1 /* 2 * mm/mmap.c 3 * 4 * Written by obz. 5 * 6 * Address space accounting code <alan@lxorguk.ukuu.org.uk> 7 */ 8 9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 10 11 #include <linux/kernel.h> 12 #include <linux/slab.h> 13 #include <linux/backing-dev.h> 14 #include <linux/mm.h> 15 #include <linux/vmacache.h> 16 #include <linux/shm.h> 17 #include <linux/mman.h> 18 #include <linux/pagemap.h> 19 #include <linux/swap.h> 20 #include <linux/syscalls.h> 21 #include <linux/capability.h> 22 #include <linux/init.h> 23 #include <linux/file.h> 24 #include <linux/fs.h> 25 #include <linux/personality.h> 26 #include <linux/security.h> 27 #include <linux/hugetlb.h> 28 #include <linux/profile.h> 29 #include <linux/export.h> 30 #include <linux/mount.h> 31 #include <linux/mempolicy.h> 32 #include <linux/rmap.h> 33 #include <linux/mmu_notifier.h> 34 #include <linux/mmdebug.h> 35 #include <linux/perf_event.h> 36 #include <linux/audit.h> 37 #include <linux/khugepaged.h> 38 #include <linux/uprobes.h> 39 #include <linux/rbtree_augmented.h> 40 #include <linux/sched/sysctl.h> 41 #include <linux/notifier.h> 42 #include <linux/memory.h> 43 #include <linux/printk.h> 44 #include <linux/userfaultfd_k.h> 45 #include <linux/moduleparam.h> 46 47 #include <asm/uaccess.h> 48 #include <asm/cacheflush.h> 49 #include <asm/tlb.h> 50 #include <asm/mmu_context.h> 51 52 #include "internal.h" 53 54 #ifndef arch_mmap_check 55 #define arch_mmap_check(addr, len, flags) (0) 56 #endif 57 58 #ifndef arch_rebalance_pgtables 59 #define arch_rebalance_pgtables(addr, len) (addr) 60 #endif 61 62 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS 63 const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; 64 const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX; 65 int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS; 66 #endif 67 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS 68 const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; 69 const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; 70 int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; 71 #endif 72 73 static bool ignore_rlimit_data = true; 74 core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644); 75 76 static void unmap_region(struct mm_struct *mm, 77 struct vm_area_struct *vma, struct vm_area_struct *prev, 78 unsigned long start, unsigned long end); 79 80 /* description of effects of mapping type and prot in current implementation. 81 * this is due to the limited x86 page protection hardware. The expected 82 * behavior is in parens: 83 * 84 * map_type prot 85 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 86 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 87 * w: (no) no w: (no) no w: (yes) yes w: (no) no 88 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 89 * 90 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 91 * w: (no) no w: (no) no w: (copy) copy w: (no) no 92 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 93 * 94 */ 95 pgprot_t protection_map[16] = { 96 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 97 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 98 }; 99 100 pgprot_t vm_get_page_prot(unsigned long vm_flags) 101 { 102 return __pgprot(pgprot_val(protection_map[vm_flags & 103 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | 104 pgprot_val(arch_vm_get_page_prot(vm_flags))); 105 } 106 EXPORT_SYMBOL(vm_get_page_prot); 107 108 static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags) 109 { 110 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags)); 111 } 112 113 /* Update vma->vm_page_prot to reflect vma->vm_flags. */ 114 void vma_set_page_prot(struct vm_area_struct *vma) 115 { 116 unsigned long vm_flags = vma->vm_flags; 117 118 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags); 119 if (vma_wants_writenotify(vma)) { 120 vm_flags &= ~VM_SHARED; 121 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, 122 vm_flags); 123 } 124 } 125 126 127 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */ 128 int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */ 129 unsigned long sysctl_overcommit_kbytes __read_mostly; 130 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; 131 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ 132 unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ 133 /* 134 * Make sure vm_committed_as in one cacheline and not cacheline shared with 135 * other variables. It can be updated by several CPUs frequently. 