mm/mmap.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * mm/mmap.c
   4  *
   5  * Written by obz.
   6  *
   7  * Address space accounting code        <alan@lxorguk.ukuu.org.uk>
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/kernel.h>
  13 #include <linux/slab.h>
  14 #include <linux/backing-dev.h>
  15 #include <linux/mm.h>
  16 #include <linux/vmacache.h>
  17 #include <linux/shm.h>
  18 #include <linux/mman.h>
  19 #include <linux/pagemap.h>
  20 #include <linux/swap.h>
  21 #include <linux/syscalls.h>
  22 #include <linux/capability.h>
  23 #include <linux/init.h>
  24 #include <linux/file.h>
  25 #include <linux/fs.h>
  26 #include <linux/personality.h>
  27 #include <linux/security.h>
  28 #include <linux/hugetlb.h>
  29 #include <linux/shmem_fs.h>
  30 #include <linux/profile.h>
  31 #include <linux/export.h>
  32 #include <linux/mount.h>
  33 #include <linux/mempolicy.h>
  34 #include <linux/rmap.h>
  35 #include <linux/mmu_notifier.h>
  36 #include <linux/mmdebug.h>
  37 #include <linux/perf_event.h>
  38 #include <linux/audit.h>
  39 #include <linux/khugepaged.h>
  40 #include <linux/uprobes.h>
  41 #include <linux/rbtree_augmented.h>
  42 #include <linux/notifier.h>
  43 #include <linux/memory.h>
  44 #include <linux/printk.h>
  45 #include <linux/userfaultfd_k.h>
  46 #include <linux/moduleparam.h>
  47 #include <linux/pkeys.h>
  48 #include <linux/oom.h>
  49 #include <linux/sched/mm.h>
  50
  51 #include <linux/uaccess.h>
  52 #include <asm/cacheflush.h>
  53 #include <asm/tlb.h>
  54 #include <asm/mmu_context.h>
  55
  56 #define CREATE_TRACE_POINTS
  57 #include <trace/events/mmap.h>
  58
  59 #include "internal.h"
  60
  61 #ifndef arch_mmap_check
  62 #define arch_mmap_check(addr, len, flags)       (0)
  63 #endif
  64
  65 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
  66 const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
  67 const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
  68 int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
  69 #endif
  70 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
  71 const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
  72 const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
  73 int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
  74 #endif
  75
  76 static bool ignore_rlimit_data;
  77 core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
  78
  79 static void unmap_region(struct mm_struct *mm,
  80                 struct vm_area_struct *vma, struct vm_area_struct *prev,
  81                 unsigned long start, unsigned long end);
  82
  83 /* description of effects of mapping type and prot in current implementation.
  84  * this is due to the limited x86 page protection hardware.  The expected
  85  * behavior is in parens:
  86  *
  87  * map_type     prot
  88  *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
  89  * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
  90  *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
  91  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
  92  *
  93  * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
  94  *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
  95  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
  96  *
  97  * On arm64, PROT_EXEC has the following behaviour for both MAP_SHARED and
  98  * MAP_PRIVATE (with Enhanced PAN supported):
  99  *                                                              r: (no) no
 100  *                                                              w: (no) no
 101  *                                                              x: (yes) yes
 102  */
 103 pgprot_t protection_map[16] __ro_after_init = {
 104         __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
 105         __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
 106 };
 107
 108 #ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
 109 static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
 110 {
 111         return prot;
 112 }
 113 #endif
 114
 115 pgprot_t vm_get_page_prot(unsigned long vm_flags)
 116 {
 117         pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
 118                                 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
 119                         pgprot_val(arch_vm_get_page_prot(vm_flags)));
 120
 121         return arch_filter_pgprot(ret);
 122 }
 123 EXPORT_SYMBOL(vm_get_page_prot);
 124
 125 static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
 126 {
 127         return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
 128 }
 129
 130 /* Update vma->vm_page_prot to reflect vma->vm_flags. */
 131 void vma_set_page_prot(struct vm_area_struct *vma)
 132 {
 133         unsigned long vm_flags = vma->vm_flags;
 134         pgprot_t vm_page_prot;
 135
 136         vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
 137         if (vma_wants_writenotify(vma, vm_page_prot)) {
 138                 vm_flags &= ~VM_SHARED;
 139                 vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags);
 140         }
 141         /* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */
 142         WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
 143 }
 144
 145 /*
 146  * Requires inode->i_mapping->i_mmap_rwsem
 147  */
 148 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
 149                 struct file *file, struct address_space *mapping)
 150 {
 151         if (vma->vm_flags & VM_SHARED)
 152                 mapping_unmap_writable(mapping);
 153
 154         flush_dcache_mmap_lock(mapping);
 155         vma_interval_tree_remove(vma, &mapping->i_mmap);
 156         flush_dcache_mmap_unlock(mapping);
 157 }
 158
 159 /*
 160  * Unlink a file-based vm structure from its interval tree, to hide
 161  * vma from rmap and vmtruncate before freeing its page tables.
 162  */
 163 void unlink_file_vma(struct vm_area_struct *vma)
 164 {
 165         struct file *file = vma->vm_file;
 166
 167         if (file) {
 168                 struct address_space *mapping = file->f_mapping;
 169                 i_mmap_lock_write(mapping);
 170                 __remove_shared_vm_struct(vma, file, mapping);
 171                 i_mmap_unlock_write(mapping);
 172         }
 173 }
 174
 175 /*
 176  * Close a vm structure and free it, returning the next.
 177  */
 178 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
 179 {
 180         struct vm_area_struct *next = vma->vm_next;
 181
 182         might_sleep();
 183         if (vma->vm_ops && vma->vm_ops->close)
 184                 vma->vm_ops->close(vma);
 185         if (vma->vm_file)
 186                 fput(vma->vm_file);
 187         mpol_put(vma_policy(vma));
 188         vm_area_free(vma);
 189         return next;
 190 }
 191
 192 static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags,
 193                 struct list_head *uf);
 194 SYSCALL_DEFINE1(brk, unsigned long, brk)
 195 {
 196         unsigned long newbrk, oldbrk, origbrk;
 197         struct mm_struct *mm = current->mm;
 198         struct vm_area_struct *next;
 199         unsigned long min_brk;
 200         bool populate;
 201         bool downgraded = false;
 202         LIST_HEAD(uf);
 203
 204         if (mmap_write_lock_killable(mm))
 205                 return -EINTR;
 206
 207         origbrk = mm->brk;
 208
 209 #ifdef CONFIG_COMPAT_BRK
 210         /*
 211          * CONFIG_COMPAT_BRK can still be overridden by setting
 212          * randomize_va_space to 2, which will still cause mm->start_brk
 213          * to be arbitrarily shifted
 214          */
 215         if (current->brk_randomized)
 216                 min_brk = mm->start_brk;
 217         else
 218                 min_brk = mm->end_data;
 219 #else
 220         min_brk = mm->start_brk;
 221 #endif
 222         if (brk < min_brk)
 223                 goto out;
 224
 225         /*
 226          * Check against rlimit here. If this check is done later after the test
 227          * of oldbrk with newbrk then it can escape the test and let the data
 228          * segment grow beyond its set limit the in case where the limit is
 229          * not page aligned -Ram Gupta
 230          */
 231         if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
 232                               mm->end_data, mm->start_data))
 233                 goto out;
 234
 235         newbrk = PAGE_ALIGN(brk);
 236         oldbrk = PAGE_ALIGN(mm->brk);
 237         if (oldbrk == newbrk) {
 238                 mm->brk = brk;
 239                 goto success;
 240         }
 241
 242         /*
 243          * Always allow shrinking brk.
 244          * __do_munmap() may downgrade mmap_lock to read.
 245          */
 246         if (brk <= mm->brk) {
 247                 int ret;
 248
 249                 /*
 250                  * mm->brk must to be protected by write mmap_lock so update it
 251                  * before downgrading mmap_lock. When __do_munmap() fails,
 252                  * mm->brk will be restored from origbrk.
 253                  */
 254                 mm->brk = brk;
 255                 ret = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true);
 256                 if (ret < 0) {
 257                         mm->brk = origbrk;
 258                         goto out;
 259                 } else if (ret == 1) {
 260                         downgraded = true;
 261                 }
 262                 goto success;
 263         }
 264
 265         /* Check against existing mmap mappings. */
 266         next = find_vma(mm, oldbrk);
 267         if (next && newbrk + PAGE_SIZE > vm_start_gap(next))
 268                 goto out;
 269
 270         /* Ok, looks good - let it rip. */
 271         if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0)
 272                 goto out;
 273         mm->brk = brk;
 274
 275 success:
 276         populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
 277         if (downgraded)
 278                 mmap_read_unlock(mm);
 279         else
 280                 mmap_write_unlock(mm);
 281         userfaultfd_unmap_complete(mm, &uf);
 282         if (populate)
 283                 mm_populate(oldbrk, newbrk - oldbrk);
 284         return brk;
 285
 286 out:
 287         mmap_write_unlock(mm);
 288         return origbrk;
 289 }
 290
 291 static inline unsigned long vma_compute_gap(struct vm_area_struct *vma)
 292 {
 293         unsigned long gap, prev_end;
 294
 295         /*
 296          * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we
 297          * allow two stack_guard_gaps between them here, and when choosing
 298          * an unmapped area; whereas when expanding we only require one.
 299          * That's a little inconsistent, but keeps the code here simpler.
 300          */
 301         gap = vm_start_gap(vma);
 302         if (vma->vm_prev) {
 303                 prev_end = vm_end_gap(vma->vm_prev);
 304                 if (gap > prev_end)
 305                         gap -= prev_end;
 306                 else
 307                         gap = 0;
 308         }
 309         return gap;
 310 }
 311
 312 #ifdef CONFIG_DEBUG_VM_RB
 313 static unsigned long vma_compute_subtree_gap(struct vm_area_struct *vma)
 314 {
 315         unsigned long max = vma_compute_gap(vma), subtree_gap;
 316         if (vma->vm_rb.rb_left) {
 317                 subtree_gap = rb_entry(vma->vm_rb.rb_left,
 318                                 struct vm_area_struct, vm_rb)->rb_subtree_gap;
 319                 if (subtree_gap > max)
 320                         max = subtree_gap;
 321         }
 322         if (vma->vm_rb.rb_right) {
 323                 subtree_gap = rb_entry(vma->vm_rb.rb_right,
 324                                 struct vm_area_struct, vm_rb)->rb_subtree_gap;
 325                 if (subtree_gap > max)
 326                         max = subtree_gap;
 327         }
 328         return max;
 329 }
 330
 331 static int browse_rb(struct mm_struct *mm)
 332 {
 333         struct rb_root *root = &mm->mm_rb;
 334         int i = 0, j, bug = 0;
 335         struct rb_node *nd, *pn = NULL;
 336         unsigned long prev = 0, pend = 0;
 337
 338         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
 339                 struct vm_area_struct *vma;
 340                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
 341                 if (vma->vm_start < prev) {
 342                         pr_emerg("vm_start %lx < prev %lx\n",
 343                                   vma->vm_start, prev);
 344                         bug = 1;
 345                 }
 346                 if (vma->vm_start < pend) {
 347                         pr_emerg("vm_start %lx < pend %lx\n",
 348                                   vma->vm_start, pend);
 349                         bug = 1;
 350                 }
 351                 if (vma->vm_start > vma->vm_end) {
 352                         pr_emerg("vm_start %lx > vm_end %lx\n",
 353                                   vma->vm_start, vma->vm_end);
 354                         bug = 1;
 355                 }
 356                 spin_lock(&mm->page_table_lock);
 357                 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
 358                         pr_emerg("free gap %lx, correct %lx\n",
 359                                vma->rb_subtree_gap,
 360                                vma_compute_subtree_gap(vma));
 361                         bug = 1;
 362                 }
 363                 spin_unlock(&mm->page_table_lock);
 364                 i++;
 365                 pn = nd;
 366                 prev = vma->vm_start;
 367                 pend = vma->vm_end;
 368         }
 369         j = 0;
 370         for (nd = pn; nd; nd = rb_prev(nd))
 371                 j++;
 372         if (i != j) {
 373                 pr_emerg("backwards %d, forwards %d\n", j, i);
 374                 bug = 1;
 375         }
 376         return bug ? -1 : i;
 377 }
 378
 379 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
 380 {
 381         struct rb_node *nd;
 382
 383         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
 384                 struct vm_area_struct *vma;
 385                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
 386                 VM_BUG_ON_VMA(vma != ignore &&
 387                         vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
 388                         vma);
 389         }
 390 }
 391
 392 static void validate_mm(struct mm_struct *mm)
 393 {
 394         int bug = 0;
 395         int i = 0;
 396         unsigned long highest_address = 0;
 397         struct vm_area_struct *vma = mm->mmap;
 398
 399         while (vma) {
 400                 struct anon_vma *anon_vma = vma->anon_vma;
 401                 struct anon_vma_chain *avc;
 402
 403                 if (anon_vma) {
 404                         anon_vma_lock_read(anon_vma);
 405                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 406                                 anon_vma_interval_tree_verify(avc);
 407                         anon_vma_unlock_read(anon_vma);
 408                 }
 409
 410                 highest_address = vm_end_gap(vma);
 411                 vma = vma->vm_next;
 412                 i++;
 413         }
 414         if (i != mm->map_count) {
 415                 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
 416                 bug = 1;
 417         }
 418         if (highest_address != mm->highest_vm_end) {
 419                 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
 420                           mm->highest_vm_end, highest_address);
 421                 bug = 1;
 422         }
 423         i = browse_rb(mm);
 424         if (i != mm->map_count) {
 425                 if (i != -1)
 426                         pr_emerg("map_count %d rb %d\n", mm->map_count, i);
 427                 bug = 1;
 428         }
 429         VM_BUG_ON_MM(bug, mm);
 430 }
 431 #else
 432 #define validate_mm_rb(root, ignore) do { } while (0)
 433 #define validate_mm(mm) do { } while (0)
 434 #endif
 435
 436 RB_DECLARE_CALLBACKS_MAX(static, vma_gap_callbacks,
 437                          struct vm_area_struct, vm_rb,
 438                          unsigned long, rb_subtree_gap, vma_compute_gap)
 439
 440 /*
 441  * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
 442  * vma->vm_prev->vm_end values changed, without modifying the vma's position
 443  * in the rbtree.
 444  */
 445 static void vma_gap_update(struct vm_area_struct *vma)
 446 {
 447         /*
 448          * As it turns out, RB_DECLARE_CALLBACKS_MAX() already created
 449          * a callback function that does exactly what we want.
 450          */
 451         vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
 452 }
 453
 454 static inline void vma_rb_insert(struct vm_area_struct *vma,
 455                                  struct rb_root *root)
 456 {
 457         /* All rb_subtree_gap values must be consistent prior to insertion */
 458         validate_mm_rb(root, NULL);
 459
 460         rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
 461 }
 462
 463 static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
 464 {
 465         /*
 466          * Note rb_erase_augmented is a fairly large inline function,
 467          * so make sure we instantiate it only once with our desired
 468          * augmented rbtree callbacks.
 469          */
 470         rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
 471 }
 472
 473 static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma,
 474                                                 struct rb_root *root,
 475                                                 struct vm_area_struct *ignore)
 476 {
 477         /*
 478          * All rb_subtree_gap values must be consistent prior to erase,
 479          * with the possible exception of
 480          *
 481          * a. the "next" vma being erased if next->vm_start was reduced in
 482          *    __vma_adjust() -> __vma_unlink()
 483          * b. the vma being erased in detach_vmas_to_be_unmapped() ->
 484          *    vma_rb_erase()
 485          */
 486         validate_mm_rb(root, ignore);
 487
 488         __vma_rb_erase(vma, root);
 489 }
 490
 491 static __always_inline void vma_rb_erase(struct vm_area_struct *vma,
 492                                          struct rb_root *root)
 493 {
 494         vma_rb_erase_ignore(vma, root, vma);
 495 }
 496
 497 /*
 498  * vma has some anon_vma assigned, and is already inserted on that
 499  * anon_vma's interval trees.
