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
 324                if (vma->vm_start > vma->vm_end)
 325                        printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
 326                i++;
 327                pn = nd;
 328                prev = vma->vm_start;
 329                pend = vma->vm_end;
 330        }
 331        j = 0;
 332        for (nd = pn; nd; nd = rb_prev(nd)) {
 333                j++;
 334        }
 335        if (i != j)
 336                printk("backwards %d, forwards %d\n", j, i), i = 0;
 337        return i;
 338}
 339
 340void validate_mm(struct mm_struct *mm)
 341{
 342        int bug = 0;
 343        int i = 0;
 344        struct vm_area_struct *tmp = mm->mmap;
 345        while (tmp) {
 346                tmp = tmp->vm_next;
 347                i++;
 348        }
 349        if (i != mm->map_count)
 350                printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
 351        i = browse_rb(&mm->mm_rb);
 352        if (i != mm->map_count)
 353                printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
 354        BUG_ON(bug);
 355}
 356#else
 357#define validate_mm(mm) do { } while (0)
 358#endif
 359
 360static struct vm_area_struct *
 361find_vma_prepare(struct mm_struct *mm, unsigned long addr,
 362                struct vm_area_struct **pprev, struct rb_node ***rb_link,
 363                struct rb_node ** rb_parent)
 364{
 365        struct vm_area_struct * vma;
 366        struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
 367
 368        __rb_link = &mm->mm_rb.rb_node;
 369        rb_prev = __rb_parent = NULL;
 370        vma = NULL;
 371
 372        while (*__rb_link) {
 373                struct vm_area_struct *vma_tmp;
 374
 375                __rb_parent = *__rb_link;
 376                vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
 377
 378                if (vma_tmp->vm_end > addr) {
 379                        vma = vma_tmp;
 380                        if (vma_tmp->vm_start <= addr)
 381                                break;
 382                        __rb_link = &__rb_parent->rb_left;
 383                } else {
 384                        rb_prev = __rb_parent;
 385                        __rb_link = &__rb_parent->rb_right;
 386                }
 387        }
 388
 389        *pprev = NULL;
 390        if (rb_prev)
 391                *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 392        *rb_link = __rb_link;
 393        *rb_parent = __rb_parent;
 394        return vma;
 395}
 396
 397static inline void
 398__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
 399                struct vm_area_struct *prev, struct rb_node *rb_parent)
 400{
 401        struct vm_area_struct *next;
 402
 403        vma->vm_prev = prev;
 404        if (prev) {
 405                next = prev->vm_next;
 406                prev->vm_next = vma;
 407        } else {
 408                mm->mmap = vma;
 409                if (rb_parent)
 410                        next = rb_entry(rb_parent,
 411                                        struct vm_area_struct, vm_rb);
 412                else
 413                        next = NULL;
 414        }
 415        vma->vm_next = next;
 416        if (next)
 417                next->vm_prev = vma;
 418}
 419
 420void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
 421                struct rb_node **rb_link, struct rb_node *rb_parent)
 422{
 423        rb_link_node(&vma->vm_rb, rb_parent, rb_link);
 424        rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 425}
 426
 427static void __vma_link_file(struct vm_area_struct *vma)
 428{
 429        struct file *file;
 430
 431        file = vma->vm_file;
 432        if (file) {
 433                struct address_space *mapping = file->f_mapping;
 434
 435                if (vma->vm_flags & VM_DENYWRITE)
 436                        atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
 437                if (vma->vm_flags & VM_SHARED)
 438                        mapping->i_mmap_writable++;
 439
 440                flush_dcache_mmap_lock(mapping);
 441                if (unlikely(vma->vm_flags & VM_NONLINEAR))
 442                        vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
 443                else
 444                        vma_prio_tree_insert(vma, &mapping->i_mmap);
 445                flush_dcache_mmap_unlock(mapping);
 446        }
 447}
 448
 449static void
 450__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 451        struct vm_area_struct *prev, struct rb_node **rb_link,
 452        struct rb_node *rb_parent)
 453{
 454        __vma_link_list(mm, vma, prev, rb_parent);
 455        __vma_link_rb(mm, vma, rb_link, rb_parent);
 456}
 457
 458static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 459                        struct vm_area_struct *prev, struct rb_node **rb_link,
 460                        struct rb_node *rb_parent)
 461{
 462        struct address_space *mapping = NULL;
 463
 464        if (vma->vm_file)
 465                mapping = vma->vm_file->f_mapping;
 466
 467        if (mapping) {
 468                spin_lock(&mapping->i_mmap_lock);
 469                vma->vm_truncate_count = mapping->truncate_count;
 470        }
 471
 472        __vma_link(mm, vma, prev, rb_link, rb_parent);
 473        __vma_link_file(vma);
 474
 475        if (mapping)
 476                spin_unlock(&mapping->i_mmap_lock);
 477
 478        mm->map_count++;
 479        validate_mm(mm);
 480}
 481
 482/*
 483 * Helper for vma_adjust in the split_vma insert case:
 484 * insert vm structure into list and rbtree and anon_vma,
 485 * but it has already been inserted into prio_tree earlier.
 486 */
 487static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
 488{
 489        struct vm_area_struct *__vma, *prev;
 490        struct rb_node **rb_link, *rb_parent;
 491
 492        __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
 493        BUG_ON(__vma && __vma->vm_start < vma->vm_end);
 494        __vma_link(mm, vma, prev, rb_link, rb_parent);
 495        mm->map_count++;
 496}
 497
 498static inline void
 499__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
 500                struct vm_area_struct *prev)
 501{
 502        struct vm_area_struct *next = vma->vm_next;
 503
 504        prev->vm_next = next;
 505        if (next)
 506                next->vm_prev = prev;
 507        rb_erase(&vma->vm_rb, &mm->mm_rb);
 508        if (mm->mmap_cache == vma)
 509                mm->mmap_cache = prev;
 510}
 511
 512/*
 513 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
 514 * is already present in an i_mmap tree without adjusting the tree.
 515 * The following helper function should be used when such adjustments
 516 * are necessary.  The "insert" vma (if any) is to be inserted
 517 * before we drop the necessary locks.
 518 */
 519int vma_adjust(struct vm_area_struct *vma, unsigned long start,
 520        unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
 521{
 522        struct mm_struct *mm = vma->vm_mm;
 523        struct vm_area_struct *next = vma->vm_next;
 524        struct vm_area_struct *importer = NULL;
 525        struct address_space *mapping = NULL;
 526        struct prio_tree_root *root = NULL;
 527        struct anon_vma *anon_vma = NULL;
 528        struct file *file = vma->vm_file;
 529        long adjust_next = 0;
 530        int remove_next = 0;
 531
 532        if (next && !insert) {
 533                struct vm_area_struct *exporter = NULL;
 534
 535                if (end >= next->vm_end) {
 536                        /*
 537                         * vma expands, overlapping all the next, and
 538                         * perhaps the one after too (mprotect case 6).
 539                         */
 540again:                  remove_next = 1 + (end > next->vm_end);
 541                        end = next->vm_end;
 542                        exporter = next;
 543                        importer = vma;
 544                } else if (end > next->vm_start) {
 545                        /*
 546                         * vma expands, overlapping part of the next:
 547                         * mprotect case 5 shifting the boundary up.
 548                         */
 549                        adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
 550                        exporter = next;
 551                        importer = vma;
 552                } else if (end < vma->vm_end) {
 553                        /*
 554                         * vma shrinks, and !insert tells it's not
 555                         * split_vma inserting another: so it must be
 556                         * mprotect case 4 shifting the boundary down.
 557                         */
 558                        adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
 559                        exporter = vma;
 560                        importer = next;
 561                }
 562
 563                /*
 564                 * Easily overlooked: when mprotect shifts the boundary,
 565                 * make sure the expanding vma has anon_vma set if the
 566                 * shrinking vma had, to cover any anon pages imported.
 567                 */
 568                if (exporter && exporter->anon_vma && !importer->anon_vma) {
 569                        if (anon_vma_clone(importer, exporter))
 570                                return -ENOMEM;
 571                        importer->anon_vma = exporter->anon_vma;
 572                }
 573        }
 574
 575        if (file) {
 576                mapping = file->f_mapping;
 577                if (!(vma->vm_flags & VM_NONLINEAR))
 578                        root = &mapping->i_mmap;
 579                spin_lock(&mapping->i_mmap_lock);
 580                if (importer &&
 581                    vma->vm_truncate_count != next->vm_truncate_count) {
 582                        /*
 583                         * unmap_mapping_range might be in progress:
 584                         * ensure that the expanding vma is rescanned.
 585                         */
 586                        importer->vm_truncate_count = 0;
 587                }
 588                if (insert) {
 589                        insert->vm_truncate_count = vma->vm_truncate_count;
 590                        /*
 591                         * Put into prio_tree now, so instantiated pages
 592                         * are visible to arm/parisc __flush_dcache_page
 593                         * throughout; but we cannot insert into address
 594                         * space until vma start or end is updated.
 595                         */
 596                        __vma_link_file(insert);
 597                }
 598        }
 599
 600        vma_adjust_trans_huge(vma, start, end, adjust_next);
 601
 602        /*
 603         * When changing only vma->vm_end, we don't really need anon_vma
 604         * lock. This is a fairly rare case by itself, but the anon_vma
 605         * lock may be shared between many sibling processes.  Skipping
 606         * the lock for brk adjustments makes a difference sometimes.