136 */ 137 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; 138 139 /* 140 * The global memory commitment made in the system can be a metric 141 * that can be used to drive ballooning decisions when Linux is hosted 142 * as a guest. On Hyper-V, the host implements a policy engine for dynamically 143 * balancing memory across competing virtual machines that are hosted. 144 * Several metrics drive this policy engine including the guest reported 145 * memory commitment. 146 */ 147 unsigned long vm_memory_committed(void) 148 { 149 return percpu_counter_read_positive(&vm_committed_as); 150 } 151 EXPORT_SYMBOL_GPL(vm_memory_committed); 152 153 /* 154 * Check that a process has enough memory to allocate a new virtual 155 * mapping. 0 means there is enough memory for the allocation to 156 * succeed and -ENOMEM implies there is not. 157 * 158 * We currently support three overcommit policies, which are set via the 159 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 160 * 161 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 162 * Additional code 2002 Jul 20 by Robert Love. 163 * 164 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 165 * 166 * Note this is a helper function intended to be used by LSMs which 167 * wish to use this logic. 168 */ 169 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 170 { 171 long free, allowed, reserve; 172 173 VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) < 174 -(s64)vm_committed_as_batch * num_online_cpus(), 175 "memory commitment underflow"); 176 177 vm_acct_memory(pages); 178 179 /* 180 * Sometimes we want to use more memory than we have 181 */ 182 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 183 return 0; 184 185 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 186 free = global_page_state(NR_FREE_PAGES); 187 free += global_page_state(NR_FILE_PAGES); 188 189 /* 190 * shmem pages shouldn't be counted as free in this 191 * case, they can't be purged, only swapped out, and 192 * that won't affect the overall amount of available 193 * memory in the system. 194 */ 195 free -= global_page_state(NR_SHMEM); 196 197 free += get_nr_swap_pages(); 198 199 /* 200 * Any slabs which are created with the 201 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 202 * which are reclaimable, under pressure. The dentry 203 * cache and most inode caches should fall into this 204 */ 205 free += global_page_state(NR_SLAB_RECLAIMABLE); 206 207 /* 208 * Leave reserved pages. The pages are not for anonymous pages. 209 */ 210 if (free <= totalreserve_pages) 211 goto error; 212 else 213 free -= totalreserve_pages; 214 215 /* 216 * Reserve some for root 217 */ 218 if (!cap_sys_admin) 219 free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); 220 221 if (free > pages) 222 return 0; 223 224 goto error; 225 } 226 227 allowed = vm_commit_limit(); 228 /* 229 * Reserve some for root 230 */ 231 if (!cap_sys_admin) 232 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); 233 234 /* 235 * Don't let a single process grow so big a user can't recover 236 */ 237 if (mm) { 238 reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10); 239 allowed -= min_t(long, mm->total_vm / 32, reserve); 240 } 241 242 if (percpu_counter_read_positive(&vm_committed_as) < allowed) 243 return 0; 244 error: 245 vm_unacct_memory(pages); 246 247 return -ENOMEM; 248 } 249 250 /* 251 * Requires inode->i_mapping->i_mmap_rwsem 252 */ 253 static void __remove_shared_vm_struct(struct vm_area_struct *vma, 254 struct file *file, struct address_space *mapping) 255 { 256 if (vma->vm_flags & VM_DENYWRITE) 257 atomic_inc(&file_inode(file)->i_writecount); 258 if (vma->vm_flags & VM_SHARED) 259 mapping_unmap_writable(mapping); 260 261 flush_dcache_mmap_lock(mapping); 262 vma_interval_tree_remove(vma, &mapping->i_mmap); 263 flush_dcache_mmap_unlock(mapping); 264 } 265 266 /* 267 * Unlink a file-based vm structure from its interval tree, to hide 268 * vma from rmap and vmtruncate before freeing its page tables. 