 500  *
 501  * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
 502  * vma must be removed from the anon_vma's interval trees using
 503  * anon_vma_interval_tree_pre_update_vma().
 504  *
 505  * After the update, the vma will be reinserted using
 506  * anon_vma_interval_tree_post_update_vma().
 507  *
 508  * The entire update must be protected by exclusive mmap_lock and by
 509  * the root anon_vma's mutex.
 510  */
 511 static inline void
 512 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
 513 {
 514         struct anon_vma_chain *avc;
 515
 516         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 517                 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
 518 }
 519
 520 static inline void
 521 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
 522 {
 523         struct anon_vma_chain *avc;
 524
 525         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
 526                 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
 527 }
 528
 529 static int find_vma_links(struct mm_struct *mm, unsigned long addr,
 530                 unsigned long end, struct vm_area_struct **pprev,
 531                 struct rb_node ***rb_link, struct rb_node **rb_parent)
 532 {
 533         struct rb_node **__rb_link, *__rb_parent, *rb_prev;
 534
 535         mmap_assert_locked(mm);
 536         __rb_link = &mm->mm_rb.rb_node;
 537         rb_prev = __rb_parent = NULL;
 538
 539         while (*__rb_link) {
 540                 struct vm_area_struct *vma_tmp;
 541
 542                 __rb_parent = *__rb_link;
 543                 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
 544
 545                 if (vma_tmp->vm_end > addr) {
 546                         /* Fail if an existing vma overlaps the area */
 547                         if (vma_tmp->vm_start < end)
 548                                 return -ENOMEM;
 549                         __rb_link = &__rb_parent->rb_left;
 550                 } else {
 551                         rb_prev = __rb_parent;
 552                         __rb_link = &__rb_parent->rb_right;
 553                 }
 554         }
 555
 556         *pprev = NULL;
 557         if (rb_prev)
 558                 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 559         *rb_link = __rb_link;
 560         *rb_parent = __rb_parent;
 561         return 0;
 562 }
 563
 564 /*
 565  * vma_next() - Get the next VMA.
 566  * @mm: The mm_struct.
 567  * @vma: The current vma.
 568  *
 569  * If @vma is NULL, return the first vma in the mm.
 570  *
 571  * Returns: The next VMA after @vma.
 572  */
 573 static inline struct vm_area_struct *vma_next(struct mm_struct *mm,
 574                                          struct vm_area_struct *vma)
 575 {
 576         if (!vma)
 577                 return mm->mmap;
 578
 579         return vma->vm_next;
 580 }
 581
 582 /*
 583  * munmap_vma_range() - munmap VMAs that overlap a range.
 584  * @mm: The mm struct
 585  * @start: The start of the range.
 586  * @len: The length of the range.
 587  * @pprev: pointer to the pointer that will be set to previous vm_area_struct
 588  * @rb_link: the rb_node
 589  * @rb_parent: the parent rb_node
 590  *
 591  * Find all the vm_area_struct that overlap from @start to
 592  * @end and munmap them.  Set @pprev to the previous vm_area_struct.
 593  *
 594  * Returns: -ENOMEM on munmap failure or 0 on success.
 595  */
 596 static inline int
 597 munmap_vma_range(struct mm_struct *mm, unsigned long start, unsigned long len,
 598                  struct vm_area_struct **pprev, struct rb_node ***link,
 599                  struct rb_node **parent, struct list_head *uf)
 600 {
 601
 602         while (find_vma_links(mm, start, start + len, pprev, link, parent))
 603                 if (do_munmap(mm, start, len, uf))
 604                         return -ENOMEM;
 605
 606         return 0;
 607 }
 608 static unsigned long count_vma_pages_range(struct mm_struct *mm,
 609                 unsigned long addr, unsigned long end)
 610 {
 611         unsigned long nr_pages = 0;
 612         struct vm_area_struct *vma;
 613
 614         /* Find first overlapping mapping */
 615         vma = find_vma_intersection(mm, addr, end);
 616         if (!vma)
 617                 return 0;
 618
 619         nr_pages = (min(end, vma->vm_end) -
 620                 max(addr, vma->vm_start)) >> PAGE_SHIFT;
 621
 622         /* Iterate over the rest of the overlaps */
 623         for (vma = vma->vm_next; vma; vma = vma->vm_next) {
 624                 unsigned long overlap_len;
 625
 626                 if (vma->vm_start > end)
 627                         break;
 628
 629                 overlap_len = min(end, vma->vm_end) - vma->vm_start;
 630                 nr_pages += overlap_len >> PAGE_SHIFT;
 631         }
 632
 633         return nr_pages;
 634 }
 635
 636 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
 637                 struct rb_node **rb_link, struct rb_node *rb_parent)
 638 {
 639         /* Update tracking information for the gap following the new vma. */
 640         if (vma->vm_next)
 641                 vma_gap_update(vma->vm_next);
 642         else
 643                 mm->highest_vm_end = vm_end_gap(vma);
 644
 645         /*
 646          * vma->vm_prev wasn't known when we followed the rbtree to find the
 647          * correct insertion point for that vma. As a result, we could not
 648          * update the vma vm_rb parents rb_subtree_gap values on the way down.
 649          * So, we first insert the vma with a zero rb_subtree_gap value
 650          * (to be consistent with what we did on the way down), and then
 651          * immediately update the gap to the correct value. Finally we
 652          * rebalance the rbtree after all augmented values have been set.
 653          */
 654         rb_link_node(&vma->vm_rb, rb_parent, rb_link);
 655         vma->rb_subtree_gap = 0;
 656         vma_gap_update(vma);
 657         vma_rb_insert(vma, &mm->mm_rb);
 658 }
 659
 660 static void __vma_link_file(struct vm_area_struct *vma)
 661 {
 662         struct file *file;
 663
 664         file = vma->vm_file;
 665         if (file) {
 666                 struct address_space *mapping = file->f_mapping;
 667
 668                 if (vma->vm_flags & VM_SHARED)
 669                         mapping_allow_writable(mapping);
 670
 671                 flush_dcache_mmap_lock(mapping);
 672                 vma_interval_tree_insert(vma, &mapping->i_mmap);
 673                 flush_dcache_mmap_unlock(mapping);
 674         }
 675 }
 676
 677 static void
 678 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 679         struct vm_area_struct *prev, struct rb_node **rb_link,
 680         struct rb_node *rb_parent)
 681 {
 682         __vma_link_list(mm, vma, prev);
 683         __vma_link_rb(mm, vma, rb_link, rb_parent);
 684 }
 685
 686 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
 687                         struct vm_area_struct *prev, struct rb_node **rb_link,
 688                         struct rb_node *rb_parent)
 689 {
 690         struct address_space *mapping = NULL;
 691
 692         if (vma->vm_file) {
 693                 mapping = vma->vm_file->f_mapping;
 694                 i_mmap_lock_write(mapping);
 695         }
 696
 697         __vma_link(mm, vma, prev, rb_link, rb_parent);
 698         __vma_link_file(vma);
 699
 700         if (mapping)
 701                 i_mmap_unlock_write(mapping);
 702
 703         mm->map_count++;
 704         validate_mm(mm);
 705 }
 706
 707 /*
 708  * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
 709  * mm's list and rbtree.  It has already been inserted into the interval tree.
 710  */
 711 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
 712 {
 713         struct vm_area_struct *prev;
 714         struct rb_node **rb_link, *rb_parent;
 715
 716         if (find_vma_links(mm, vma->vm_start, vma->vm_end,
 717                            &prev, &rb_link, &rb_parent))
 718                 BUG();
 719         __vma_link(mm, vma, prev, rb_link, rb_parent);
 720         mm->map_count++;
 721 }
 722
 723 static __always_inline void __vma_unlink(struct mm_struct *mm,
 724                                                 struct vm_area_struct *vma,
 725                                                 struct vm_area_struct *ignore)
 726 {
 727         vma_rb_erase_ignore(vma, &mm->mm_rb, ignore);
 728         __vma_unlink_list(mm, vma);
 729         /* Kill the cache */
 730         vmacache_invalidate(mm);
 731 }
 732
 733 /*
 734  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
 735  * is already present in an i_mmap tree without adjusting the tree.
 736  * The following helper function should be used when such adjustments
 737  * are necessary.  The "insert" vma (if any) is to be inserted
 738  * before we drop the necessary locks.
 739  */
 740 int __vma_adjust(struct vm_area_struct *vma, unsigned long start,
 741         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
 742         struct vm_area_struct *expand)
 743 {
 744         struct mm_struct *mm = vma->vm_mm;
 745         struct vm_area_struct *next = vma->vm_next, *orig_vma = vma;
 746         struct address_space *mapping = NULL;
 747         struct rb_root_cached *root = NULL;
 748         struct anon_vma *anon_vma = NULL;
 749         struct file *file = vma->vm_file;
 750         bool start_changed = false, end_changed = false;
 751         long adjust_next = 0;
 752         int remove_next = 0;
 753
 754         if (next && !insert) {
 755                 struct vm_area_struct *exporter = NULL, *importer = NULL;
 756
 757                 if (end >= next->vm_end) {
 758                         /*
 759                          * vma expands, overlapping all the next, and
 760                          * perhaps the one after too (mprotect case 6).
 761                          * The only other cases that gets here are
 762                          * case 1, case 7 and case 8.
 763                          */
 764                         if (next == expand) {
 765                                 /*
 766                                  * The only case where we don't expand "vma"
 767                                  * and we expand "next" instead is case 8.
 768                                  */
 769                                 VM_WARN_ON(end != next->vm_end);
 770                                 /*
 771                                  * remove_next == 3 means we're
 772                                  * removing "vma" and that to do so we
 773                                  * swapped "vma" and "next".
 774                                  */
 775                                 remove_next = 3;
 776                                 VM_WARN_ON(file != next->vm_file);
 777                                 swap(vma, next);
 778                         } else {
 779                                 VM_WARN_ON(expand != vma);
 780                                 /*
 781                                  * case 1, 6, 7, remove_next == 2 is case 6,
 782                                  * remove_next == 1 is case 1 or 7.
 783                                  */
 784                                 remove_next = 1 + (end > next->vm_end);
 785                                 VM_WARN_ON(remove_next == 2 &&
 786                                            end != next->vm_next->vm_end);
 787                                 /* trim end to next, for case 6 first pass */
 788                                 end = next->vm_end;
 789                         }
 790
 791                         exporter = next;
 792                         importer = vma;
 793
 794                         /*
 795                          * If next doesn't have anon_vma, import from vma after
 796                          * next, if the vma overlaps with it.
 797                          */
 798                         if (remove_next == 2 && !next->anon_vma)
 799                                 exporter = next->vm_next;
 800
 801                 } else if (end > next->vm_start) {
 802                         /*
 803                          * vma expands, overlapping part of the next:
 804                          * mprotect case 5 shifting the boundary up.
 805                          */
 806                         adjust_next = (end - next->vm_start);
 807                         exporter = next;
 808                         importer = vma;
 809                         VM_WARN_ON(expand != importer);
 810                 } else if (end < vma->vm_end) {
 811                         /*
 812                          * vma shrinks, and !insert tells it's not
 813                          * split_vma inserting another: so it must be
 814                          * mprotect case 4 shifting the boundary down.
 815                          */
 816                         adjust_next = -(vma->vm_end - end);
 817                         exporter = vma;
 818                         importer = next;
 819                         VM_WARN_ON(expand != importer);
 820                 }
 821
 822                 /*
 823                  * Easily overlooked: when mprotect shifts the boundary,
 824                  * make sure the expanding vma has anon_vma set if the
 825                  * shrinking vma had, to cover any anon pages imported.
 826                  */
 827                 if (exporter && exporter->anon_vma && !importer->anon_vma) {
 828                         int error;
 829
 830                         importer->anon_vma = exporter->anon_vma;
 831                         error = anon_vma_clone(importer, exporter);
 832                         if (error)
 833                                 return error;
 834                 }
 835         }
 836 again:
 837         vma_adjust_trans_huge(orig_vma, start, end, adjust_next);
 838
 839         if (file) {
 840                 mapping = file->f_mapping;
 841                 root = &mapping->i_mmap;
 842                 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
 843
 844                 if (adjust_next)
 845                         uprobe_munmap(next, next->vm_start, next->vm_end);
 846
 847                 i_mmap_lock_write(mapping);
 848                 if (insert) {
 849                         /*
 850                          * Put into interval tree now, so instantiated pages
 851                          * are visible to arm/parisc __flush_dcache_page
 852                          * throughout; but we cannot insert into address
 853                          * space until vma start or end is updated.
 854                          */
 855                         __vma_link_file(insert);
 856                 }
 857         }
 858
 859         anon_vma = vma->anon_vma;
 860         if (!anon_vma && adjust_next)
 861                 anon_vma = next->anon_vma;
 862         if (anon_vma) {
 863                 VM_WARN_ON(adjust_next && next->anon_vma &&
 864                            anon_vma != next->anon_vma);
 865                 anon_vma_lock_write(anon_vma);
 866                 anon_vma_interval_tree_pre_update_vma(vma);
 867                 if (adjust_next)
 868                         anon_vma_interval_tree_pre_update_vma(next);
 869         }
 870
 871         if (file) {
 872                 flush_dcache_mmap_lock(mapping);
 873                 vma_interval_tree_remove(vma, root);
 874                 if (adjust_next)
 875                         vma_interval_tree_remove(next, root);
 876         }
 877
 878         if (start != vma->vm_start) {
 879                 vma->vm_start = start;
 880                 start_changed = true;
 881         }
 882         if (end != vma->vm_end) {
 883                 vma->vm_end = end;
 884                 end_changed = true;
 885         }
 886         vma->vm_pgoff = pgoff;
 887         if (adjust_next) {
 888                 next->vm_start += adjust_next;
 889                 next->vm_pgoff += adjust_next >> PAGE_SHIFT;
 890         }
 891
 892         if (file) {
 893                 if (adjust_next)
 894                         vma_interval_tree_insert(next, root);
 895                 vma_interval_tree_insert(vma, root);
 896                 flush_dcache_mmap_unlock(mapping);
 897         }
 898
 899         if (remove_next) {
 900                 /*
 901                  * vma_merge has merged next into vma, and needs
 902                  * us to remove next before dropping the locks.
 903                  */
 904                 if (remove_next != 3)
 905                         __vma_unlink(mm, next, next);
 906                 else
 907                         /*
 908                          * vma is not before next if they've been
 909                          * swapped.
 910                          *
 911                          * pre-swap() next->vm_start was reduced so
 912                          * tell validate_mm_rb to ignore pre-swap()
 913                          * "next" (which is stored in post-swap()
 914                          * "vma").
 915                          */
 916                         __vma_unlink(mm, next, vma);
 917                 if (file)
 918                         __remove_shared_vm_struct(next, file, mapping);
 919         } else if (insert) {
 920                 /*
 921                  * split_vma has split insert from vma, and needs
 922                  * us to insert it before dropping the locks
 923                  * (it may either follow vma or precede it).
 924                  */
 925                 __insert_vm_struct(mm, insert);
 926         } else {
 927                 if (start_changed)
 928                         vma_gap_update(vma);
 929                 if (end_changed) {
 930                         if (!next)
 931                                 mm->highest_vm_end = vm_end_gap(vma);
 932                         else if (!adjust_next)
 933                                 vma_gap_update(next);
 934                 }
 935         }
 936
 937         if (anon_vma) {
 938                 anon_vma_interval_tree_post_update_vma(vma);
 939                 if (adjust_next)
 940                         anon_vma_interval_tree_post_update_vma(next);
 941                 anon_vma_unlock_write(anon_vma);
 942         }
 943
 944         if (file) {
 945                 i_mmap_unlock_write(mapping);
 946                 uprobe_mmap(vma);
 947
 948                 if (adjust_next)
 949                         uprobe_mmap(next);
 950         }
 951
 952         if (remove_next) {
 953                 if (file) {
 954                         uprobe_munmap(next, next->vm_start, next->vm_end);
 955                         fput(file);
 956                 }
 957                 if (next->anon_vma)
 958                         anon_vma_merge(vma, next);
 959                 mm->map_count--;
 960                 mpol_put(vma_policy(next));
 961                 vm_area_free(next);
 962                 /*
 963                  * In mprotect's case 6 (see comments on vma_merge),
 964                  * we must remove another next too. It would clutter
 965                  * up the code too much to do both in one go.