 607         */
 608        if (vma->anon_vma && (insert || importer || start != vma->vm_start)) {
 609                anon_vma = vma->anon_vma;
 610                anon_vma_lock(anon_vma);
 611        }
 612
 613        if (root) {
 614                flush_dcache_mmap_lock(mapping);
 615                vma_prio_tree_remove(vma, root);
 616                if (adjust_next)
 617                        vma_prio_tree_remove(next, root);
 618        }
 619
 620        vma->vm_start = start;
 621        vma->vm_end = end;
 622        vma->vm_pgoff = pgoff;
 623        if (adjust_next) {
 624                next->vm_start += adjust_next << PAGE_SHIFT;
 625                next->vm_pgoff += adjust_next;
 626        }
 627
 628        if (root) {
 629                if (adjust_next)
 630                        vma_prio_tree_insert(next, root);
 631                vma_prio_tree_insert(vma, root);
 632                flush_dcache_mmap_unlock(mapping);
 633        }
 634
 635        if (remove_next) {
 636                /*
 637                 * vma_merge has merged next into vma, and needs
 638                 * us to remove next before dropping the locks.
 639                 */
 640                __vma_unlink(mm, next, vma);
 641                if (file)
 642                        __remove_shared_vm_struct(next, file, mapping);
 643        } else if (insert) {
 644                /*
 645                 * split_vma has split insert from vma, and needs
 646                 * us to insert it before dropping the locks
 647                 * (it may either follow vma or precede it).
 648                 */
 649                __insert_vm_struct(mm, insert);
 650        }
 651
 652        if (anon_vma)
 653                anon_vma_unlock(anon_vma);
 654        if (mapping)
 655                spin_unlock(&mapping->i_mmap_lock);
 656
 657        if (remove_next) {
 658                if (file) {
 659                        fput(file);
 660                        if (next->vm_flags & VM_EXECUTABLE)
 661                                removed_exe_file_vma(mm);
 662                }
 663                if (next->anon_vma)
 664                        anon_vma_merge(vma, next);
 665                mm->map_count--;
 666                mpol_put(vma_policy(next));
 667                kmem_cache_free(vm_area_cachep, next);
 668                /*
 669                 * In mprotect's case 6 (see comments on vma_merge),
 670                 * we must remove another next too. It would clutter
 671                 * up the code too much to do both in one go.
 672                 */
 673                if (remove_next == 2) {
 674                        next = vma->vm_next;
 675                        goto again;
 676                }
 677        }
 678
 679        validate_mm(mm);
 680
 681        return 0;
 682}
 683
 684/*
 685 * If the vma has a ->close operation then the driver probably needs to release
 686 * per-vma resources, so we don't attempt to merge those.
 687 */
 688static inline int is_mergeable_vma(struct vm_area_struct *vma,
 689                        struct file *file, unsigned long vm_flags)
 690{
 691        /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
 692        if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
 693                return 0;
 694        if (vma->vm_file != file)
 695                return 0;
 696        if (vma->vm_ops && vma->vm_ops->close)
 697                return 0;
 698        return 1;
 699}
 700
 701static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
 702                                        struct anon_vma *anon_vma2)
 703{
 704        return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
 705}
 706
 707/*
 708 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 709 * in front of (at a lower virtual address and file offset than) the vma.
 710 *
 711 * We cannot merge two vmas if they have differently assigned (non-NULL)
 712 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 713 *
 714 * We don't check here for the merged mmap wrapping around the end of pagecache
 715 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
 716 * wrap, nor mmaps which cover the final page at index -1UL.
 717 */
 718static int
 719can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
 720        struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
 721{
 722        if (is_mergeable_vma(vma, file, vm_flags) &&
 723            is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
 724                if (vma->vm_pgoff == vm_pgoff)
 725                        return 1;
 726        }
 727        return 0;
 728}
 729
 730/*
 731 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 732 * beyond (at a higher virtual address and file offset than) the vma.
 733 *
 734 * We cannot merge two vmas if they have differently assigned (non-NULL)
 735 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 736 */
 737static int
 738can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
 739        struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
 740{
 741        if (is_mergeable_vma(vma, file, vm_flags) &&
 742            is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
 743                pgoff_t vm_pglen;
 744                vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 745                if (vma->vm_pgoff + vm_pglen == vm_pgoff)
 746                        return 1;
 747        }
 748        return 0;
 749}
 750
 751/*
 752 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
 753 * whether that can be merged with its predecessor or its successor.
 754 * Or both (it neatly fills a hole).
 755 *
 756 * In most cases - when called for mmap, brk or mremap - [addr,end) is
 757 * certain not to be mapped by the time vma_merge is called; but when
 758 * called for mprotect, it is certain to be already mapped (either at
 759 * an offset within prev, or at the start of next), and the flags of
 760 * this area are about to be changed to vm_flags - and the no-change
 761 * case has already been eliminated.
 762 *
 763 * The following mprotect cases have to be considered, where AAAA is
 764 * the area passed down from mprotect_fixup, never extending beyond one
 765 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
 766 *
 767 *     AAAA             AAAA                AAAA          AAAA
 768 *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
 769 *    cannot merge    might become    might become    might become
 770 *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
 771 *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
 772 *    mremap move:                                    PPPPNNNNNNNN 8
 773 *        AAAA
 774 *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
 775 *    might become    case 1 below    case 2 below    case 3 below
 776 *
 777 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
 778 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
 779 */
 780struct vm_area_struct *vma_merge(struct mm_struct *mm,
 781                        struct vm_area_struct *prev, unsigned long addr,
 782                        unsigned long end, unsigned long vm_flags,
 783                        struct anon_vma *anon_vma, struct file *file,
 784                        pgoff_t pgoff, struct mempolicy *policy)
 785{
 786        pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
 787        struct vm_area_struct *area, *next;
 788        int err;
 789
 790        /*
 791         * We later require that vma->vm_flags == vm_flags,
 792         * so this tests vma->vm_flags & VM_SPECIAL, too.
 793         */
 794        if (vm_flags & VM_SPECIAL)
 795                return NULL;
 796
 797        if (prev)
 798                next = prev->vm_next;
 799        else
 800                next = mm->mmap;
 801        area = next;
 802        if (next && next->vm_end == end)                /* cases 6, 7, 8 */
 803                next = next->vm_next;
 804
 805        /*
 806         * Can it merge with the predecessor?
 807         */
 808        if (prev && prev->vm_end == addr &&
 809                        mpol_equal(vma_policy(prev), policy) &&
 810                        can_vma_merge_after(prev, vm_flags,
 811                                                anon_vma, file, pgoff)) {
 812                /*
 813                 * OK, it can.  Can we now merge in the successor as well?
 814                 */
 815                if (next && end == next->vm_start &&
 816                                mpol_equal(policy, vma_policy(next)) &&
 817                                can_vma_merge_before(next, vm_flags,
 818                                        anon_vma, file, pgoff+pglen) &&
 819                                is_mergeable_anon_vma(prev->anon_vma,
 820                                                      next->anon_vma)) {
 821                                                        /* cases 1, 6 */
 822                        err = vma_adjust(prev, prev->vm_start,
 823                                next->vm_end, prev->vm_pgoff, NULL);
 824                } else                                  /* cases 2, 5, 7 */
 825                        err = vma_adjust(prev, prev->vm_start,
 826                                end, prev->vm_pgoff, NULL);
 827                if (err)
 828                        return NULL;
 829                khugepaged_enter_vma_merge(prev);
 830                return prev;
 831        }
 832
 833        /*
 834         * Can this new request be merged in front of next?
 835         */
 836        if (next && end == next->vm_start &&
 837                        mpol_equal(policy, vma_policy(next)) &&
 838                        can_vma_merge_before(next, vm_flags,
 839                                        anon_vma, file, pgoff+pglen)) {
 840                if (prev && addr < prev->vm_end)        /* case 4 */
 841                        err = vma_adjust(prev, prev->vm_start,
 842                                addr, prev->vm_pgoff, NULL);
 843                else                                    /* cases 3, 8 */
 844                        err = vma_adjust(area, addr, next->vm_end,
 845                                next->vm_pgoff - pglen, NULL);
 846                if (err)
 847                        return NULL;
 848                khugepaged_enter_vma_merge(area);
 849                return area;
 850        }
 851
 852        return NULL;
 853}
 854
 855/*
 856 * Rough compatbility check to quickly see if it's even worth looking
 857 * at sharing an anon_vma.
 858 *
 859 * They need to have the same vm_file, and the flags can only differ
 860 * in things that mprotect may change.
 861 *
 862 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
 863 * we can merge the two vma's. For example, we refuse to merge a vma if
 864 * there is a vm_ops->close() function, because that indicates that the
 865 * driver is doing some kind of reference counting. But that doesn't
 866 * really matter for the anon_vma sharing case.
 867 */
 868static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
 869{
 870        return a->vm_end == b->vm_start &&
 871                mpol_equal(vma_policy(a), vma_policy(b)) &&
 872                a->vm_file == b->vm_file &&
 873                !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
 874                b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
 875}
 876
 877/*
 878 * Do some basic sanity checking to see if we can re-use the anon_vma
 879 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
 880 * the same as 'old', the other will be the new one that is trying
 881 * to share the anon_vma.
 882 *
 883 * NOTE! This runs with mm_sem held for reading, so it is possible that
 884 * the anon_vma of 'old' is concurrently in the process of being set up
 885 * by another page fault trying to merge _that_. But that's ok: if it
 886 * is being set up, that automatically means that it will be a singleton
 887 * acceptable for merging, so we can do all of this optimistically. But
 888 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
 889 *
 890 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
 891 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
 892 * is to return an anon_vma that is "complex" due to having gone through
 893 * a fork).
 894 *
 895 * We also make sure that the two vma's are compatible (adjacent,
 896 * and with the same memory policies). That's all stable, even with just
 897 * a read lock on the mm_sem.
