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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11#include <linux/kernel.h>
  12#include <linux/slab.h>
  13#include <linux/backing-dev.h>
  14#include <linux/mm.h>
  15#include <linux/vmacache.h>
  16#include <linux/shm.h>
  17#include <linux/mman.h>
  18#include <linux/pagemap.h>
  19#include <linux/swap.h>
  20#include <linux/syscalls.h>
  21#include <linux/capability.h>
  22#include <linux/init.h>
  23#include <linux/file.h>
  24#include <linux/fs.h>
  25#include <linux/personality.h>
  26#include <linux/security.h>
  27#include <linux/hugetlb.h>
  28#include <linux/profile.h>
  29#include <linux/export.h>
  30#include <linux/mount.h>
  31#include <linux/mempolicy.h>
  32#include <linux/rmap.h>
  33#include <linux/mmu_notifier.h>
  34#include <linux/mmdebug.h>
  35#include <linux/perf_event.h>
  36#include <linux/audit.h>
  37#include <linux/khugepaged.h>
  38#include <linux/uprobes.h>
  39#include <linux/rbtree_augmented.h>
  40#include <linux/sched/sysctl.h>
  41#include <linux/notifier.h>
  42#include <linux/memory.h>
  43#include <linux/printk.h>
  44#include <linux/userfaultfd_k.h>
  45
  46#include <asm/uaccess.h>
  47#include <asm/cacheflush.h>
  48#include <asm/tlb.h>
  49#include <asm/mmu_context.h>
  50
  51#include "internal.h"
  52
  53#ifndef arch_mmap_check
  54#define arch_mmap_check(addr, len, flags)       (0)
  55#endif
  56
  57#ifndef arch_rebalance_pgtables
  58#define arch_rebalance_pgtables(addr, len)              (addr)
  59#endif
  60
  61static void unmap_region(struct mm_struct *mm,
  62                struct vm_area_struct *vma, struct vm_area_struct *prev,
  63                unsigned long start, unsigned long end);
  64
  65/* description of effects of mapping type and prot in current implementation.
  66 * this is due to the limited x86 page protection hardware.  The expected
  67 * behavior is in parens:
  68 *
  69 * map_type     prot
  70 *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
  71 * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
  72 *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
  73 *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
  74 *
  75 * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
  76 *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
  77 *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
  78 *
  79 */
  80pgprot_t protection_map[16] = {
  81        __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
  82        __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
  83};
  84
  85pgprot_t vm_get_page_prot(unsigned long vm_flags)
  86{
  87        return __pgprot(pgprot_val(protection_map[vm_flags &
  88                                (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
  89                        pgprot_val(arch_vm_get_page_prot(vm_flags)));
  90}
  91EXPORT_SYMBOL(vm_get_page_prot);
  92
  93static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
  94{
  95        return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
  96}
  97
  98/* Update vma->vm_page_prot to reflect vma->vm_flags. */
  99void vma_set_page_prot(struct vm_area_struct *vma)
 100{
 101        unsigned long vm_flags = vma->vm_flags;
 102
 103        vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
 104        if (vma_wants_writenotify(vma)) {
 105                vm_flags &= ~VM_SHARED;
 106                vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot,
 107                                                     vm_flags);
 108        }
 109}
 110
 111
 112int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS;  /* heuristic overcommit */
 113int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
 114unsigned long sysctl_overcommit_kbytes __read_mostly;
 115int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
 116unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
 117unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
 118/*
 119 * Make sure vm_committed_as in one cacheline and not cacheline shared with
 120 * other variables. It can be updated by several CPUs frequently.
 121 */
 122struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
 123
 124/*
 125 * The global memory commitment made in the system can be a metric
 126 * that can be used to drive ballooning decisions when Linux is hosted
 127 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
 128 * balancing memory across competing virtual machines that are hosted.
 129 * Several metrics drive this policy engine including the guest reported
 130 * memory commitment.
 131 */
 132unsigned long vm_memory_committed(void)
 133{
 134        return percpu_counter_read_positive(&vm_committed_as);
 135}
 136EXPORT_SYMBOL_GPL(vm_memory_committed);
 137
 138/*
 139 * Check that a process has enough memory to allocate a new virtual
 140 * mapping. 0 means there is enough memory for the allocation to
 141 * succeed and -ENOMEM implies there is not.
 142 *
 143 * We currently support three overcommit policies, which are set via the
 144 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
 145 *
 146 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
 147 * Additional code 2002 Jul 20 by Robert Love.
 148 *
 149 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
 150 *
 151 * Note this is a helper function intended to be used by LSMs which
 152 * wish to use this logic.
 153 */
 154int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
 155{
 156        long free, allowed, reserve;
 157
 158        VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
 159                        -(s64)vm_committed_as_batch * num_online_cpus(),
 160                        "memory commitment underflow");
 161
 162        vm_acct_memory(pages);
 163
 164        /*
 165         * Sometimes we want to use more memory than we have
 166         */
 167        if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
 168                return 0;
 169
 170        if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
 171                free = global_page_state(NR_FREE_PAGES);
 172                free += global_page_state(NR_FILE_PAGES);
 173
 174                /*
 175                 * shmem pages shouldn't be counted as free in this
 176                 * case, they can't be purged, only swapped out, and
 177                 * that won't affect the overall amount of available
 178                 * memory in the system.
 179                 */
 180                free -= global_page_state(NR_SHMEM);
 181
 182                free += get_nr_swap_pages();
 183
 184                /*
 185                 * Any slabs which are created with the
 186                 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
 187                 * which are reclaimable, under pressure.  The dentry
 188                 * cache and most inode caches should fall into this
 189                 */
 190                free += global_page_state(NR_SLAB_RECLAIMABLE);
 191
 192                /*
 193                 * Leave reserved pages. The pages are not for anonymous pages.
 194                 */
 195                if (free <= totalreserve_pages)
 196                        goto error;
 197                else
 198                        free -= totalreserve_pages;
 199
 200                /*
 201                 * Reserve some for root
 202                 */
 203                if (!cap_sys_admin)
 204                        free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
 205
 206                if (free > pages)
 207                        return 0;
 208
 209                goto error;
 210        }
 211
 212        allowed = vm_commit_limit();
 213        /*
 214         * Reserve some for root
 215         */
 216        if (!cap_sys_admin)
 217                allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
 218
 219        /*
 220         * Don't let a single process grow so big a user can't recover
 221         */
 222        if (mm) {
 223                reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
 224                allowed -= min_t(long, mm->total_vm / 32, reserve);
 225        }
 226
 227        if (percpu_counter_read_positive(&vm_committed_as) < allowed)
 228                return 0;
 229error:
 230        vm_unacct_memory(pages);
 231
 232        return -ENOMEM;
 233}
 234
 235/*
 236 * Requires inode->i_mapping->i_mmap_rwsem
 237 */
 238static void __remove_shared_vm_struct(struct vm_area_struct *vma,
 239                struct file *file, struct address_space *mapping)
 240{
 241        if (vma->vm_flags & VM_DENYWRITE)
 242                atomic_inc(&file_inode(file)->i_writecount);
 243        if (vma->vm_flags & VM_SHARED)
 244                mapping_unmap_writable(mapping);
 245
 246        flush_dcache_mmap_lock(mapping);
 247        vma_interval_tree_remove(vma, &mapping->i_mmap);
 248        flush_dcache_mmap_unlock(mapping);
 249}
 250
 251/*
 252 * Unlink a file-based vm structure from its interval tree, to hide
 253 * vma from rmap and vmtruncate before freeing its page tables.
 254 */
 255void unlink_file_vma(struct vm_area_struct *vma)
 256{
 257        struct file *file = vma->vm_file;
 258
 259        if (file) {
 260                struct address_space *mapping = file->f_mapping;
 261                i_mmap_lock_write(mapping);
 262                __remove_shared_vm_struct(vma, file, mapping);
 263                i_mmap_unlock_write(mapping);
 264        }
 265}
 266
 267/*
 268 * Close a vm structure and free it, returning the next.
 269 */
 270static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 271{
 272        struct vm_area_struct *next = vma->vm_next;
 273
 274        might_sleep();
 275        if (vma->vm_ops && vma->vm_ops->close)
 276                vma->vm_ops->close(vma);
 277        if (vma->vm_file)
 278                fput(vma->vm_file);
 279        mpol_put(vma_policy(vma));
 280        kmem_cache_free(vm_area_cachep, vma);
 281        return next;
 282}
 283
 284static unsigned long do_brk(unsigned long addr, unsigned long len);
 285
 286SYSCALL_DEFINE1(brk, unsigned long, brk)
 287{
 288        unsigned long retval;
 289        unsigned long newbrk, oldbrk;
 290        struct mm_struct *mm = current->mm;
 291        unsigned long min_brk;
 292        bool populate;
 293
 294        down_write(&mm->mmap_sem);
 295
 296#ifdef CONFIG_COMPAT_BRK
 297        /*
 298         * CONFIG_COMPAT_BRK can still be overridden by setting
 299         * randomize_va_space to 2, which will still cause mm->start_brk
 300         * to be arbitrarily shifted
 301         */
 302        if (current->brk_randomized)
 303                min_brk = mm->start_brk;
 304        else
 305                min_brk = mm->end_data;
 306#else
 307        min_brk = mm->start_brk;
 308#endif
 309        if (brk < min_brk)
 310                goto out;
 311
 312        /*
 313         * Check against rlimit here. If this check is done later after the test
 314         * of oldbrk with newbrk then it can escape the test and let the data
 315         * segment grow beyond its set limit the in case where the limit is
 316         * not page aligned -Ram Gupta
 317         */
 318        if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
 319                              mm->end_data, mm->start_data))
 320                goto out;
 321
 322        newbrk = PAGE_ALIGN(brk);
 323        oldbrk = PAGE_ALIGN(mm->brk);
 324        if (oldbrk == newbrk)
 325                goto set_brk;
 326
 327        /* Always allow shrinking brk. */
 328        if (brk <= mm->brk) {
 329                if (!do_munmap(mm, newbrk, oldbrk-newbrk))
 330                        goto set_brk;
 331                goto out;
 332        }
 333
 334        /* Check against existing mmap mappings. */
 335        if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
 336                goto out;
 337
 338        /* Ok, looks good - let it rip. */
 339        if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
 340                goto out;
 341
 342set_brk:
 343        mm->brk = brk;
 344        populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
 345        up_write(&mm->mmap_sem);
 346        if (populate)
 347                mm_populate(oldbrk, newbrk - oldbrk);
 348        return brk;
 349
 350out:
 351        retval = mm->brk;
 352        up_write(&mm->mmap_sem);
 353        return retval;
 354}
 355
 356static long vma_compute_subtree_gap(struct vm_area_struct *vma)
 357{
 358        unsigned long max, subtree_gap;
 359        max = vma->vm_start;
 360        if (vma->vm_prev)
 361                max -= vma->vm_prev->vm_end;
 362        if (vma->vm_rb.rb_left) {
 363                subtree_gap = rb_entry(vma->vm_rb.rb_left,
 364                                struct vm_area_struct, vm_rb)->rb_subtree_gap;
 365                if (subtree_gap > max)
 366                        max = subtree_gap;
 367        }
 368        if (vma->vm_rb.rb_right) {
 369                subtree_gap = rb_entry(vma->vm_rb.rb_right,
 370                                struct vm_area_struct, vm_rb)->rb_subtree_gap;
 371                if (subtree_gap > max)
 372                        max = subtree_gap;
 373        }
 374        return max;
 375}
 376
 377#ifdef CONFIG_DEBUG_VM_RB
 378static int browse_rb(struct rb_root *root)
 379{
 380        int i = 0, j, bug = 0;
 381        struct rb_node *nd, *pn = NULL;
 382        unsigned long prev = 0, pend = 0;
 383
 384        for (nd = rb_first(root); nd; nd = rb_next(nd)) {
 385                struct vm_area_struct *vma;
 386                vma = rb_entry(nd, struct vm_area_struct, vm_rb);
 387                if (vma->vm_start < prev) {
 388                        pr_emerg("vm_start %lx < prev %lx\n",
 389                                  vma->vm_start, prev);
 390                        bug = 1;
 391                }
 392                if (vma->vm_start < pend) {
 393                        pr_emerg("vm_start %lx < pend %lx\n",
 394                                  vma->vm_start, pend);
 395                        bug = 1;
 396                }
 397                if (vma->vm_start > vma->vm_end) {
 398                        pr_emerg("vm_start %lx > vm_end %lx\n",
 399                                  vma->vm_start, vma->vm_end);
 400                        bug = 1;
 401                }
 402                if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
 403                        pr_emerg("free gap %lx, correct %lx\n",
 404                               vma->rb_subtree_gap,
 405                               vma_compute_subtree_gap(vma));
 406                        bug = 1;
 407                }
 408                i++;
 409                pn = nd;
 410                prev = vma->vm_start;
 411                pend = vma->vm_end;
 412        }
 413        j = 0;
 414        for (nd = pn; nd; nd = rb_prev(nd))
 415                j++;
 416        if (i != j) {
 417                pr_emerg("backwards %d, forwards %d\n", j, i);
 418                bug = 1;
 419        }
 420        return bug ? -1 : i;
 421}
 422
 423static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
 424{
 425        struct rb_node *nd;
 426
 427        for (nd = rb_first(root); nd; nd = rb_next(nd)) {
 428                struct vm_area_struct *vma;
 429                vma = rb_entry(nd, struct vm_area_struct, vm_rb);
 430                VM_BUG_ON_VMA(vma != ignore &&
 431                        vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
 432                        vma);
 433        }
 434}
 435
 436static void validate_mm(struct mm_struct *mm)
 437{
 438        int bug = 0;
 439        int i = 0;
 440        unsigned long highest_address = 0;
 441        struct vm_area_struct *vma = mm->mmap;
 442
 443        while (vma) {
 444                struct anon_vma_chain *avc;
 445
 446                vma_lock_anon_vma(vma);
 447                list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 448                        anon_vma_interval_tree_verify(avc);
 449                vma_unlock_anon_vma(vma);
 450                highest_address = vma->vm_end;
 451                vma = vma->vm_next;
 452                i++;
 453        }
 454        if (i != mm->map_count) {
 455                pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
 456                bug = 1;
 457        }
 458        if (highest_address != mm->highest_vm_end) {
 459                pr_emerg("mm->highest_vm_end %lx, found %lx\n",
 460                          mm->highest_vm_end, highest_address);
 461                bug = 1;
 462        }
 463        i = browse_rb(&mm->mm_rb);
 464        if (i != mm->map_count) {
 465                if (i != -1)
 466                        pr_emerg("map_count %d rb %d\n", mm->map_count, i);
 467                bug = 1;
 468        }
 469        VM_BUG_ON_MM(bug, mm);
 470}
 471#else
 472#define validate_mm_rb(root, ignore) do { } while (0)
 473#define validate_mm(mm) do { } while (0)
 474#endif
 475
 476RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
 477                     unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
 478
 479/*
 480 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
 481 * vma->vm_prev->vm_end values changed, without modifying the vma's position
 482 * in the rbtree.