269 */ 270 void unlink_file_vma(struct vm_area_struct *vma) 271 { 272 struct file *file = vma->vm_file; 273 274 if (file) { 275 struct address_space *mapping = file->f_mapping; 276 i_mmap_lock_write(mapping); 277 __remove_shared_vm_struct(vma, file, mapping); 278 i_mmap_unlock_write(mapping); 279 } 280 } 281 282 /* 283 * Close a vm structure and free it, returning the next. 284 */ 285 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 286 { 287 struct vm_area_struct *next = vma->vm_next; 288 289 might_sleep(); 290 if (vma->vm_ops && vma->vm_ops->close) 291 vma->vm_ops->close(vma); 292 if (vma->vm_file) 293 fput(vma->vm_file); 294 mpol_put(vma_policy(vma)); 295 kmem_cache_free(vm_area_cachep, vma); 296 return next; 297 } 298 299 static unsigned long do_brk(unsigned long addr, unsigned long len); 300 301 SYSCALL_DEFINE1(brk, unsigned long, brk) 302 { 303 unsigned long retval; 304 unsigned long newbrk, oldbrk; 305 struct mm_struct *mm = current->mm; 306 unsigned long min_brk; 307 bool populate; 308 309 down_write(&mm->mmap_sem); 310 311 #ifdef CONFIG_COMPAT_BRK 312 /* 313 * CONFIG_COMPAT_BRK can still be overridden by setting 314 * randomize_va_space to 2, which will still cause mm->start_brk 315 * to be arbitrarily shifted 316 */ 317 if (current->brk_randomized) 318 min_brk = mm->start_brk; 319 else 320 min_brk = mm->end_data; 321 #else 322 min_brk = mm->start_brk; 323 #endif 324 if (brk < min_brk) 325 goto out; 326 327 /* 328 * Check against rlimit here. If this check is done later after the test 329 * of oldbrk with newbrk then it can escape the test and let the data 330 * segment grow beyond its set limit the in case where the limit is 331 * not page aligned -Ram Gupta 332 */ 333 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk, 334 mm->end_data, mm->start_data)) 335 goto out; 336 337 newbrk = PAGE_ALIGN(brk); 338 oldbrk = PAGE_ALIGN(mm->brk); 339 if (oldbrk == newbrk) 340 goto set_brk; 341 342 /* Always allow shrinking brk. */ 343 if (brk <= mm->brk) { 344 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 345 goto set_brk; 346 goto out; 347 } 348 349 /* Check against existing mmap mappings. */ 350 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 351 goto out; 352 353 /* Ok, looks good - let it rip. */ 354 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 355 goto out; 356 357 set_brk: 358 mm->brk = brk; 359 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; 360 up_write(&mm->mmap_sem); 361 if (populate) 362 mm_populate(oldbrk, newbrk - oldbrk); 363 return brk; 364 365 out: 366 retval = mm->brk; 367 up_write(&mm->mmap_sem); 368 return retval; 369 } 370 371 static long vma_compute_subtree_gap(struct vm_area_struct *vma) 372 { 373 unsigned long max, subtree_gap; 374 max = vma->vm_start; 375 if (vma->vm_prev) 376 max -= vma->vm_prev->vm_end; 377 if (vma->vm_rb.rb_left) { 378 subtree_gap = rb_entry(vma->vm_rb.rb_left, 379 struct vm_area_struct, vm_rb)->rb_subtree_gap; 380 if (subtree_gap > max) 381 max = subtree_gap; 382 } 383 if (vma->vm_rb.rb_right) { 384 subtree_gap = rb_entry(vma->vm_rb.rb_right, 385 struct vm_area_struct, vm_rb)->rb_subtree_gap; 386 if (subtree_gap > max) 387 max = subtree_gap; 388 } 389 return max; 390 } 391 392 #ifdef CONFIG_DEBUG_VM_RB 393 static int browse_rb(struct rb_root *root) 394 { 395 int i = 0, j, bug = 0; 396 struct rb_node *nd, *pn = NULL; 397 unsigned long prev = 0, pend = 0; 398 399 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 400 struct vm_area_struct *vma; 401 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 402 if (vma->vm_start < prev) { 403 pr_emerg("vm_start %lx < prev %lx\n", 404 vma->vm_start, prev); 405 bug = 1; 406 } 407 if (vma->vm_start < pend) { 408 pr_emerg("vm_start %lx < pend %lx\n", 409 vma->vm_start, pend); 410 bug = 1; 411 } 412 if (vma->vm_start > vma->vm_end) { 413 pr_emerg("vm_start %lx > vm_end %lx\n", 414 vma->vm_start, vma->vm_end); 415 bug = 1; 416 } 417 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) { 418 pr_emerg("free gap %lx, correct %lx\n", 419 vma->rb_subtree_gap, 420 vma_compute_subtree_gap(vma)); 421 bug = 1; 422 } 423 i++; 424 pn = nd; 425 prev = vma->vm_start; 426 pend = vma->vm_end; 427 } 428 j = 0; 429 for (nd = pn; nd; nd = rb_prev(nd)) 430 j++; 431 if (i != j) { 432 pr_emerg("backwards %d, forwards %d\n", j, i); 433 bug = 1; 434 } 435 return bug ? -1 : i; 436 } 437 438 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore) 439 { 440 struct rb_node *nd; 441 442 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 443 struct vm_area_struct *vma; 444 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 445 VM_BUG_ON_VMA(vma != ignore && 446 vma->rb_subtree_gap != vma_compute_subtree_gap(vma), 447 vma); 448 } 449 } 450 451 static void validate_mm(struct mm_struct *mm) 452 { 453 int bug = 0; 454 int i = 0; 455 unsigned long highest_address = 0; 456 struct vm_area_struct *vma = mm->mmap; 457 458 while (vma) { 459 struct anon_vma_chain *avc; 460 461 vma_lock_anon_vma(vma); 462 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 463 anon_vma_interval_tree_verify(avc); 464 vma_unlock_anon_vma(vma); 465 highest_address = vma->vm_end; 466 vma = vma->vm_next; 467 i++; 468 } 469 if (i != mm->map_count) { 470 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i); 471 bug = 1; 472 } 473 if (highest_address != mm->highest_vm_end) { 474 pr_emerg("mm->highest_vm_end %lx, found %lx\n", 475 mm->highest_vm_end, highest_address); 476 bug = 1; 477 } 478 i = browse_rb(&mm->mm_rb); 479 if (i != mm->map_count) { 480 if (i != -1) 481 pr_emerg("map_count %d rb %d\n", mm->map_count, i); 482 bug = 1; 483 } 484 VM_BUG_ON_MM(bug, mm); 485 } 486 #else 487 #define validate_mm_rb(root, ignore) do { } while (0) 488 #define validate_mm(mm) do { } while (0) 489 #endif 490 491 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb, 492 unsigned long, rb_subtree_gap, vma_compute_subtree_gap) 493 494 /* 495 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or 496 * vma->vm_prev->vm_end values changed, without modifying the vma's position 497 * in the rbtree. 498 */ 499 static void vma_gap_update(struct vm_area_struct *vma) 500 { 501 /* 502 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback 503 * function that does exacltly what we want. 504 */ 505 vma_gap_callbacks_propagate(&vma->vm_rb, NULL); 506 } 507 508 static inline void vma_rb_insert(struct vm_area_struct *vma, 509 struct rb_root *root) 510 { 511 /* All rb_subtree_gap values must be consistent prior to insertion */ 512 validate_mm_rb(root, NULL); 513 514 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks); 515 } 516 517 static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) 518 { 519 /* 520 * All rb_subtree_gap values must be consistent prior to erase, 521 * with the possible exception of the vma being erased. 522 */ 523 validate_mm_rb(root, vma); 524 525 /* 526 * Note rb_erase_augmented is a fairly large inline function, 527 * so make sure we instantiate it only once with our desired 528 * augmented rbtree callbacks. 529 */ 530 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); 531 } 532 533 /* 534 * vma has some anon_vma assigned, and is already inserted on that 535 * anon_vma's interval trees. 536 * 537 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the 538 * vma must be removed from the anon_vma's interval trees using 539 * anon_vma_interval_tree_pre_update_vma(). 540 * 541 * After the update, the vma will be reinserted using 542 * anon_vma_interval_tree_post_update_vma(). 543 * 544 * The entire update must be protected by exclusive mmap_sem and by 545 * the root anon_vma's mutex. 546 */ 547 static inline void 548 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) 549 { 550 struct anon_vma_chain *avc; 551 552 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 553 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); 554 } 555 556 static inline void 557 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) 558 { 559 struct anon_vma_chain *avc; 560 561 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 562 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); 563 } 564 565 static int find_vma_links(struct mm_struct *mm, unsigned long addr, 566 unsigned long end, struct vm_area_struct **pprev, 567 struct rb_node ***rb_link, struct rb_node **rb_parent) 568 { 569 struct rb_node **__rb_link, *__rb_parent, *rb_prev; 570 571 __rb_link = &mm->mm_rb.rb_node; 572 rb_prev = __rb_parent = NULL; 573 574 while (*__rb_link) { 575 struct vm_area_struct *vma_tmp; 576 577 __rb_parent = *__rb_link; 578 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 579 580 if (vma_tmp->vm_end > addr) { 581 /* Fail if an existing vma overlaps the area */ 582 if (vma_tmp->vm_start < end) 583 return -ENOMEM; 584 __rb_link = &__rb_parent->rb_left; 585 } else { 586 rb_prev = __rb_parent; 587 __rb_link = &__rb_parent->rb_right; 588 } 589 } 590 591 *pprev = NULL; 592 if (rb_prev) 593 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 594 *rb_link = __rb_link; 595 *rb_parent = __rb_parent; 596 return 0; 597 } 598 599 static unsigned long count_vma_pages_range(struct mm_struct *mm, 600 unsigned long addr, unsigned long end) 601 { 602 unsigned long nr_pages = 0; 603 struct vm_area_struct *vma; 604 605 /* Find first overlaping mapping */ 606 vma = find_vma_intersection(mm, addr, end); 607 if (!vma) 608 return 0; 609 610 nr_pages = (min(end, vma->vm_end) - 611 