 966                  */
 967                 if (remove_next != 3) {
 968                         /*
 969                          * If "next" was removed and vma->vm_end was
 970                          * expanded (up) over it, in turn
 971                          * "next->vm_prev->vm_end" changed and the
 972                          * "vma->vm_next" gap must be updated.
 973                          */
 974                         next = vma->vm_next;
 975                 } else {
 976                         /*
 977                          * For the scope of the comment "next" and
 978                          * "vma" considered pre-swap(): if "vma" was
 979                          * removed, next->vm_start was expanded (down)
 980                          * over it and the "next" gap must be updated.
 981                          * Because of the swap() the post-swap() "vma"
 982                          * actually points to pre-swap() "next"
 983                          * (post-swap() "next" as opposed is now a
 984                          * dangling pointer).
 985                          */
 986                         next = vma;
 987                 }
 988                 if (remove_next == 2) {
 989                         remove_next = 1;
 990                         end = next->vm_end;
 991                         goto again;
 992                 }
 993                 else if (next)
 994                         vma_gap_update(next);
 995                 else {
 996                         /*
 997                          * If remove_next == 2 we obviously can't
 998                          * reach this path.
 999                          *
1000                          * If remove_next == 3 we can't reach this
1001                          * path because pre-swap() next is always not
1002                          * NULL. pre-swap() "next" is not being
1003                          * removed and its next->vm_end is not altered
1004                          * (and furthermore "end" already matches
1005                          * next->vm_end in remove_next == 3).
1006                          *
1007                          * We reach this only in the remove_next == 1
1008                          * case if the "next" vma that was removed was
1009                          * the highest vma of the mm. However in such
1010                          * case next->vm_end == "end" and the extended
1011                          * "vma" has vma->vm_end == next->vm_end so
1012                          * mm->highest_vm_end doesn't need any update
1013                          * in remove_next == 1 case.
1014                          */
1015                         VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma));
1016                 }
1017         }
1018         if (insert && file)
1019                 uprobe_mmap(insert);
1020
1021         validate_mm(mm);
1022
1023         return 0;
1024 }
1025
1026 /*
1027  * If the vma has a ->close operation then the driver probably needs to release
1028  * per-vma resources, so we don't attempt to merge those.
1029  */
1030 static inline int is_mergeable_vma(struct vm_area_struct *vma,
1031                                 struct file *file, unsigned long vm_flags,
1032                                 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1033 {
1034         /*
1035          * VM_SOFTDIRTY should not prevent from VMA merging, if we
1036          * match the flags but dirty bit -- the caller should mark
1037          * merged VMA as dirty. If dirty bit won't be excluded from
1038          * comparison, we increase pressure on the memory system forcing
1039          * the kernel to generate new VMAs when old one could be
1040          * extended instead.
1041          */
1042         if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
1043                 return 0;
1044         if (vma->vm_file != file)
1045                 return 0;
1046         if (vma->vm_ops && vma->vm_ops->close)
1047                 return 0;
1048         if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
1049                 return 0;
1050         return 1;
1051 }
1052
1053 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
1054                                         struct anon_vma *anon_vma2,
1055                                         struct vm_area_struct *vma)
1056 {
1057         /*
1058          * The list_is_singular() test is to avoid merging VMA cloned from
1059          * parents. This can improve scalability caused by anon_vma lock.
1060          */
1061         if ((!anon_vma1 || !anon_vma2) && (!vma ||
1062                 list_is_singular(&vma->anon_vma_chain)))
1063                 return 1;
1064         return anon_vma1 == anon_vma2;
1065 }
1066
1067 /*
1068  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1069  * in front of (at a lower virtual address and file offset than) the vma.
1070  *
1071  * We cannot merge two vmas if they have differently assigned (non-NULL)
1072  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1073  *
1074  * We don't check here for the merged mmap wrapping around the end of pagecache
1075  * indices (16TB on ia32) because do_mmap() does not permit mmap's which
1076  * wrap, nor mmaps which cover the final page at index -1UL.
1077  */
1078 static int
1079 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
1080                      struct anon_vma *anon_vma, struct file *file,
1081                      pgoff_t vm_pgoff,
1082                      struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1083 {
1084         if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1085             is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1086                 if (vma->vm_pgoff == vm_pgoff)
1087                         return 1;
1088         }
1089         return 0;
1090 }
1091
1092 /*
1093  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
1094  * beyond (at a higher virtual address and file offset than) the vma.
1095  *
1096  * We cannot merge two vmas if they have differently assigned (non-NULL)
1097  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
1098  */
1099 static int
1100 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
1101                     struct anon_vma *anon_vma, struct file *file,
1102                     pgoff_t vm_pgoff,
1103                     struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1104 {
1105         if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
1106             is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
1107                 pgoff_t vm_pglen;
1108                 vm_pglen = vma_pages(vma);
1109                 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
1110                         return 1;
1111         }
1112         return 0;
1113 }
1114
1115 /*
1116  * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1117  * whether that can be merged with its predecessor or its successor.
1118  * Or both (it neatly fills a hole).
1119  *
1120  * In most cases - when called for mmap, brk or mremap - [addr,end) is
1121  * certain not to be mapped by the time vma_merge is called; but when
1122  * called for mprotect, it is certain to be already mapped (either at
1123  * an offset within prev, or at the start of next), and the flags of
1124  * this area are about to be changed to vm_flags - and the no-change
1125  * case has already been eliminated.
1126  *
1127  * The following mprotect cases have to be considered, where AAAA is
1128  * the area passed down from mprotect_fixup, never extending beyond one
1129  * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1130  *
1131  *     AAAA             AAAA                   AAAA
1132  *    PPPPPPNNNNNN    PPPPPPNNNNNN       PPPPPPNNNNNN
1133  *    cannot merge    might become       might become
1134  *                    PPNNNNNNNNNN       PPPPPPPPPPNN
1135  *    mmap, brk or    case 4 below       case 5 below
1136  *    mremap move:
1137  *                        AAAA               AAAA
1138  *                    PPPP    NNNN       PPPPNNNNXXXX
1139  *                    might become       might become
1140  *                    PPPPPPPPPPPP 1 or  PPPPPPPPPPPP 6 or
1141  *                    PPPPPPPPNNNN 2 or  PPPPPPPPXXXX 7 or
1142  *                    PPPPNNNNNNNN 3     PPPPXXXXXXXX 8
1143  *
1144  * It is important for case 8 that the vma NNNN overlapping the
1145  * region AAAA is never going to extended over XXXX. Instead XXXX must
1146  * be extended in region AAAA and NNNN must be removed. This way in
1147  * all cases where vma_merge succeeds, the moment vma_adjust drops the
1148  * rmap_locks, the properties of the merged vma will be already
1149  * correct for the whole merged range. Some of those properties like
1150  * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
1151  * be correct for the whole merged range immediately after the
1152  * rmap_locks are released. Otherwise if XXXX would be removed and
1153  * NNNN would be extended over the XXXX range, remove_migration_ptes
1154  * or other rmap walkers (if working on addresses beyond the "end"
1155  * parameter) may establish ptes with the wrong permissions of NNNN
1156  * instead of the right permissions of XXXX.
1157  */
1158 struct vm_area_struct *vma_merge(struct mm_struct *mm,
1159                         struct vm_area_struct *prev, unsigned long addr,
1160                         unsigned long end, unsigned long vm_flags,
1161                         struct anon_vma *anon_vma, struct file *file,
1162                         pgoff_t pgoff, struct mempolicy *policy,
1163                         struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
1164 {
1165         pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1166         struct vm_area_struct *area, *next;
1167         int err;
1168
1169         /*
1170          * We later require that vma->vm_flags == vm_flags,
1171          * so this tests vma->vm_flags & VM_SPECIAL, too.
1172          */
1173         if (vm_flags & VM_SPECIAL)
1174                 return NULL;
1175
1176         next = vma_next(mm, prev);
1177         area = next;
1178         if (area && area->vm_end == end)                /* cases 6, 7, 8 */
1179                 next = next->vm_next;
1180
1181         /* verify some invariant that must be enforced by the caller */
1182         VM_WARN_ON(prev && addr <= prev->vm_start);
1183         VM_WARN_ON(area && end > area->vm_end);
1184         VM_WARN_ON(addr >= end);
1185
1186         /*
1187          * Can it merge with the predecessor?
1188          */
1189         if (prev && prev->vm_end == addr &&
1190                         mpol_equal(vma_policy(prev), policy) &&
1191                         can_vma_merge_after(prev, vm_flags,
1192                                             anon_vma, file, pgoff,
1193                                             vm_userfaultfd_ctx)) {
1194                 /*
1195                  * OK, it can.  Can we now merge in the successor as well?
1196                  */
1197                 if (next && end == next->vm_start &&
1198                                 mpol_equal(policy, vma_policy(next)) &&
1199                                 can_vma_merge_before(next, vm_flags,
1200                                                      anon_vma, file,
1201                                                      pgoff+pglen,
1202                                                      vm_userfaultfd_ctx) &&
1203                                 is_mergeable_anon_vma(prev->anon_vma,
1204                                                       next->anon_vma, NULL)) {
1205                                                         /* cases 1, 6 */
1206                         err = __vma_adjust(prev, prev->vm_start,
1207                                          next->vm_end, prev->vm_pgoff, NULL,
1208                                          prev);
1209                 } else                                  /* cases 2, 5, 7 */
1210                         err = __vma_adjust(prev, prev->vm_start,
1211                                          end, prev->vm_pgoff, NULL, prev);
1212                 if (err)
1213                         return NULL;
1214                 khugepaged_enter_vma_merge(prev, vm_flags);
1215                 return prev;
1216         }
1217
1218         /*
1219          * Can this new request be merged in front of next?
1220          */
1221         if (next && end == next->vm_start &&
1222                         mpol_equal(policy, vma_policy(next)) &&
1223                         can_vma_merge_before(next, vm_flags,
1224                                              anon_vma, file, pgoff+pglen,
1225                                              vm_userfaultfd_ctx)) {
1226                 if (prev && addr < prev->vm_end)        /* case 4 */
1227                         err = __vma_adjust(prev, prev->vm_start,
1228                                          addr, prev->vm_pgoff, NULL, next);
1229                 else {                                  /* cases 3, 8 */
1230                         err = __vma_adjust(area, addr, next->vm_end,
1231                                          next->vm_pgoff - pglen, NULL, next);
1232                         /*
1233                          * In case 3 area is already equal to next and
1234                          * this is a noop, but in case 8 "area" has
1235                          * been removed and next was expanded over it.
1236                          */
1237                         area = next;
1238                 }
1239                 if (err)
1240                         return NULL;
1241                 khugepaged_enter_vma_merge(area, vm_flags);
1242                 return area;
1243         }
1244
1245         return NULL;
1246 }
1247
1248 /*
1249  * Rough compatibility check to quickly see if it's even worth looking
1250  * at sharing an anon_vma.
1251  *
1252  * They need to have the same vm_file, and the flags can only differ
1253  * in things that mprotect may change.
1254  *
1255  * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1256  * we can merge the two vma's. For example, we refuse to merge a vma if
1257  * there is a vm_ops->close() function, because that indicates that the
1258  * driver is doing some kind of reference counting. But that doesn't
1259  * really matter for the anon_vma sharing case.
1260  */
1261 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1262 {
1263         return a->vm_end == b->vm_start &&
1264                 mpol_equal(vma_policy(a), vma_policy(b)) &&
1265                 a->vm_file == b->vm_file &&
1266                 !((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) &&
1267                 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1268 }
1269
1270 /*
1271  * Do some basic sanity checking to see if we can re-use the anon_vma
1272  * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1273  * the same as 'old', the other will be the new one that is trying
1274  * to share the anon_vma.
1275  *
1276  * NOTE! This runs with mm_sem held for reading, so it is possible that
1277  * the anon_vma of 'old' is concurrently in the process of being set up
1278  * by another page fault trying to merge _that_. But that's ok: if it
1279  * is being set up, that automatically means that it will be a singleton
1280  * acceptable for merging, so we can do all of this optimistically. But
1281  * we do that READ_ONCE() to make sure that we never re-load the pointer.
1282  *
1283  * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1284  * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1285  * is to return an anon_vma that is "complex" due to having gone through
1286  * a fork).
1287  *
1288  * We also make sure that the two vma's are compatible (adjacent,
1289  * and with the same memory policies). That's all stable, even with just
1290  * a read lock on the mm_sem.
1291  */
1292 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1293 {
1294         if (anon_vma_compatible(a, b)) {
1295                 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1296
1297                 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1298                         return anon_vma;
1299         }
1300         return NULL;
1301 }
1302
1303 /*
1304  * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1305  * neighbouring vmas for a suitable anon_vma, before it goes off
1306  * to allocate a new anon_vma.  It checks because a repetitive
1307  * sequence of mprotects and faults may otherwise lead to distinct
1308  * anon_vmas being allocated, preventing vma merge in subsequent
1309  * mprotect.
1310  */
1311 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1312 {
1313         struct anon_vma *anon_vma = NULL;
1314
1315         /* Try next first. */
1316         if (vma->vm_next) {
1317                 anon_vma = reusable_anon_vma(vma->vm_next, vma, vma->vm_next);
1318                 if (anon_vma)
1319                         return anon_vma;
1320         }
1321
1322         /* Try prev next. */
1323         if (vma->vm_prev)
1324                 anon_vma = reusable_anon_vma(vma->vm_prev, vma->vm_prev, vma);
1325
1326         /*
1327          * We might reach here with anon_vma == NULL if we can't find
1328          * any reusable anon_vma.
1329          * There's no absolute need to look only at touching neighbours:
1330          * we could search further afield for "compatible" anon_vmas.
1331          * But it would probably just be a waste of time searching,
1332          * or lead to too many vmas hanging off the same anon_vma.
1333          * We're trying to allow mprotect remerging later on,
1334          * not trying to minimize memory used for anon_vmas.
1335          */
1336         return anon_vma;
1337 }
1338
1339 /*
1340  * If a hint addr is less than mmap_min_addr change hint to be as
1341  * low as possible but still greater than mmap_min_addr
1342  */
1343 static inline unsigned long round_hint_to_min(unsigned long hint)
1344 {
1345         hint &= PAGE_MASK;
1346         if (((void *)hint != NULL) &&
1347             (hint < mmap_min_addr))
1348                 return PAGE_ALIGN(mmap_min_addr);
1349         return hint;
1350 }
1351
1352 int mlock_future_check(struct mm_struct *mm, unsigned long flags,
1353                        unsigned long len)
1354 {
1355         unsigned long locked, lock_limit;
1356
1357         /*  mlock MCL_FUTURE? */
1358         if (flags & VM_LOCKED) {
1359                 locked = len >> PAGE_SHIFT;
1360                 locked += mm->locked_vm;
1361                 lock_limit = rlimit(RLIMIT_MEMLOCK);
1362                 lock_limit >>= PAGE_SHIFT;
1363                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1364                         return -EAGAIN;
1365         }
1366         return 0;
1367 }
1368
1369 static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
1370 {
1371         if (S_ISREG(inode->i_mode))
1372                 return MAX_LFS_FILESIZE;
1373
1374         if (S_ISBLK(inode->i_mode))
1375                 return MAX_LFS_FILESIZE;
1376
1377         if (S_ISSOCK(inode->i_mode))
1378                 return MAX_LFS_FILESIZE;
1379
1380         /* Special "we do even unsigned file positions" case */
1381         if (file->f_mode & FMODE_UNSIGNED_OFFSET)
1382                 return 0;
1383
1384         /* Yes, random drivers might want more. But I'm tired of buggy drivers */
1385         return ULONG_MAX;
1386 }
1387
1388 static inline bool file_mmap_ok(struct file *file, struct inode *inode,
1389                                 unsigned long pgoff, unsigned long len)
1390 {
1391         u64 maxsize = file_mmap_size_max(file, inode);
1392
1393         if (maxsize && len > maxsize)
1394                 return false;
1395         maxsize -= len;
1396         if (pgoff > maxsize >> PAGE_SHIFT)
1397                 return false;
1398         return true;
1399 }
1400
1401 /*
1402  * The caller must write-lock current->mm->mmap_lock.