 483 */
 484static void vma_gap_update(struct vm_area_struct *vma)
 485{
 486        /*
 487         * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
 488         * function that does exacltly what we want.
 489         */
 490        vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
 491}
 492
 493static inline void vma_rb_insert(struct vm_area_struct *vma,
 494                                 struct rb_root *root)
 495{
 496        /* All rb_subtree_gap values must be consistent prior to insertion */
 497        validate_mm_rb(root, NULL);
 498
 499        rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
 500}
 501
 502static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
 503{
 504        /*
 505         * All rb_subtree_gap values must be consistent prior to erase,
 506         * with the possible exception of the vma being erased.
 507         */
 508        validate_mm_rb(root, vma);
 509
 510        /*
 511         * Note rb_erase_augmented is a fairly large inline function,
 512         * so make sure we instantiate it only once with our desired
 513         * augmented rbtree callbacks.
 514         */
 515        rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
 516}
 517
 518/*
 519 * vma has some anon_vma assigned, and is already inserted on that
 520 * anon_vma's interval trees.
 521 *
 522 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
 523 * vma must be removed from the anon_vma's interval trees using
 524 * anon_vma_interval_tree_pre_update_vma().
 525 *
 526 * After the update, the vma will be reinserted using
 527 * anon_vma_interval_tree_post_update_vma().
 528 *
 529 * The entire update must be protected by exclusive mmap_sem and by
 530 * the root anon_vma's mutex.
 531 */
 532static inline void
 533anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
 534{
 535        struct anon_vma_chain *avc;
 536
 537        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 538                anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
 539}
 540
 541static inline void
 542anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
 543{
 544        struct anon_vma_chain *avc;
 545
 546        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 547                anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
 548}
 549
 550static int find_vma_links(struct mm_struct *mm, unsigned long addr,
 551                unsigned long end, struct vm_area_struct **pprev,
 552                struct rb_node ***rb_link, struct rb_node **rb_parent)
 553{
 554        struct rb_node **__rb_link, *__rb_parent, *rb_prev;
 555
 556        __rb_link = &mm->mm_rb.rb_node;
 557        rb_prev = __rb_parent = NULL;
 558
 559        while (*__rb_link) {
 560                struct vm_area_struct *vma_tmp;
 561
 562                __rb_parent = *__rb_link;
 563                vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
 564
 565                if (vma_tmp->vm_end > addr) {
 566                        /* Fail if an existing vma overlaps the area */
 567                        if (vma_tmp->vm_start < end)
 568                                return -ENOMEM;
 569                        __rb_link = &__rb_parent->rb_left;
 570                } else {
 571                        rb_prev = __rb_parent;
 572                        __rb_link = &__rb_parent->rb_right;
 573                }
 574        }
 575
 576        *pprev = NULL;
 577        if (rb_prev)
 578                *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 579        *rb_link = __rb_link;
 580        *rb_parent = __rb_parent;
 581        return 0;
 582}
 583
 584static unsigned long count_vma_pages_range(struct mm_struct *mm,
 585                unsigned long addr, unsigned long end)
 586{
 587        unsigned long nr_pages = 0;
 588        struct vm_area_struct *vma;
 589
 590        /* Find first overlaping mapping */
 591        vma = find_vma_intersection(mm, addr, end);
 592        if (!vma)
 593                return 0;
 594
 595        nr_pages = (min(end, vma->vm_end) -
 596                max(addr, vma->vm_start)) >> PAGE_SHIFT;
 597
 598        /* Iterate over the rest of the overlaps */
 599        for (vma = vma->vm_next; vma; vma = vma->vm_next) {
 600                unsigned long overlap_len;
 601
 602                if (vma->vm_start > end)
 603                        break;
 604
 605                overlap_len = min(end, vma->vm_end) - vma->vm_start;
 606                nr_pages += overlap_len >> PAGE_SHIFT;
 607        }
 608
 609        return nr_pages;
 610}
 611
 612void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
 613                struct rb_node **rb_link, struct rb_node *rb_parent)
 614{
 615        /* Update tracking information for the gap following the new vma. */
 616        if (vma->vm_next)
 617                vma_gap_update(vma->vm_next);
 618        else
 619                mm->highest_vm_end = vma->vm_end;
 620
 621        /*
 622         * vma->vm_prev wasn't known when we followed the rbtree to find the
 623         * correct insertion point for that vma. As a result, we could not
 624         * update the vma vm_rb parents rb_subtree_gap values on the way down.
 625         * So, we first insert the vma with a zero rb_subtree_gap value
 626         * (to be consistent with what we did on the way down), and then
 627         * immediately update the gap to the correct value. Finally we
 628         * rebalance the rbtree after all augmented values have been set.
 629         */
 630        rb_link_node(&vma->vm_rb, rb_parent, rb_link);
 631        vma->rb_subtree_gap = 0;
 632        vma_gap_update(vma);
 633        vma_rb_insert(vma, &mm->mm_rb);
 634}
 635
 636static void __vma_link_file(struct vm_area_struct *vma)
 637{
 638        struct file *file;
 639
 640        file = vma->vm_file;
 641        if (file) {
 642                struct address_space *mapping = file->f_mapping;
 643
 644                if (vma->vm_flags & VM_DENYWRITE)
 645                        atomic_dec(&file_inode(file)->i_writecount);
 646                if (vma->vm_flags & VM_SHARED)
 647                        atomic_inc(&mapping->i_mmap_writable);
 648
 649                flush_dcache_mmap_lock(mapping);
 650                vma_interval_tree_insert(vma, &mapping->i_mmap);
 651                flush_dcache_mmap_unlock(mapping);
 652        }
 653}
 654
 655static void
 656__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 657        struct vm_area_struct *prev, struct rb_node **rb_link,
 658        struct rb_node *rb_parent)
 659{
 660        __vma_link_list(mm, vma, prev, rb_parent);
 661        __vma_link_rb(mm, vma, rb_link, rb_parent);
 662}
 663
 664static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 665                        struct vm_area_struct *prev, struct rb_node **rb_link,
 666                        struct rb_node *rb_parent)
 667{
 668        struct address_space *mapping = NULL;
 669
 670        if (vma->vm_file) {
 671                mapping = vma->vm_file->f_mapping;
 672                i_mmap_lock_write(mapping);
 673        }
 674
 675        __vma_link(mm, vma, prev, rb_link, rb_parent);
 676        __vma_link_file(vma);
 677
 678        if (mapping)
 679                i_mmap_unlock_write(mapping);
 680
 681        mm->map_count++;
 682        validate_mm(mm);
 683}
 684
 685/*
 686 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
 687 * mm's list and rbtree.  It has already been inserted into the interval tree.
 688 */
 689static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
 690{
 691        struct vm_area_struct *prev;
 692        struct rb_node **rb_link, *rb_parent;
 693
 694        if (find_vma_links(mm, vma->vm_start, vma->vm_end,
 695                           &prev, &rb_link, &rb_parent))
 696                BUG();
 697        __vma_link(mm, vma, prev, rb_link, rb_parent);
 698        mm->map_count++;
 699}
 700
 701static inline void
 702__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
 703                struct vm_area_struct *prev)
 704{
 705        struct vm_area_struct *next;
 706
 707        vma_rb_erase(vma, &mm->mm_rb);
 708        prev->vm_next = next = vma->vm_next;
 709        if (next)
 710                next->vm_prev = prev;
 711
 712        /* Kill the cache */
 713        vmacache_invalidate(mm);
 714}
 715
 716/*
 717 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
 718 * is already present in an i_mmap tree without adjusting the tree.
 719 * The following helper function should be used when such adjustments
 720 * are necessary.  The "insert" vma (if any) is to be inserted
 721 * before we drop the necessary locks.
 722 */
 723int vma_adjust(struct vm_area_struct *vma, unsigned long start,
 724        unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
 725{
 726        struct mm_struct *mm = vma->vm_mm;
 727        struct vm_area_struct *next = vma->vm_next;
 728        struct vm_area_struct *importer = NULL;
 729        struct address_space *mapping = NULL;
 730        struct rb_root *root = NULL;
 731        struct anon_vma *anon_vma = NULL;
 732        struct file *file = vma->vm_file;
 733        bool start_changed = false, end_changed = false;
 734        long adjust_next = 0;
 735        int remove_next = 0;
 736
 737        if (next && !insert) {
 738                struct vm_area_struct *exporter = NULL;
 739
 740                if (end >= next->vm_end) {
 741                        /*
 742                         * vma expands, overlapping all the next, and
 743                         * perhaps the one after too (mprotect case 6).
 744                         */
 745again:                  remove_next = 1 + (end > next->vm_end);
 746                        end = next->vm_end;
 747                        exporter = next;
 748                        importer = vma;
 749                } else if (end > next->vm_start) {
 750                        /*
 751                         * vma expands, overlapping part of the next:
 752                         * mprotect case 5 shifting the boundary up.
 753                         */
 754                        adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
 755                        exporter = next;
 756                        importer = vma;
 757                } else if (end < vma->vm_end) {
 758                        /*
 759                         * vma shrinks, and !insert tells it's not
 760                         * split_vma inserting another: so it must be
 761                         * mprotect case 4 shifting the boundary down.
 762                         */
 763                        adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
 764                        exporter = vma;
 765                        importer = next;
 766                }
 767
 768                /*
 769                 * Easily overlooked: when mprotect shifts the boundary,
 770                 * make sure the expanding vma has anon_vma set if the
 771                 * shrinking vma had, to cover any anon pages imported.
 772                 */
 773                if (exporter && exporter->anon_vma && !importer->anon_vma) {
 774                        int error;
 775
 776                        importer->anon_vma = exporter->anon_vma;
 777                        error = anon_vma_clone(importer, exporter);
 778                        if (error)
 779                                return error;
 780                }
 781        }
 782
 783        if (file) {
 784                mapping = file->f_mapping;
 785                root = &mapping->i_mmap;
 786                uprobe_munmap(vma, vma->vm_start, vma->vm_end);
 787
 788                if (adjust_next)
 789                        uprobe_munmap(next, next->vm_start, next->vm_end);
 790
 791                i_mmap_lock_write(mapping);
 792                if (insert) {
 793                        /*
 794                         * Put into interval tree now, so instantiated pages
 795                         * are visible to arm/parisc __flush_dcache_page
 796                         * throughout; but we cannot insert into address
 797                         * space until vma start or end is updated.
 798                         */
 799                        __vma_link_file(insert);
 800                }
 801        }
 802
 803        vma_adjust_trans_huge(vma, start, end, adjust_next);
 804
 805        anon_vma = vma->anon_vma;
 806        if (!anon_vma && adjust_next)
 807                anon_vma = next->anon_vma;
 808        if (anon_vma) {
 809                VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
 810                          anon_vma != next->anon_vma, next);
 811                anon_vma_lock_write(anon_vma);
 812                anon_vma_interval_tree_pre_update_vma(vma);
 813                if (adjust_next)
 814                        anon_vma_interval_tree_pre_update_vma(next);
 815        }
 816
 817        if (root) {
 818                flush_dcache_mmap_lock(mapping);
 819                vma_interval_tree_remove(vma, root);
 820                if (adjust_next)
 821                        vma_interval_tree_remove(next, root);
 822        }
 823
 824        if (start != vma->vm_start) {
 825                vma->vm_start = start;
 826                start_changed = true;
 827        }
 828        if (end != vma->vm_end) {
 829                vma->vm_end = end;
 830                end_changed = true;
 831        }
 832        vma->vm_pgoff = pgoff;
 833        if (adjust_next) {
 834                next->vm_start += adjust_next << PAGE_SHIFT;
 835                next->vm_pgoff += adjust_next;
 836        }
 837
 838        if (root) {
 839                if (adjust_next)
 840                        vma_interval_tree_insert(next, root);
 841                vma_interval_tree_insert(vma, root);
 842                flush_dcache_mmap_unlock(mapping);
 843        }
 844
 845        if (remove_next) {
 846                /*
 847                 * vma_merge has merged next into vma, and needs
 848                 * us to remove next before dropping the locks.
 849                 */
 850                __vma_unlink(mm, next, vma);
 851                if (file)
 852                        __remove_shared_vm_struct(next, file, mapping);
 853        } else if (insert) {
 854                /*
 855                 * split_vma has split insert from vma, and needs
 856                 * us to insert it before dropping the locks
 857                 * (it may either follow vma or precede it).