max(addr, vma->vm_start)) >> PAGE_SHIFT; 612 613 /* Iterate over the rest of the overlaps */ 614 for (vma = vma->vm_next; vma; vma = vma->vm_next) { 615 unsigned long overlap_len; 616 617 if (vma->vm_start > end) 618 break; 619 620 overlap_len = min(end, vma->vm_end) - vma->vm_start; 621 nr_pages += overlap_len >> PAGE_SHIFT; 622 } 623 624 return nr_pages; 625 } 626 627 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 628 struct rb_node **rb_link, struct rb_node *rb_parent) 629 { 630 /* Update tracking information for the gap following the new vma. */ 631 if (vma->vm_next) 632 vma_gap_update(vma->vm_next); 633 else 634 mm->highest_vm_end = vma->vm_end; 635 636 /* 637 * vma->vm_prev wasn't known when we followed the rbtree to find the 638 * correct insertion point for that vma. As a result, we could not 639 * update the vma vm_rb parents rb_subtree_gap values on the way down. 640 * So, we first insert the vma with a zero rb_subtree_gap value 641 * (to be consistent with what we did on the way down), and then 642 * immediately update the gap to the correct value. Finally we 643 * rebalance the rbtree after all augmented values have been set. 644 */ 645 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 646 vma->rb_subtree_gap = 0; 647 vma_gap_update(vma); 648 vma_rb_insert(vma, &mm->mm_rb); 649 } 650 651 static void __vma_link_file(struct vm_area_struct *vma) 652 { 653 struct file *file; 654 655 file = vma->vm_file; 656 if (file) { 657 struct address_space *mapping = file->f_mapping; 658 659 if (vma->vm_flags & VM_DENYWRITE) 660 atomic_dec(&file_inode(file)->i_writecount); 661 if (vma->vm_flags & VM_SHARED) 662 atomic_inc(&mapping->i_mmap_writable); 663 664 flush_dcache_mmap_lock(mapping); 665 vma_interval_tree_insert(vma, &mapping->i_mmap); 666 flush_dcache_mmap_unlock(mapping); 667 } 668 } 669 670 static void 671 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 672 struct vm_area_struct *prev, struct rb_node **rb_link, 673 struct rb_node *rb_parent) 674 { 675 __vma_link_list(mm, vma, prev, rb_parent); 676 __vma_link_rb(mm, vma, rb_link, rb_parent); 677 } 678 679 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 680 struct vm_area_struct *prev, struct rb_node **rb_link, 681 struct rb_node *rb_parent) 682 { 683 struct address_space *mapping = NULL; 684 685 if (vma->vm_file) { 686 mapping = vma->vm_file->f_mapping; 687 i_mmap_lock_write(mapping); 688 } 689 690 __vma_link(mm, vma, prev, rb_link, rb_parent); 691 __vma_link_file(vma); 692 693 if (mapping) 694 i_mmap_unlock_write(mapping); 695 696 mm->map_count++; 697 validate_mm(mm); 698 } 699 700 /* 701 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the 702 * mm's list and rbtree. It has already been inserted into the interval tree. 703 */ 704 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) 705 { 706 struct vm_area_struct *prev; 707 struct rb_node **rb_link, *rb_parent; 708 709 if (find_vma_links(mm, vma->vm_start, vma->vm_end, 710 &prev, &rb_link, &rb_parent)) 711 BUG(); 712 __vma_link(mm, vma, prev, rb_link, rb_parent); 713 mm->map_count++; 714 } 715 716 static inline void 717 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 718 struct vm_area_struct *prev) 719 { 720 struct vm_area_struct *next; 721 722 vma_rb_erase(vma, &mm->mm_rb); 723 prev->vm_next = next = vma->vm_next; 724 if (next) 725 next->vm_prev = prev; 726 727 /* Kill the cache */ 728 vmacache_invalidate(mm); 729 } 730 731 /* 732 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 733 * is already present in an i_mmap tree without adjusting the tree. 734 * The following helper function should be used when such adjustments 735 * are necessary. The "insert" vma (if any) is to be inserted 736 * before we drop the necessary locks. 737 */ 738 int vma_adjust(struct vm_area_struct *vma, unsigned long start, 739 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 740 { 741 struct mm_struct *mm = vma->vm_mm; 742 struct vm_area_struct *next = vma->vm_next; 743 struct vm_area_struct *importer = NULL; 744 struct address_space *mapping = NULL; 745 struct rb_root *root = NULL; 746 struct anon_vma *anon_vma = NULL; 747 struct file *file = vma->vm_file; 748 bool start_changed = false, end_changed = false; 749 long adjust_next = 0; 750 int remove_next = 0; 751 752 if (next && !insert) { 753 struct vm_area_struct *exporter = NULL; 754 755 if (end >= next->vm_end) { 756 /* 757 * vma expands, overlapping all the next, and 758 * perhaps the one after too (mprotect case 6). 