1403  */
1404 unsigned long do_mmap(struct file *file, unsigned long addr,
1405                         unsigned long len, unsigned long prot,
1406                         unsigned long flags, unsigned long pgoff,
1407                         unsigned long *populate, struct list_head *uf)
1408 {
1409         struct mm_struct *mm = current->mm;
1410         vm_flags_t vm_flags;
1411         int pkey = 0;
1412
1413         *populate = 0;
1414
1415         if (!len)
1416                 return -EINVAL;
1417
1418         /*
1419          * Does the application expect PROT_READ to imply PROT_EXEC?
1420          *
1421          * (the exception is when the underlying filesystem is noexec
1422          *  mounted, in which case we dont add PROT_EXEC.)
1423          */
1424         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1425                 if (!(file && path_noexec(&file->f_path)))
1426                         prot |= PROT_EXEC;
1427
1428         /* force arch specific MAP_FIXED handling in get_unmapped_area */
1429         if (flags & MAP_FIXED_NOREPLACE)
1430                 flags |= MAP_FIXED;
1431
1432         if (!(flags & MAP_FIXED))
1433                 addr = round_hint_to_min(addr);
1434
1435         /* Careful about overflows.. */
1436         len = PAGE_ALIGN(len);
1437         if (!len)
1438                 return -ENOMEM;
1439
1440         /* offset overflow? */
1441         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1442                 return -EOVERFLOW;
1443
1444         /* Too many mappings? */
1445         if (mm->map_count > sysctl_max_map_count)
1446                 return -ENOMEM;
1447
1448         /* Obtain the address to map to. we verify (or select) it and ensure
1449          * that it represents a valid section of the address space.
1450          */
1451         addr = get_unmapped_area(file, addr, len, pgoff, flags);
1452         if (IS_ERR_VALUE(addr))
1453                 return addr;
1454
1455         if (flags & MAP_FIXED_NOREPLACE) {
1456                 if (find_vma_intersection(mm, addr, addr + len))
1457                         return -EEXIST;
1458         }
1459
1460         if (prot == PROT_EXEC) {
1461                 pkey = execute_only_pkey(mm);
1462                 if (pkey < 0)
1463                         pkey = 0;
1464         }
1465
1466         /* Do simple checking here so the lower-level routines won't have
1467          * to. we assume access permissions have been handled by the open
1468          * of the memory object, so we don't do any here.
1469          */
1470         vm_flags = calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1471                         mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1472
1473         if (flags & MAP_LOCKED)
1474                 if (!can_do_mlock())
1475                         return -EPERM;
1476
1477         if (mlock_future_check(mm, vm_flags, len))
1478                 return -EAGAIN;
1479
1480         if (file) {
1481                 struct inode *inode = file_inode(file);
1482                 unsigned long flags_mask;
1483
1484                 if (!file_mmap_ok(file, inode, pgoff, len))
1485                         return -EOVERFLOW;
1486
1487                 flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
1488
1489                 switch (flags & MAP_TYPE) {
1490                 case MAP_SHARED:
1491                         /*
1492                          * Force use of MAP_SHARED_VALIDATE with non-legacy
1493                          * flags. E.g. MAP_SYNC is dangerous to use with
1494                          * MAP_SHARED as you don't know which consistency model
1495                          * you will get. We silently ignore unsupported flags
1496                          * with MAP_SHARED to preserve backward compatibility.
1497                          */
1498                         flags &= LEGACY_MAP_MASK;
1499                         fallthrough;
1500                 case MAP_SHARED_VALIDATE:
1501                         if (flags & ~flags_mask)
1502                                 return -EOPNOTSUPP;
1503                         if (prot & PROT_WRITE) {
1504                                 if (!(file->f_mode & FMODE_WRITE))
1505                                         return -EACCES;
1506                                 if (IS_SWAPFILE(file->f_mapping->host))
1507                                         return -ETXTBSY;
1508                         }
1509
1510                         /*
1511                          * Make sure we don't allow writing to an append-only
1512                          * file..
1513                          */
1514                         if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1515                                 return -EACCES;
1516
1517                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1518                         if (!(file->f_mode & FMODE_WRITE))
1519                                 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1520                         fallthrough;
1521                 case MAP_PRIVATE:
1522                         if (!(file->f_mode & FMODE_READ))
1523                                 return -EACCES;
1524                         if (path_noexec(&file->f_path)) {
1525                                 if (vm_flags & VM_EXEC)
1526                                         return -EPERM;
1527                                 vm_flags &= ~VM_MAYEXEC;
1528                         }
1529
1530                         if (!file->f_op->mmap)
1531                                 return -ENODEV;
1532                         if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1533                                 return -EINVAL;
1534                         break;
1535
1536                 default:
1537                         return -EINVAL;
1538                 }
1539         } else {
1540                 switch (flags & MAP_TYPE) {
1541                 case MAP_SHARED:
1542                         if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1543                                 return -EINVAL;
1544                         /*
1545                          * Ignore pgoff.
1546                          */
1547                         pgoff = 0;
1548                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1549                         break;
1550                 case MAP_PRIVATE:
1551                         /*
1552                          * Set pgoff according to addr for anon_vma.
1553                          */
1554                         pgoff = addr >> PAGE_SHIFT;
1555                         break;
1556                 default:
1557                         return -EINVAL;
1558                 }
1559         }
1560
1561         /*
1562          * Set 'VM_NORESERVE' if we should not account for the
1563          * memory use of this mapping.
1564          */
1565         if (flags & MAP_NORESERVE) {
1566                 /* We honor MAP_NORESERVE if allowed to overcommit */
1567                 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1568                         vm_flags |= VM_NORESERVE;
1569
1570                 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1571                 if (file && is_file_hugepages(file))
1572                         vm_flags |= VM_NORESERVE;
1573         }
1574
1575         addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
1576         if (!IS_ERR_VALUE(addr) &&
1577             ((vm_flags & VM_LOCKED) ||
1578              (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1579                 *populate = len;
1580         return addr;
1581 }
1582
1583 unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1584                               unsigned long prot, unsigned long flags,
1585                               unsigned long fd, unsigned long pgoff)
1586 {
1587         struct file *file = NULL;
1588         unsigned long retval;
1589
1590         if (!(flags & MAP_ANONYMOUS)) {
1591                 audit_mmap_fd(fd, flags);
1592                 file = fget(fd);
1593                 if (!file)
1594                         return -EBADF;
1595                 if (is_file_hugepages(file)) {
1596                         len = ALIGN(len, huge_page_size(hstate_file(file)));
1597                 } else if (unlikely(flags & MAP_HUGETLB)) {
1598                         retval = -EINVAL;
1599                         goto out_fput;
1600                 }
1601         } else if (flags & MAP_HUGETLB) {
1602                 struct ucounts *ucounts = NULL;
1603                 struct hstate *hs;
1604
1605                 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1606                 if (!hs)
1607                         return -EINVAL;
1608
1609                 len = ALIGN(len, huge_page_size(hs));
1610                 /*
1611                  * VM_NORESERVE is used because the reservations will be
1612                  * taken when vm_ops->mmap() is called
1613                  * A dummy user value is used because we are not locking
1614                  * memory so no accounting is necessary
1615                  */
1616                 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1617                                 VM_NORESERVE,
1618                                 &ucounts, HUGETLB_ANONHUGE_INODE,
1619                                 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1620                 if (IS_ERR(file))
1621                         return PTR_ERR(file);
1622         }
1623
1624         retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1625 out_fput:
1626         if (file)
1627                 fput(file);
1628         return retval;
1629 }
1630
1631 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1632                 unsigned long, prot, unsigned long, flags,
1633                 unsigned long, fd, unsigned long, pgoff)
1634 {
1635         return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1636 }
1637
1638 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1639 struct mmap_arg_struct {
1640         unsigned long addr;
1641         unsigned long len;
1642         unsigned long prot;
1643         unsigned long flags;
1644         unsigned long fd;
1645         unsigned long offset;
1646 };
1647
1648 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1649 {
1650         struct mmap_arg_struct a;
1651
1652         if (copy_from_user(&a, arg, sizeof(a)))
1653                 return -EFAULT;
1654         if (offset_in_page(a.offset))
1655                 return -EINVAL;
1656
1657         return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1658                                a.offset >> PAGE_SHIFT);
1659 }
1660 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1661
1662 /*
1663  * Some shared mappings will want the pages marked read-only
1664  * to track write events. If so, we'll downgrade vm_page_prot
1665  * to the private version (using protection_map[] without the
1666  * VM_SHARED bit).
1667  */
1668 int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
1669 {
1670         vm_flags_t vm_flags = vma->vm_flags;
1671         const struct vm_operations_struct *vm_ops = vma->vm_ops;
1672
1673         /* If it was private or non-writable, the write bit is already clear */
1674         if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1675                 return 0;
1676
1677         /* The backer wishes to know when pages are first written to? */
1678         if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1679                 return 1;
1680
1681         /* The open routine did something to the protections that pgprot_modify
1682          * won't preserve? */
1683         if (pgprot_val(vm_page_prot) !=
1684             pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags)))
1685                 return 0;
1686
1687         /*
1688          * Do we need to track softdirty? hugetlb does not support softdirty
1689          * tracking yet.
1690          */
1691         if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY) &&
1692             !is_vm_hugetlb_page(vma))
1693                 return 1;
1694
1695         /* Specialty mapping? */
1696         if (vm_flags & VM_PFNMAP)
1697                 return 0;
1698
1699         /* Can the mapping track the dirty pages? */
1700         return vma->vm_file && vma->vm_file->f_mapping &&
1701                 mapping_can_writeback(vma->vm_file->f_mapping);
1702 }
1703
1704 /*
1705  * We account for memory if it's a private writeable mapping,
1706  * not hugepages and VM_NORESERVE wasn't set.
1707  */
1708 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1709 {
1710         /*
1711          * hugetlb has its own accounting separate from the core VM
1712          * VM_HUGETLB may not be set yet so we cannot check for that flag.
1713          */
1714         if (file && is_file_hugepages(file))
1715                 return 0;
1716
1717         return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1718 }
1719
1720 unsigned long mmap_region(struct file *file, unsigned long addr,
1721                 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
1722                 struct list_head *uf)
1723 {
1724         struct mm_struct *mm = current->mm;
1725         struct vm_area_struct *vma, *prev, *merge;
1726         int error;
1727         struct rb_node **rb_link, *rb_parent;
1728         unsigned long charged = 0;
1729
1730         /* Check against address space limit. */
1731         if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
1732                 unsigned long nr_pages;
1733
1734                 /*
1735                  * MAP_FIXED may remove pages of mappings that intersects with
1736                  * requested mapping. Account for the pages it would unmap.
1737                  */
1738                 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1739
1740                 if (!may_expand_vm(mm, vm_flags,
1741                                         (len >> PAGE_SHIFT) - nr_pages))
1742                         return -ENOMEM;
1743         }
1744
1745         /* Clear old maps, set up prev, rb_link, rb_parent, and uf */
1746         if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf))
1747                 return -ENOMEM;
1748         /*
1749          * Private writable mapping: check memory availability
1750          */
1751         if (accountable_mapping(file, vm_flags)) {
1752                 charged = len >> PAGE_SHIFT;
1753                 if (security_vm_enough_memory_mm(mm, charged))
1754                         return -ENOMEM;
1755                 vm_flags |= VM_ACCOUNT;
1756         }
1757
1758         /*
1759          * Can we just expand an old mapping?
1760          */
1761         vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1762                         NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1763         if (vma)
1764                 goto out;
1765
1766         /*
1767          * Determine the object being mapped and call the appropriate
1768          * specific mapper. the address has already been validated, but
1769          * not unmapped, but the maps are removed from the list.
1770          */
1771         vma = vm_area_alloc(mm);
1772         if (!vma) {
1773                 error = -ENOMEM;
1774                 goto unacct_error;
1775         }
1776
1777         vma->vm_start = addr;
1778         vma->vm_end = addr + len;
1779         vma->vm_flags = vm_flags;
1780         vma->vm_page_prot = vm_get_page_prot(vm_flags);
1781         vma->vm_pgoff = pgoff;
1782
1783         if (file) {
1784                 if (vm_flags & VM_SHARED) {
1785                         error = mapping_map_writable(file->f_mapping);
1786                         if (error)
1787                                 goto free_vma;
1788                 }
1789
1790                 vma->vm_file = get_file(file);
1791                 error = call_mmap(file, vma);
1792                 if (error)
1793                         goto unmap_and_free_vma;
1794
1795                 /* Can addr have changed??
1796                  *
1797                  * Answer: Yes, several device drivers can do it in their
1798                  *         f_op->mmap method. -DaveM
1799                  * Bug: If addr is changed, prev, rb_link, rb_parent should
1800                  *      be updated for vma_link()
1801                  */
1802                 WARN_ON_ONCE(addr != vma->vm_start);
1803
1804                 addr = vma->vm_start;
1805
1806                 /* If vm_flags changed after call_mmap(), we should try merge vma again
1807                  * as we may succeed this time.
1808                  */
1809                 if (unlikely(vm_flags != vma->vm_flags && prev)) {
1810                         merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags,
1811                                 NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX);
1812                         if (merge) {
1813                                 /* ->mmap() can change vma->vm_file and fput the original file. So
1814                                  * fput the vma->vm_file here or we would add an extra fput for file
1815                                  * and cause general protection fault ultimately.
1816                                  */
1817                                 fput(vma->vm_file);
1818                                 vm_area_free(vma);
1819                                 vma = merge;
1820                                 /* Update vm_flags to pick up the change. */
1821                                 vm_flags = vma->vm_flags;
1822                                 goto unmap_writable;
1823                         }
1824                 }
1825
1826                 vm_flags = vma->vm_flags;
1827         } else if (vm_flags & VM_SHARED) {
1828                 error = shmem_zero_setup(vma);
1829                 if (error)
1830                         goto free_vma;
1831         } else {
1832                 vma_set_anonymous(vma);
1833         }
1834
1835         /* Allow architectures to sanity-check the vm_flags */
1836         if (!arch_validate_flags(vma->vm_flags)) {
1837                 error = -EINVAL;
1838                 if (file)
1839                         goto close_and_free_vma;
1840                 else
1841                         goto free_vma;
1842         }
1843
1844         vma_link(mm, vma, prev, rb_link, rb_parent);
1845         /* Once vma denies write, undo our temporary denial count */
1846 unmap_writable:
1847         if (file && vm_flags & VM_SHARED)
1848                 mapping_unmap_writable(file->f_mapping);
1849         file = vma->vm_file;
1850 out:
1851         perf_event_mmap(vma);
1852
1853         vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
1854         if (vm_flags & VM_LOCKED) {
1855                 if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
1856                                         is_vm_hugetlb_page(vma) ||
1857                                         vma == get_gate_vma(current->mm))
1858                         vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
1859                 else
1860                         mm->locked_vm += (len >> PAGE_SHIFT);
1861         }
1862
1863         if (file)
1864                 uprobe_mmap(vma);
1865
1866         /*
1867          * New (or expanded) vma always get soft dirty status.
1868          * Otherwise user-space soft-dirty page tracker won't
1869          * be able to distinguish situation when vma area unmapped,
1870          * then new mapped in-place (which must be aimed as
1871          * a completely new data area).