 858                 */
 859                __insert_vm_struct(mm, insert);
 860        } else {
 861                if (start_changed)
 862                        vma_gap_update(vma);
 863                if (end_changed) {
 864                        if (!next)
 865                                mm->highest_vm_end = end;
 866                        else if (!adjust_next)
 867                                vma_gap_update(next);
 868                }
 869        }
 870
 871        if (anon_vma) {
 872                anon_vma_interval_tree_post_update_vma(vma);
 873                if (adjust_next)
 874                        anon_vma_interval_tree_post_update_vma(next);
 875                anon_vma_unlock_write(anon_vma);
 876        }
 877        if (mapping)
 878                i_mmap_unlock_write(mapping);
 879
 880        if (root) {
 881                uprobe_mmap(vma);
 882
 883                if (adjust_next)
 884                        uprobe_mmap(next);
 885        }
 886
 887        if (remove_next) {
 888                if (file) {
 889                        uprobe_munmap(next, next->vm_start, next->vm_end);
 890                        fput(file);
 891                }
 892                if (next->anon_vma)
 893                        anon_vma_merge(vma, next);
 894                mm->map_count--;
 895                mpol_put(vma_policy(next));
 896                kmem_cache_free(vm_area_cachep, next);
 897                /*
 898                 * In mprotect's case 6 (see comments on vma_merge),
 899                 * we must remove another next too. It would clutter
 900                 * up the code too much to do both in one go.
 901                 */
 902                next = vma->vm_next;
 903                if (remove_next == 2)
 904                        goto again;
 905                else if (next)
 906                        vma_gap_update(next);
 907                else
 908                        mm->highest_vm_end = end;
 909        }
 910        if (insert && file)
 911                uprobe_mmap(insert);
 912
 913        validate_mm(mm);
 914
 915        return 0;
 916}
 917
 918/*
 919 * If the vma has a ->close operation then the driver probably needs to release
 920 * per-vma resources, so we don't attempt to merge those.
 921 */
 922static inline int is_mergeable_vma(struct vm_area_struct *vma,
 923                                struct file *file, unsigned long vm_flags,
 924                                struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
 925{
 926        /*
 927         * VM_SOFTDIRTY should not prevent from VMA merging, if we
 928         * match the flags but dirty bit -- the caller should mark
 929         * merged VMA as dirty. If dirty bit won't be excluded from
 930         * comparison, we increase pressue on the memory system forcing
 931         * the kernel to generate new VMAs when old one could be
 932         * extended instead.
 933         */
 934        if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
 935                return 0;
 936        if (vma->vm_file != file)
 937                return 0;
 938        if (vma->vm_ops && vma->vm_ops->close)
 939                return 0;
 940        if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
 941                return 0;
 942        return 1;
 943}
 944
 945static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
 946                                        struct anon_vma *anon_vma2,
 947                                        struct vm_area_struct *vma)
 948{
 949        /*
 950         * The list_is_singular() test is to avoid merging VMA cloned from
 951         * parents. This can improve scalability caused by anon_vma lock.
 952         */
 953        if ((!anon_vma1 || !anon_vma2) && (!vma ||
 954                list_is_singular(&vma->anon_vma_chain)))
 955                return 1;
 956        return anon_vma1 == anon_vma2;
 957}
 958
 959/*
 960 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 961 * in front of (at a lower virtual address and file offset than) the vma.
 962 *
 963 * We cannot merge two vmas if they have differently assigned (non-NULL)
 964 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 965 *
 966 * We don't check here for the merged mmap wrapping around the end of pagecache
 967 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
 968 * wrap, nor mmaps which cover the final page at index -1UL.
 969 */
 970static int
 971can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
 972                     struct anon_vma *anon_vma, struct file *file,
 973                     pgoff_t vm_pgoff,
 974                     struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
 975{
 976        if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
 977            is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 978                if (vma->vm_pgoff == vm_pgoff)
 979                        return 1;
 980        }
 981        return 0;
 982}
 983
 984/*
 985 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
 986 * beyond (at a higher virtual address and file offset than) the vma.
 987 *
 988 * We cannot merge two vmas if they have differently assigned (non-NULL)
 989 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
 990 */
 991static int
 992can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
 993                    struct anon_vma *anon_vma, struct file *file,
 994                    pgoff_t vm_pgoff,
 995                    struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
 996{
 997        if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
 998            is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 999                pgoff_t vm_pglen;
1000                vm_pglen = vma_pages(vma);
1001                if (vma->vm_pgoff + vm_pglen == vm_pgoff)
1002                        return 1;
1003        }
1004        return 0;
1005}
1006
1007/*
1008 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1009 * whether that can be merged with its predecessor or its successor.
1010 * Or both (it neatly fills a hole).
1011 *
1012 * In most cases - when called for mmap, brk or mremap - [addr,end) is
1013 * certain not to be mapped by the time vma_merge is called; but when
1014 * called for mprotect, it is certain to be already mapped (either at
1015 * an offset within prev, or at the start of next), and the flags of
1016 * this area are about to be changed to vm_flags - and the no-change
1017 * case has already been eliminated.
1018 *
1019 * The following mprotect cases have to be considered, where AAAA is
1020 * the area passed down from mprotect_fixup, never extending beyond one
1021 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1022 *
1023 *     AAAA             AAAA                AAAA          AAAA
1024 *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
1025 *    cannot merge    might become    might become    might become
1026 *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
1027 *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
1028 *    mremap move:                                    PPPPNNNNNNNN 8
1029 *        AAAA
1030 *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
1031 *    might become    case 1 below    case 2 below    case 3 below
1032 *
1033 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
1034 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
1035 */
1036struct vm_area_struct *vma_merge(struct mm_struct *mm,
1037                        struct vm_area_struct *prev, unsigned long addr,
1038                        unsigned long end, unsigned long vm_flags,
1039                        struct anon_vma *anon_vma, struct file *file,
1040                        pgoff_t pgoff, struct mempolicy *policy,
1041                        struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1042{
1043        pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1044        struct vm_area_struct *area, *next;
1045        int err;
1046
1047        /*
1048         * We later require that vma->vm_flags == vm_flags,
1049         * so this tests vma->vm_flags & VM_SPECIAL, too.
1050         */
1051        if (vm_flags & VM_SPECIAL)
1052                return NULL;
1053
1054        if (prev)
1055                next = prev->vm_next;
1056        else
1057                next = mm->mmap;
1058        area = next;
1059        if (next && next->vm_end == end)                /* cases 6, 7, 8 */
1060                next = next->vm_next;
1061
1062        /*
1063         * Can it merge with the predecessor?
1064         */
1065        if (prev && prev->vm_end == addr &&
1066                        mpol_equal(vma_policy(prev), policy) &&
1067                        can_vma_merge_after(prev, vm_flags,
1068                                            anon_vma, file, pgoff,
1069                                            vm_userfaultfd_ctx)) {
1070                /*
1071                 * OK, it can.  Can we now merge in the successor as well?
1072                 */
1073                if (next && end == next->vm_start &&
1074                                mpol_equal(policy, vma_policy(next)) &&
1075                                can_vma_merge_before(next, vm_flags,
1076                                                     anon_vma, file,
1077                                                     pgoff+pglen,
1078                                                     vm_userfaultfd_ctx) &&
1079                                is_mergeable_anon_vma(prev->anon_vma,
1080                                                      next->anon_vma, NULL)) {
1081                                                        /* cases 1, 6 */
1082                        err = vma_adjust(prev, prev->vm_start,
1083                                next->vm_end, prev->vm_pgoff, NULL);
1084                } else                                  /* cases 2, 5, 7 */
1085                        err = vma_adjust(prev, prev->vm_start,
1086                                end, prev->vm_pgoff, NULL);
1087                if (err)
1088                        return NULL;
1089                khugepaged_enter_vma_merge(prev, vm_flags);
1090                return prev;
1091        }
1092
1093        /*
1094         * Can this new request be merged in front of next?
1095         */
1096        if (next && end == next->vm_start &&
1097                        mpol_equal(policy, vma_policy(next)) &&
1098                        can_vma_merge_before(next, vm_flags,
1099                                             anon_vma, file, pgoff+pglen,
1100                                             vm_userfaultfd_ctx)) {
1101                if (prev && addr < prev->vm_end)        /* case 4 */
1102                        err = vma_adjust(prev, prev->vm_start,
1103                                addr, prev->vm_pgoff, NULL);
1104                else                                    /* cases 3, 8 */
1105                        err = vma_adjust(area, addr, next->vm_end,
1106                                next->vm_pgoff - pglen, NULL);
1107                if (err)
1108                        return NULL;
1109                khugepaged_enter_vma_merge(area, vm_flags);
1110                return area;
1111        }
1112
1113        return NULL;
1114}
1115
1116/*
1117 * Rough compatbility check to quickly see if it's even worth looking
1118 * at sharing an anon_vma.
1119 *
1120 * They need to have the same vm_file, and the flags can only differ
1121 * in things that mprotect may change.
1122 *
1123 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1124 * we can merge the two vma's. For example, we refuse to merge a vma if
1125 * there is a vm_ops->close() function, because that indicates that the
1126 * driver is doing some kind of reference counting. But that doesn't
1127 * really matter for the anon_vma sharing case.
1128 */
1129static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1130{
1131        return a->vm_end == b->vm_start &&
1132                mpol_equal(vma_policy(a), vma_policy(b)) &&
1133                a->vm_file == b->vm_file &&
1134                !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1135                b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1136}
1137
1138/*
1139 * Do some basic sanity checking to see if we can re-use the anon_vma
1140 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1141 * the same as 'old', the other will be the new one that is trying
1142 * to share the anon_vma.
1143 *
1144 * NOTE! This runs with mm_sem held for reading, so it is possible that
1145 * the anon_vma of 'old' is concurrently in the process of being set up
1146 * by another page fault trying to merge _that_. But that's ok: if it
1147 * is being set up, that automatically means that it will be a singleton
1148 * acceptable for merging, so we can do all of this optimistically. But
1149 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1150 *
1151 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1152 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1153 * is to return an anon_vma that is "complex" due to having gone through
1154 * a fork).
1155 *
1156 * We also make sure that the two vma's are compatible (adjacent,
1157 * and with the same memory policies). That's all stable, even with just
1158 * a read lock on the mm_sem.
1159 */
1160static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1161{
1162        if (anon_vma_compatible(a, b)) {
1163                struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1164
1165                if (anon_vma && list_is_singular(&old->anon_vma_chain))
1166                        return anon_vma;
1167        }
1168        return NULL;
1169}
1170
1171/*
1172 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1173 * neighbouring vmas for a suitable anon_vma, before it goes off
1174 * to allocate a new anon_vma.  It checks because a repetitive
1175 * sequence of mprotects and faults may otherwise lead to distinct
1176 * anon_vmas being allocated, preventing vma merge in subsequent
1177 * mprotect.
1178 */
1179struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1180{
1181        struct anon_vma *anon_vma;
1182        struct vm_area_struct *near;
1183
1184        near = vma->vm_next;
1185        if (!near)
1186                goto try_prev;
1187
1188        anon_vma = reusable_anon_vma(near, vma, near);
1189        if (anon_vma)
1190                return anon_vma;
1191try_prev:
1192        near = vma->vm_prev;
1193        if (!near)
1194                goto none;
1195
1196        anon_vma = reusable_anon_vma(near, near, vma);
1197        if (anon_vma)
1198                return anon_vma;
1199none:
1200        /*
1201         * There's no absolute need to look only at touching neighbours:
1202         * we could search further afield for "compatible" anon_vmas.
1203         * But it would probably just be a waste of time searching,
1204         * or lead to too many vmas hanging off the same anon_vma.
1205         * We're trying to allow mprotect remerging later on,
1206         * not trying to minimize memory used for anon_vmas.
1207         */
1208        return NULL;
1209}
1210
1211#ifdef CONFIG_PROC_FS
1212void vm_stat_account(struct mm_struct *mm, unsigned long flags,
1213                                                struct file *file, long pages)
1214{
1215        const unsigned long stack_flags
1216                = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
1217
1218        mm->total_vm += pages;
1219
1220        if (file) {
1221                mm->shared_vm += pages;
1222                if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
1223                        mm->exec_vm += pages;
1224        } else if (flags & stack_flags)
1225                mm->stack_vm += pages;
1226}
1227#endif /* CONFIG_PROC_FS */
1228
1229/*
1230 * If a hint addr is less than mmap_min_addr change hint to be as
1231 * low as possible but still greater than mmap_min_addr
1232 */
1233static inline unsigned long round_hint_to_min(unsigned long hint)
1234{
1235        hint &= PAGE_MASK;
1236        if (((void *)hint != NULL) &&
1237            (hint < mmap_min_addr))
1238                return PAGE_ALIGN(mmap_min_addr);
1239        return hint;
1240}
1241
1242static inline int mlock_future_check(struct mm_struct *mm,
1243                                     unsigned long flags,
1244                                     unsigned long len)
1245{
1246        unsigned long locked, lock_limit;
1247
1248        /*  mlock MCL_FUTURE? */
1249        if (flags & VM_LOCKED) {
1250                locked = len >> PAGE_SHIFT;
1251                locked += mm->locked_vm;
1252                lock_limit = rlimit(RLIMIT_MEMLOCK);
1253                lock_limit >>= PAGE_SHIFT;
1254                if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1255                        return -EAGAIN;
1256        }
1257        return 0;
1258}
1259
1260/*
1261 * The caller must hold down_write(&current->mm->mmap_sem).
1262 */
1263unsigned long do_mmap(struct file *file, unsigned long addr,
1264                        unsigned long len, unsigned long prot,
1265                        unsigned long flags, vm_flags_t vm_flags,
1266                        unsigned long pgoff, unsigned long *populate)
1267{
1268        struct mm_struct *mm = current->mm;
1269
1270        *populate = 0;
1271
1272        if (!len)
1273                return -EINVAL;
1274
1275        /*
1276         * Does the application expect PROT_READ to imply PROT_EXEC?