 898 */
 899static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
 900{
 901        if (anon_vma_compatible(a, b)) {
 902                struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
 903
 904                if (anon_vma && list_is_singular(&old->anon_vma_chain))
 905                        return anon_vma;
 906        }
 907        return NULL;
 908}
 909
 910/*
 911 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
 912 * neighbouring vmas for a suitable anon_vma, before it goes off
 913 * to allocate a new anon_vma.  It checks because a repetitive
 914 * sequence of mprotects and faults may otherwise lead to distinct
 915 * anon_vmas being allocated, preventing vma merge in subsequent
 916 * mprotect.
 917 */
 918struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
 919{
 920        struct anon_vma *anon_vma;
 921        struct vm_area_struct *near;
 922
 923        near = vma->vm_next;
 924        if (!near)
 925                goto try_prev;
 926
 927        anon_vma = reusable_anon_vma(near, vma, near);
 928        if (anon_vma)
 929                return anon_vma;
 930try_prev:
 931        /*
 932         * It is potentially slow to have to call find_vma_prev here.
 933         * But it's only on the first write fault on the vma, not
 934         * every time, and we could devise a way to avoid it later
 935         * (e.g. stash info in next's anon_vma_node when assigning
 936         * an anon_vma, or when trying vma_merge).  Another time.
 937         */
 938        BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
 939        if (!near)
 940                goto none;
 941
 942        anon_vma = reusable_anon_vma(near, near, vma);
 943        if (anon_vma)
 944                return anon_vma;
 945none:
 946        /*
 947         * There's no absolute need to look only at touching neighbours:
 948         * we could search further afield for "compatible" anon_vmas.
 949         * But it would probably just be a waste of time searching,
 950         * or lead to too many vmas hanging off the same anon_vma.
 951         * We're trying to allow mprotect remerging later on,
 952         * not trying to minimize memory used for anon_vmas.
 953         */
 954        return NULL;
 955}
 956
 957#ifdef CONFIG_PROC_FS
 958void vm_stat_account(struct mm_struct *mm, unsigned long flags,
 959                                                struct file *file, long pages)
 960{
 961        const unsigned long stack_flags
 962                = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
 963
 964        if (file) {
 965                mm->shared_vm += pages;
 966                if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
 967                        mm->exec_vm += pages;
 968        } else if (flags & stack_flags)
 969                mm->stack_vm += pages;
 970        if (flags & (VM_RESERVED|VM_IO))
 971                mm->reserved_vm += pages;
 972}
 973#endif /* CONFIG_PROC_FS */
 974
 975/*
 976 * The caller must hold down_write(&current->mm->mmap_sem).
 977 */
 978
 979unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
 980                        unsigned long len, unsigned long prot,
 981                        unsigned long flags, unsigned long pgoff)
 982{
 983        struct mm_struct * mm = current->mm;
 984        struct inode *inode;
 985        unsigned int vm_flags;
 986        int error;
 987        unsigned long reqprot = prot;
 988
 989        /*
 990         * Does the application expect PROT_READ to imply PROT_EXEC?
 991         *
 992         * (the exception is when the underlying filesystem is noexec
 993         *  mounted, in which case we dont add PROT_EXEC.)
 994         */
 995        if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
 996                if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
 997                        prot |= PROT_EXEC;
 998
 999        if (!len)
1000                return -EINVAL;
1001
1002        if (!(flags & MAP_FIXED))
1003                addr = round_hint_to_min(addr);
1004
1005        /* Careful about overflows.. */
1006        len = PAGE_ALIGN(len);
1007        if (!len)
1008                return -ENOMEM;
1009
1010        /* offset overflow? */
1011        if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1012               return -EOVERFLOW;
1013
1014        /* Too many mappings? */
1015        if (mm->map_count > sysctl_max_map_count)
1016                return -ENOMEM;
1017
1018        /* Obtain the address to map to. we verify (or select) it and ensure
1019         * that it represents a valid section of the address space.
1020         */
1021        addr = get_unmapped_area(file, addr, len, pgoff, flags);
1022        if (addr & ~PAGE_MASK)
1023                return addr;
1024
1025        /* Do simple checking here so the lower-level routines won't have
1026         * to. we assume access permissions have been handled by the open
1027         * of the memory object, so we don't do any here.
1028         */
1029        vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1030                        mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1031
1032        if (flags & MAP_LOCKED)
1033                if (!can_do_mlock())
1034                        return -EPERM;
1035
1036        /* mlock MCL_FUTURE? */
1037        if (vm_flags & VM_LOCKED) {
1038                unsigned long locked, lock_limit;
1039                locked = len >> PAGE_SHIFT;
1040                locked += mm->locked_vm;
1041                lock_limit = rlimit(RLIMIT_MEMLOCK);
1042                lock_limit >>= PAGE_SHIFT;
1043                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1044                        return -EAGAIN;
1045        }
1046
1047        inode = file ? file->f_path.dentry->d_inode : NULL;
1048
1049        if (file) {
1050                switch (flags & MAP_TYPE) {
1051                case MAP_SHARED:
1052                        if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1053                                return -EACCES;
1054
1055                        /*
1056                         * Make sure we don't allow writing to an append-only
1057                         * file..
1058                         */
1059                        if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1060                                return -EACCES;
1061
1062                        /*
1063                         * Make sure there are no mandatory locks on the file.
1064                         */
1065                        if (locks_verify_locked(inode))
1066                                return -EAGAIN;
1067
1068                        vm_flags |= VM_SHARED | VM_MAYSHARE;
1069                        if (!(file->f_mode & FMODE_WRITE))
1070                                vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1071
1072                        /* fall through */
1073                case MAP_PRIVATE:
1074                        if (!(file->f_mode & FMODE_READ))
1075                                return -EACCES;
1076                        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1077                                if (vm_flags & VM_EXEC)
1078                                        return -EPERM;
1079                                vm_flags &= ~VM_MAYEXEC;
1080                        }
1081
1082                        if (!file->f_op || !file->f_op->mmap)
1083                                return -ENODEV;
1084                        break;
1085
1086                default:
1087                        return -EINVAL;
1088                }
1089        } else {
1090                switch (flags & MAP_TYPE) {
1091                case MAP_SHARED:
1092                        /*
1093                         * Ignore pgoff.
1094                         */
1095                        pgoff = 0;
1096                        vm_flags |= VM_SHARED | VM_MAYSHARE;
1097                        break;
1098                case MAP_PRIVATE:
1099                        /*
1100                         * Set pgoff according to addr for anon_vma.
1101                         */
1102                        pgoff = addr >> PAGE_SHIFT;
1103                        break;
1104                default:
1105                        return -EINVAL;
1106                }
1107        }
1108
1109        error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1110        if (error)
1111                return error;
1112
1113        return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1114}
1115EXPORT_SYMBOL(do_mmap_pgoff);
1116
1117SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1118                unsigned long, prot, unsigned long, flags,
1119                unsigned long, fd, unsigned long, pgoff)
1120{
1121        struct file *file = NULL;
1122        unsigned long retval = -EBADF;
1123
1124        if (!(flags & MAP_ANONYMOUS)) {
1125                audit_mmap_fd(fd, flags);
1126                if (unlikely(flags & MAP_HUGETLB))
1127                        return -EINVAL;
1128                file = fget(fd);
1129                if (!file)
1130                        goto out;
1131        } else if (flags & MAP_HUGETLB) {
1132                struct user_struct *user = NULL;
1133                /*
1134                 * VM_NORESERVE is used because the reservations will be
1135                 * taken when vm_ops->mmap() is called
1136                 * A dummy user value is used because we are not locking
1137                 * memory so no accounting is necessary
1138                 */
1139                len = ALIGN(len, huge_page_size(&default_hstate));
1140                file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE,
1141                                                &user, HUGETLB_ANONHUGE_INODE);
1142                if (IS_ERR(file))
1143                        return PTR_ERR(file);
1144        }
1145
1146        flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1147
1148        down_write(&current->mm->mmap_sem);
1149        retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1150        up_write(&current->mm->mmap_sem);
1151
1152        if (file)
1153                fput(file);
1154out:
1155        return retval;
1156}
1157
1158#ifdef __ARCH_WANT_SYS_OLD_MMAP
1159struct mmap_arg_struct {
1160        unsigned long addr;
1161        unsigned long len;
1162        unsigned long prot;
1163        unsigned long flags;
1164        unsigned long fd;
1165        unsigned long offset;
1166};
1167
1168SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1169{
1170        struct mmap_arg_struct a;
1171
1172        if (copy_from_user(&a, arg, sizeof(a)))
1173                return -EFAULT;
1174        if (a.offset & ~PAGE_MASK)
1175                return -EINVAL;
1176
1177        return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1178                              a.offset >> PAGE_SHIFT);
1179}
1180#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1181
1182/*
1183 * Some shared mappigns will want the pages marked read-only
1184 * to track write events. If so, we'll downgrade vm_page_prot
1185 * to the private version (using protection_map[] without the
1186 * VM_SHARED bit).
1187 */
1188int vma_wants_writenotify(struct vm_area_struct *vma)
1189{
1190        unsigned int vm_flags = vma->vm_flags;
1191
1192        /* If it was private or non-writable, the write bit is already clear */
1193        if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1194                return 0;
1195
1196        /* The backer wishes to know when pages are first written to? */
1197        if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1198                return 1;
1199
1200        /* The open routine did something to the protections already? */
1201        if (pgprot_val(vma->vm_page_prot) !=
1202            pgprot_val(vm_get_page_prot(vm_flags)))
1203                return 0;
1204
1205        /* Specialty mapping? */
1206        if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1207                return 0;
1208
1209        /* Can the mapping track the dirty pages? */
1210        return vma->vm_file && vma->vm_file->f_mapping &&
1211                mapping_cap_account_dirty(vma->vm_file->f_mapping);
1212}
1213
1214/*
1215 * We account for memory if it's a private writeable mapping,
1216 * not hugepages and VM_NORESERVE wasn't set.