1872          */
1873         vma->vm_flags |= VM_SOFTDIRTY;
1874
1875         vma_set_page_prot(vma);
1876
1877         return addr;
1878
1879 close_and_free_vma:
1880         if (vma->vm_ops && vma->vm_ops->close)
1881                 vma->vm_ops->close(vma);
1882 unmap_and_free_vma:
1883         fput(vma->vm_file);
1884         vma->vm_file = NULL;
1885
1886         /* Undo any partial mapping done by a device driver. */
1887         unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1888         if (vm_flags & VM_SHARED)
1889                 mapping_unmap_writable(file->f_mapping);
1890 free_vma:
1891         vm_area_free(vma);
1892 unacct_error:
1893         if (charged)
1894                 vm_unacct_memory(charged);
1895         return error;
1896 }
1897
1898 static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1899 {
1900         /*
1901          * We implement the search by looking for an rbtree node that
1902          * immediately follows a suitable gap. That is,
1903          * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1904          * - gap_end   = vma->vm_start        >= info->low_limit  + length;
1905          * - gap_end - gap_start >= length
1906          */
1907
1908         struct mm_struct *mm = current->mm;
1909         struct vm_area_struct *vma;
1910         unsigned long length, low_limit, high_limit, gap_start, gap_end;
1911
1912         /* Adjust search length to account for worst case alignment overhead */
1913         length = info->length + info->align_mask;
1914         if (length < info->length)
1915                 return -ENOMEM;
1916
1917         /* Adjust search limits by the desired length */
1918         if (info->high_limit < length)
1919                 return -ENOMEM;
1920         high_limit = info->high_limit - length;
1921
1922         if (info->low_limit > high_limit)
1923                 return -ENOMEM;
1924         low_limit = info->low_limit + length;
1925
1926         /* Check if rbtree root looks promising */
1927         if (RB_EMPTY_ROOT(&mm->mm_rb))
1928                 goto check_highest;
1929         vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1930         if (vma->rb_subtree_gap < length)
1931                 goto check_highest;
1932
1933         while (true) {
1934                 /* Visit left subtree if it looks promising */
1935                 gap_end = vm_start_gap(vma);
1936                 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1937                         struct vm_area_struct *left =
1938                                 rb_entry(vma->vm_rb.rb_left,
1939                                          struct vm_area_struct, vm_rb);
1940                         if (left->rb_subtree_gap >= length) {
1941                                 vma = left;
1942                                 continue;
1943                         }
1944                 }
1945
1946                 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
1947 check_current:
1948                 /* Check if current node has a suitable gap */
1949                 if (gap_start > high_limit)
1950                         return -ENOMEM;
1951                 if (gap_end >= low_limit &&
1952                     gap_end > gap_start && gap_end - gap_start >= length)
1953                         goto found;
1954
1955                 /* Visit right subtree if it looks promising */
1956                 if (vma->vm_rb.rb_right) {
1957                         struct vm_area_struct *right =
1958                                 rb_entry(vma->vm_rb.rb_right,
1959                                          struct vm_area_struct, vm_rb);
1960                         if (right->rb_subtree_gap >= length) {
1961                                 vma = right;
1962                                 continue;
1963                         }
1964                 }
1965
1966                 /* Go back up the rbtree to find next candidate node */
1967                 while (true) {
1968                         struct rb_node *prev = &vma->vm_rb;
1969                         if (!rb_parent(prev))
1970                                 goto check_highest;
1971                         vma = rb_entry(rb_parent(prev),
1972                                        struct vm_area_struct, vm_rb);
1973                         if (prev == vma->vm_rb.rb_left) {
1974                                 gap_start = vm_end_gap(vma->vm_prev);
1975                                 gap_end = vm_start_gap(vma);
1976                                 goto check_current;
1977                         }
1978                 }
1979         }
1980
1981 check_highest:
1982         /* Check highest gap, which does not precede any rbtree node */
1983         gap_start = mm->highest_vm_end;
1984         gap_end = ULONG_MAX;  /* Only for VM_BUG_ON below */
1985         if (gap_start > high_limit)
1986                 return -ENOMEM;
1987
1988 found:
1989         /* We found a suitable gap. Clip it with the original low_limit. */
1990         if (gap_start < info->low_limit)
1991                 gap_start = info->low_limit;
1992
1993         /* Adjust gap address to the desired alignment */
1994         gap_start += (info->align_offset - gap_start) & info->align_mask;
1995
1996         VM_BUG_ON(gap_start + info->length > info->high_limit);
1997         VM_BUG_ON(gap_start + info->length > gap_end);
1998         return gap_start;
1999 }
2000
2001 static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
2002 {
2003         struct mm_struct *mm = current->mm;
2004         struct vm_area_struct *vma;
2005         unsigned long length, low_limit, high_limit, gap_start, gap_end;
2006
2007         /* Adjust search length to account for worst case alignment overhead */
2008         length = info->length + info->align_mask;
2009         if (length < info->length)
2010                 return -ENOMEM;
2011
2012         /*
2013          * Adjust search limits by the desired length.
2014          * See implementation comment at top of unmapped_area().
2015          */
2016         gap_end = info->high_limit;
2017         if (gap_end < length)
2018                 return -ENOMEM;
2019         high_limit = gap_end - length;
2020
2021         if (info->low_limit > high_limit)
2022                 return -ENOMEM;
2023         low_limit = info->low_limit + length;
2024
2025         /* Check highest gap, which does not precede any rbtree node */
2026         gap_start = mm->highest_vm_end;
2027         if (gap_start <= high_limit)
2028                 goto found_highest;
2029
2030         /* Check if rbtree root looks promising */
2031         if (RB_EMPTY_ROOT(&mm->mm_rb))
2032                 return -ENOMEM;
2033         vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
2034         if (vma->rb_subtree_gap < length)
2035                 return -ENOMEM;
2036
2037         while (true) {
2038                 /* Visit right subtree if it looks promising */
2039                 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0;
2040                 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
2041                         struct vm_area_struct *right =
2042                                 rb_entry(vma->vm_rb.rb_right,
2043                                          struct vm_area_struct, vm_rb);
2044                         if (right->rb_subtree_gap >= length) {
2045                                 vma = right;
2046                                 continue;
2047                         }
2048                 }
2049
2050 check_current:
2051                 /* Check if current node has a suitable gap */
2052                 gap_end = vm_start_gap(vma);
2053                 if (gap_end < low_limit)
2054                         return -ENOMEM;
2055                 if (gap_start <= high_limit &&
2056                     gap_end > gap_start && gap_end - gap_start >= length)
2057                         goto found;
2058
2059                 /* Visit left subtree if it looks promising */
2060                 if (vma->vm_rb.rb_left) {
2061                         struct vm_area_struct *left =
2062                                 rb_entry(vma->vm_rb.rb_left,
2063                                          struct vm_area_struct, vm_rb);
2064                         if (left->rb_subtree_gap >= length) {
2065                                 vma = left;
2066                                 continue;
2067                         }
2068                 }
2069
2070                 /* Go back up the rbtree to find next candidate node */
2071                 while (true) {
2072                         struct rb_node *prev = &vma->vm_rb;
2073                         if (!rb_parent(prev))
2074                                 return -ENOMEM;
2075                         vma = rb_entry(rb_parent(prev),
2076                                        struct vm_area_struct, vm_rb);
2077                         if (prev == vma->vm_rb.rb_right) {
2078                                 gap_start = vma->vm_prev ?
2079                                         vm_end_gap(vma->vm_prev) : 0;
2080                                 goto check_current;
2081                         }
2082                 }
2083         }
2084
2085 found:
2086         /* We found a suitable gap. Clip it with the original high_limit. */
2087         if (gap_end > info->high_limit)
2088                 gap_end = info->high_limit;
2089
2090 found_highest:
2091         /* Compute highest gap address at the desired alignment */
2092         gap_end -= info->length;
2093         gap_end -= (gap_end - info->align_offset) & info->align_mask;
2094
2095         VM_BUG_ON(gap_end < info->low_limit);
2096         VM_BUG_ON(gap_end < gap_start);
2097         return gap_end;
2098 }
2099
2100 /*
2101  * Search for an unmapped address range.
2102  *
2103  * We are looking for a range that:
2104  * - does not intersect with any VMA;
2105  * - is contained within the [low_limit, high_limit) interval;
2106  * - is at least the desired size.
2107  * - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
2108  */
2109 unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
2110 {
2111         unsigned long addr;
2112
2113         if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
2114                 addr = unmapped_area_topdown(info);
2115         else
2116                 addr = unmapped_area(info);
2117
2118         trace_vm_unmapped_area(addr, info);
2119         return addr;
2120 }
2121
2122 /* Get an address range which is currently unmapped.
2123  * For shmat() with addr=0.
2124  *
2125  * Ugly calling convention alert:
2126  * Return value with the low bits set means error value,
2127  * ie
2128  *      if (ret & ~PAGE_MASK)
2129  *              error = ret;
2130  *
2131  * This function "knows" that -ENOMEM has the bits set.
2132  */
2133 #ifndef HAVE_ARCH_UNMAPPED_AREA
2134 unsigned long
2135 arch_get_unmapped_area(struct file *filp, unsigned long addr,
2136                 unsigned long len, unsigned long pgoff, unsigned long flags)
2137 {
2138         struct mm_struct *mm = current->mm;
2139         struct vm_area_struct *vma, *prev;
2140         struct vm_unmapped_area_info info;
2141         const unsigned long mmap_end = arch_get_mmap_end(addr);
2142
2143         if (len > mmap_end - mmap_min_addr)
2144                 return -ENOMEM;
2145
2146         if (flags & MAP_FIXED)
2147                 return addr;
2148
2149         if (addr) {
2150                 addr = PAGE_ALIGN(addr);
2151                 vma = find_vma_prev(mm, addr, &prev);
2152                 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
2153                     (!vma || addr + len <= vm_start_gap(vma)) &&
2154                     (!prev || addr >= vm_end_gap(prev)))
2155                         return addr;
2156         }
2157
2158         info.flags = 0;
2159         info.length = len;
2160         info.low_limit = mm->mmap_base;
2161         info.high_limit = mmap_end;
2162         info.align_mask = 0;
2163         info.align_offset = 0;
2164         return vm_unmapped_area(&info);
2165 }
2166 #endif
2167
2168 /*
2169  * This mmap-allocator allocates new areas top-down from below the
2170  * stack's low limit (the base):
2171  */
2172 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
2173 unsigned long
2174 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
2175                           unsigned long len, unsigned long pgoff,
2176                           unsigned long flags)
2177 {
2178         struct vm_area_struct *vma, *prev;
2179         struct mm_struct *mm = current->mm;
2180         struct vm_unmapped_area_info info;
2181         const unsigned long mmap_end = arch_get_mmap_end(addr);
2182
2183         /* requested length too big for entire address space */
2184         if (len > mmap_end - mmap_min_addr)
2185                 return -ENOMEM;
2186
2187         if (flags & MAP_FIXED)
2188                 return addr;
2189
2190         /* requesting a specific address */
2191         if (addr) {
2192                 addr = PAGE_ALIGN(addr);
2193                 vma = find_vma_prev(mm, addr, &prev);
2194                 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
2195                                 (!vma || addr + len <= vm_start_gap(vma)) &&
2196                                 (!prev || addr >= vm_end_gap(prev)))
2197                         return addr;
2198         }
2199
2200         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
2201         info.length = len;
2202         info.low_limit = max(PAGE_SIZE, mmap_min_addr);
2203         info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
2204         info.align_mask = 0;
2205         info.align_offset = 0;
2206         addr = vm_unmapped_area(&info);
2207
2208         /*
2209          * A failed mmap() very likely causes application failure,
2210          * so fall back to the bottom-up function here. This scenario
2211          * can happen with large stack limits and large mmap()
2212          * allocations.
2213          */
2214         if (offset_in_page(addr)) {
2215                 VM_BUG_ON(addr != -ENOMEM);
2216                 info.flags = 0;
2217                 info.low_limit = TASK_UNMAPPED_BASE;
2218                 info.high_limit = mmap_end;
2219                 addr = vm_unmapped_area(&info);
2220         }
2221
2222         return addr;
2223 }
2224 #endif
2225
2226 unsigned long
2227 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
2228                 unsigned long pgoff, unsigned long flags)
2229 {
2230         unsigned long (*get_area)(struct file *, unsigned long,
2231                                   unsigned long, unsigned long, unsigned long);
2232
2233         unsigned long error = arch_mmap_check(addr, len, flags);
2234         if (error)
2235                 return error;
2236
2237         /* Careful about overflows.. */
2238         if (len > TASK_SIZE)
2239                 return -ENOMEM;
2240
2241         get_area = current->mm->get_unmapped_area;
2242         if (file) {
2243                 if (file->f_op->get_unmapped_area)
2244                         get_area = file->f_op->get_unmapped_area;
2245         } else if (flags & MAP_SHARED) {
2246                 /*
2247                  * mmap_region() will call shmem_zero_setup() to create a file,
2248                  * so use shmem's get_unmapped_area in case it can be huge.
2249                  * do_mmap() will clear pgoff, so match alignment.
2250                  */
2251                 pgoff = 0;
2252                 get_area = shmem_get_unmapped_area;
2253         }
2254
2255         addr = get_area(file, addr, len, pgoff, flags);
2256         if (IS_ERR_VALUE(addr))
2257                 return addr;
2258
2259         if (addr > TASK_SIZE - len)
2260                 return -ENOMEM;
2261         if (offset_in_page(addr))
2262                 return -EINVAL;
2263
2264         error = security_mmap_addr(addr);
2265         return error ? error : addr;
2266 }
2267
2268 EXPORT_SYMBOL(get_unmapped_area);
2269
2270 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
2271 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
2272 {
2273         struct rb_node *rb_node;
2274         struct vm_area_struct *vma;
2275
2276         mmap_assert_locked(mm);
2277         /* Check the cache first. */
2278         vma = vmacache_find(mm, addr);
2279         if (likely(vma))
2280                 return vma;
2281
2282         rb_node = mm->mm_rb.rb_node;
2283
2284         while (rb_node) {
2285                 struct vm_area_struct *tmp;
2286
2287                 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2288
2289                 if (tmp->vm_end > addr) {
2290                         vma = tmp;
2291                         if (tmp->vm_start <= addr)
2292                                 break;
2293                         rb_node = rb_node->rb_left;
2294                 } else
2295                         rb_node = rb_node->rb_right;
2296         }
2297
2298         if (vma)
2299                 vmacache_update(addr, vma);
2300         return vma;
2301 }
2302
2303 EXPORT_SYMBOL(find_vma);
2304
2305 /*
2306  * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2307  */
2308 struct vm_area_struct *
2309 find_vma_prev(struct mm_struct *mm, unsigned long addr,
2310                         struct vm_area_struct **pprev)
2311 {
2312         struct vm_area_struct *vma;
2313
2314         vma = find_vma(mm, addr);
2315         if (vma) {
2316                 *pprev = vma->vm_prev;
2317         } else {
2318                 struct rb_node *rb_node = rb_last(&mm->mm_rb);
2319
2320                 *pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL;
2321         }
2322         return vma;
2323 }
2324
2325 /*
2326  * Verify that the stack growth is acceptable and
2327  * update accounting. This is shared with both the
2328  * grow-up and grow-down cases.
2329  */
2330 static int acct_stack_growth(struct vm_area_struct *vma,
2331                              unsigned long size, unsigned long grow)
2332 {
2333         struct mm_struct *mm = vma->vm_mm;
2334         unsigned long new_start;
2335
2336         /* address space limit tests */
2337         if (!may_expand_vm(mm, vma->vm_flags, grow))
2338                 return -ENOMEM;
2339
2340         /* Stack limit test */
2341         if (size > rlimit(RLIMIT_STACK))
2342                 return -ENOMEM;
2343
2344         /* mlock limit tests */
2345         if (vma->vm_flags & VM_LOCKED) {
2346                 unsigned long locked;
2347                 unsigned long limit;
2348                 locked = mm->locked_vm + grow;
2349                 limit = rlimit(RLIMIT_MEMLOCK);
2350                 limit >>= PAGE_SHIFT;
2351                 if (locked > limit && !capable(CAP_IPC_LOCK))
2352                         return -ENOMEM;
2353         }
2354
2355         /* Check to ensure the stack will not grow into a hugetlb-only region */
2356         new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2357                         vma->vm_end - size;
2358         if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2359                 return -EFAULT;
2360
2361         /*
2362          * Overcommit..  This must be the final test, as it will
2363          * update security statistics.
2364          */
2365         if (security_vm_enough_memory_mm(mm, grow))
2366                 return -ENOMEM;
2367
2368         return 0;
2369 }
2370
2371 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2372 /*
2373  * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2374  * vma is the last one with address > vma->vm_end.  Have to extend vma.