1277         *
1278         * (the exception is when the underlying filesystem is noexec
1279         *  mounted, in which case we dont add PROT_EXEC.)
1280         */
1281        if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1282                if (!(file && path_noexec(&file->f_path)))
1283                        prot |= PROT_EXEC;
1284
1285        if (!(flags & MAP_FIXED))
1286                addr = round_hint_to_min(addr);
1287
1288        /* Careful about overflows.. */
1289        len = PAGE_ALIGN(len);
1290        if (!len)
1291                return -ENOMEM;
1292
1293        /* offset overflow? */
1294        if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1295                return -EOVERFLOW;
1296
1297        /* Too many mappings? */
1298        if (mm->map_count > sysctl_max_map_count)
1299                return -ENOMEM;
1300
1301        /* Obtain the address to map to. we verify (or select) it and ensure
1302         * that it represents a valid section of the address space.
1303         */
1304        addr = get_unmapped_area(file, addr, len, pgoff, flags);
1305        if (addr & ~PAGE_MASK)
1306                return addr;
1307
1308        /* Do simple checking here so the lower-level routines won't have
1309         * to. we assume access permissions have been handled by the open
1310         * of the memory object, so we don't do any here.
1311         */
1312        vm_flags |= calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1313                        mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1314
1315        if (flags & MAP_LOCKED)
1316                if (!can_do_mlock())
1317                        return -EPERM;
1318
1319        if (mlock_future_check(mm, vm_flags, len))
1320                return -EAGAIN;
1321
1322        if (file) {
1323                struct inode *inode = file_inode(file);
1324
1325                switch (flags & MAP_TYPE) {
1326                case MAP_SHARED:
1327                        if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1328                                return -EACCES;
1329
1330                        /*
1331                         * Make sure we don't allow writing to an append-only
1332                         * file..
1333                         */
1334                        if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1335                                return -EACCES;
1336
1337                        /*
1338                         * Make sure there are no mandatory locks on the file.
1339                         */
1340                        if (locks_verify_locked(file))
1341                                return -EAGAIN;
1342
1343                        vm_flags |= VM_SHARED | VM_MAYSHARE;
1344                        if (!(file->f_mode & FMODE_WRITE))
1345                                vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1346
1347                        /* fall through */
1348                case MAP_PRIVATE:
1349                        if (!(file->f_mode & FMODE_READ))
1350                                return -EACCES;
1351                        if (path_noexec(&file->f_path)) {
1352                                if (vm_flags & VM_EXEC)
1353                                        return -EPERM;
1354                                vm_flags &= ~VM_MAYEXEC;
1355                        }
1356
1357                        if (!file->f_op->mmap)
1358                                return -ENODEV;
1359                        if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1360                                return -EINVAL;
1361                        break;
1362
1363                default:
1364                        return -EINVAL;
1365                }
1366        } else {
1367                switch (flags & MAP_TYPE) {
1368                case MAP_SHARED:
1369                        if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1370                                return -EINVAL;
1371                        /*
1372                         * Ignore pgoff.
1373                         */
1374                        pgoff = 0;
1375                        vm_flags |= VM_SHARED | VM_MAYSHARE;
1376                        break;
1377                case MAP_PRIVATE:
1378                        /*
1379                         * Set pgoff according to addr for anon_vma.
1380                         */
1381                        pgoff = addr >> PAGE_SHIFT;
1382                        break;
1383                default:
1384                        return -EINVAL;
1385                }
1386        }
1387
1388        /*
1389         * Set 'VM_NORESERVE' if we should not account for the
1390         * memory use of this mapping.
1391         */
1392        if (flags & MAP_NORESERVE) {
1393                /* We honor MAP_NORESERVE if allowed to overcommit */
1394                if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1395                        vm_flags |= VM_NORESERVE;
1396
1397                /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1398                if (file && is_file_hugepages(file))
1399                        vm_flags |= VM_NORESERVE;
1400        }
1401
1402        addr = mmap_region(file, addr, len, vm_flags, pgoff);
1403        if (!IS_ERR_VALUE(addr) &&
1404            ((vm_flags & VM_LOCKED) ||
1405             (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1406                *populate = len;
1407        return addr;
1408}
1409
1410SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1411                unsigned long, prot, unsigned long, flags,
1412                unsigned long, fd, unsigned long, pgoff)
1413{
1414        struct file *file = NULL;
1415        unsigned long retval = -EBADF;
1416
1417        if (!(flags & MAP_ANONYMOUS)) {
1418                audit_mmap_fd(fd, flags);
1419                file = fget(fd);
1420                if (!file)
1421                        goto out;
1422                if (is_file_hugepages(file))
1423                        len = ALIGN(len, huge_page_size(hstate_file(file)));
1424                retval = -EINVAL;
1425                if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1426                        goto out_fput;
1427        } else if (flags & MAP_HUGETLB) {
1428                struct user_struct *user = NULL;
1429                struct hstate *hs;
1430
1431                hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1432                if (!hs)
1433                        return -EINVAL;
1434
1435                len = ALIGN(len, huge_page_size(hs));
1436                /*
1437                 * VM_NORESERVE is used because the reservations will be
1438                 * taken when vm_ops->mmap() is called
1439                 * A dummy user value is used because we are not locking
1440                 * memory so no accounting is necessary
1441                 */
1442                file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1443                                VM_NORESERVE,
1444                                &user, HUGETLB_ANONHUGE_INODE,
1445                                (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1446                if (IS_ERR(file))
1447                        return PTR_ERR(file);
1448        }
1449
1450        flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1451
1452        retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1453out_fput:
1454        if (file)
1455                fput(file);
1456out:
1457        return retval;
1458}
1459
1460#ifdef __ARCH_WANT_SYS_OLD_MMAP
1461struct mmap_arg_struct {
1462        unsigned long addr;
1463        unsigned long len;
1464        unsigned long prot;
1465        unsigned long flags;
1466        unsigned long fd;
1467        unsigned long offset;
1468};
1469
1470SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1471{
1472        struct mmap_arg_struct a;
1473
1474        if (copy_from_user(&a, arg, sizeof(a)))
1475                return -EFAULT;
1476        if (a.offset & ~PAGE_MASK)
1477                return -EINVAL;
1478
1479        return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1480                              a.offset >> PAGE_SHIFT);
1481}
1482#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1483
1484/*
1485 * Some shared mappigns will want the pages marked read-only
1486 * to track write events. If so, we'll downgrade vm_page_prot
1487 * to the private version (using protection_map[] without the
1488 * VM_SHARED bit).
1489 */
1490int vma_wants_writenotify(struct vm_area_struct *vma)
1491{
1492        vm_flags_t vm_flags = vma->vm_flags;
1493        const struct vm_operations_struct *vm_ops = vma->vm_ops;
1494
1495        /* If it was private or non-writable, the write bit is already clear */
1496        if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1497                return 0;
1498
1499        /* The backer wishes to know when pages are first written to? */
1500        if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1501                return 1;
1502
1503        /* The open routine did something to the protections that pgprot_modify
1504         * won't preserve? */
1505        if (pgprot_val(vma->vm_page_prot) !=
1506            pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags)))
1507                return 0;
1508
1509        /* Do we need to track softdirty? */
1510        if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1511                return 1;
1512
1513        /* Specialty mapping? */
1514        if (vm_flags & VM_PFNMAP)
1515                return 0;
1516
1517        /* Can the mapping track the dirty pages? */
1518        return vma->vm_file && vma->vm_file->f_mapping &&
1519                mapping_cap_account_dirty(vma->vm_file->f_mapping);
1520}
1521
1522/*
1523 * We account for memory if it's a private writeable mapping,
1524 * not hugepages and VM_NORESERVE wasn't set.
1525 */
1526static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1527{
1528        /*
1529         * hugetlb has its own accounting separate from the core VM
1530         * VM_HUGETLB may not be set yet so we cannot check for that flag.
1531         */
1532        if (file && is_file_hugepages(file))
1533                return 0;
1534
1535        return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1536}
1537
1538unsigned long mmap_region(struct file *file, unsigned long addr,
1539                unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1540{
1541        struct mm_struct *mm = current->mm;
1542        struct vm_area_struct *vma, *prev;
1543        int error;
1544        struct rb_node **rb_link, *rb_parent;
1545        unsigned long charged = 0;
1546
1547        /* Check against address space limit. */
1548        if (!may_expand_vm(mm, len >> PAGE_SHIFT)) {
1549                unsigned long nr_pages;
1550
1551                /*
1552                 * MAP_FIXED may remove pages of mappings that intersects with
1553                 * requested mapping. Account for the pages it would unmap.
1554                 */
1555                if (!(vm_flags & MAP_FIXED))
1556                        return -ENOMEM;
1557
1558                nr_pages = count_vma_pages_range(mm, addr, addr + len);
1559
1560                if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages))
1561                        return -ENOMEM;
1562        }
1563
1564        /* Clear old maps */
1565        error = -ENOMEM;
1566        while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
1567                              &rb_parent)) {
1568                if (do_munmap(mm, addr, len))
1569                        return -ENOMEM;
1570        }
1571
1572        /*
1573         * Private writable mapping: check memory availability
1574         */
1575        if (accountable_mapping(file, vm_flags)) {
1576                charged = len >> PAGE_SHIFT;
1577                if (security_vm_enough_memory_mm(mm, charged))
1578                        return -ENOMEM;
1579                vm_flags |= VM_ACCOUNT;
1580        }
1581
1582        /*
1583         * Can we just expand an old mapping?
1584         */
1585        vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1586                        NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1587        if (vma)
1588                goto out;
1589
1590        /*
1591         * Determine the object being mapped and call the appropriate
1592         * specific mapper. the address has already been validated, but
1593         * not unmapped, but the maps are removed from the list.
1594         */
1595        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1596        if (!vma) {
1597                error = -ENOMEM;
1598                goto unacct_error;
1599        }
1600
1601        vma->vm_mm = mm;
1602        vma->vm_start = addr;
1603        vma->vm_end = addr + len;
1604        vma->vm_flags = vm_flags;
1605        vma->vm_page_prot = vm_get_page_prot(vm_flags);
1606        vma->vm_pgoff = pgoff;
1607        INIT_LIST_HEAD(&vma->anon_vma_chain);
1608
1609        if (file) {
1610                if (vm_flags & VM_DENYWRITE) {
1611                        error = deny_write_access(file);
1612                        if (error)
1613                                goto free_vma;
1614                }
1615                if (vm_flags & VM_SHARED) {
1616                        error = mapping_map_writable(file->f_mapping);
1617                        if (error)
1618                                goto allow_write_and_free_vma;
1619                }
1620
1621                /* ->mmap() can change vma->vm_file, but must guarantee that
1622                 * vma_link() below can deny write-access if VM_DENYWRITE is set
1623                 * and map writably if VM_SHARED is set. This usually means the
1624                 * new file must not have been exposed to user-space, yet.
1625                 */
1626                vma->vm_file = get_file(file);
1627                error = file->f_op->mmap(file, vma);
1628                if (error)
1629                        goto unmap_and_free_vma;
1630
1631                /* Can addr have changed??
1632                 *
1633                 * Answer: Yes, several device drivers can do it in their
1634                 *         f_op->mmap method. -DaveM
1635                 * Bug: If addr is changed, prev, rb_link, rb_parent should
1636                 *      be updated for vma_link()
1637                 */
1638                WARN_ON_ONCE(addr != vma->vm_start);
1639
1640                addr = vma->vm_start;
1641                vm_flags = vma->vm_flags;
1642        } else if (vm_flags & VM_SHARED) {
1643                error = shmem_zero_setup(vma);
1644                if (error)
1645                        goto free_vma;
1646        }
1647
1648        vma_link(mm, vma, prev, rb_link, rb_parent);
1649        /* Once vma denies write, undo our temporary denial count */
1650        if (file) {
1651                if (vm_flags & VM_SHARED)
1652                        mapping_unmap_writable(file->f_mapping);
1653                if (vm_flags & VM_DENYWRITE)
1654                        allow_write_access(file);
1655        }
1656        file = vma->vm_file;
1657out:
1658        perf_event_mmap(vma);
1659
1660        vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1661        if (vm_flags & VM_LOCKED) {
1662                if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1663                                        vma == get_gate_vma(current->mm)))
1664                        mm->locked_vm += (len >> PAGE_SHIFT);
1665                else
1666                        vma->vm_flags &= ~VM_LOCKED;
1667        }
1668
1669        if (file)
1670                uprobe_mmap(vma);
1671
1672        /*
1673         * New (or expanded) vma always get soft dirty status.
1674         * Otherwise user-space soft-dirty page tracker won't
1675         * be able to distinguish situation when vma area unmapped,
1676         * then new mapped in-place (which must be aimed as
1677         * a completely new data area).