1217 */
1218static inline int accountable_mapping(struct file *file, unsigned int vm_flags)
1219{
1220        /*
1221         * hugetlb has its own accounting separate from the core VM
1222         * VM_HUGETLB may not be set yet so we cannot check for that flag.
1223         */
1224        if (file && is_file_hugepages(file))
1225                return 0;
1226
1227        return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1228}
1229
1230unsigned long mmap_region(struct file *file, unsigned long addr,
1231                          unsigned long len, unsigned long flags,
1232                          unsigned int vm_flags, unsigned long pgoff)
1233{
1234        struct mm_struct *mm = current->mm;
1235        struct vm_area_struct *vma, *prev;
1236        int correct_wcount = 0;
1237        int error;
1238        struct rb_node **rb_link, *rb_parent;
1239        unsigned long charged = 0;
1240        struct inode *inode =  file ? file->f_path.dentry->d_inode : NULL;
1241
1242        /* Clear old maps */
1243        error = -ENOMEM;
1244munmap_back:
1245        vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1246        if (vma && vma->vm_start < addr + len) {
1247                if (do_munmap(mm, addr, len))
1248                        return -ENOMEM;
1249                goto munmap_back;
1250        }
1251
1252        /* Check against address space limit. */
1253        if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1254                return -ENOMEM;
1255
1256        /*
1257         * Set 'VM_NORESERVE' if we should not account for the
1258         * memory use of this mapping.
1259         */
1260        if ((flags & MAP_NORESERVE)) {
1261                /* We honor MAP_NORESERVE if allowed to overcommit */
1262                if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1263                        vm_flags |= VM_NORESERVE;
1264
1265                /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1266                if (file && is_file_hugepages(file))
1267                        vm_flags |= VM_NORESERVE;
1268        }
1269
1270        /*
1271         * Private writable mapping: check memory availability
1272         */
1273        if (accountable_mapping(file, vm_flags)) {
1274                charged = len >> PAGE_SHIFT;
1275                if (security_vm_enough_memory(charged))
1276                        return -ENOMEM;
1277                vm_flags |= VM_ACCOUNT;
1278        }
1279
1280        /*
1281         * Can we just expand an old mapping?
1282         */
1283        vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1284        if (vma)
1285                goto out;
1286
1287        /*
1288         * Determine the object being mapped and call the appropriate
1289         * specific mapper. the address has already been validated, but
1290         * not unmapped, but the maps are removed from the list.
1291         */
1292        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1293        if (!vma) {
1294                error = -ENOMEM;
1295                goto unacct_error;
1296        }
1297
1298        vma->vm_mm = mm;
1299        vma->vm_start = addr;
1300        vma->vm_end = addr + len;
1301        vma->vm_flags = vm_flags;
1302        vma->vm_page_prot = vm_get_page_prot(vm_flags);
1303        vma->vm_pgoff = pgoff;
1304        INIT_LIST_HEAD(&vma->anon_vma_chain);
1305
1306        if (file) {
1307                error = -EINVAL;
1308                if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1309                        goto free_vma;
1310                if (vm_flags & VM_DENYWRITE) {
1311                        error = deny_write_access(file);
1312                        if (error)
1313                                goto free_vma;
1314                        correct_wcount = 1;
1315                }
1316                vma->vm_file = file;
1317                get_file(file);
1318                error = file->f_op->mmap(file, vma);
1319                if (error)
1320                        goto unmap_and_free_vma;
1321                if (vm_flags & VM_EXECUTABLE)
1322                        added_exe_file_vma(mm);
1323
1324                /* Can addr have changed??
1325                 *
1326                 * Answer: Yes, several device drivers can do it in their
1327                 *         f_op->mmap method. -DaveM
1328                 */
1329                addr = vma->vm_start;
1330                pgoff = vma->vm_pgoff;
1331                vm_flags = vma->vm_flags;
1332        } else if (vm_flags & VM_SHARED) {
1333                error = shmem_zero_setup(vma);
1334                if (error)
1335                        goto free_vma;
1336        }
1337
1338        if (vma_wants_writenotify(vma)) {
1339                pgprot_t pprot = vma->vm_page_prot;
1340
1341                /* Can vma->vm_page_prot have changed??
1342                 *
1343                 * Answer: Yes, drivers may have changed it in their
1344                 *         f_op->mmap method.
1345                 *
1346                 * Ensures that vmas marked as uncached stay that way.
1347                 */
1348                vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1349                if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1350                        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1351        }
1352
1353        vma_link(mm, vma, prev, rb_link, rb_parent);
1354        file = vma->vm_file;
1355
1356        /* Once vma denies write, undo our temporary denial count */
1357        if (correct_wcount)
1358                atomic_inc(&inode->i_writecount);
1359out:
1360        perf_event_mmap(vma);
1361
1362        mm->total_vm += len >> PAGE_SHIFT;
1363        vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1364        if (vm_flags & VM_LOCKED) {
1365                if (!mlock_vma_pages_range(vma, addr, addr + len))
1366                        mm->locked_vm += (len >> PAGE_SHIFT);
1367        } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1368                make_pages_present(addr, addr + len);
1369        return addr;
1370
1371unmap_and_free_vma:
1372        if (correct_wcount)
1373                atomic_inc(&inode->i_writecount);
1374        vma->vm_file = NULL;
1375        fput(file);
1376
1377        /* Undo any partial mapping done by a device driver. */
1378        unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1379        charged = 0;
1380free_vma:
1381        kmem_cache_free(vm_area_cachep, vma);
1382unacct_error:
1383        if (charged)
1384                vm_unacct_memory(charged);
1385        return error;
1386}
1387
1388/* Get an address range which is currently unmapped.
1389 * For shmat() with addr=0.
1390 *
1391 * Ugly calling convention alert:
1392 * Return value with the low bits set means error value,
1393 * ie
1394 *      if (ret & ~PAGE_MASK)
1395 *              error = ret;
1396 *
1397 * This function "knows" that -ENOMEM has the bits set.
1398 */
1399#ifndef HAVE_ARCH_UNMAPPED_AREA
1400unsigned long
1401arch_get_unmapped_area(struct file *filp, unsigned long addr,
1402                unsigned long len, unsigned long pgoff, unsigned long flags)
1403{
1404        struct mm_struct *mm = current->mm;
1405        struct vm_area_struct *vma;
1406        unsigned long start_addr;
1407
1408        if (len > TASK_SIZE)
1409                return -ENOMEM;
1410
1411        if (flags & MAP_FIXED)
1412                return addr;
1413
1414        if (addr) {
1415                addr = PAGE_ALIGN(addr);
1416                vma = find_vma(mm, addr);
1417                if (TASK_SIZE - len >= addr &&
1418                    (!vma || addr + len <= vma->vm_start))
1419                        return addr;
1420        }
1421        if (len > mm->cached_hole_size) {
1422                start_addr = addr = mm->free_area_cache;
1423        } else {
1424                start_addr = addr = TASK_UNMAPPED_BASE;
1425                mm->cached_hole_size = 0;
1426        }
1427
1428full_search:
1429        for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1430                /* At this point:  (!vma || addr < vma->vm_end). */
1431                if (TASK_SIZE - len < addr) {
1432                        /*
1433                         * Start a new search - just in case we missed
1434                         * some holes.
1435                         */
1436                        if (start_addr != TASK_UNMAPPED_BASE) {
1437                                addr = TASK_UNMAPPED_BASE;
1438                                start_addr = addr;
1439                                mm->cached_hole_size = 0;
1440                                goto full_search;
1441                        }
1442                        return -ENOMEM;
1443                }
1444                if (!vma || addr + len <= vma->vm_start) {
1445                        /*
1446                         * Remember the place where we stopped the search:
1447                         */
1448                        mm->free_area_cache = addr + len;
1449                        return addr;
1450                }
1451                if (addr + mm->cached_hole_size < vma->vm_start)
1452                        mm->cached_hole_size = vma->vm_start - addr;
1453                addr = vma->vm_end;
1454        }
1455}
1456#endif  
1457
1458void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1459{
1460        /*
1461         * Is this a new hole at the lowest possible address?