2375  */
2376 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2377 {
2378         struct mm_struct *mm = vma->vm_mm;
2379         struct vm_area_struct *next;
2380         unsigned long gap_addr;
2381         int error = 0;
2382
2383         if (!(vma->vm_flags & VM_GROWSUP))
2384                 return -EFAULT;
2385
2386         /* Guard against exceeding limits of the address space. */
2387         address &= PAGE_MASK;
2388         if (address >= (TASK_SIZE & PAGE_MASK))
2389                 return -ENOMEM;
2390         address += PAGE_SIZE;
2391
2392         /* Enforce stack_guard_gap */
2393         gap_addr = address + stack_guard_gap;
2394
2395         /* Guard against overflow */
2396         if (gap_addr < address || gap_addr > TASK_SIZE)
2397                 gap_addr = TASK_SIZE;
2398
2399         next = vma->vm_next;
2400         if (next && next->vm_start < gap_addr && vma_is_accessible(next)) {
2401                 if (!(next->vm_flags & VM_GROWSUP))
2402                         return -ENOMEM;
2403                 /* Check that both stack segments have the same anon_vma? */
2404         }
2405
2406         /* We must make sure the anon_vma is allocated. */
2407         if (unlikely(anon_vma_prepare(vma)))
2408                 return -ENOMEM;
2409
2410         /*
2411          * vma->vm_start/vm_end cannot change under us because the caller
2412          * is required to hold the mmap_lock in read mode.  We need the
2413          * anon_vma lock to serialize against concurrent expand_stacks.
2414          */
2415         anon_vma_lock_write(vma->anon_vma);
2416
2417         /* Somebody else might have raced and expanded it already */
2418         if (address > vma->vm_end) {
2419                 unsigned long size, grow;
2420
2421                 size = address - vma->vm_start;
2422                 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2423
2424                 error = -ENOMEM;
2425                 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2426                         error = acct_stack_growth(vma, size, grow);
2427                         if (!error) {
2428                                 /*
2429                                  * vma_gap_update() doesn't support concurrent
2430                                  * updates, but we only hold a shared mmap_lock
2431                                  * lock here, so we need to protect against
2432                                  * concurrent vma expansions.
2433                                  * anon_vma_lock_write() doesn't help here, as
2434                                  * we don't guarantee that all growable vmas
2435                                  * in a mm share the same root anon vma.
2436                                  * So, we reuse mm->page_table_lock to guard
2437                                  * against concurrent vma expansions.
2438                                  */
2439                                 spin_lock(&mm->page_table_lock);
2440                                 if (vma->vm_flags & VM_LOCKED)
2441                                         mm->locked_vm += grow;
2442                                 vm_stat_account(mm, vma->vm_flags, grow);
2443                                 anon_vma_interval_tree_pre_update_vma(vma);
2444                                 vma->vm_end = address;
2445                                 anon_vma_interval_tree_post_update_vma(vma);
2446                                 if (vma->vm_next)
2447                                         vma_gap_update(vma->vm_next);
2448                                 else
2449                                         mm->highest_vm_end = vm_end_gap(vma);
2450                                 spin_unlock(&mm->page_table_lock);
2451
2452                                 perf_event_mmap(vma);
2453                         }
2454                 }
2455         }
2456         anon_vma_unlock_write(vma->anon_vma);
2457         khugepaged_enter_vma_merge(vma, vma->vm_flags);
2458         validate_mm(mm);
2459         return error;
2460 }
2461 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2462
2463 /*
2464  * vma is the first one with address < vma->vm_start.  Have to extend vma.
2465  */
2466 int expand_downwards(struct vm_area_struct *vma,
2467                                    unsigned long address)
2468 {
2469         struct mm_struct *mm = vma->vm_mm;
2470         struct vm_area_struct *prev;
2471         int error = 0;
2472
2473         address &= PAGE_MASK;
2474         if (address < mmap_min_addr)
2475                 return -EPERM;
2476
2477         /* Enforce stack_guard_gap */
2478         prev = vma->vm_prev;
2479         /* Check that both stack segments have the same anon_vma? */
2480         if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
2481                         vma_is_accessible(prev)) {
2482                 if (address - prev->vm_end < stack_guard_gap)
2483                         return -ENOMEM;
2484         }
2485
2486         /* We must make sure the anon_vma is allocated. */
2487         if (unlikely(anon_vma_prepare(vma)))
2488                 return -ENOMEM;
2489
2490         /*
2491          * vma->vm_start/vm_end cannot change under us because the caller
2492          * is required to hold the mmap_lock in read mode.  We need the
2493          * anon_vma lock to serialize against concurrent expand_stacks.
2494          */
2495         anon_vma_lock_write(vma->anon_vma);
2496
2497         /* Somebody else might have raced and expanded it already */
2498         if (address < vma->vm_start) {
2499                 unsigned long size, grow;
2500
2501                 size = vma->vm_end - address;
2502                 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2503
2504                 error = -ENOMEM;
2505                 if (grow <= vma->vm_pgoff) {
2506                         error = acct_stack_growth(vma, size, grow);
2507                         if (!error) {
2508                                 /*
2509                                  * vma_gap_update() doesn't support concurrent
2510                                  * updates, but we only hold a shared mmap_lock
2511                                  * lock here, so we need to protect against
2512                                  * concurrent vma expansions.
2513                                  * anon_vma_lock_write() doesn't help here, as
2514                                  * we don't guarantee that all growable vmas
2515                                  * in a mm share the same root anon vma.
2516                                  * So, we reuse mm->page_table_lock to guard
2517                                  * against concurrent vma expansions.
2518                                  */
2519                                 spin_lock(&mm->page_table_lock);
2520                                 if (vma->vm_flags & VM_LOCKED)
2521                                         mm->locked_vm += grow;
2522                                 vm_stat_account(mm, vma->vm_flags, grow);
2523                                 anon_vma_interval_tree_pre_update_vma(vma);
2524                                 vma->vm_start = address;
2525                                 vma->vm_pgoff -= grow;
2526                                 anon_vma_interval_tree_post_update_vma(vma);
2527                                 vma_gap_update(vma);
2528                                 spin_unlock(&mm->page_table_lock);
2529
2530                                 perf_event_mmap(vma);
2531                         }
2532                 }
2533         }
2534         anon_vma_unlock_write(vma->anon_vma);
2535         khugepaged_enter_vma_merge(vma, vma->vm_flags);
2536         validate_mm(mm);
2537         return error;
2538 }
2539
2540 /* enforced gap between the expanding stack and other mappings. */
2541 unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
2542
2543 static int __init cmdline_parse_stack_guard_gap(char *p)
2544 {
2545         unsigned long val;
2546         char *endptr;
2547
2548         val = simple_strtoul(p, &endptr, 10);
2549         if (!*endptr)
2550                 stack_guard_gap = val << PAGE_SHIFT;
2551
2552         return 1;
2553 }
2554 __setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
2555
2556 #ifdef CONFIG_STACK_GROWSUP
2557 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2558 {
2559         return expand_upwards(vma, address);
2560 }
2561
2562 struct vm_area_struct *
2563 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2564 {
2565         struct vm_area_struct *vma, *prev;
2566
2567         addr &= PAGE_MASK;
2568         vma = find_vma_prev(mm, addr, &prev);
2569         if (vma && (vma->vm_start <= addr))
2570                 return vma;
2571         /* don't alter vm_end if the coredump is running */
2572         if (!prev || expand_stack(prev, addr))
2573                 return NULL;
2574         if (prev->vm_flags & VM_LOCKED)
2575                 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2576         return prev;
2577 }
2578 #else
2579 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2580 {
2581         return expand_downwards(vma, address);
2582 }
2583
2584 struct vm_area_struct *
2585 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2586 {
2587         struct vm_area_struct *vma;
2588         unsigned long start;
2589
2590         addr &= PAGE_MASK;
2591         vma = find_vma(mm, addr);
2592         if (!vma)
2593                 return NULL;
2594         if (vma->vm_start <= addr)
2595                 return vma;
2596         if (!(vma->vm_flags & VM_GROWSDOWN))
2597                 return NULL;
2598         start = vma->vm_start;
2599         if (expand_stack(vma, addr))
2600                 return NULL;
2601         if (vma->vm_flags & VM_LOCKED)
2602                 populate_vma_page_range(vma, addr, start, NULL);
2603         return vma;
2604 }
2605 #endif
2606
2607 EXPORT_SYMBOL_GPL(find_extend_vma);
2608
2609 /*
2610  * Ok - we have the memory areas we should free on the vma list,
2611  * so release them, and do the vma updates.
2612  *
2613  * Called with the mm semaphore held.
2614  */
2615 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2616 {
2617         unsigned long nr_accounted = 0;
2618
2619         /* Update high watermark before we lower total_vm */
2620         update_hiwater_vm(mm);
2621         do {
2622                 long nrpages = vma_pages(vma);
2623
2624                 if (vma->vm_flags & VM_ACCOUNT)
2625                         nr_accounted += nrpages;
2626                 vm_stat_account(mm, vma->vm_flags, -nrpages);
2627                 vma = remove_vma(vma);
2628         } while (vma);
2629         vm_unacct_memory(nr_accounted);
2630         validate_mm(mm);
2631 }
2632
2633 /*
2634  * Get rid of page table information in the indicated region.
2635  *
2636  * Called with the mm semaphore held.
2637  */
2638 static void unmap_region(struct mm_struct *mm,
2639                 struct vm_area_struct *vma, struct vm_area_struct *prev,
2640                 unsigned long start, unsigned long end)
2641 {
2642         struct vm_area_struct *next = vma_next(mm, prev);
2643         struct mmu_gather tlb;
2644         struct vm_area_struct *cur_vma;
2645
2646         lru_add_drain();
2647         tlb_gather_mmu(&tlb, mm);
2648         update_hiwater_rss(mm);
2649         unmap_vmas(&tlb, vma, start, end);
2650
2651         /*
2652          * Ensure we have no stale TLB entries by the time this mapping is
2653          * removed from the rmap.
2654          * Note that we don't have to worry about nested flushes here because
2655          * we're holding the mm semaphore for removing the mapping - so any
2656          * concurrent flush in this region has to be coming through the rmap,
2657          * and we synchronize against that using the rmap lock.
2658          */
2659         for (cur_vma = vma; cur_vma; cur_vma = cur_vma->vm_next) {
2660                 if ((cur_vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) != 0) {
2661                         tlb_flush_mmu(&tlb);
2662                         break;
2663                 }
2664         }
2665
2666         free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2667                                  next ? next->vm_start : USER_PGTABLES_CEILING);
2668         tlb_finish_mmu(&tlb);
2669 }
2670
2671 /*
2672  * Create a list of vma's touched by the unmap, removing them from the mm's
2673  * vma list as we go..
2674  */
2675 static bool
2676 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2677         struct vm_area_struct *prev, unsigned long end)
2678 {
2679         struct vm_area_struct **insertion_point;
2680         struct vm_area_struct *tail_vma = NULL;
2681
2682         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2683         vma->vm_prev = NULL;
2684         do {
2685                 vma_rb_erase(vma, &mm->mm_rb);
2686                 mm->map_count--;
2687                 tail_vma = vma;
2688                 vma = vma->vm_next;
2689         } while (vma && vma->vm_start < end);
2690         *insertion_point = vma;
2691         if (vma) {
2692                 vma->vm_prev = prev;
2693                 vma_gap_update(vma);
2694         } else
2695                 mm->highest_vm_end = prev ? vm_end_gap(prev) : 0;
2696         tail_vma->vm_next = NULL;
2697
2698         /* Kill the cache */
2699         vmacache_invalidate(mm);
2700
2701         /*
2702          * Do not downgrade mmap_lock if we are next to VM_GROWSDOWN or
2703          * VM_GROWSUP VMA. Such VMAs can change their size under
2704          * down_read(mmap_lock) and collide with the VMA we are about to unmap.
2705          */
2706         if (vma && (vma->vm_flags & VM_GROWSDOWN))
2707                 return false;
2708         if (prev && (prev->vm_flags & VM_GROWSUP))
2709                 return false;
2710         return true;
2711 }
2712
2713 /*
2714  * __split_vma() bypasses sysctl_max_map_count checking.  We use this where it
2715  * has already been checked or doesn't make sense to fail.
2716  */
2717 int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2718                 unsigned long addr, int new_below)
2719 {
2720         struct vm_area_struct *new;
2721         int err;
2722
2723         if (vma->vm_ops && vma->vm_ops->may_split) {
2724                 err = vma->vm_ops->may_split(vma, addr);
2725                 if (err)
2726                         return err;
2727         }
2728
2729         new = vm_area_dup(vma);
2730         if (!new)
2731                 return -ENOMEM;
2732
2733         if (new_below)
2734                 new->vm_end = addr;
2735         else {
2736                 new->vm_start = addr;
2737                 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2738         }
2739
2740         err = vma_dup_policy(vma, new);
2741         if (err)
2742                 goto out_free_vma;
2743
2744         err = anon_vma_clone(new, vma);
2745         if (err)
2746                 goto out_free_mpol;
2747
2748         if (new->vm_file)
2749                 get_file(new->vm_file);
2750
2751         if (new->vm_ops && new->vm_ops->open)
2752                 new->vm_ops->open(new);
2753
2754         if (new_below)
2755                 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2756                         ((addr - new->vm_start) >> PAGE_SHIFT), new);
2757         else
2758                 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2759
2760         /* Success. */
2761         if (!err)
2762                 return 0;
2763
2764         /* Clean everything up if vma_adjust failed. */
2765         if (new->vm_ops && new->vm_ops->close)
2766                 new->vm_ops->close(new);
2767         if (new->vm_file)
2768                 fput(new->vm_file);
2769         unlink_anon_vmas(new);
2770  out_free_mpol:
2771         mpol_put(vma_policy(new));
2772  out_free_vma:
2773         vm_area_free(new);
2774         return err;
2775 }
2776
2777 /*
2778  * Split a vma into two pieces at address 'addr', a new vma is allocated
2779  * either for the first part or the tail.
2780  */
2781 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2782               unsigned long addr, int new_below)
2783 {
2784         if (mm->map_count >= sysctl_max_map_count)
2785                 return -ENOMEM;
2786
2787         return __split_vma(mm, vma, addr, new_below);
2788 }
2789
2790 static inline void
2791 unlock_range(struct vm_area_struct *start, unsigned long limit)
2792 {
2793         struct mm_struct *mm = start->vm_mm;
2794         struct vm_area_struct *tmp = start;
2795
2796         while (tmp && tmp->vm_start < limit) {
2797                 if (tmp->vm_flags & VM_LOCKED) {
2798                         mm->locked_vm -= vma_pages(tmp);
2799                         munlock_vma_pages_all(tmp);
2800                 }
2801
2802                 tmp = tmp->vm_next;
2803         }
2804 }
2805
2806 /* Munmap is split into 2 main parts -- this part which finds
2807  * what needs doing, and the areas themselves, which do the
2808  * work.  This now handles partial unmappings.
2809  * Jeremy Fitzhardinge <jeremy@goop.org>
2810  */
2811 int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2812                 struct list_head *uf, bool downgrade)
2813 {
2814         unsigned long end;
2815         struct vm_area_struct *vma, *prev, *last;
2816
2817         if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2818                 return -EINVAL;
2819
2820         len = PAGE_ALIGN(len);
2821         end = start + len;
2822         if (len == 0)
2823                 return -EINVAL;
2824
2825         /*
2826          * arch_unmap() might do unmaps itself.  It must be called
2827          * and finish any rbtree manipulation before this code
2828          * runs and also starts to manipulate the rbtree.
2829          */
2830         arch_unmap(mm, start, end);
2831
2832         /* Find the first overlapping VMA where start < vma->vm_end */
2833         vma = find_vma_intersection(mm, start, end);
2834         if (!vma)
2835                 return 0;
2836         prev = vma->vm_prev;
2837
2838         /*
2839          * If we need to split any vma, do it now to save pain later.
2840          *
2841          * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2842          * unmapped vm_area_struct will remain in use: so lower split_vma
2843          * places tmp vma above, and higher split_vma places tmp vma below.