1678         */
1679        vma->vm_flags |= VM_SOFTDIRTY;
1680
1681        vma_set_page_prot(vma);
1682
1683        return addr;
1684
1685unmap_and_free_vma:
1686        vma->vm_file = NULL;
1687        fput(file);
1688
1689        /* Undo any partial mapping done by a device driver. */
1690        unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1691        charged = 0;
1692        if (vm_flags & VM_SHARED)
1693                mapping_unmap_writable(file->f_mapping);
1694allow_write_and_free_vma:
1695        if (vm_flags & VM_DENYWRITE)
1696                allow_write_access(file);
1697free_vma:
1698        kmem_cache_free(vm_area_cachep, vma);
1699unacct_error:
1700        if (charged)
1701                vm_unacct_memory(charged);
1702        return error;
1703}
1704
1705unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1706{
1707        /*
1708         * We implement the search by looking for an rbtree node that
1709         * immediately follows a suitable gap. That is,
1710         * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1711         * - gap_end   = vma->vm_start        >= info->low_limit  + length;
1712         * - gap_end - gap_start >= length
1713         */
1714
1715        struct mm_struct *mm = current->mm;
1716        struct vm_area_struct *vma;
1717        unsigned long length, low_limit, high_limit, gap_start, gap_end;
1718
1719        /* Adjust search length to account for worst case alignment overhead */
1720        length = info->length + info->align_mask;
1721        if (length < info->length)
1722                return -ENOMEM;
1723
1724        /* Adjust search limits by the desired length */
1725        if (info->high_limit < length)
1726                return -ENOMEM;
1727        high_limit = info->high_limit - length;
1728
1729        if (info->low_limit > high_limit)
1730                return -ENOMEM;
1731        low_limit = info->low_limit + length;
1732
1733        /* Check if rbtree root looks promising */
1734        if (RB_EMPTY_ROOT(&mm->mm_rb))
1735                goto check_highest;
1736        vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1737        if (vma->rb_subtree_gap < length)
1738                goto check_highest;
1739
1740        while (true) {
1741                /* Visit left subtree if it looks promising */
1742                gap_end = vma->vm_start;
1743                if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1744                        struct vm_area_struct *left =
1745                                rb_entry(vma->vm_rb.rb_left,
1746                                         struct vm_area_struct, vm_rb);
1747                        if (left->rb_subtree_gap >= length) {
1748                                vma = left;
1749                                continue;
1750                        }
1751                }
1752
1753                gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1754check_current:
1755                /* Check if current node has a suitable gap */
1756                if (gap_start > high_limit)
1757                        return -ENOMEM;
1758                if (gap_end >= low_limit && gap_end - gap_start >= length)
1759                        goto found;
1760
1761                /* Visit right subtree if it looks promising */
1762                if (vma->vm_rb.rb_right) {
1763                        struct vm_area_struct *right =
1764                                rb_entry(vma->vm_rb.rb_right,
1765                                         struct vm_area_struct, vm_rb);
1766                        if (right->rb_subtree_gap >= length) {
1767                                vma = right;
1768                                continue;
1769                        }
1770                }
1771
1772                /* Go back up the rbtree to find next candidate node */
1773                while (true) {
1774                        struct rb_node *prev = &vma->vm_rb;
1775                        if (!rb_parent(prev))
1776                                goto check_highest;
1777                        vma = rb_entry(rb_parent(prev),
1778                                       struct vm_area_struct, vm_rb);
1779                        if (prev == vma->vm_rb.rb_left) {
1780                                gap_start = vma->vm_prev->vm_end;
1781                                gap_end = vma->vm_start;
1782                                goto check_current;
1783                        }
1784                }
1785        }
1786
1787check_highest:
1788        /* Check highest gap, which does not precede any rbtree node */
1789        gap_start = mm->highest_vm_end;
1790        gap_end = ULONG_MAX;  /* Only for VM_BUG_ON below */
1791        if (gap_start > high_limit)
1792                return -ENOMEM;
1793
1794found:
1795        /* We found a suitable gap. Clip it with the original low_limit. */
1796        if (gap_start < info->low_limit)
1797                gap_start = info->low_limit;
1798
1799        /* Adjust gap address to the desired alignment */
1800        gap_start += (info->align_offset - gap_start) & info->align_mask;
1801
1802        VM_BUG_ON(gap_start + info->length > info->high_limit);
1803        VM_BUG_ON(gap_start + info->length > gap_end);
1804        return gap_start;
1805}
1806
1807unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1808{
1809        struct mm_struct *mm = current->mm;
1810        struct vm_area_struct *vma;
1811        unsigned long length, low_limit, high_limit, gap_start, gap_end;
1812
1813        /* Adjust search length to account for worst case alignment overhead */
1814        length = info->length + info->align_mask;
1815        if (length < info->length)
1816                return -ENOMEM;
1817
1818        /*
1819         * Adjust search limits by the desired length.
1820         * See implementation comment at top of unmapped_area().
1821         */
1822        gap_end = info->high_limit;
1823        if (gap_end < length)
1824                return -ENOMEM;
1825        high_limit = gap_end - length;
1826
1827        if (info->low_limit > high_limit)
1828                return -ENOMEM;
1829        low_limit = info->low_limit + length;
1830
1831        /* Check highest gap, which does not precede any rbtree node */
1832        gap_start = mm->highest_vm_end;
1833        if (gap_start <= high_limit)
1834                goto found_highest;
1835
1836        /* Check if rbtree root looks promising */
1837        if (RB_EMPTY_ROOT(&mm->mm_rb))
1838                return -ENOMEM;
1839        vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1840        if (vma->rb_subtree_gap < length)
1841                return -ENOMEM;
1842
1843        while (true) {
1844                /* Visit right subtree if it looks promising */
1845                gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1846                if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1847                        struct vm_area_struct *right =
1848                                rb_entry(vma->vm_rb.rb_right,
1849                                         struct vm_area_struct, vm_rb);
1850                        if (right->rb_subtree_gap >= length) {
1851                                vma = right;
1852                                continue;
1853                        }
1854                }
1855
1856check_current:
1857                /* Check if current node has a suitable gap */
1858                gap_end = vma->vm_start;
1859                if (gap_end < low_limit)
1860                        return -ENOMEM;
1861                if (gap_start <= high_limit && gap_end - gap_start >= length)
1862                        goto found;
1863
1864                /* Visit left subtree if it looks promising */
1865                if (vma->vm_rb.rb_left) {
1866                        struct vm_area_struct *left =
1867                                rb_entry(vma->vm_rb.rb_left,
1868                                         struct vm_area_struct, vm_rb);
1869                        if (left->rb_subtree_gap >= length) {
1870                                vma = left;
1871                                continue;
1872                        }
1873                }
1874
1875                /* Go back up the rbtree to find next candidate node */
1876                while (true) {
1877                        struct rb_node *prev = &vma->vm_rb;
1878                        if (!rb_parent(prev))
1879                                return -ENOMEM;
1880                        vma = rb_entry(rb_parent(prev),
1881                                       struct vm_area_struct, vm_rb);
1882                        if (prev == vma->vm_rb.rb_right) {
1883                                gap_start = vma->vm_prev ?
1884                                        vma->vm_prev->vm_end : 0;
1885                                goto check_current;
1886                        }
1887                }
1888        }
1889
1890found:
1891        /* We found a suitable gap. Clip it with the original high_limit. */
1892        if (gap_end > info->high_limit)
1893                gap_end = info->high_limit;
1894
1895found_highest:
1896        /* Compute highest gap address at the desired alignment */
1897        gap_end -= info->length;
1898        gap_end -= (gap_end - info->align_offset) & info->align_mask;
1899
1900        VM_BUG_ON(gap_end < info->low_limit);
1901        VM_BUG_ON(gap_end < gap_start);
1902        return gap_end;
1903}
1904
1905/* Get an address range which is currently unmapped.
1906 * For shmat() with addr=0.
1907 *
1908 * Ugly calling convention alert:
1909 * Return value with the low bits set means error value,
1910 * ie
1911 *      if (ret & ~PAGE_MASK)
1912 *              error = ret;
1913 *
1914 * This function "knows" that -ENOMEM has the bits set.
1915 */
1916#ifndef HAVE_ARCH_UNMAPPED_AREA
1917unsigned long
1918arch_get_unmapped_area(struct file *filp, unsigned long addr,
1919                unsigned long len, unsigned long pgoff, unsigned long flags)
1920{
1921        struct mm_struct *mm = current->mm;
1922        struct vm_area_struct *vma;
1923        struct vm_unmapped_area_info info;
1924
1925        if (len > TASK_SIZE - mmap_min_addr)
1926                return -ENOMEM;
1927
1928        if (flags & MAP_FIXED)
1929                return addr;
1930
1931        if (addr) {
1932                addr = PAGE_ALIGN(addr);
1933                vma = find_vma(mm, addr);
1934                if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1935                    (!vma || addr + len <= vma->vm_start))
1936                        return addr;
1937        }
1938
1939        info.flags = 0;
1940        info.length = len;
1941        info.low_limit = mm->mmap_base;
1942        info.high_limit = TASK_SIZE;
1943        info.align_mask = 0;
1944        return vm_unmapped_area(&info);
1945}
1946#endif
1947
1948/*
1949 * This mmap-allocator allocates new areas top-down from below the
1950 * stack's low limit (the base):
1951 */
1952#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1953unsigned long
1954arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1955                          const unsigned long len, const unsigned long pgoff,
1956                          const unsigned long flags)
1957{
1958        struct vm_area_struct *vma;
1959        struct mm_struct *mm = current->mm;
1960        unsigned long addr = addr0;
1961        struct vm_unmapped_area_info info;
1962
1963        /* requested length too big for entire address space */
1964        if (len > TASK_SIZE - mmap_min_addr)
1965                return -ENOMEM;
1966
1967        if (flags & MAP_FIXED)
1968                return addr;
1969
1970        /* requesting a specific address */
1971        if (addr) {
1972                addr = PAGE_ALIGN(addr);
1973                vma = find_vma(mm, addr);
1974                if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1975                                (!vma || addr + len <= vma->vm_start))
1976                        return addr;
1977        }
1978
1979        info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1980        info.length = len;
1981        info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1982        info.high_limit = mm->mmap_base;
1983        info.align_mask = 0;
1984        addr = vm_unmapped_area(&info);
1985
1986        /*
1987         * A failed mmap() very likely causes application failure,
1988         * so fall back to the bottom-up function here. This scenario
1989         * can happen with large stack limits and large mmap()
1990         * allocations.
1991         */
1992        if (addr & ~PAGE_MASK) {
1993                VM_BUG_ON(addr != -ENOMEM);
1994                info.flags = 0;
1995                info.low_limit = TASK_UNMAPPED_BASE;
1996                info.high_limit = TASK_SIZE;
1997                addr = vm_unmapped_area(&info);
1998        }
1999
2000        return addr;
2001}
2002#endif
2003
2004unsigned long
2005get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
2006                unsigned long pgoff, unsigned long flags)
2007{
2008        unsigned long (*get_area)(struct file *, unsigned long,
2009                                  unsigned long, unsigned long, unsigned long);
2010
2011        unsigned long error = arch_mmap_check(addr, len, flags);
2012        if (error)
2013                return error;
2014
2015        /* Careful about overflows.. */
2016        if (len > TASK_SIZE)
2017                return -ENOMEM;
2018
2019        get_area = current->mm->get_unmapped_area;
2020        if (file && file->f_op->get_unmapped_area)
2021                get_area = file->f_op->get_unmapped_area;
2022        addr = get_area(file, addr, len, pgoff, flags);
2023        if (IS_ERR_VALUE(addr))
2024                return addr;
2025
2026        if (addr > TASK_SIZE - len)
2027                return -ENOMEM;
2028        if (addr & ~PAGE_MASK)
2029                return -EINVAL;
2030
2031        addr = arch_rebalance_pgtables(addr, len);
2032        error = security_mmap_addr(addr);
2033        return error ? error : addr;
2034}
2035
2036EXPORT_SYMBOL(get_unmapped_area);
2037
2038/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
2039struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
2040{
2041        struct rb_node *rb_node;
2042        struct vm_area_struct *vma;
2043
2044        /* Check the cache first. */
2045        vma = vmacache_find(mm, addr);
2046        if (likely(vma))
2047                return vma;
2048
2049        rb_node = mm->mm_rb.rb_node;
2050        vma = NULL;
2051
2052        while (rb_node) {
2053                struct vm_area_struct *tmp;
2054
2055                tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2056
2057                if (tmp->vm_end > addr) {
2058                        vma = tmp;
2059                        if (tmp->vm_start <= addr)
2060                                break;
2061                        rb_node = rb_node->rb_left;
2062                } else
2063                        rb_node = rb_node->rb_right;
2064        }
2065
2066        if (vma)
2067                vmacache_update(addr, vma);
2068        return vma;
2069}
2070
2071EXPORT_SYMBOL(find_vma);
2072
2073/*
2074 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2075 */
2076struct vm_area_struct *
2077find_vma_prev(struct mm_struct *mm, unsigned long addr,
2078                        struct vm_area_struct **pprev)
2079{
2080        struct vm_area_struct *vma;
2081
2082        vma = find_vma(mm, addr);
2083        if (vma) {
2084                *pprev = vma->vm_prev;
2085        } else {
2086                struct rb_node *rb_node = mm->mm_rb.rb_node;
2087                *pprev = NULL;
2088                while (rb_node) {
2089                        *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2090                        rb_node = rb_node->rb_right;
2091                }
2092        }
2093        return vma;
2094}
2095
2096/*
2097 * Verify that the stack growth is acceptable and
2098 * update accounting. This is shared with both the
2099 * grow-up and grow-down cases.
2100 */
2101static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
2102{
2103        struct mm_struct *mm = vma->vm_mm;
2104        struct rlimit *rlim = current->signal->rlim;
2105        unsigned long new_start, actual_size;
2106
2107        /* address space limit tests */
2108        if (!may_expand_vm(mm, grow))
2109                return -ENOMEM;
2110
2111        /* Stack limit test */
2112        actual_size = size;
2113        if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
2114                actual_size -= PAGE_SIZE;
2115        if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
2116                return -ENOMEM;
2117
2118        /* mlock limit tests */
2119        if (vma->vm_flags & VM_LOCKED) {
2120                unsigned long locked;
2121                unsigned long limit;
2122                locked = mm->locked_vm + grow;
2123                limit = READ_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
2124                limit >>= PAGE_SHIFT;
2125                if (locked > limit && !capable(CAP_IPC_LOCK))
2126                        return -ENOMEM;
2127        }
2128
2129        /* Check to ensure the stack will not grow into a hugetlb-only region */
2130        new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2131                        vma->vm_end - size;
2132        if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2133                return -EFAULT;
2134
2135        /*
2136         * Overcommit..  This must be the final test, as it will
2137         * update security statistics.