1462         */
1463        if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1464                mm->free_area_cache = addr;
1465                mm->cached_hole_size = ~0UL;
1466        }
1467}
1468
1469/*
1470 * This mmap-allocator allocates new areas top-down from below the
1471 * stack's low limit (the base):
1472 */
1473#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1474unsigned long
1475arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1476                          const unsigned long len, const unsigned long pgoff,
1477                          const unsigned long flags)
1478{
1479        struct vm_area_struct *vma;
1480        struct mm_struct *mm = current->mm;
1481        unsigned long addr = addr0;
1482
1483        /* requested length too big for entire address space */
1484        if (len > TASK_SIZE)
1485                return -ENOMEM;
1486
1487        if (flags & MAP_FIXED)
1488                return addr;
1489
1490        /* requesting a specific address */
1491        if (addr) {
1492                addr = PAGE_ALIGN(addr);
1493                vma = find_vma(mm, addr);
1494                if (TASK_SIZE - len >= addr &&
1495                                (!vma || addr + len <= vma->vm_start))
1496                        return addr;
1497        }
1498
1499        /* check if free_area_cache is useful for us */
1500        if (len <= mm->cached_hole_size) {
1501                mm->cached_hole_size = 0;
1502                mm->free_area_cache = mm->mmap_base;
1503        }
1504
1505        /* either no address requested or can't fit in requested address hole */
1506        addr = mm->free_area_cache;
1507
1508        /* make sure it can fit in the remaining address space */
1509        if (addr > len) {
1510                vma = find_vma(mm, addr-len);
1511                if (!vma || addr <= vma->vm_start)
1512                        /* remember the address as a hint for next time */
1513                        return (mm->free_area_cache = addr-len);
1514        }
1515
1516        if (mm->mmap_base < len)
1517                goto bottomup;
1518
1519        addr = mm->mmap_base-len;
1520
1521        do {
1522                /*
1523                 * Lookup failure means no vma is above this address,
1524                 * else if new region fits below vma->vm_start,
1525                 * return with success:
1526                 */
1527                vma = find_vma(mm, addr);
1528                if (!vma || addr+len <= vma->vm_start)
1529                        /* remember the address as a hint for next time */
1530                        return (mm->free_area_cache = addr);
1531
1532                /* remember the largest hole we saw so far */
1533                if (addr + mm->cached_hole_size < vma->vm_start)
1534                        mm->cached_hole_size = vma->vm_start - addr;
1535
1536                /* try just below the current vma->vm_start */
1537                addr = vma->vm_start-len;
1538        } while (len < vma->vm_start);
1539
1540bottomup:
1541        /*
1542         * A failed mmap() very likely causes application failure,
1543         * so fall back to the bottom-up function here. This scenario
1544         * can happen with large stack limits and large mmap()
1545         * allocations.
1546         */
1547        mm->cached_hole_size = ~0UL;
1548        mm->free_area_cache = TASK_UNMAPPED_BASE;
1549        addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1550        /*
1551         * Restore the topdown base:
1552         */
1553        mm->free_area_cache = mm->mmap_base;
1554        mm->cached_hole_size = ~0UL;
1555
1556        return addr;
1557}
1558#endif
1559
1560void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1561{
1562        /*
1563         * Is this a new hole at the highest possible address?
1564         */
1565        if (addr > mm->free_area_cache)
1566                mm->free_area_cache = addr;
1567
1568        /* dont allow allocations above current base */
1569        if (mm->free_area_cache > mm->mmap_base)
1570                mm->free_area_cache = mm->mmap_base;
1571}
1572
1573unsigned long
1574get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1575                unsigned long pgoff, unsigned long flags)
1576{
1577        unsigned long (*get_area)(struct file *, unsigned long,
1578                                  unsigned long, unsigned long, unsigned long);
1579
1580        unsigned long error = arch_mmap_check(addr, len, flags);
1581        if (error)
1582                return error;
1583
1584        /* Careful about overflows.. */
1585        if (len > TASK_SIZE)
1586                return -ENOMEM;
1587
1588        get_area = current->mm->get_unmapped_area;
1589        if (file && file->f_op && file->f_op->get_unmapped_area)
1590                get_area = file->f_op->get_unmapped_area;
1591        addr = get_area(file, addr, len, pgoff, flags);
1592        if (IS_ERR_VALUE(addr))
1593                return addr;
1594
1595        if (addr > TASK_SIZE - len)
1596                return -ENOMEM;
1597        if (addr & ~PAGE_MASK)
1598                return -EINVAL;
1599
1600        return arch_rebalance_pgtables(addr, len);
1601}
1602
1603EXPORT_SYMBOL(get_unmapped_area);
1604
1605/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1606struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1607{
1608        struct vm_area_struct *vma = NULL;
1609
1610        if (mm) {
1611                /* Check the cache first. */
1612                /* (Cache hit rate is typically around 35%.) */
1613                vma = mm->mmap_cache;
1614                if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1615                        struct rb_node * rb_node;
1616
1617                        rb_node = mm->mm_rb.rb_node;
1618                        vma = NULL;
1619
1620                        while (rb_node) {
1621                                struct vm_area_struct * vma_tmp;
1622
1623                                vma_tmp = rb_entry(rb_node,
1624                                                struct vm_area_struct, vm_rb);
1625
1626                                if (vma_tmp->vm_end > addr) {
1627                                        vma = vma_tmp;
1628                                        if (vma_tmp->vm_start <= addr)
1629                                                break;
1630                                        rb_node = rb_node->rb_left;
1631                                } else
1632                                        rb_node = rb_node->rb_right;
1633                        }
1634                        if (vma)
1635                                mm->mmap_cache = vma;
1636                }
1637        }
1638        return vma;
1639}
1640
1641EXPORT_SYMBOL(find_vma);
1642
1643/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1644struct vm_area_struct *
1645find_vma_prev(struct mm_struct *mm, unsigned long addr,
1646                        struct vm_area_struct **pprev)
1647{
1648        struct vm_area_struct *vma = NULL, *prev = NULL;
1649        struct rb_node *rb_node;
1650        if (!mm)
1651                goto out;
1652
1653        /* Guard against addr being lower than the first VMA */
1654        vma = mm->mmap;
1655
1656        /* Go through the RB tree quickly. */
1657        rb_node = mm->mm_rb.rb_node;
1658
1659        while (rb_node) {
1660                struct vm_area_struct *vma_tmp;
1661                vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1662
1663                if (addr < vma_tmp->vm_end) {
1664                        rb_node = rb_node->rb_left;
1665                } else {
1666                        prev = vma_tmp;
1667                        if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1668                                break;
1669                        rb_node = rb_node->rb_right;
1670                }
1671        }
1672
1673out:
1674        *pprev = prev;
1675        return prev ? prev->vm_next : vma;
1676}
1677
1678/*
1679 * Verify that the stack growth is acceptable and
1680 * update accounting. This is shared with both the
1681 * grow-up and grow-down cases.
1682 */
1683static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1684{
1685        struct mm_struct *mm = vma->vm_mm;
1686        struct rlimit *rlim = current->signal->rlim;
1687        unsigned long new_start;
1688
1689        /* address space limit tests */
1690        if (!may_expand_vm(mm, grow))
1691                return -ENOMEM;
1692
1693        /* Stack limit test */
1694        if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1695                return -ENOMEM;
1696
1697        /* mlock limit tests */
1698        if (vma->vm_flags & VM_LOCKED) {
1699                unsigned long locked;
1700                unsigned long limit;
1701                locked = mm->locked_vm + grow;
1702                limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1703                limit >>= PAGE_SHIFT;
1704                if (locked > limit && !capable(CAP_IPC_LOCK))
1705                        return -ENOMEM;
1706        }
1707
1708        /* Check to ensure the stack will not grow into a hugetlb-only region */
1709        new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1710                        vma->vm_end - size;
1711        if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1712                return -EFAULT;
1713
1714        /*
1715         * Overcommit..  This must be the final test, as it will
1716         * update security statistics.
1717         */
1718        if (security_vm_enough_memory_mm(mm, grow))
1719                return -ENOMEM;
1720
1721        /* Ok, everything looks good - let it rip */
1722        mm->total_vm += grow;
1723        if (vma->vm_flags & VM_LOCKED)
1724                mm->locked_vm += grow;
1725        vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1726        return 0;
1727}
1728
1729#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1730/*
1731 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1732 * vma is the last one with address > vma->vm_end.  Have to extend vma.
1733 */
1734int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1735{
1736        int error;
1737
1738        if (!(vma->vm_flags & VM_GROWSUP))
1739                return -EFAULT;
1740
1741        /*
1742         * We must make sure the anon_vma is allocated
1743         * so that the anon_vma locking is not a noop.
1744         */
1745        if (unlikely(anon_vma_prepare(vma)))
1746                return -ENOMEM;
1747        vma_lock_anon_vma(vma);
1748
1749        /*
1750         * vma->vm_start/vm_end cannot change under us because the caller
1751         * is required to hold the mmap_sem in read mode.  We need the
1752         * anon_vma lock to serialize against concurrent expand_stacks.
1753         * Also guard against wrapping around to address 0.
1754         */
1755        if (address < PAGE_ALIGN(address+4))
1756                address = PAGE_ALIGN(address+4);
1757        else {
1758                vma_unlock_anon_vma(vma);
1759                return -ENOMEM;
1760        }
1761        error = 0;
1762
1763        /* Somebody else might have raced and expanded it already */
1764        if (address > vma->vm_end) {
1765                unsigned long size, grow;
1766
1767                size = address - vma->vm_start;
1768                grow = (address - vma->vm_end) >> PAGE_SHIFT;
1769
1770                error = -ENOMEM;
1771                if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
1772                        error = acct_stack_growth(vma, size, grow);
1773                        if (!error) {
1774                                vma->vm_end = address;
1775                                perf_event_mmap(vma);
1776                        }
1777                }
1778        }
1779        vma_unlock_anon_vma(vma);
1780        khugepaged_enter_vma_merge(vma);
1781        return error;
1782}
1783#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1784
1785/*
1786 * vma is the first one with address < vma->vm_start.  Have to extend vma.
1787 */
1788static int expand_downwards(struct vm_area_struct *vma,
1789                                   unsigned long address)
1790{
1791        int error;
1792
1793        /*
1794         * We must make sure the anon_vma is allocated
1795         * so that the anon_vma locking is not a noop.
1796         */
1797        if (unlikely(anon_vma_prepare(vma)))
1798                return -ENOMEM;
1799
1800        address &= PAGE_MASK;
1801        error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1802        if (error)
1803                return error;
1804
1805        vma_lock_anon_vma(vma);
1806
1807        /*
1808         * vma->vm_start/vm_end cannot change under us because the caller
1809         * is required to hold the mmap_sem in read mode.  We need the
1810         * anon_vma lock to serialize against concurrent expand_stacks.