2844          */
2845         if (start > vma->vm_start) {
2846                 int error;
2847
2848                 /*
2849                  * Make sure that map_count on return from munmap() will
2850                  * not exceed its limit; but let map_count go just above
2851                  * its limit temporarily, to help free resources as expected.
2852                  */
2853                 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2854                         return -ENOMEM;
2855
2856                 error = __split_vma(mm, vma, start, 0);
2857                 if (error)
2858                         return error;
2859                 prev = vma;
2860         }
2861
2862         /* Does it split the last one? */
2863         last = find_vma(mm, end);
2864         if (last && end > last->vm_start) {
2865                 int error = __split_vma(mm, last, end, 1);
2866                 if (error)
2867                         return error;
2868         }
2869         vma = vma_next(mm, prev);
2870
2871         if (unlikely(uf)) {
2872                 /*
2873                  * If userfaultfd_unmap_prep returns an error the vmas
2874                  * will remain split, but userland will get a
2875                  * highly unexpected error anyway. This is no
2876                  * different than the case where the first of the two
2877                  * __split_vma fails, but we don't undo the first
2878                  * split, despite we could. This is unlikely enough
2879                  * failure that it's not worth optimizing it for.
2880                  */
2881                 int error = userfaultfd_unmap_prep(vma, start, end, uf);
2882                 if (error)
2883                         return error;
2884         }
2885
2886         /*
2887          * unlock any mlock()ed ranges before detaching vmas
2888          */
2889         if (mm->locked_vm)
2890                 unlock_range(vma, end);
2891
2892         /* Detach vmas from rbtree */
2893         if (!detach_vmas_to_be_unmapped(mm, vma, prev, end))
2894                 downgrade = false;
2895
2896         if (downgrade)
2897                 mmap_write_downgrade(mm);
2898
2899         unmap_region(mm, vma, prev, start, end);
2900
2901         /* Fix up all other VM information */
2902         remove_vma_list(mm, vma);
2903
2904         return downgrade ? 1 : 0;
2905 }
2906
2907 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2908               struct list_head *uf)
2909 {
2910         return __do_munmap(mm, start, len, uf, false);
2911 }
2912
2913 static int __vm_munmap(unsigned long start, size_t len, bool downgrade)
2914 {
2915         int ret;
2916         struct mm_struct *mm = current->mm;
2917         LIST_HEAD(uf);
2918
2919         if (mmap_write_lock_killable(mm))
2920                 return -EINTR;
2921
2922         ret = __do_munmap(mm, start, len, &uf, downgrade);
2923         /*
2924          * Returning 1 indicates mmap_lock is downgraded.
2925          * But 1 is not legal return value of vm_munmap() and munmap(), reset
2926          * it to 0 before return.
2927          */
2928         if (ret == 1) {
2929                 mmap_read_unlock(mm);
2930                 ret = 0;
2931         } else
2932                 mmap_write_unlock(mm);
2933
2934         userfaultfd_unmap_complete(mm, &uf);
2935         return ret;
2936 }
2937
2938 int vm_munmap(unsigned long start, size_t len)
2939 {
2940         return __vm_munmap(start, len, false);
2941 }
2942 EXPORT_SYMBOL(vm_munmap);
2943
2944 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2945 {
2946         addr = untagged_addr(addr);
2947         profile_munmap(addr);
2948         return __vm_munmap(addr, len, true);
2949 }
2950
2951
2952 /*
2953  * Emulation of deprecated remap_file_pages() syscall.
2954  */
2955 SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2956                 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2957 {
2958
2959         struct mm_struct *mm = current->mm;
2960         struct vm_area_struct *vma;
2961         unsigned long populate = 0;
2962         unsigned long ret = -EINVAL;
2963         struct file *file;
2964
2965         pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n",
2966                      current->comm, current->pid);
2967
2968         if (prot)
2969                 return ret;
2970         start = start & PAGE_MASK;
2971         size = size & PAGE_MASK;
2972
2973         if (start + size <= start)
2974                 return ret;
2975
2976         /* Does pgoff wrap? */
2977         if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2978                 return ret;
2979
2980         if (mmap_write_lock_killable(mm))
2981                 return -EINTR;
2982
2983         vma = vma_lookup(mm, start);
2984
2985         if (!vma || !(vma->vm_flags & VM_SHARED))
2986                 goto out;
2987
2988         if (start + size > vma->vm_end) {
2989                 struct vm_area_struct *next;
2990
2991                 for (next = vma->vm_next; next; next = next->vm_next) {
2992                         /* hole between vmas ? */
2993                         if (next->vm_start != next->vm_prev->vm_end)
2994                                 goto out;
2995
2996                         if (next->vm_file != vma->vm_file)
2997                                 goto out;
2998
2999                         if (next->vm_flags != vma->vm_flags)
3000                                 goto out;
3001
3002                         if (start + size <= next->vm_end)
3003                                 break;
3004                 }
3005
3006                 if (!next)
3007                         goto out;
3008         }
3009
3010         prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
3011         prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
3012         prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
3013
3014         flags &= MAP_NONBLOCK;
3015         flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
3016         if (vma->vm_flags & VM_LOCKED)
3017                 flags |= MAP_LOCKED;
3018
3019         file = get_file(vma->vm_file);
3020         ret = do_mmap(vma->vm_file, start, size,
3021                         prot, flags, pgoff, &populate, NULL);
3022         fput(file);
3023 out:
3024         mmap_write_unlock(mm);
3025         if (populate)
3026                 mm_populate(ret, populate);
3027         if (!IS_ERR_VALUE(ret))
3028                 ret = 0;
3029         return ret;
3030 }
3031
3032 /*
3033  *  this is really a simplified "do_mmap".  it only handles
3034  *  anonymous maps.  eventually we may be able to do some
3035  *  brk-specific accounting here.
3036  */
3037 static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags, struct list_head *uf)
3038 {
3039         struct mm_struct *mm = current->mm;
3040         struct vm_area_struct *vma, *prev;
3041         struct rb_node **rb_link, *rb_parent;
3042         pgoff_t pgoff = addr >> PAGE_SHIFT;
3043         int error;
3044         unsigned long mapped_addr;
3045
3046         /* Until we need other flags, refuse anything except VM_EXEC. */
3047         if ((flags & (~VM_EXEC)) != 0)
3048                 return -EINVAL;
3049         flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
3050
3051         mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
3052         if (IS_ERR_VALUE(mapped_addr))
3053                 return mapped_addr;
3054
3055         error = mlock_future_check(mm, mm->def_flags, len);
3056         if (error)
3057                 return error;
3058
3059         /* Clear old maps, set up prev, rb_link, rb_parent, and uf */
3060         if (munmap_vma_range(mm, addr, len, &prev, &rb_link, &rb_parent, uf))
3061                 return -ENOMEM;
3062
3063         /* Check against address space limits *after* clearing old maps... */
3064         if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
3065                 return -ENOMEM;
3066
3067         if (mm->map_count > sysctl_max_map_count)
3068                 return -ENOMEM;
3069
3070         if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
3071                 return -ENOMEM;
3072
3073         /* Can we just expand an old private anonymous mapping? */
3074         vma = vma_merge(mm, prev, addr, addr + len, flags,
3075                         NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
3076         if (vma)
3077                 goto out;
3078
3079         /*
3080          * create a vma struct for an anonymous mapping
3081          */
3082         vma = vm_area_alloc(mm);
3083         if (!vma) {
3084                 vm_unacct_memory(len >> PAGE_SHIFT);
3085                 return -ENOMEM;
3086         }
3087
3088         vma_set_anonymous(vma);
3089         vma->vm_start = addr;
3090         vma->vm_end = addr + len;
3091         vma->vm_pgoff = pgoff;
3092         vma->vm_flags = flags;
3093         vma->vm_page_prot = vm_get_page_prot(flags);
3094         vma_link(mm, vma, prev, rb_link, rb_parent);
3095 out:
3096         perf_event_mmap(vma);
3097         mm->total_vm += len >> PAGE_SHIFT;
3098         mm->data_vm += len >> PAGE_SHIFT;
3099         if (flags & VM_LOCKED)
3100                 mm->locked_vm += (len >> PAGE_SHIFT);
3101         vma->vm_flags |= VM_SOFTDIRTY;
3102         return 0;
3103 }
3104
3105 int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
3106 {
3107         struct mm_struct *mm = current->mm;
3108         unsigned long len;
3109         int ret;
3110         bool populate;
3111         LIST_HEAD(uf);
3112
3113         len = PAGE_ALIGN(request);
3114         if (len < request)
3115                 return -ENOMEM;
3116         if (!len)
3117                 return 0;
3118
3119         if (mmap_write_lock_killable(mm))
3120                 return -EINTR;
3121
3122         ret = do_brk_flags(addr, len, flags, &uf);
3123         populate = ((mm->def_flags & VM_LOCKED) != 0);
3124         mmap_write_unlock(mm);
3125         userfaultfd_unmap_complete(mm, &uf);
3126         if (populate && !ret)
3127                 mm_populate(addr, len);
3128         return ret;
3129 }
3130 EXPORT_SYMBOL(vm_brk_flags);
3131
3132 int vm_brk(unsigned long addr, unsigned long len)
3133 {
3134         return vm_brk_flags(addr, len, 0);
3135 }
3136 EXPORT_SYMBOL(vm_brk);
3137
3138 /* Release all mmaps. */
3139 void exit_mmap(struct mm_struct *mm)
3140 {
3141         struct mmu_gather tlb;
3142         struct vm_area_struct *vma;
3143         unsigned long nr_accounted = 0;
3144
3145         /* mm's last user has gone, and its about to be pulled down */
3146         mmu_notifier_release(mm);
3147
3148         if (unlikely(mm_is_oom_victim(mm))) {
3149                 /*
3150                  * Manually reap the mm to free as much memory as possible.
3151                  * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard
3152                  * this mm from further consideration.  Taking mm->mmap_lock for
3153                  * write after setting MMF_OOM_SKIP will guarantee that the oom
3154                  * reaper will not run on this mm again after mmap_lock is
3155                  * dropped.
3156                  *
3157                  * Nothing can be holding mm->mmap_lock here and the above call
3158                  * to mmu_notifier_release(mm) ensures mmu notifier callbacks in
3159                  * __oom_reap_task_mm() will not block.
3160                  *
3161                  * This needs to be done before calling munlock_vma_pages_all(),
3162                  * which clears VM_LOCKED, otherwise the oom reaper cannot
3163                  * reliably test it.
3164                  */
3165                 (void)__oom_reap_task_mm(mm);
3166
3167                 set_bit(MMF_OOM_SKIP, &mm->flags);
3168                 mmap_write_lock(mm);
3169                 mmap_write_unlock(mm);
3170         }
3171
3172         if (mm->locked_vm)
3173                 unlock_range(mm->mmap, ULONG_MAX);
3174
3175         arch_exit_mmap(mm);
3176
3177         vma = mm->mmap;
3178         if (!vma)       /* Can happen if dup_mmap() received an OOM */
3179                 return;
3180
3181         lru_add_drain();
3182         flush_cache_mm(mm);
3183         tlb_gather_mmu_fullmm(&tlb, mm);
3184         /* update_hiwater_rss(mm) here? but nobody should be looking */
3185         /* Use -1 here to ensure all VMAs in the mm are unmapped */
3186         unmap_vmas(&tlb, vma, 0, -1);
3187         free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
3188         tlb_finish_mmu(&tlb);
3189
3190         /*
3191          * Walk the list again, actually closing and freeing it,
3192          * with preemption enabled, without holding any MM locks.
3193          */
3194         while (vma) {
3195                 if (vma->vm_flags & VM_ACCOUNT)
3196                         nr_accounted += vma_pages(vma);
3197                 vma = remove_vma(vma);
3198                 cond_resched();
3199         }
3200         vm_unacct_memory(nr_accounted);
3201 }
3202
3203 /* Insert vm structure into process list sorted by address
3204  * and into the inode's i_mmap tree.  If vm_file is non-NULL
3205  * then i_mmap_rwsem is taken here.
3206  */
3207 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
3208 {
3209         struct vm_area_struct *prev;
3210         struct rb_node **rb_link, *rb_parent;
3211
3212         if (find_vma_links(mm, vma->vm_start, vma->vm_end,
3213                            &prev, &rb_link, &rb_parent))
3214                 return -ENOMEM;
3215         if ((vma->vm_flags & VM_ACCOUNT) &&
3216              security_vm_enough_memory_mm(mm, vma_pages(vma)))
3217                 return -ENOMEM;
3218
3219         /*
3220          * The vm_pgoff of a purely anonymous vma should be irrelevant
3221          * until its first write fault, when page's anon_vma and index
3222          * are set.  But now set the vm_pgoff it will almost certainly
3223          * end up with (unless mremap moves it elsewhere before that
3224          * first wfault), so /proc/pid/maps tells a consistent story.
3225          *
3226          * By setting it to reflect the virtual start address of the
3227          * vma, merges and splits can happen in a seamless way, just
3228          * using the existing file pgoff checks and manipulations.
3229          * Similarly in do_mmap and in do_brk_flags.
3230          */
3231         if (vma_is_anonymous(vma)) {
3232                 BUG_ON(vma->anon_vma);
3233                 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
3234         }
3235
3236         vma_link(mm, vma, prev, rb_link, rb_parent);
3237         return 0;
3238 }
3239
3240 /*
3241  * Copy the vma structure to a new location in the same mm,
3242  * prior to moving page table entries, to effect an mremap move.
3243  */
3244 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
3245         unsigned long addr, unsigned long len, pgoff_t pgoff,
3246         bool *need_rmap_locks)
3247 {
3248         struct vm_area_struct *vma = *vmap;
3249         unsigned long vma_start = vma->vm_start;
3250         struct mm_struct *mm = vma->vm_mm;
3251         struct vm_area_struct *new_vma, *prev;
3252         struct rb_node **rb_link, *rb_parent;
3253         bool faulted_in_anon_vma = true;
3254
3255         /*
3256          * If anonymous vma has not yet been faulted, update new pgoff
3257          * to match new location, to increase its chance of merging.
3258          */
3259         if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
3260                 pgoff = addr >> PAGE_SHIFT;
3261                 faulted_in_anon_vma = false;
3262         }
3263
3264         if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
3265                 return NULL;    /* should never get here */
3266         new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
3267                             vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
3268                             vma->vm_userfaultfd_ctx);
3269         if (new_vma) {
3270                 /*
3271                  * Source vma may have been merged into new_vma
3272                  */
3273                 if (unlikely(vma_start >= new_vma->vm_start &&
3274                              vma_start < new_vma->vm_end)) {
3275                         /*
3276                          * The only way we can get a vma_merge with
3277                          * self during an mremap is if the vma hasn't
3278                          * been faulted in yet and we were allowed to
3279                          * reset the dst vma->vm_pgoff to the
3280                          * destination address of the mremap to allow
3281                          * the merge to happen. mremap must change the
3282                          * vm_pgoff linearity between src and dst vmas
3283                          * (in turn preventing a vma_merge) to be
3284                          * safe. It is only safe to keep the vm_pgoff
3285                          * linear if there are no pages mapped yet.