2138         */
2139        if (security_vm_enough_memory_mm(mm, grow))
2140                return -ENOMEM;
2141
2142        /* Ok, everything looks good - let it rip */
2143        if (vma->vm_flags & VM_LOCKED)
2144                mm->locked_vm += grow;
2145        vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
2146        return 0;
2147}
2148
2149#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2150/*
2151 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2152 * vma is the last one with address > vma->vm_end.  Have to extend vma.
2153 */
2154int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2155{
2156        int error;
2157
2158        if (!(vma->vm_flags & VM_GROWSUP))
2159                return -EFAULT;
2160
2161        /*
2162         * We must make sure the anon_vma is allocated
2163         * so that the anon_vma locking is not a noop.
2164         */
2165        if (unlikely(anon_vma_prepare(vma)))
2166                return -ENOMEM;
2167        vma_lock_anon_vma(vma);
2168
2169        /*
2170         * vma->vm_start/vm_end cannot change under us because the caller
2171         * is required to hold the mmap_sem in read mode.  We need the
2172         * anon_vma lock to serialize against concurrent expand_stacks.
2173         * Also guard against wrapping around to address 0.
2174         */
2175        if (address < PAGE_ALIGN(address+4))
2176                address = PAGE_ALIGN(address+4);
2177        else {
2178                vma_unlock_anon_vma(vma);
2179                return -ENOMEM;
2180        }
2181        error = 0;
2182
2183        /* Somebody else might have raced and expanded it already */
2184        if (address > vma->vm_end) {
2185                unsigned long size, grow;
2186
2187                size = address - vma->vm_start;
2188                grow = (address - vma->vm_end) >> PAGE_SHIFT;
2189
2190                error = -ENOMEM;
2191                if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2192                        error = acct_stack_growth(vma, size, grow);
2193                        if (!error) {
2194                                /*
2195                                 * vma_gap_update() doesn't support concurrent
2196                                 * updates, but we only hold a shared mmap_sem
2197                                 * lock here, so we need to protect against
2198                                 * concurrent vma expansions.
2199                                 * vma_lock_anon_vma() doesn't help here, as
2200                                 * we don't guarantee that all growable vmas
2201                                 * in a mm share the same root anon vma.
2202                                 * So, we reuse mm->page_table_lock to guard
2203                                 * against concurrent vma expansions.
2204                                 */
2205                                spin_lock(&vma->vm_mm->page_table_lock);
2206                                anon_vma_interval_tree_pre_update_vma(vma);
2207                                vma->vm_end = address;
2208                                anon_vma_interval_tree_post_update_vma(vma);
2209                                if (vma->vm_next)
2210                                        vma_gap_update(vma->vm_next);
2211                                else
2212                                        vma->vm_mm->highest_vm_end = address;
2213                                spin_unlock(&vma->vm_mm->page_table_lock);
2214
2215                                perf_event_mmap(vma);
2216                        }
2217                }
2218        }
2219        vma_unlock_anon_vma(vma);
2220        khugepaged_enter_vma_merge(vma, vma->vm_flags);
2221        validate_mm(vma->vm_mm);
2222        return error;
2223}
2224#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2225
2226/*
2227 * vma is the first one with address < vma->vm_start.  Have to extend vma.
2228 */
2229int expand_downwards(struct vm_area_struct *vma,
2230                                   unsigned long address)
2231{
2232        int error;
2233
2234        /*
2235         * We must make sure the anon_vma is allocated
2236         * so that the anon_vma locking is not a noop.
2237         */
2238        if (unlikely(anon_vma_prepare(vma)))
2239                return -ENOMEM;
2240
2241        address &= PAGE_MASK;
2242        error = security_mmap_addr(address);
2243        if (error)
2244                return error;
2245
2246        vma_lock_anon_vma(vma);
2247
2248        /*
2249         * vma->vm_start/vm_end cannot change under us because the caller
2250         * is required to hold the mmap_sem in read mode.  We need the
2251         * anon_vma lock to serialize against concurrent expand_stacks.
2252         */
2253
2254        /* Somebody else might have raced and expanded it already */
2255        if (address < vma->vm_start) {
2256                unsigned long size, grow;
2257
2258                size = vma->vm_end - address;
2259                grow = (vma->vm_start - address) >> PAGE_SHIFT;
2260
2261                error = -ENOMEM;
2262                if (grow <= vma->vm_pgoff) {
2263                        error = acct_stack_growth(vma, size, grow);
2264                        if (!error) {
2265                                /*
2266                                 * vma_gap_update() doesn't support concurrent
2267                                 * updates, but we only hold a shared mmap_sem
2268                                 * lock here, so we need to protect against
2269                                 * concurrent vma expansions.
2270                                 * vma_lock_anon_vma() doesn't help here, as
2271                                 * we don't guarantee that all growable vmas
2272                                 * in a mm share the same root anon vma.
2273                                 * So, we reuse mm->page_table_lock to guard
2274                                 * against concurrent vma expansions.
2275                                 */
2276                                spin_lock(&vma->vm_mm->page_table_lock);
2277                                anon_vma_interval_tree_pre_update_vma(vma);
2278                                vma->vm_start = address;
2279                                vma->vm_pgoff -= grow;
2280                                anon_vma_interval_tree_post_update_vma(vma);
2281                                vma_gap_update(vma);
2282                                spin_unlock(&vma->vm_mm->page_table_lock);
2283
2284                                perf_event_mmap(vma);
2285                        }
2286                }
2287        }
2288        vma_unlock_anon_vma(vma);
2289        khugepaged_enter_vma_merge(vma, vma->vm_flags);
2290        validate_mm(vma->vm_mm);
2291        return error;
2292}
2293
2294/*
2295 * Note how expand_stack() refuses to expand the stack all the way to
2296 * abut the next virtual mapping, *unless* that mapping itself is also
2297 * a stack mapping. We want to leave room for a guard page, after all
2298 * (the guard page itself is not added here, that is done by the
2299 * actual page faulting logic)
2300 *
2301 * This matches the behavior of the guard page logic (see mm/memory.c:
2302 * check_stack_guard_page()), which only allows the guard page to be
2303 * removed under these circumstances.
2304 */
2305#ifdef CONFIG_STACK_GROWSUP
2306int expand_stack(struct vm_area_struct *vma, unsigned long address)
2307{
2308        struct vm_area_struct *next;
2309
2310        address &= PAGE_MASK;
2311        next = vma->vm_next;
2312        if (next && next->vm_start == address + PAGE_SIZE) {
2313                if (!(next->vm_flags & VM_GROWSUP))
2314                        return -ENOMEM;
2315        }
2316        return expand_upwards(vma, address);
2317}
2318
2319struct vm_area_struct *
2320find_extend_vma(struct mm_struct *mm, unsigned long addr)
2321{
2322        struct vm_area_struct *vma, *prev;
2323
2324        addr &= PAGE_MASK;
2325        vma = find_vma_prev(mm, addr, &prev);
2326        if (vma && (vma->vm_start <= addr))
2327                return vma;
2328        if (!prev || expand_stack(prev, addr))
2329                return NULL;
2330        if (prev->vm_flags & VM_LOCKED)
2331                populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2332        return prev;
2333}
2334#else
2335int expand_stack(struct vm_area_struct *vma, unsigned long address)
2336{
2337        struct vm_area_struct *prev;
2338
2339        address &= PAGE_MASK;
2340        prev = vma->vm_prev;
2341        if (prev && prev->vm_end == address) {
2342                if (!(prev->vm_flags & VM_GROWSDOWN))
2343                        return -ENOMEM;
2344        }
2345        return expand_downwards(vma, address);
2346}
2347
2348struct vm_area_struct *
2349find_extend_vma(struct mm_struct *mm, unsigned long addr)
2350{
2351        struct vm_area_struct *vma;
2352        unsigned long start;
2353
2354        addr &= PAGE_MASK;
2355        vma = find_vma(mm, addr);
2356        if (!vma)
2357                return NULL;
2358        if (vma->vm_start <= addr)
2359                return vma;
2360        if (!(vma->vm_flags & VM_GROWSDOWN))
2361                return NULL;
2362        start = vma->vm_start;
2363        if (expand_stack(vma, addr))
2364                return NULL;
2365        if (vma->vm_flags & VM_LOCKED)
2366                populate_vma_page_range(vma, addr, start, NULL);
2367        return vma;
2368}
2369#endif
2370
2371EXPORT_SYMBOL_GPL(find_extend_vma);
2372
2373/*
2374 * Ok - we have the memory areas we should free on the vma list,
2375 * so release them, and do the vma updates.
2376 *
2377 * Called with the mm semaphore held.
2378 */
2379static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2380{
2381        unsigned long nr_accounted = 0;
2382
2383        /* Update high watermark before we lower total_vm */
2384        update_hiwater_vm(mm);
2385        do {
2386                long nrpages = vma_pages(vma);
2387
2388                if (vma->vm_flags & VM_ACCOUNT)
2389                        nr_accounted += nrpages;
2390                vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2391                vma = remove_vma(vma);
2392        } while (vma);
2393        vm_unacct_memory(nr_accounted);
2394        validate_mm(mm);
2395}
2396
2397/*
2398 * Get rid of page table information in the indicated region.
2399 *
2400 * Called with the mm semaphore held.
2401 */
2402static void unmap_region(struct mm_struct *mm,
2403                struct vm_area_struct *vma, struct vm_area_struct *prev,
2404                unsigned long start, unsigned long end)
2405{
2406        struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2407        struct mmu_gather tlb;
2408
2409        lru_add_drain();
2410        tlb_gather_mmu(&tlb, mm, start, end);
2411        update_hiwater_rss(mm);
2412        unmap_vmas(&tlb, vma, start, end);
2413        free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2414                                 next ? next->vm_start : USER_PGTABLES_CEILING);
2415        tlb_finish_mmu(&tlb, start, end);
2416}
2417
2418/*
2419 * Create a list of vma's touched by the unmap, removing them from the mm's
2420 * vma list as we go..
2421 */
2422static void
2423detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2424        struct vm_area_struct *prev, unsigned long end)
2425{
2426        struct vm_area_struct **insertion_point;
2427        struct vm_area_struct *tail_vma = NULL;
2428
2429        insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2430        vma->vm_prev = NULL;
2431        do {
2432                vma_rb_erase(vma, &mm->mm_rb);
2433                mm->map_count--;
2434                tail_vma = vma;
2435                vma = vma->vm_next;
2436        } while (vma && vma->vm_start < end);
2437        *insertion_point = vma;
2438        if (vma) {
2439                vma->vm_prev = prev;
2440                vma_gap_update(vma);
2441        } else
2442                mm->highest_vm_end = prev ? prev->vm_end : 0;
2443        tail_vma->vm_next = NULL;
2444
2445        /* Kill the cache */
2446        vmacache_invalidate(mm);
2447}
2448
2449/*
2450 * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
2451 * munmap path where it doesn't make sense to fail.
2452 */
2453static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2454              unsigned long addr, int new_below)
2455{
2456        struct vm_area_struct *new;
2457        int err;
2458
2459        if (is_vm_hugetlb_page(vma) && (addr &
2460                                        ~(huge_page_mask(hstate_vma(vma)))))
2461                return -EINVAL;
2462
2463        new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2464        if (!new)
2465                return -ENOMEM;
2466
2467        /* most fields are the same, copy all, and then fixup */
2468        *new = *vma;
2469
2470        INIT_LIST_HEAD(&new->anon_vma_chain);
2471
2472        if (new_below)
2473                new->vm_end = addr;
2474        else {
2475                new->vm_start = addr;
2476                new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2477        }
2478
2479        err = vma_dup_policy(vma, new);
2480        if (err)
2481                goto out_free_vma;
2482
2483        err = anon_vma_clone(new, vma);
2484        if (err)
2485                goto out_free_mpol;
2486
2487        if (new->vm_file)
2488                get_file(new->vm_file);
2489
2490        if (new->vm_ops && new->vm_ops->open)
2491                new->vm_ops->open(new);
2492
2493        if (new_below)
2494                err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2495                        ((addr - new->vm_start) >> PAGE_SHIFT), new);
2496        else
2497                err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2498
2499        /* Success. */
2500        if (!err)
2501                return 0;
2502
2503        /* Clean everything up if vma_adjust failed. */
2504        if (new->vm_ops && new->vm_ops->close)
2505                new->vm_ops->close(new);
2506        if (new->vm_file)
2507                fput(new->vm_file);
2508        unlink_anon_vmas(new);
2509 out_free_mpol:
2510        mpol_put(vma_policy(new));
2511 out_free_vma:
2512        kmem_cache_free(vm_area_cachep, new);
2513        return err;
2514}
2515
2516/*
2517 * Split a vma into two pieces at address 'addr', a new vma is allocated
2518 * either for the first part or the tail.
2519 */
2520int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2521              unsigned long addr, int new_below)
2522{
2523        if (mm->map_count >= sysctl_max_map_count)
2524                return -ENOMEM;
2525
2526        return __split_vma(mm, vma, addr, new_below);
2527}
2528
2529/* Munmap is split into 2 main parts -- this part which finds
2530 * what needs doing, and the areas themselves, which do the
2531 * work.  This now handles partial unmappings.
2532 * Jeremy Fitzhardinge <jeremy@goop.org>
2533 */
2534int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2535{
2536        unsigned long end;
2537        struct vm_area_struct *vma, *prev, *last;
2538
2539        if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2540                return -EINVAL;
2541
2542        len = PAGE_ALIGN(len);
2543        if (len == 0)
2544                return -EINVAL;
2545
2546        /* Find the first overlapping VMA */
2547        vma = find_vma(mm, start);
2548        if (!vma)
2549                return 0;
2550        prev = vma->vm_prev;
2551        /* we have  start < vma->vm_end  */
2552
2553        /* if it doesn't overlap, we have nothing.. */
2554        end = start + len;
2555        if (vma->vm_start >= end)
2556                return 0;
2557
2558        /*
2559         * If we need to split any vma, do it now to save pain later.