1811         */
1812
1813        /* Somebody else might have raced and expanded it already */
1814        if (address < vma->vm_start) {
1815                unsigned long size, grow;
1816
1817                size = vma->vm_end - address;
1818                grow = (vma->vm_start - address) >> PAGE_SHIFT;
1819
1820                error = -ENOMEM;
1821                if (grow <= vma->vm_pgoff) {
1822                        error = acct_stack_growth(vma, size, grow);
1823                        if (!error) {
1824                                vma->vm_start = address;
1825                                vma->vm_pgoff -= grow;
1826                                perf_event_mmap(vma);
1827                        }
1828                }
1829        }
1830        vma_unlock_anon_vma(vma);
1831        khugepaged_enter_vma_merge(vma);
1832        return error;
1833}
1834
1835int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1836{
1837        return expand_downwards(vma, address);
1838}
1839
1840#ifdef CONFIG_STACK_GROWSUP
1841int expand_stack(struct vm_area_struct *vma, unsigned long address)
1842{
1843        return expand_upwards(vma, address);
1844}
1845
1846struct vm_area_struct *
1847find_extend_vma(struct mm_struct *mm, unsigned long addr)
1848{
1849        struct vm_area_struct *vma, *prev;
1850
1851        addr &= PAGE_MASK;
1852        vma = find_vma_prev(mm, addr, &prev);
1853        if (vma && (vma->vm_start <= addr))
1854                return vma;
1855        if (!prev || expand_stack(prev, addr))
1856                return NULL;
1857        if (prev->vm_flags & VM_LOCKED) {
1858                mlock_vma_pages_range(prev, addr, prev->vm_end);
1859        }
1860        return prev;
1861}
1862#else
1863int expand_stack(struct vm_area_struct *vma, unsigned long address)
1864{
1865        return expand_downwards(vma, address);
1866}
1867
1868struct vm_area_struct *
1869find_extend_vma(struct mm_struct * mm, unsigned long addr)
1870{
1871        struct vm_area_struct * vma;
1872        unsigned long start;
1873
1874        addr &= PAGE_MASK;
1875        vma = find_vma(mm,addr);
1876        if (!vma)
1877                return NULL;
1878        if (vma->vm_start <= addr)
1879                return vma;
1880        if (!(vma->vm_flags & VM_GROWSDOWN))
1881                return NULL;
1882        start = vma->vm_start;
1883        if (expand_stack(vma, addr))
1884                return NULL;
1885        if (vma->vm_flags & VM_LOCKED) {
1886                mlock_vma_pages_range(vma, addr, start);
1887        }
1888        return vma;
1889}
1890#endif
1891
1892/*
1893 * Ok - we have the memory areas we should free on the vma list,
1894 * so release them, and do the vma updates.
1895 *
1896 * Called with the mm semaphore held.
1897 */
1898static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1899{
1900        /* Update high watermark before we lower total_vm */
1901        update_hiwater_vm(mm);
1902        do {
1903                long nrpages = vma_pages(vma);
1904
1905                mm->total_vm -= nrpages;
1906                vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1907                vma = remove_vma(vma);
1908        } while (vma);
1909        validate_mm(mm);
1910}
1911
1912/*
1913 * Get rid of page table information in the indicated region.
1914 *
1915 * Called with the mm semaphore held.
1916 */
1917static void unmap_region(struct mm_struct *mm,
1918                struct vm_area_struct *vma, struct vm_area_struct *prev,
1919                unsigned long start, unsigned long end)
1920{
1921        struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1922        struct mmu_gather *tlb;
1923        unsigned long nr_accounted = 0;
1924
1925        lru_add_drain();
1926        tlb = tlb_gather_mmu(mm, 0);
1927        update_hiwater_rss(mm);
1928        unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1929        vm_unacct_memory(nr_accounted);
1930        free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1931                                 next? next->vm_start: 0);
1932        tlb_finish_mmu(tlb, start, end);
1933}
1934
1935/*
1936 * Create a list of vma's touched by the unmap, removing them from the mm's
1937 * vma list as we go..
1938 */
1939static void
1940detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1941        struct vm_area_struct *prev, unsigned long end)
1942{
1943        struct vm_area_struct **insertion_point;
1944        struct vm_area_struct *tail_vma = NULL;
1945        unsigned long addr;
1946
1947        insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1948        vma->vm_prev = NULL;
1949        do {
1950                rb_erase(&vma->vm_rb, &mm->mm_rb);
1951                mm->map_count--;
1952                tail_vma = vma;
1953                vma = vma->vm_next;
1954        } while (vma && vma->vm_start < end);
1955        *insertion_point = vma;
1956        if (vma)
1957                vma->vm_prev = prev;
1958        tail_vma->vm_next = NULL;
1959        if (mm->unmap_area == arch_unmap_area)
1960                addr = prev ? prev->vm_end : mm->mmap_base;
1961        else
1962                addr = vma ?  vma->vm_start : mm->mmap_base;
1963        mm->unmap_area(mm, addr);
1964        mm->mmap_cache = NULL;          /* Kill the cache. */
1965}
1966
1967/*
1968 * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
1969 * munmap path where it doesn't make sense to fail.
1970 */
1971static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1972              unsigned long addr, int new_below)
1973{
1974        struct mempolicy *pol;
1975        struct vm_area_struct *new;
1976        int err = -ENOMEM;
1977
1978        if (is_vm_hugetlb_page(vma) && (addr &
1979                                        ~(huge_page_mask(hstate_vma(vma)))))
1980                return -EINVAL;
1981
1982        new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1983        if (!new)
1984                goto out_err;
1985
1986        /* most fields are the same, copy all, and then fixup */
1987        *new = *vma;
1988
1989        INIT_LIST_HEAD(&new->anon_vma_chain);
1990
1991        if (new_below)
1992                new->vm_end = addr;
1993        else {
1994                new->vm_start = addr;
1995                new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1996        }
1997
1998        pol = mpol_dup(vma_policy(vma));
1999        if (IS_ERR(pol)) {
2000                err = PTR_ERR(pol);
2001                goto out_free_vma;
2002        }
2003        vma_set_policy(new, pol);
2004
2005        if (anon_vma_clone(new, vma))
2006                goto out_free_mpol;
2007
2008        if (new->vm_file) {
2009                get_file(new->vm_file);
2010                if (vma->vm_flags & VM_EXECUTABLE)
2011                        added_exe_file_vma(mm);
2012        }
2013
2014        if (new->vm_ops && new->vm_ops->open)
2015                new->vm_ops->open(new);
2016
2017        if (new_below)
2018                err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2019                        ((addr - new->vm_start) >> PAGE_SHIFT), new);
2020        else
2021                err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2022
2023        /* Success. */
2024        if (!err)
2025                return 0;
2026
2027        /* Clean everything up if vma_adjust failed. */
2028        if (new->vm_ops && new->vm_ops->close)
2029                new->vm_ops->close(new);
2030        if (new->vm_file) {
2031                if (vma->vm_flags & VM_EXECUTABLE)
2032                        removed_exe_file_vma(mm);
2033                fput(new->vm_file);
2034        }
2035        unlink_anon_vmas(new);
2036 out_free_mpol:
2037        mpol_put(pol);
2038 out_free_vma:
2039        kmem_cache_free(vm_area_cachep, new);
2040 out_err:
2041        return err;
2042}
2043
2044/*
2045 * Split a vma into two pieces at address 'addr', a new vma is allocated
2046 * either for the first part or the tail.
2047 */
2048int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2049              unsigned long addr, int new_below)
2050{
2051        if (mm->map_count >= sysctl_max_map_count)
2052                return -ENOMEM;
2053
2054        return __split_vma(mm, vma, addr, new_below);
2055}
2056
2057/* Munmap is split into 2 main parts -- this part which finds
2058 * what needs doing, and the areas themselves, which do the
2059 * work.  This now handles partial unmappings.
2060 * Jeremy Fitzhardinge <jeremy@goop.org>
2061 */
2062int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2063{
2064        unsigned long end;
2065        struct vm_area_struct *vma, *prev, *last;
2066
2067        if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2068                return -EINVAL;
2069
2070        if ((len = PAGE_ALIGN(len)) == 0)
2071                return -EINVAL;
2072
2073        /* Find the first overlapping VMA */
2074        vma = find_vma_prev(mm, start, &prev);
2075        if (!vma)
2076                return 0;
2077        /* we have  start < vma->vm_end  */
2078
2079        /* if it doesn't overlap, we have nothing.. */
2080        end = start + len;
2081        if (vma->vm_start >= end)
2082                return 0;
2083
2084        /*
2085         * If we need to split any vma, do it now to save pain later.
2086         *
2087         * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2088         * unmapped vm_area_struct will remain in use: so lower split_vma
2089         * places tmp vma above, and higher split_vma places tmp vma below.
2090         */
2091        if (start > vma->vm_start) {
2092                int error;
2093
2094                /*
2095                 * Make sure that map_count on return from munmap() will
2096                 * not exceed its limit; but let map_count go just above
2097                 * its limit temporarily, to help free resources as expected.