759 */ 760 again: remove_next = 1 + (end > next->vm_end); 761 end = next->vm_end; 762 exporter = next; 763 importer = vma; 764 } else if (end > next->vm_start) { 765 /* 766 * vma expands, overlapping part of the next: 767 * mprotect case 5 shifting the boundary up. 768 */ 769 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 770 exporter = next; 771 importer = vma; 772 } else if (end < vma->vm_end) { 773 /* 774 * vma shrinks, and !insert tells it's not 775 * split_vma inserting another: so it must be 776 * mprotect case 4 shifting the boundary down. 777 */ 778 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT); 779 exporter = vma; 780 importer = next; 781 } 782 783 /* 784 * Easily overlooked: when mprotect shifts the boundary, 785 * make sure the expanding vma has anon_vma set if the 786 * shrinking vma had, to cover any anon pages imported. 787 */ 788 if (exporter && exporter->anon_vma && !importer->anon_vma) { 789 int error; 790 791 importer->anon_vma = exporter->anon_vma; 792 error = anon_vma_clone(importer, exporter); 793 if (error) 794 return error; 795 } 796 } 797 798 if (file) { 799 mapping = file->f_mapping; 800 root = &mapping->i_mmap; 801 uprobe_munmap(vma, vma->vm_start, vma->vm_end); 802 803 if (adjust_next) 804 uprobe_munmap(next, next->vm_start, next->vm_end); 805 806 i_mmap_lock_write(mapping); 807 if (insert) { 808 /* 809 * Put into interval tree now, so instantiated pages 810 * are visible to arm/parisc __flush_dcache_page 811 * throughout; but we cannot insert into address 812 * space until vma start or end is updated. 813 */ 814 __vma_link_file(insert); 815 } 816 } 817 818 vma_adjust_trans_huge(vma, start, end, adjust_next); 819 820 anon_vma = vma->anon_vma; 821 if (!anon_vma && adjust_next) 822 anon_vma = next->anon_vma; 823 if (anon_vma) { 824 VM_BUG_ON_VMA(adjust_next && next->anon_vma && 825 anon_vma != next->anon_vma, next); 826 anon_vma_lock_write(anon_vma); 827 anon_vma_interval_tree_pre_update_vma(vma); 828 if (adjust_next) 829 anon_vma_interval_tree_pre_update_vma(next); 830 } 831 832 if (root) { 833 flush_dcache_mmap_lock(mapping); 834 vma_interval_tree_remove(vma, root); 835 if (adjust_next) 836 vma_interval_tree_remove(next, root); 837 } 838 839 if (start != vma->vm_start) { 840 vma->vm_start = start; 841 start_changed = true; 842 } 843 if (end != vma->vm_end) { 844 vma->vm_end = end; 845 end_changed = true; 846 } 847 vma->vm_pgoff = pgoff; 848 if (adjust_next) { 849 next->vm_start += adjust_next << PAGE_SHIFT; 850 next->vm_pgoff += adjust_next; 851 } 852 853 if (root) { 854 if (adjust_next) 855 vma_interval_tree_insert(next, root); 856 vma_interval_tree_insert(vma, root); 857 flush_dcache_mmap_unlock(mapping); 858 } 859 860 if (remove_next) { 861 /* 862 * vma_merge has merged next into vma, and needs 863 * us to remove next before dropping the locks. 864 */ 865 __vma_unlink(mm, next, vma); 866 if (file) 867 __remove_shared_vm_struct(next, file, mapping); 868 } else if (insert) { 869 /* 870 * split_vma has split insert from vma, and needs 871 * us to insert it before dropping the locks 872 * (it may either follow vma or precede it). 873 */ 874 __insert_vm_struct(mm, insert); 875 } else { 876 if (start_changed) 877 vma_gap_update(vma); 878 if (end_changed) { 879 if (!next) 880 mm->highest_vm_end = end; 881 else if (!adjust_next) 882 vma_gap_update(next); 883 } 884 } 885 886 if (anon_vma) { 887 anon_vma_interval_tree_post_update_vma(vma); 888 if (adjust_next) 889 anon_vma_interval_tree_post_update_vma(next); 890 anon_vma_unlock_write(anon_vma); 891 } 892 if (mapping) 893 i_mmap_unlock_write(mapping); 894 895 if (root) { 896 uprobe_mmap(vma); 897 898 if (adjust_next) 899 uprobe_mmap(next); 900 } 901 902 if (remove_next) { 903 if (file) { 904 uprobe_munmap(next, next->vm_start, next->vm_end); 905 fput(file); 906 } 907 if (next->anon_vma) 908 anon_vma_merge(vma, next); 909 mm->map_count--; 910 mpol_put(vma_policy(next)); 911 kmem_cache_free(vm_area_cachep, next); 912 /* 913 * In mprotect's case 6 (see comments on vma_merge), 914 * we must remove another next too. It would clutter 915 * up the code too much to do both in one go. 916 */ 917 next = vma->vm_next; 918 if (remove_next == 2) 919 goto again; 920 else if (next) 921 vma_gap_update(next); 922 else 923 mm->highest_vm_end = end; 924 } 925 if (insert && file) 926 uprobe_mmap(insert); 927 928 validate_mm(mm); 929 930 return 0; 931 } 932 933 /* 934 * If the vma has a ->close operation then the driver probably needs to release 935 * per-vma resources, so we don't attempt to merge those. 