2560         *
2561         * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2562         * unmapped vm_area_struct will remain in use: so lower split_vma
2563         * places tmp vma above, and higher split_vma places tmp vma below.
2564         */
2565        if (start > vma->vm_start) {
2566                int error;
2567
2568                /*
2569                 * Make sure that map_count on return from munmap() will
2570                 * not exceed its limit; but let map_count go just above
2571                 * its limit temporarily, to help free resources as expected.
2572                 */
2573                if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2574                        return -ENOMEM;
2575
2576                error = __split_vma(mm, vma, start, 0);
2577                if (error)
2578                        return error;
2579                prev = vma;
2580        }
2581
2582        /* Does it split the last one? */
2583        last = find_vma(mm, end);
2584        if (last && end > last->vm_start) {
2585                int error = __split_vma(mm, last, end, 1);
2586                if (error)
2587                        return error;
2588        }
2589        vma = prev ? prev->vm_next : mm->mmap;
2590
2591        /*
2592         * unlock any mlock()ed ranges before detaching vmas
2593         */
2594        if (mm->locked_vm) {
2595                struct vm_area_struct *tmp = vma;
2596                while (tmp && tmp->vm_start < end) {
2597                        if (tmp->vm_flags & VM_LOCKED) {
2598                                mm->locked_vm -= vma_pages(tmp);
2599                                munlock_vma_pages_all(tmp);
2600                        }
2601                        tmp = tmp->vm_next;
2602                }
2603        }
2604
2605        /*
2606         * Remove the vma's, and unmap the actual pages
2607         */
2608        detach_vmas_to_be_unmapped(mm, vma, prev, end);
2609        unmap_region(mm, vma, prev, start, end);
2610
2611        arch_unmap(mm, vma, start, end);
2612
2613        /* Fix up all other VM information */
2614        remove_vma_list(mm, vma);
2615
2616        return 0;
2617}
2618
2619int vm_munmap(unsigned long start, size_t len)
2620{
2621        int ret;
2622        struct mm_struct *mm = current->mm;
2623
2624        down_write(&mm->mmap_sem);
2625        ret = do_munmap(mm, start, len);
2626        up_write(&mm->mmap_sem);
2627        return ret;
2628}
2629EXPORT_SYMBOL(vm_munmap);
2630
2631SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2632{
2633        profile_munmap(addr);
2634        return vm_munmap(addr, len);
2635}
2636
2637
2638/*
2639 * Emulation of deprecated remap_file_pages() syscall.
2640 */
2641SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2642                unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2643{
2644
2645        struct mm_struct *mm = current->mm;
2646        struct vm_area_struct *vma;
2647        unsigned long populate = 0;
2648        unsigned long ret = -EINVAL;
2649        struct file *file;
2650
2651        pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. "
2652                        "See Documentation/vm/remap_file_pages.txt.\n",
2653                        current->comm, current->pid);
2654
2655        if (prot)
2656                return ret;
2657        start = start & PAGE_MASK;
2658        size = size & PAGE_MASK;
2659
2660        if (start + size <= start)
2661                return ret;
2662
2663        /* Does pgoff wrap? */
2664        if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2665                return ret;
2666
2667        down_write(&mm->mmap_sem);
2668        vma = find_vma(mm, start);
2669
2670        if (!vma || !(vma->vm_flags & VM_SHARED))
2671                goto out;
2672
2673        if (start < vma->vm_start || start + size > vma->vm_end)
2674                goto out;
2675
2676        if (pgoff == linear_page_index(vma, start)) {
2677                ret = 0;
2678                goto out;
2679        }
2680
2681        prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
2682        prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
2683        prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
2684
2685        flags &= MAP_NONBLOCK;
2686        flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
2687        if (vma->vm_flags & VM_LOCKED) {
2688                flags |= MAP_LOCKED;
2689                /* drop PG_Mlocked flag for over-mapped range */
2690                munlock_vma_pages_range(vma, start, start + size);
2691        }
2692
2693        file = get_file(vma->vm_file);
2694        ret = do_mmap_pgoff(vma->vm_file, start, size,
2695                        prot, flags, pgoff, &populate);
2696        fput(file);
2697out:
2698        up_write(&mm->mmap_sem);
2699        if (populate)
2700                mm_populate(ret, populate);
2701        if (!IS_ERR_VALUE(ret))
2702                ret = 0;
2703        return ret;
2704}
2705
2706static inline void verify_mm_writelocked(struct mm_struct *mm)
2707{
2708#ifdef CONFIG_DEBUG_VM
2709        if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2710                WARN_ON(1);
2711                up_read(&mm->mmap_sem);
2712        }
2713#endif
2714}
2715
2716/*
2717 *  this is really a simplified "do_mmap".  it only handles
2718 *  anonymous maps.  eventually we may be able to do some
2719 *  brk-specific accounting here.
2720 */
2721static unsigned long do_brk(unsigned long addr, unsigned long len)
2722{
2723        struct mm_struct *mm = current->mm;
2724        struct vm_area_struct *vma, *prev;
2725        unsigned long flags;
2726        struct rb_node **rb_link, *rb_parent;
2727        pgoff_t pgoff = addr >> PAGE_SHIFT;
2728        int error;
2729
2730        len = PAGE_ALIGN(len);
2731        if (!len)
2732                return addr;
2733
2734        flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2735
2736        error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2737        if (error & ~PAGE_MASK)
2738                return error;
2739
2740        error = mlock_future_check(mm, mm->def_flags, len);
2741        if (error)
2742                return error;
2743
2744        /*
2745         * mm->mmap_sem is required to protect against another thread
2746         * changing the mappings in case we sleep.
2747         */
2748        verify_mm_writelocked(mm);
2749
2750        /*
2751         * Clear old maps.  this also does some error checking for us
2752         */
2753        while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
2754                              &rb_parent)) {
2755                if (do_munmap(mm, addr, len))
2756                        return -ENOMEM;
2757        }
2758
2759        /* Check against address space limits *after* clearing old maps... */
2760        if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2761                return -ENOMEM;
2762
2763        if (mm->map_count > sysctl_max_map_count)
2764                return -ENOMEM;
2765
2766        if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2767                return -ENOMEM;
2768
2769        /* Can we just expand an old private anonymous mapping? */
2770        vma = vma_merge(mm, prev, addr, addr + len, flags,
2771                        NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
2772        if (vma)
2773                goto out;
2774
2775        /*
2776         * create a vma struct for an anonymous mapping
2777         */
2778        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2779        if (!vma) {
2780                vm_unacct_memory(len >> PAGE_SHIFT);
2781                return -ENOMEM;
2782        }
2783
2784        INIT_LIST_HEAD(&vma->anon_vma_chain);
2785        vma->vm_mm = mm;
2786        vma->vm_start = addr;
2787        vma->vm_end = addr + len;
2788        vma->vm_pgoff = pgoff;
2789        vma->vm_flags = flags;
2790        vma->vm_page_prot = vm_get_page_prot(flags);
2791        vma_link(mm, vma, prev, rb_link, rb_parent);
2792out:
2793        perf_event_mmap(vma);
2794        mm->total_vm += len >> PAGE_SHIFT;
2795        if (flags & VM_LOCKED)
2796                mm->locked_vm += (len >> PAGE_SHIFT);
2797        vma->vm_flags |= VM_SOFTDIRTY;
2798        return addr;
2799}
2800
2801unsigned long vm_brk(unsigned long addr, unsigned long len)
2802{
2803        struct mm_struct *mm = current->mm;
2804        unsigned long ret;
2805        bool populate;
2806
2807        down_write(&mm->mmap_sem);
2808        ret = do_brk(addr, len);
2809        populate = ((mm->def_flags & VM_LOCKED) != 0);
2810        up_write(&mm->mmap_sem);
2811        if (populate)
2812                mm_populate(addr, len);
2813        return ret;
2814}
2815EXPORT_SYMBOL(vm_brk);
2816
2817/* Release all mmaps. */
2818void exit_mmap(struct mm_struct *mm)
2819{
2820        struct mmu_gather tlb;
2821        struct vm_area_struct *vma;
2822        unsigned long nr_accounted = 0;
2823
2824        /* mm's last user has gone, and its about to be pulled down */
2825        mmu_notifier_release(mm);
2826
2827        if (mm->locked_vm) {
2828                vma = mm->mmap;
2829                while (vma) {
2830                        if (vma->vm_flags & VM_LOCKED)
2831                                munlock_vma_pages_all(vma);
2832                        vma = vma->vm_next;
2833                }
2834        }
2835
2836        arch_exit_mmap(mm);
2837
2838        vma = mm->mmap;
2839        if (!vma)       /* Can happen if dup_mmap() received an OOM */
2840                return;
2841
2842        lru_add_drain();
2843        flush_cache_mm(mm);
2844        tlb_gather_mmu(&tlb, mm, 0, -1);
2845        /* update_hiwater_rss(mm) here? but nobody should be looking */
2846        /* Use -1 here to ensure all VMAs in the mm are unmapped */
2847        unmap_vmas(&tlb, vma, 0, -1);
2848
2849        free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2850        tlb_finish_mmu(&tlb, 0, -1);
2851
2852        /*
2853         * Walk the list again, actually closing and freeing it,
2854         * with preemption enabled, without holding any MM locks.
2855         */
2856        while (vma) {
2857                if (vma->vm_flags & VM_ACCOUNT)
2858                        nr_accounted += vma_pages(vma);
2859                vma = remove_vma(vma);
2860        }
2861        vm_unacct_memory(nr_accounted);
2862}
2863
2864/* Insert vm structure into process list sorted by address
2865 * and into the inode's i_mmap tree.  If vm_file is non-NULL
2866 * then i_mmap_rwsem is taken here.
2867 */
2868int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2869{
2870        struct vm_area_struct *prev;
2871        struct rb_node **rb_link, *rb_parent;
2872
2873        if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2874                           &prev, &rb_link, &rb_parent))
2875                return -ENOMEM;
2876        if ((vma->vm_flags & VM_ACCOUNT) &&
2877             security_vm_enough_memory_mm(mm, vma_pages(vma)))
2878                return -ENOMEM;
2879
2880        /*
2881         * The vm_pgoff of a purely anonymous vma should be irrelevant
2882         * until its first write fault, when page's anon_vma and index
2883         * are set.  But now set the vm_pgoff it will almost certainly
2884         * end up with (unless mremap moves it elsewhere before that
2885         * first wfault), so /proc/pid/maps tells a consistent story.
2886         *
2887         * By setting it to reflect the virtual start address of the
2888         * vma, merges and splits can happen in a seamless way, just
2889         * using the existing file pgoff checks and manipulations.
2890         * Similarly in do_mmap_pgoff and in do_brk.
2891         */
2892        if (vma_is_anonymous(vma)) {
2893                BUG_ON(vma->anon_vma);
2894                vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2895        }
2896
2897        vma_link(mm, vma, prev, rb_link, rb_parent);
2898        return 0;
2899}
2900
2901/*
2902 * Copy the vma structure to a new location in the same mm,
2903 * prior to moving page table entries, to effect an mremap move.
2904 */
2905struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2906        unsigned long addr, unsigned long len, pgoff_t pgoff,
2907        bool *need_rmap_locks)
2908{
2909        struct vm_area_struct *vma = *vmap;
2910        unsigned long vma_start = vma->vm_start;
2911        struct mm_struct *mm = vma->vm_mm;
2912        struct vm_area_struct *new_vma, *prev;
2913        struct rb_node **rb_link, *rb_parent;
2914        bool faulted_in_anon_vma = true;
2915
2916        /*
2917         * If anonymous vma has not yet been faulted, update new pgoff
2918         * to match new location, to increase its chance of merging.
2919         */
2920        if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
2921                pgoff = addr >> PAGE_SHIFT;
2922                faulted_in_anon_vma = false;
2923        }
2924
2925        if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
2926                return NULL;    /* should never get here */
2927        new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2928                            vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
2929                            vma->vm_userfaultfd_ctx);
2930        if (new_vma) {
2931                /*
2932                 * Source vma may have been merged into new_vma
2933                 */
2934                if (unlikely(vma_start >= new_vma->vm_start &&
2935                             vma_start < new_vma->vm_end)) {
2936                        /*
2937                         * The only way we can get a vma_merge with
2938                         * self during an mremap is if the vma hasn't
2939                         * been faulted in yet and we were allowed to
2940                         * reset the dst vma->vm_pgoff to the
2941                         * destination address of the mremap to allow
2942                         * the merge to happen. mremap must change the
2943                         * vm_pgoff linearity between src and dst vmas
2944                         * (in turn preventing a vma_merge) to be
2945                         * safe. It is only safe to keep the vm_pgoff
2946                         * linear if there are no pages mapped yet.