2098                 */
2099                if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2100                        return -ENOMEM;
2101
2102                error = __split_vma(mm, vma, start, 0);
2103                if (error)
2104                        return error;
2105                prev = vma;
2106        }
2107
2108        /* Does it split the last one? */
2109        last = find_vma(mm, end);
2110        if (last && end > last->vm_start) {
2111                int error = __split_vma(mm, last, end, 1);
2112                if (error)
2113                        return error;
2114        }
2115        vma = prev? prev->vm_next: mm->mmap;
2116
2117        /*
2118         * unlock any mlock()ed ranges before detaching vmas
2119         */
2120        if (mm->locked_vm) {
2121                struct vm_area_struct *tmp = vma;
2122                while (tmp && tmp->vm_start < end) {
2123                        if (tmp->vm_flags & VM_LOCKED) {
2124                                mm->locked_vm -= vma_pages(tmp);
2125                                munlock_vma_pages_all(tmp);
2126                        }
2127                        tmp = tmp->vm_next;
2128                }
2129        }
2130
2131        /*
2132         * Remove the vma's, and unmap the actual pages
2133         */
2134        detach_vmas_to_be_unmapped(mm, vma, prev, end);
2135        unmap_region(mm, vma, prev, start, end);
2136
2137        /* Fix up all other VM information */
2138        remove_vma_list(mm, vma);
2139
2140        return 0;
2141}
2142
2143EXPORT_SYMBOL(do_munmap);
2144
2145SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2146{
2147        int ret;
2148        struct mm_struct *mm = current->mm;
2149
2150        profile_munmap(addr);
2151
2152        down_write(&mm->mmap_sem);
2153        ret = do_munmap(mm, addr, len);
2154        up_write(&mm->mmap_sem);
2155        return ret;
2156}
2157
2158static inline void verify_mm_writelocked(struct mm_struct *mm)
2159{
2160#ifdef CONFIG_DEBUG_VM
2161        if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2162                WARN_ON(1);
2163                up_read(&mm->mmap_sem);
2164        }
2165#endif
2166}
2167
2168/*
2169 *  this is really a simplified "do_mmap".  it only handles
2170 *  anonymous maps.  eventually we may be able to do some
2171 *  brk-specific accounting here.
2172 */
2173unsigned long do_brk(unsigned long addr, unsigned long len)
2174{
2175        struct mm_struct * mm = current->mm;
2176        struct vm_area_struct * vma, * prev;
2177        unsigned long flags;
2178        struct rb_node ** rb_link, * rb_parent;
2179        pgoff_t pgoff = addr >> PAGE_SHIFT;
2180        int error;
2181
2182        len = PAGE_ALIGN(len);
2183        if (!len)
2184                return addr;
2185
2186        error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2187        if (error)
2188                return error;
2189
2190        flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2191
2192        error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2193        if (error & ~PAGE_MASK)
2194                return error;
2195
2196        /*
2197         * mlock MCL_FUTURE?
2198         */
2199        if (mm->def_flags & VM_LOCKED) {
2200                unsigned long locked, lock_limit;
2201                locked = len >> PAGE_SHIFT;
2202                locked += mm->locked_vm;
2203                lock_limit = rlimit(RLIMIT_MEMLOCK);
2204                lock_limit >>= PAGE_SHIFT;
2205                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2206                        return -EAGAIN;
2207        }
2208
2209        /*
2210         * mm->mmap_sem is required to protect against another thread
2211         * changing the mappings in case we sleep.
2212         */
2213        verify_mm_writelocked(mm);
2214
2215        /*
2216         * Clear old maps.  this also does some error checking for us
2217         */
2218 munmap_back:
2219        vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2220        if (vma && vma->vm_start < addr + len) {
2221                if (do_munmap(mm, addr, len))
2222                        return -ENOMEM;
2223                goto munmap_back;
2224        }
2225
2226        /* Check against address space limits *after* clearing old maps... */
2227        if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2228                return -ENOMEM;
2229
2230        if (mm->map_count > sysctl_max_map_count)
2231                return -ENOMEM;
2232
2233        if (security_vm_enough_memory(len >> PAGE_SHIFT))
2234                return -ENOMEM;
2235
2236        /* Can we just expand an old private anonymous mapping? */
2237        vma = vma_merge(mm, prev, addr, addr + len, flags,
2238                                        NULL, NULL, pgoff, NULL);
2239        if (vma)
2240                goto out;
2241
2242        /*
2243         * create a vma struct for an anonymous mapping
2244         */
2245        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2246        if (!vma) {
2247                vm_unacct_memory(len >> PAGE_SHIFT);
2248                return -ENOMEM;
2249        }
2250
2251        INIT_LIST_HEAD(&vma->anon_vma_chain);
2252        vma->vm_mm = mm;
2253        vma->vm_start = addr;
2254        vma->vm_end = addr + len;
2255        vma->vm_pgoff = pgoff;
2256        vma->vm_flags = flags;
2257        vma->vm_page_prot = vm_get_page_prot(flags);
2258        vma_link(mm, vma, prev, rb_link, rb_parent);
2259out:
2260        perf_event_mmap(vma);
2261        mm->total_vm += len >> PAGE_SHIFT;
2262        if (flags & VM_LOCKED) {
2263                if (!mlock_vma_pages_range(vma, addr, addr + len))
2264                        mm->locked_vm += (len >> PAGE_SHIFT);
2265        }
2266        return addr;
2267}
2268
2269EXPORT_SYMBOL(do_brk);
2270
2271/* Release all mmaps. */
2272void exit_mmap(struct mm_struct *mm)
2273{
2274        struct mmu_gather *tlb;
2275        struct vm_area_struct *vma;
2276        unsigned long nr_accounted = 0;
2277        unsigned long end;
2278
2279        /* mm's last user has gone, and its about to be pulled down */
2280        mmu_notifier_release(mm);
2281
2282        if (mm->locked_vm) {
2283                vma = mm->mmap;
2284                while (vma) {
2285                        if (vma->vm_flags & VM_LOCKED)
2286                                munlock_vma_pages_all(vma);
2287                        vma = vma->vm_next;
2288                }
2289        }
2290
2291        arch_exit_mmap(mm);
2292
2293        vma = mm->mmap;
2294        if (!vma)       /* Can happen if dup_mmap() received an OOM */
2295                return;
2296
2297        lru_add_drain();
2298        flush_cache_mm(mm);
2299        tlb = tlb_gather_mmu(mm, 1);
2300        /* update_hiwater_rss(mm) here? but nobody should be looking */
2301        /* Use -1 here to ensure all VMAs in the mm are unmapped */
2302        end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2303        vm_unacct_memory(nr_accounted);
2304
2305        free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
2306        tlb_finish_mmu(tlb, 0, end);
2307
2308        /*
2309         * Walk the list again, actually closing and freeing it,
2310         * with preemption enabled, without holding any MM locks.
2311         */
2312        while (vma)
2313                vma = remove_vma(vma);
2314
2315        BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2316}
2317
2318/* Insert vm structure into process list sorted by address
2319 * and into the inode's i_mmap tree.  If vm_file is non-NULL
2320 * then i_mmap_lock is taken here.
2321 */
2322int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2323{
2324        struct vm_area_struct * __vma, * prev;
2325        struct rb_node ** rb_link, * rb_parent;
2326
2327        /*
2328         * The vm_pgoff of a purely anonymous vma should be irrelevant
2329         * until its first write fault, when page's anon_vma and index
2330         * are set.  But now set the vm_pgoff it will almost certainly
2331         * end up with (unless mremap moves it elsewhere before that
2332         * first wfault), so /proc/pid/maps tells a consistent story.
2333         *
2334         * By setting it to reflect the virtual start address of the
2335         * vma, merges and splits can happen in a seamless way, just
2336         * using the existing file pgoff checks and manipulations.
2337         * Similarly in do_mmap_pgoff and in do_brk.
2338         */
2339        if (!vma->vm_file) {
2340                BUG_ON(vma->anon_vma);
2341                vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2342        }
2343        __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2344        if (__vma && __vma->vm_start < vma->vm_end)
2345                return -ENOMEM;
2346        if ((vma->vm_flags & VM_ACCOUNT) &&
2347             security_vm_enough_memory_mm(mm, vma_pages(vma)))
2348                return -ENOMEM;
2349        vma_link(mm, vma, prev, rb_link, rb_parent);
2350        return 0;
2351}
2352
2353/*
2354 * Copy the vma structure to a new location in the same mm,
2355 * prior to moving page table entries, to effect an mremap move.
2356 */
2357struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2358        unsigned long addr, unsigned long len, pgoff_t pgoff)
2359{
2360        struct vm_area_struct *vma = *vmap;
2361        unsigned long vma_start = vma->vm_start;
2362        struct mm_struct *mm = vma->vm_mm;
2363        struct vm_area_struct *new_vma, *prev;
2364        struct rb_node **rb_link, *rb_parent;
2365        struct mempolicy *pol;
2366
2367        /*
2368         * If anonymous vma has not yet been faulted, update new pgoff
2369         * to match new location, to increase its chance of merging.