3286                          */
3287                         VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
3288                         *vmap = vma = new_vma;
3289                 }
3290                 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
3291         } else {
3292                 new_vma = vm_area_dup(vma);
3293                 if (!new_vma)
3294                         goto out;
3295                 new_vma->vm_start = addr;
3296                 new_vma->vm_end = addr + len;
3297                 new_vma->vm_pgoff = pgoff;
3298                 if (vma_dup_policy(vma, new_vma))
3299                         goto out_free_vma;
3300                 if (anon_vma_clone(new_vma, vma))
3301                         goto out_free_mempol;
3302                 if (new_vma->vm_file)
3303                         get_file(new_vma->vm_file);
3304                 if (new_vma->vm_ops && new_vma->vm_ops->open)
3305                         new_vma->vm_ops->open(new_vma);
3306                 vma_link(mm, new_vma, prev, rb_link, rb_parent);
3307                 *need_rmap_locks = false;
3308         }
3309         return new_vma;
3310
3311 out_free_mempol:
3312         mpol_put(vma_policy(new_vma));
3313 out_free_vma:
3314         vm_area_free(new_vma);
3315 out:
3316         return NULL;
3317 }
3318
3319 /*
3320  * Return true if the calling process may expand its vm space by the passed
3321  * number of pages
3322  */
3323 bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
3324 {
3325         if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
3326                 return false;
3327
3328         if (is_data_mapping(flags) &&
3329             mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
3330                 /* Workaround for Valgrind */
3331                 if (rlimit(RLIMIT_DATA) == 0 &&
3332                     mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
3333                         return true;
3334
3335                 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
3336                              current->comm, current->pid,
3337                              (mm->data_vm + npages) << PAGE_SHIFT,
3338                              rlimit(RLIMIT_DATA),
3339                              ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
3340
3341                 if (!ignore_rlimit_data)
3342                         return false;
3343         }
3344
3345         return true;
3346 }
3347
3348 void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
3349 {
3350         mm->total_vm += npages;
3351
3352         if (is_exec_mapping(flags))
3353                 mm->exec_vm += npages;
3354         else if (is_stack_mapping(flags))
3355                 mm->stack_vm += npages;
3356         else if (is_data_mapping(flags))
3357                 mm->data_vm += npages;
3358 }
3359
3360 static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
3361
3362 /*
3363  * Having a close hook prevents vma merging regardless of flags.
3364  */
3365 static void special_mapping_close(struct vm_area_struct *vma)
3366 {
3367 }
3368
3369 static const char *special_mapping_name(struct vm_area_struct *vma)
3370 {
3371         return ((struct vm_special_mapping *)vma->vm_private_data)->name;
3372 }
3373
3374 static int special_mapping_mremap(struct vm_area_struct *new_vma)
3375 {
3376         struct vm_special_mapping *sm = new_vma->vm_private_data;
3377
3378         if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
3379                 return -EFAULT;
3380
3381         if (sm->mremap)
3382                 return sm->mremap(sm, new_vma);
3383
3384         return 0;
3385 }
3386
3387 static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr)
3388 {
3389         /*
3390          * Forbid splitting special mappings - kernel has expectations over
3391          * the number of pages in mapping. Together with VM_DONTEXPAND
3392          * the size of vma should stay the same over the special mapping's
3393          * lifetime.
3394          */
3395         return -EINVAL;
3396 }
3397
3398 static const struct vm_operations_struct special_mapping_vmops = {
3399         .close = special_mapping_close,
3400         .fault = special_mapping_fault,
3401         .mremap = special_mapping_mremap,
3402         .name = special_mapping_name,
3403         /* vDSO code relies that VVAR can't be accessed remotely */
3404         .access = NULL,
3405         .may_split = special_mapping_split,
3406 };
3407
3408 static const struct vm_operations_struct legacy_special_mapping_vmops = {
3409         .close = special_mapping_close,
3410         .fault = special_mapping_fault,
3411 };
3412
3413 static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
3414 {
3415         struct vm_area_struct *vma = vmf->vma;
3416         pgoff_t pgoff;
3417         struct page **pages;
3418
3419         if (vma->vm_ops == &legacy_special_mapping_vmops) {
3420                 pages = vma->vm_private_data;
3421         } else {
3422                 struct vm_special_mapping *sm = vma->vm_private_data;
3423
3424                 if (sm->fault)
3425                         return sm->fault(sm, vmf->vma, vmf);
3426
3427                 pages = sm->pages;
3428         }
3429
3430         for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3431                 pgoff--;
3432
3433         if (*pages) {
3434                 struct page *page = *pages;
3435                 get_page(page);
3436                 vmf->page = page;
3437                 return 0;
3438         }
3439
3440         return VM_FAULT_SIGBUS;
3441 }
3442
3443 static struct vm_area_struct *__install_special_mapping(
3444         struct mm_struct *mm,
3445         unsigned long addr, unsigned long len,
3446         unsigned long vm_flags, void *priv,
3447         const struct vm_operations_struct *ops)
3448 {
3449         int ret;
3450         struct vm_area_struct *vma;
3451
3452         vma = vm_area_alloc(mm);
3453         if (unlikely(vma == NULL))
3454                 return ERR_PTR(-ENOMEM);
3455
3456         vma->vm_start = addr;
3457         vma->vm_end = addr + len;
3458
3459         vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3460         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3461
3462         vma->vm_ops = ops;
3463         vma->vm_private_data = priv;
3464
3465         ret = insert_vm_struct(mm, vma);
3466         if (ret)
3467                 goto out;
3468
3469         vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
3470
3471         perf_event_mmap(vma);
3472
3473         return vma;
3474
3475 out:
3476         vm_area_free(vma);
3477         return ERR_PTR(ret);
3478 }
3479
3480 bool vma_is_special_mapping(const struct vm_area_struct *vma,
3481         const struct vm_special_mapping *sm)
3482 {
3483         return vma->vm_private_data == sm &&
3484                 (vma->vm_ops == &special_mapping_vmops ||
3485                  vma->vm_ops == &legacy_special_mapping_vmops);
3486 }
3487
3488 /*
3489  * Called with mm->mmap_lock held for writing.
3490  * Insert a new vma covering the given region, with the given flags.
3491  * Its pages are supplied by the given array of struct page *.
3492  * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3493  * The region past the last page supplied will always produce SIGBUS.
3494  * The array pointer and the pages it points to are assumed to stay alive
3495  * for as long as this mapping might exist.
3496  */
3497 struct vm_area_struct *_install_special_mapping(
3498         struct mm_struct *mm,
3499         unsigned long addr, unsigned long len,
3500         unsigned long vm_flags, const struct vm_special_mapping *spec)
3501 {
3502         return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3503                                         &special_mapping_vmops);
3504 }
3505
3506 int install_special_mapping(struct mm_struct *mm,
3507                             unsigned long addr, unsigned long len,
3508                             unsigned long vm_flags, struct page **pages)
3509 {
3510         struct vm_area_struct *vma = __install_special_mapping(
3511                 mm, addr, len, vm_flags, (void *)pages,
3512                 &legacy_special_mapping_vmops);
3513
3514         return PTR_ERR_OR_ZERO(vma);
3515 }
3516
3517 static DEFINE_MUTEX(mm_all_locks_mutex);
3518
3519 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3520 {
3521         if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3522                 /*
3523                  * The LSB of head.next can't change from under us
3524                  * because we hold the mm_all_locks_mutex.
3525                  */
3526                 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock);
3527                 /*
3528                  * We can safely modify head.next after taking the
3529                  * anon_vma->root->rwsem. If some other vma in this mm shares
3530                  * the same anon_vma we won't take it again.
3531                  *
3532                  * No need of atomic instructions here, head.next
3533                  * can't change from under us thanks to the
3534                  * anon_vma->root->rwsem.
3535                  */
3536                 if (__test_and_set_bit(0, (unsigned long *)
3537                                        &anon_vma->root->rb_root.rb_root.rb_node))
3538                         BUG();
3539         }
3540 }
3541
3542 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3543 {
3544         if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3545                 /*
3546                  * AS_MM_ALL_LOCKS can't change from under us because
3547                  * we hold the mm_all_locks_mutex.
3548                  *
3549                  * Operations on ->flags have to be atomic because
3550                  * even if AS_MM_ALL_LOCKS is stable thanks to the
3551                  * mm_all_locks_mutex, there may be other cpus
3552                  * changing other bitflags in parallel to us.
3553                  */
3554                 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3555                         BUG();
3556                 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock);
3557         }
3558 }
3559
3560 /*
3561  * This operation locks against the VM for all pte/vma/mm related
3562  * operations that could ever happen on a certain mm. This includes
3563  * vmtruncate, try_to_unmap, and all page faults.
3564  *
3565  * The caller must take the mmap_lock in write mode before calling
3566  * mm_take_all_locks(). The caller isn't allowed to release the
3567  * mmap_lock until mm_drop_all_locks() returns.
3568  *
3569  * mmap_lock in write mode is required in order to block all operations
3570  * that could modify pagetables and free pages without need of
3571  * altering the vma layout. It's also needed in write mode to avoid new
3572  * anon_vmas to be associated with existing vmas.
3573  *
3574  * A single task can't take more than one mm_take_all_locks() in a row
3575  * or it would deadlock.
3576  *
3577  * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3578  * mapping->flags avoid to take the same lock twice, if more than one
3579  * vma in this mm is backed by the same anon_vma or address_space.
3580  *
3581  * We take locks in following order, accordingly to comment at beginning
3582  * of mm/rmap.c:
3583  *   - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3584  *     hugetlb mapping);
3585  *   - all i_mmap_rwsem locks;
3586  *   - all anon_vma->rwseml
3587  *
3588  * We can take all locks within these types randomly because the VM code
3589  * doesn't nest them and we protected from parallel mm_take_all_locks() by
3590  * mm_all_locks_mutex.
3591  *
3592  * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3593  * that may have to take thousand of locks.
3594  *
3595  * mm_take_all_locks() can fail if it's interrupted by signals.
3596  */
3597 int mm_take_all_locks(struct mm_struct *mm)
3598 {
3599         struct vm_area_struct *vma;
3600         struct anon_vma_chain *avc;
3601
3602         BUG_ON(mmap_read_trylock(mm));
3603
3604         mutex_lock(&mm_all_locks_mutex);
3605
3606         for (vma = mm->mmap; vma; vma = vma->vm_next) {
3607                 if (signal_pending(current))
3608                         goto out_unlock;
3609                 if (vma->vm_file && vma->vm_file->f_mapping &&
3610                                 is_vm_hugetlb_page(vma))
3611                         vm_lock_mapping(mm, vma->vm_file->f_mapping);
3612         }
3613
3614         for (vma = mm->mmap; vma; vma = vma->vm_next) {
3615                 if (signal_pending(current))
3616                         goto out_unlock;
3617                 if (vma->vm_file && vma->vm_file->f_mapping &&
3618                                 !is_vm_hugetlb_page(vma))
3619                         vm_lock_mapping(mm, vma->vm_file->f_mapping);
3620         }
3621
3622         for (vma = mm->mmap; vma; vma = vma->vm_next) {
3623                 if (signal_pending(current))
3624                         goto out_unlock;
3625                 if (vma->anon_vma)
3626                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3627                                 vm_lock_anon_vma(mm, avc->anon_vma);
3628         }
3629
3630         return 0;
3631
3632 out_unlock:
3633         mm_drop_all_locks(mm);
3634         return -EINTR;
3635 }
3636
3637 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3638 {
3639         if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3640                 /*
3641                  * The LSB of head.next can't change to 0 from under
3642                  * us because we hold the mm_all_locks_mutex.
3643                  *
3644                  * We must however clear the bitflag before unlocking
3645                  * the vma so the users using the anon_vma->rb_root will
3646                  * never see our bitflag.
3647                  *
3648                  * No need of atomic instructions here, head.next
3649                  * can't change from under us until we release the
3650                  * anon_vma->root->rwsem.
3651                  */
3652                 if (!__test_and_clear_bit(0, (unsigned long *)
3653                                           &anon_vma->root->rb_root.rb_root.rb_node))
3654                         BUG();
3655                 anon_vma_unlock_write(anon_vma);
3656         }
3657 }
3658
3659 static void vm_unlock_mapping(struct address_space *mapping)
3660 {
3661         if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3662                 /*
3663                  * AS_MM_ALL_LOCKS can't change to 0 from under us
3664                  * because we hold the mm_all_locks_mutex.
3665                  */
3666                 i_mmap_unlock_write(mapping);
3667                 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3668                                         &mapping->flags))
3669                         BUG();
3670         }
3671 }
3672
3673 /*
3674  * The mmap_lock cannot be released by the caller until
3675  * mm_drop_all_locks() returns.
3676  */
3677 void mm_drop_all_locks(struct mm_struct *mm)
3678 {
3679         struct vm_area_struct *vma;
3680         struct anon_vma_chain *avc;
3681
3682         BUG_ON(mmap_read_trylock(mm));
3683         BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3684
3685         for (vma = mm->mmap; vma; vma = vma->vm_next) {
3686                 if (vma->anon_vma)
3687                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3688                                 vm_unlock_anon_vma(avc->anon_vma);
3689                 if (vma->vm_file && vma->vm_file->f_mapping)
3690                         vm_unlock_mapping(vma->vm_file->f_mapping);
3691         }
3692
3693         mutex_unlock(&mm_all_locks_mutex);
3694 }
3695
3696 /*
3697  * initialise the percpu counter for VM
3698  */
3699 void __init mmap_init(void)
3700 {
3701         int ret;
3702
3703         ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3704         VM_BUG_ON(ret);
3705 }
3706
3707 /*
3708  * Initialise sysctl_user_reserve_kbytes.
3709  *
3710  * This is intended to prevent a user from starting a single memory hogging
3711  * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3712  * mode.
3713  *
3714  * The default value is min(3% of free memory, 128MB)
3715  * 128MB is enough to recover with sshd/login, bash, and top/kill.
3716  */
3717 static int init_user_reserve(void)
3718 {
3719         unsigned long free_kbytes;
3720
3721         free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3722
3723         sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3724         return 0;
3725 }
3726 subsys_initcall(init_user_reserve);
3727
3728 /*
3729  * Initialise sysctl_admin_reserve_kbytes.
3730  *
3731  * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3732  * to log in and kill a memory hogging process.
3733  *
3734  * Systems with more than 256MB will reserve 8MB, enough to recover
3735  * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3736  * only reserve 3% of free pages by default.
3737  */
3738 static int init_admin_reserve(void)
3739 {
3740         unsigned long free_kbytes;
3741
3742         free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3743
3744         sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3745         return 0;
3746 }
3747 subsys_initcall(init_admin_reserve);
3748
3749 /*
3750  * Reinititalise user and admin reserves if memory is added or removed.
3751  *
3752  * The default user reserve max is 128MB, and the default max for the
3753  * admin reserve is 8MB. These are usually, but not always, enough to
3754  * enable recovery from a memory hogging process using login/sshd, a shell,
3755  * and tools like top. It may make sense to increase or even disable the
3756  * reserve depending on the existence of swap or variations in the recovery
3757  * tools. So, the admin may have changed them.
3758  *
3759  * If memory is added and the reserves have been eliminated or increased above
3760  * the default max, then we'll trust the admin.
3761  *
3762  * If memory is removed and there isn't enough free memory, then we
3763  * need to reset the reserves.
3764  *
3765  * Otherwise keep the reserve set by the admin.
3766  */
3767 static int reserve_mem_notifier(struct notifier_block *nb,
3768                              unsigned long action, void *data)
3769 {
3770         unsigned long tmp, free_kbytes;
3771
3772         switch (action) {
3773         case MEM_ONLINE:
3774                 /* Default max is 128MB. Leave alone if modified by operator. */
3775                 tmp = sysctl_user_reserve_kbytes;
3776                 if (0 < tmp && tmp < (1UL << 17))
3777                         init_user_reserve();
3778
3779                 /* Default max is 8MB.  Leave alone if modified by operator. */
3780                 tmp = sysctl_admin_reserve_kbytes;
3781                 if (0 < tmp && tmp < (1UL << 13))
3782                         init_admin_reserve();
3783
3784                 break;
3785         case MEM_OFFLINE:
3786                 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3787
3788                 if (sysctl_user_reserve_kbytes > free_kbytes) {
3789                         init_user_reserve();
3790                         pr_info("vm.user_reserve_kbytes reset to %lu\n",
3791                                 sysctl_user_reserve_kbytes);
3792                 }
3793
3794                 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3795                         init_admin_reserve();
3796                         pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3797                                 sysctl_admin_reserve_kbytes);
3798                 }
3799                 break;
3800         default:
3801                 break;
3802         }
3803         return NOTIFY_OK;
3804 }
3805
3806 static struct notifier_block reserve_mem_nb = {
3807         .notifier_call = reserve_mem_notifier,
3808 };
3809
3810 static int __meminit init_reserve_notifier(void)
3811 {
3812         if (register_hotmemory_notifier(&reserve_mem_nb))
3813                 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3814
3815         return 0;
3816 }
3817 subsys_initcall(init_reserve_notifier);