2947                         */
2948                        VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
2949                        *vmap = vma = new_vma;
2950                }
2951                *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
2952        } else {
2953                new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2954                if (!new_vma)
2955                        goto out;
2956                *new_vma = *vma;
2957                new_vma->vm_start = addr;
2958                new_vma->vm_end = addr + len;
2959                new_vma->vm_pgoff = pgoff;
2960                if (vma_dup_policy(vma, new_vma))
2961                        goto out_free_vma;
2962                INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2963                if (anon_vma_clone(new_vma, vma))
2964                        goto out_free_mempol;
2965                if (new_vma->vm_file)
2966                        get_file(new_vma->vm_file);
2967                if (new_vma->vm_ops && new_vma->vm_ops->open)
2968                        new_vma->vm_ops->open(new_vma);
2969                vma_link(mm, new_vma, prev, rb_link, rb_parent);
2970                *need_rmap_locks = false;
2971        }
2972        return new_vma;
2973
2974out_free_mempol:
2975        mpol_put(vma_policy(new_vma));
2976out_free_vma:
2977        kmem_cache_free(vm_area_cachep, new_vma);
2978out:
2979        return NULL;
2980}
2981
2982/*
2983 * Return true if the calling process may expand its vm space by the passed
2984 * number of pages
2985 */
2986int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2987{
2988        unsigned long cur = mm->total_vm;       /* pages */
2989        unsigned long lim;
2990
2991        lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2992
2993        if (cur + npages > lim)
2994                return 0;
2995        return 1;
2996}
2997
2998static int special_mapping_fault(struct vm_area_struct *vma,
2999                                 struct vm_fault *vmf);
3000
3001/*
3002 * Having a close hook prevents vma merging regardless of flags.
3003 */
3004static void special_mapping_close(struct vm_area_struct *vma)
3005{
3006}
3007
3008static const char *special_mapping_name(struct vm_area_struct *vma)
3009{
3010        return ((struct vm_special_mapping *)vma->vm_private_data)->name;
3011}
3012
3013static const struct vm_operations_struct special_mapping_vmops = {
3014        .close = special_mapping_close,
3015        .fault = special_mapping_fault,
3016        .name = special_mapping_name,
3017};
3018
3019static const struct vm_operations_struct legacy_special_mapping_vmops = {
3020        .close = special_mapping_close,
3021        .fault = special_mapping_fault,
3022};
3023
3024static int special_mapping_fault(struct vm_area_struct *vma,
3025                                struct vm_fault *vmf)
3026{
3027        pgoff_t pgoff;
3028        struct page **pages;
3029
3030        if (vma->vm_ops == &legacy_special_mapping_vmops)
3031                pages = vma->vm_private_data;
3032        else
3033                pages = ((struct vm_special_mapping *)vma->vm_private_data)->
3034                        pages;
3035
3036        for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3037                pgoff--;
3038
3039        if (*pages) {
3040                struct page *page = *pages;
3041                get_page(page);
3042                vmf->page = page;
3043                return 0;
3044        }
3045
3046        return VM_FAULT_SIGBUS;
3047}
3048
3049static struct vm_area_struct *__install_special_mapping(
3050        struct mm_struct *mm,
3051        unsigned long addr, unsigned long len,
3052        unsigned long vm_flags, const struct vm_operations_struct *ops,
3053        void *priv)
3054{
3055        int ret;
3056        struct vm_area_struct *vma;
3057
3058        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
3059        if (unlikely(vma == NULL))
3060                return ERR_PTR(-ENOMEM);
3061
3062        INIT_LIST_HEAD(&vma->anon_vma_chain);
3063        vma->vm_mm = mm;
3064        vma->vm_start = addr;
3065        vma->vm_end = addr + len;
3066
3067        vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3068        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3069
3070        vma->vm_ops = ops;
3071        vma->vm_private_data = priv;
3072
3073        ret = insert_vm_struct(mm, vma);
3074        if (ret)
3075                goto out;
3076
3077        mm->total_vm += len >> PAGE_SHIFT;
3078
3079        perf_event_mmap(vma);
3080
3081        return vma;
3082
3083out:
3084        kmem_cache_free(vm_area_cachep, vma);
3085        return ERR_PTR(ret);
3086}
3087
3088/*
3089 * Called with mm->mmap_sem held for writing.
3090 * Insert a new vma covering the given region, with the given flags.
3091 * Its pages are supplied by the given array of struct page *.
3092 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3093 * The region past the last page supplied will always produce SIGBUS.
3094 * The array pointer and the pages it points to are assumed to stay alive
3095 * for as long as this mapping might exist.
3096 */
3097struct vm_area_struct *_install_special_mapping(
3098        struct mm_struct *mm,
3099        unsigned long addr, unsigned long len,
3100        unsigned long vm_flags, const struct vm_special_mapping *spec)
3101{
3102        return __install_special_mapping(mm, addr, len, vm_flags,
3103                                         &special_mapping_vmops, (void *)spec);
3104}
3105
3106int install_special_mapping(struct mm_struct *mm,
3107                            unsigned long addr, unsigned long len,
3108                            unsigned long vm_flags, struct page **pages)
3109{
3110        struct vm_area_struct *vma = __install_special_mapping(
3111                mm, addr, len, vm_flags, &legacy_special_mapping_vmops,
3112                (void *)pages);
3113
3114        return PTR_ERR_OR_ZERO(vma);
3115}
3116
3117static DEFINE_MUTEX(mm_all_locks_mutex);
3118
3119static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3120{
3121        if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3122                /*
3123                 * The LSB of head.next can't change from under us
3124                 * because we hold the mm_all_locks_mutex.
3125                 */
3126                down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3127                /*
3128                 * We can safely modify head.next after taking the
3129                 * anon_vma->root->rwsem. If some other vma in this mm shares
3130                 * the same anon_vma we won't take it again.
3131                 *
3132                 * No need of atomic instructions here, head.next
3133                 * can't change from under us thanks to the
3134                 * anon_vma->root->rwsem.
3135                 */
3136                if (__test_and_set_bit(0, (unsigned long *)
3137                                       &anon_vma->root->rb_root.rb_node))
3138                        BUG();
3139        }
3140}
3141
3142static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3143{
3144        if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3145                /*
3146                 * AS_MM_ALL_LOCKS can't change from under us because
3147                 * we hold the mm_all_locks_mutex.
3148                 *
3149                 * Operations on ->flags have to be atomic because
3150                 * even if AS_MM_ALL_LOCKS is stable thanks to the
3151                 * mm_all_locks_mutex, there may be other cpus
3152                 * changing other bitflags in parallel to us.
3153                 */
3154                if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3155                        BUG();
3156                down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
3157        }
3158}
3159
3160/*
3161 * This operation locks against the VM for all pte/vma/mm related
3162 * operations that could ever happen on a certain mm. This includes
3163 * vmtruncate, try_to_unmap, and all page faults.
3164 *
3165 * The caller must take the mmap_sem in write mode before calling
3166 * mm_take_all_locks(). The caller isn't allowed to release the
3167 * mmap_sem until mm_drop_all_locks() returns.
3168 *
3169 * mmap_sem in write mode is required in order to block all operations
3170 * that could modify pagetables and free pages without need of
3171 * altering the vma layout. It's also needed in write mode to avoid new
3172 * anon_vmas to be associated with existing vmas.
3173 *
3174 * A single task can't take more than one mm_take_all_locks() in a row
3175 * or it would deadlock.
3176 *
3177 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3178 * mapping->flags avoid to take the same lock twice, if more than one
3179 * vma in this mm is backed by the same anon_vma or address_space.
3180 *
3181 * We can take all the locks in random order because the VM code
3182 * taking i_mmap_rwsem or anon_vma->rwsem outside the mmap_sem never
3183 * takes more than one of them in a row. Secondly we're protected
3184 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
3185 *
3186 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3187 * that may have to take thousand of locks.
3188 *
3189 * mm_take_all_locks() can fail if it's interrupted by signals.
3190 */
3191int mm_take_all_locks(struct mm_struct *mm)
3192{
3193        struct vm_area_struct *vma;
3194        struct anon_vma_chain *avc;
3195
3196        BUG_ON(down_read_trylock(&mm->mmap_sem));
3197
3198        mutex_lock(&mm_all_locks_mutex);
3199
3200        for (vma = mm->mmap; vma; vma = vma->vm_next) {
3201                if (signal_pending(current))
3202                        goto out_unlock;
3203                if (vma->vm_file && vma->vm_file->f_mapping)
3204                        vm_lock_mapping(mm, vma->vm_file->f_mapping);
3205        }
3206
3207        for (vma = mm->mmap; vma; vma = vma->vm_next) {
3208                if (signal_pending(current))
3209                        goto out_unlock;
3210                if (vma->anon_vma)
3211                        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3212                                vm_lock_anon_vma(mm, avc->anon_vma);
3213        }
3214
3215        return 0;
3216
3217out_unlock:
3218        mm_drop_all_locks(mm);
3219        return -EINTR;
3220}
3221
3222static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3223{
3224        if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3225                /*
3226                 * The LSB of head.next can't change to 0 from under
3227                 * us because we hold the mm_all_locks_mutex.
3228                 *
3229                 * We must however clear the bitflag before unlocking
3230                 * the vma so the users using the anon_vma->rb_root will
3231                 * never see our bitflag.
3232                 *
3233                 * No need of atomic instructions here, head.next
3234                 * can't change from under us until we release the
3235                 * anon_vma->root->rwsem.
3236                 */
3237                if (!__test_and_clear_bit(0, (unsigned long *)
3238                                          &anon_vma->root->rb_root.rb_node))
3239                        BUG();
3240                anon_vma_unlock_write(anon_vma);
3241        }
3242}
3243
3244static void vm_unlock_mapping(struct address_space *mapping)
3245{
3246        if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3247                /*
3248                 * AS_MM_ALL_LOCKS can't change to 0 from under us
3249                 * because we hold the mm_all_locks_mutex.
3250                 */
3251                i_mmap_unlock_write(mapping);
3252                if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3253                                        &mapping->flags))
3254                        BUG();
3255        }
3256}
3257
3258/*
3259 * The mmap_sem cannot be released by the caller until
3260 * mm_drop_all_locks() returns.
3261 */
3262void mm_drop_all_locks(struct mm_struct *mm)
3263{
3264        struct vm_area_struct *vma;
3265        struct anon_vma_chain *avc;
3266
3267        BUG_ON(down_read_trylock(&mm->mmap_sem));
3268        BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3269
3270        for (vma = mm->mmap; vma; vma = vma->vm_next) {
3271                if (vma->anon_vma)
3272                        list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3273                                vm_unlock_anon_vma(avc->anon_vma);
3274                if (vma->vm_file && vma->vm_file->f_mapping)
3275                        vm_unlock_mapping(vma->vm_file->f_mapping);
3276        }
3277
3278        mutex_unlock(&mm_all_locks_mutex);
3279}
3280
3281/*
3282 * initialise the VMA slab
3283 */
3284void __init mmap_init(void)
3285{
3286        int ret;
3287
3288        ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3289        VM_BUG_ON(ret);
3290}
3291
3292/*
3293 * Initialise sysctl_user_reserve_kbytes.
3294 *
3295 * This is intended to prevent a user from starting a single memory hogging
3296 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3297 * mode.
3298 *
3299 * The default value is min(3% of free memory, 128MB)
3300 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3301 */
3302static int init_user_reserve(void)
3303{
3304        unsigned long free_kbytes;
3305
3306        free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3307
3308        sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3309        return 0;
3310}
3311subsys_initcall(init_user_reserve);
3312
3313/*
3314 * Initialise sysctl_admin_reserve_kbytes.
3315 *
3316 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3317 * to log in and kill a memory hogging process.
3318 *
3319 * Systems with more than 256MB will reserve 8MB, enough to recover
3320 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3321 * only reserve 3% of free pages by default.
3322 */
3323static int init_admin_reserve(void)
3324{
3325        unsigned long free_kbytes;
3326
3327        free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3328
3329        sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3330        return 0;
3331}
3332subsys_initcall(init_admin_reserve);
3333
3334/*
3335 * Reinititalise user and admin reserves if memory is added or removed.
3336 *
3337 * The default user reserve max is 128MB, and the default max for the
3338 * admin reserve is 8MB. These are usually, but not always, enough to
3339 * enable recovery from a memory hogging process using login/sshd, a shell,
3340 * and tools like top. It may make sense to increase or even disable the
3341 * reserve depending on the existence of swap or variations in the recovery
3342 * tools. So, the admin may have changed them.
3343 *
3344 * If memory is added and the reserves have been eliminated or increased above
3345 * the default max, then we'll trust the admin.
3346 *
3347 * If memory is removed and there isn't enough free memory, then we
3348 * need to reset the reserves.
3349 *
3350 * Otherwise keep the reserve set by the admin.
3351 */
3352static int reserve_mem_notifier(struct notifier_block *nb,
3353                             unsigned long action, void *data)
3354{
3355        unsigned long tmp, free_kbytes;
3356
3357        switch (action) {
3358        case MEM_ONLINE:
3359                /* Default max is 128MB. Leave alone if modified by operator. */
3360                tmp = sysctl_user_reserve_kbytes;
3361                if (0 < tmp && tmp < (1UL << 17))
3362                        init_user_reserve();
3363
3364                /* Default max is 8MB.  Leave alone if modified by operator. */
3365                tmp = sysctl_admin_reserve_kbytes;
3366                if (0 < tmp && tmp < (1UL << 13))
3367                        init_admin_reserve();
3368
3369                break;
3370        case MEM_OFFLINE:
3371                free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3372
3373                if (sysctl_user_reserve_kbytes > free_kbytes) {
3374                        init_user_reserve();
3375                        pr_info("vm.user_reserve_kbytes reset to %lu\n",
3376                                sysctl_user_reserve_kbytes);
3377                }
3378
3379                if (sysctl_admin_reserve_kbytes > free_kbytes) {
3380                        init_admin_reserve();
3381                        pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3382                                sysctl_admin_reserve_kbytes);
3383                }
3384                break;
3385        default:
3386                break;
3387        }
3388        return NOTIFY_OK;
3389}
3390
3391static struct notifier_block reserve_mem_nb = {
3392        .notifier_call = reserve_mem_notifier,
3393};
3394
3395static int __meminit init_reserve_notifier(void)
3396{
3397        if (register_hotmemory_notifier(&reserve_mem_nb))
3398                pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3399
3400        return 0;
3401}
3402subsys_initcall(init_reserve_notifier);
3403