2370         */
2371        if (!vma->vm_file && !vma->anon_vma)
2372                pgoff = addr >> PAGE_SHIFT;
2373
2374        find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2375        new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2376                        vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2377        if (new_vma) {
2378                /*
2379                 * Source vma may have been merged into new_vma
2380                 */
2381                if (vma_start >= new_vma->vm_start &&
2382                    vma_start < new_vma->vm_end)
2383                        *vmap = new_vma;
2384        } else {
2385                new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2386                if (new_vma) {
2387                        *new_vma = *vma;
2388                        pol = mpol_dup(vma_policy(vma));
2389                        if (IS_ERR(pol))
2390                                goto out_free_vma;
2391                        INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2392                        if (anon_vma_clone(new_vma, vma))
2393                                goto out_free_mempol;
2394                        vma_set_policy(new_vma, pol);
2395                        new_vma->vm_start = addr;
2396                        new_vma->vm_end = addr + len;
2397                        new_vma->vm_pgoff = pgoff;
2398                        if (new_vma->vm_file) {
2399                                get_file(new_vma->vm_file);
2400                                if (vma->vm_flags & VM_EXECUTABLE)
2401                                        added_exe_file_vma(mm);
2402                        }
2403                        if (new_vma->vm_ops && new_vma->vm_ops->open)
2404                                new_vma->vm_ops->open(new_vma);
2405                        vma_link(mm, new_vma, prev, rb_link, rb_parent);
2406                }
2407        }
2408        return new_vma;
2409
2410 out_free_mempol:
2411        mpol_put(pol);
2412 out_free_vma:
2413        kmem_cache_free(vm_area_cachep, new_vma);
2414        return NULL;
2415}
2416
2417/*
2418 * Return true if the calling process may expand its vm space by the passed
2419 * number of pages
2420 */
2421int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2422{
2423        unsigned long cur = mm->total_vm;       /* pages */
2424        unsigned long lim;
2425
2426        lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2427
2428        if (cur + npages > lim)
2429                return 0;
2430        return 1;
2431}
2432
2433
2434static int special_mapping_fault(struct vm_area_struct *vma,
2435                                struct vm_fault *vmf)
2436{
2437        pgoff_t pgoff;
2438        struct page **pages;
2439
2440        /*
2441         * special mappings have no vm_file, and in that case, the mm
2442         * uses vm_pgoff internally. So we have to subtract it from here.
2443         * We are allowed to do this because we are the mm; do not copy
2444         * this code into drivers!
2445         */
2446        pgoff = vmf->pgoff - vma->vm_pgoff;
2447
2448        for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2449                pgoff--;
2450
2451        if (*pages) {
2452                struct page *page = *pages;
2453                get_page(page);
2454                vmf->page = page;
2455                return 0;
2456        }
2457
2458        return VM_FAULT_SIGBUS;
2459}
2460
2461/*
2462 * Having a close hook prevents vma merging regardless of flags.
2463 */
2464static void special_mapping_close(struct vm_area_struct *vma)
2465{
2466}
2467
2468static const struct vm_operations_struct special_mapping_vmops = {
2469        .close = special_mapping_close,
2470        .fault = special_mapping_fault,
2471};
2472
2473/*
2474 * Called with mm->mmap_sem held for writing.
2475 * Insert a new vma covering the given region, with the given flags.
2476 * Its pages are supplied by the given array of struct page *.
2477 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2478 * The region past the last page supplied will always produce SIGBUS.
2479 * The array pointer and the pages it points to are assumed to stay alive
2480 * for as long as this mapping might exist.
2481 */
2482int install_special_mapping(struct mm_struct *mm,
2483                            unsigned long addr, unsigned long len,
2484                            unsigned long vm_flags, struct page **pages)
2485{
2486        int ret;
2487        struct vm_area_struct *vma;
2488
2489        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2490        if (unlikely(vma == NULL))
2491                return -ENOMEM;
2492
2493        INIT_LIST_HEAD(&vma->anon_vma_chain);
2494        vma->vm_mm = mm;
2495        vma->vm_start = addr;
2496        vma->vm_end = addr + len;
2497
2498        vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2499        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2500
2501        vma->vm_ops = &special_mapping_vmops;
2502        vma->vm_private_data = pages;
2503
2504        ret = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
2505        if (ret)
2506                goto out;
2507
2508        ret = insert_vm_struct(mm, vma);
2509        if (ret)
2510                goto out;
2511
2512        mm->total_vm += len >> PAGE_SHIFT;
2513
2514        perf_event_mmap(vma);
2515
2516        return 0;
2517
2518out:
2519        kmem_cache_free(vm_area_cachep, vma);
2520        return ret;
2521}
2522
2523static DEFINE_MUTEX(mm_all_locks_mutex);
2524
2525static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2526{
2527        if (!test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2528                /*
2529                 * The LSB of head.next can't change from under us
2530                 * because we hold the mm_all_locks_mutex.
2531                 */
2532                spin_lock_nest_lock(&anon_vma->root->lock, &mm->mmap_sem);
2533                /*
2534                 * We can safely modify head.next after taking the
2535                 * anon_vma->root->lock. If some other vma in this mm shares
2536                 * the same anon_vma we won't take it again.
2537                 *
2538                 * No need of atomic instructions here, head.next
2539                 * can't change from under us thanks to the
2540                 * anon_vma->root->lock.
2541                 */
2542                if (__test_and_set_bit(0, (unsigned long *)
2543                                       &anon_vma->root->head.next))
2544                        BUG();
2545        }
2546}
2547
2548static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2549{
2550        if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2551                /*
2552                 * AS_MM_ALL_LOCKS can't change from under us because
2553                 * we hold the mm_all_locks_mutex.
2554                 *
2555                 * Operations on ->flags have to be atomic because
2556                 * even if AS_MM_ALL_LOCKS is stable thanks to the
2557                 * mm_all_locks_mutex, there may be other cpus
2558                 * changing other bitflags in parallel to us.
2559                 */
2560                if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2561                        BUG();
2562                spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
2563        }
2564}
2565
2566/*
2567 * This operation locks against the VM for all pte/vma/mm related
2568 * operations that could ever happen on a certain mm. This includes
2569 * vmtruncate, try_to_unmap, and all page faults.
2570 *
2571 * The caller must take the mmap_sem in write mode before calling
2572 * mm_take_all_locks(). The caller isn't allowed to release the
2573 * mmap_sem until mm_drop_all_locks() returns.
2574 *
2575 * mmap_sem in write mode is required in order to block all operations
2576 * that could modify pagetables and free pages without need of
2577 * altering the vma layout (for example populate_range() with
2578 * nonlinear vmas). It's also needed in write mode to avoid new
2579 * anon_vmas to be associated with existing vmas.
2580 *
2581 * A single task can't take more than one mm_take_all_locks() in a row
2582 * or it would deadlock.
2583 *
2584 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2585 * mapping->flags avoid to take the same lock twice, if more than one
2586 * vma in this mm is backed by the same anon_vma or address_space.
2587 *
2588 * We can take all the locks in random order because the VM code
2589 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
2590 * takes more than one of them in a row. Secondly we're protected
2591 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2592 *
2593 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2594 * that may have to take thousand of locks.
2595 *
2596 * mm_take_all_locks() can fail if it's interrupted by signals.
2597 */
2598int mm_take_all_locks(struct mm_struct *mm)
2599{
2600        struct vm_area_struct *vma;
2601        struct anon_vma_chain *avc;
2602        int ret = -EINTR;
2603
2604        BUG_ON(down_read_trylock(&mm->mmap_sem));
2605
2606        mutex_lock(&mm_all_locks_mutex);
2607
2608        for (vma = mm->mmap; vma; vma = vma->vm_next) {
2609                if (signal_pending(current))
2610                        goto out_unlock;
2611                if (vma->vm_file && vma->vm_file->f_mapping)
2612                        vm_lock_mapping(mm, vma->vm_file->f_mapping);
2613        }
2614
2615        for (vma = mm->mmap; vma; vma = vma->vm_next) {
2616                if (signal_pending(current))
2617                        goto out_unlock;
2618                if (vma->anon_vma)
2619                        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2620                                vm_lock_anon_vma(mm, avc->anon_vma);
2621        }
2622
2623        ret = 0;
2624
2625out_unlock:
2626        if (ret)
2627                mm_drop_all_locks(mm);
2628
2629        return ret;
2630}
2631
2632static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2633{
2634        if (test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2635                /*
2636                 * The LSB of head.next can't change to 0 from under
2637                 * us because we hold the mm_all_locks_mutex.
2638                 *
2639                 * We must however clear the bitflag before unlocking
2640                 * the vma so the users using the anon_vma->head will
2641                 * never see our bitflag.
2642                 *
2643                 * No need of atomic instructions here, head.next
2644                 * can't change from under us until we release the
2645                 * anon_vma->root->lock.
2646                 */
2647                if (!__test_and_clear_bit(0, (unsigned long *)
2648                                          &anon_vma->root->head.next))
2649                        BUG();
2650                anon_vma_unlock(anon_vma);
2651        }
2652}
2653
2654static void vm_unlock_mapping(struct address_space *mapping)
2655{
2656        if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2657                /*
2658                 * AS_MM_ALL_LOCKS can't change to 0 from under us
2659                 * because we hold the mm_all_locks_mutex.
2660                 */
2661                spin_unlock(&mapping->i_mmap_lock);
2662                if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2663                                        &mapping->flags))
2664                        BUG();
2665        }
2666}
2667
2668/*
2669 * The mmap_sem cannot be released by the caller until
2670 * mm_drop_all_locks() returns.
2671 */
2672void mm_drop_all_locks(struct mm_struct *mm)
2673{
2674        struct vm_area_struct *vma;
2675        struct anon_vma_chain *avc;
2676
2677        BUG_ON(down_read_trylock(&mm->mmap_sem));
2678        BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2679
2680        for (vma = mm->mmap; vma; vma = vma->vm_next) {
2681                if (vma->anon_vma)
2682                        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2683                                vm_unlock_anon_vma(avc->anon_vma);
2684                if (vma->vm_file && vma->vm_file->f_mapping)
2685                        vm_unlock_mapping(vma->vm_file->f_mapping);
2686        }
2687
2688        mutex_unlock(&mm_all_locks_mutex);
2689}
2690
2691/*
2692 * initialise the VMA slab
2693 */
2694void __init mmap_init(void)
2695{
2696        int ret;
2697
2698        ret = percpu_counter_init(&vm_committed_as, 0);
2699        VM_BUG_ON(ret);
2700}
2701
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