936 */ 937 static inline int is_mergeable_vma(struct vm_area_struct *vma, 938 struct file *file, unsigned long vm_flags, 939 struct vm_userfaultfd_ctx vm_userfaultfd_ctx) 940 { 941 /* 942 * VM_SOFTDIRTY should not prevent from VMA merging, if we 943 * match the flags but dirty bit -- the caller should mark 944 * merged VMA as dirty. If dirty bit won't be excluded from 945 * comparison, we increase pressue on the memory system forcing 946 * the kernel to generate new VMAs when old one could be 947 * extended instead. 948 */ 949 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY) 950 return 0; 951 if (vma->vm_file != file) 952 return 0; 953 if (vma->vm_ops && vma->vm_ops->close) 954 return 0; 955 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx)) 956 return 0; 957 return 1; 958 } 959 960 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 961 struct anon_vma *anon_vma2, 962 struct vm_area_struct *vma) 963 { 964 /* 965 * The list_is_singular() test is to avoid merging VMA cloned from 966 * parents. This can improve scalability caused by anon_vma lock. 967 */ 968 if ((!anon_vma1 || !anon_vma2) && (!vma || 969 list_is_singular(&vma->anon_vma_chain))) 970 return 1; 971 return anon_vma1 == anon_vma2; 972 } 973 974 /* 975 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 976 * in front of (at a lower virtual address and file offset than) the vma. 977 * 978 * We cannot merge two vmas if they have differently assigned (non-NULL) 979 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 980 * 981 * We don't check here for the merged mmap wrapping around the end of pagecache 982 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 983 * wrap, nor mmaps which cover the final page at index -1UL. 984 */ 985 static int 986 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 987 struct anon_vma *anon_vma, struct file *file, 988 pgoff_t vm_pgoff, 989 struct vm_userfaultfd_ctx vm_userfaultfd_ctx) 990 { 991 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && 992 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { 993 if (vma->vm_pgoff == vm_pgoff) 994 return 1; 995 } 996 return 0; 997 } 998 999 /* 1000 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 1001 * beyond (at a higher virtual address and file offset than) the vma. 1002 * 1003 * We cannot merge two vmas if they have differently assigned (non-NULL) 1004 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 1005 */ 1006 static int 1007 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 1008 struct anon_vma *anon_vma, struct file *file, 1009 pgoff_t vm_pgoff, 1010 struct vm_userfaultfd_ctx vm_userfaultfd_ctx) 1011 { 1012 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && 1013 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { 1014 pgoff_t vm_pglen; 1015 vm_pglen = vma_pages(vma); 1016 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 1017 return 1; 1018 } 1019 return 0; 1020 } 1021 1022 /* 1023 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 1024 * whether that can be merged with its predecessor or its successor. 1025 * Or both (it neatly fills a hole). 1026 * 1027 * In most cases - when called for mmap, brk or mremap - [addr,end) is 1028 * certain not to be mapped by the time vma_merge is called; but when 1029 * called for mprotect, it is certain to be already mapped (either at 1030 * an offset within prev, or at the start of next), and the flags of 1031 * this area are about to be changed to vm_flags - and the no-change 1032 * case has already been eliminated. 1033 * 1034 * The following mprotect cases have to be considered, where AAAA is 1035 * the area passed down from mprotect_fixup, never extending beyond one 1036 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 1037 * 1038 * AAAA AAAA AAAA AAAA 1039 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 1040 * cannot merge might become might become might become 1041 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 1042 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 1043 * mremap move: PPPPNNNNNNNN 8 1044 * AAAA 1045 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 1046 * might become case 1 below case 2 below case 3 below 1047 * 1048 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 1049 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 1050 */ 1051 struct vm_area_struct *vma_merge(struct mm_struct *mm, 1052 struct vm_area_struct *prev, unsigned long addr, 1053 unsigned long end, unsigned long vm_flags, 1054 struct anon_vma *anon_vma, struct file *file, 1055 pgoff_t pgoff, struct mempolicy *policy, 1056 struct vm_userfaultfd_ctx vm_userfaultfd_ctx) 1057 { 1058 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 1059 struct vm_area_struct *area, *next; 1060 int err; 1061 1062 /* 1063 * We later require that vma->vm_flags == vm_flags, 1064 * so this tests vma->vm_flags & VM_SPECIAL, too. 1065 */ 1066 if (vm_flags & VM_SPECIAL) 1067 return NULL; 1068 1069 if (prev) 1070 next = prev->vm_next; 1071 else 1072 next = mm->mmap; 1073 area = next; 1074 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 1075 next = next->vm_next; 1076 1077 /* 1078 * Can it merge with the predecessor? 1079 */ 1080 if (prev && prev->vm_end == addr && 1081 mpol_equal(vma_policy(prev), policy) && 1082 can_vma_merge_after(prev, vm_flags, 1083 anon_vma, file, pgoff, 1084 vm_userfaultfd_ctx)) { 1085 /* 1086 * OK, it can. Can we now merge in the successor as well? 1087 */ 1088 if (next && end == next->vm_start && 1089 mpol_equal(policy, vma_policy(next)) && 1090 can_vma_merge_before(next, vm_flags, 1091 anon_vma, file, 1092 pgoff+pglen, 1093 vm_userfaultfd_ctx) && 1094 is_mergeable_anon_vma(prev->anon_vma, 1095 next->anon_vma, NULL)) { 1096 /* cases 1, 6 */ 1097 err = vma_adjust(prev, prev->vm_start, 1098 next->vm_end, prev->vm_pgoff, NULL); 1099 } else /* cases 2, 5, 7 */ 1100 err = vma_adjust(prev, prev->vm_start, 1101 end, prev->vm_pgoff, NULL); 1102 if (err) 1103 return NULL; 1104 khugepaged_enter_vma_merge(prev, vm_flags); 1105 return prev; 1106 } 1107 1108 /* 1109 * Can this new request be merged in front of next? 1110 */ 1111 if (next && end == next->vm_start && 1112 mpol_equal(policy, vma_policy(next)) && 1113 can_vma_merge_before(next, vm_flags, 1114 anon_vma, file, pgoff+pglen, 1115 vm_userfaultfd_ctx)) { 1116 if (prev && addr < prev->vm_end) /* case 4 */ 1117 err = vma_adjust(prev, prev->vm_start, 1118 addr, prev->vm_pgoff, NULL); 1119 else /* cases 3, 8 */ 1120 err = vma_adjust(area, addr, next->vm_end, 1121 next->vm_pgoff - pglen, NULL); 1122 if (err) 1123 return NULL; 1124 khugepaged_enter_vma_merge(area, vm_flags); 1125 return area; 1126 } 1127 1128 return NULL; 1129 } 1130 1131 /* 1132 * Rough compatbility check to quickly see if it's even worth looking 1133 * at sharing an anon_vma. 1134 * 1135 * They need to have the same vm_file, and the flags can only differ 1136 * in things that mprotect may change. 1137 * 1138 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that 1139 * we can merge the two vma's. For example, we refuse to merge a vma if 1140 * there is a vm_ops->close() function, because that indicates that the 1141 * driver is doing some kind of reference counting. But that doesn't 1142 * really matter for the anon_vma sharing case. 1143 */ 1144 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) 1145 { 1146 return a->vm_end == b->vm_start && 1147 mpol_equal(vma_policy(a), vma_policy(b)) && 1148 a->vm_file == b->vm_file && 1149 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) && 1150 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); 1151 } 1152 1153 /* 1154 * Do some basic sanity checking to see if we can re-use the anon_vma 1155 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be 1156 * the same as 'old', the other will be the new one that is trying 1157 * to share the anon_vma. 1158 * 1159 * NOTE! This runs with mm_sem held for reading, so it is possible that 1160 * the anon_vma of 'old' is concurrently in the process of being set up 1161 * by another page fault trying to merge _that_. But that's ok: if it 1162 * is being set up, that automatically means that it will be a singleton 1163 * acceptable for merging, so we can do all of this optimistically. But 1164 * we do that READ_ONCE() to make sure that we never re-load the pointer. 1165 * 1166 * IOW: that the "list_is_singular()" test on the anon_vma_chain only 1167 * matters for the 'stable anon_vma' case (ie the thing we want to avoid 1168 * is to return an anon_vma that is "complex" due to having gone through 1169 * a fork). 1170 * 1171 * We also make sure that the two vma's are compatible (adjacent, 1172 * and with the same memory policies). That's all stable, even with just 1173 * a read lock on the mm_sem. 1174 */ 1175 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) 1176 { 1177 if (anon_vma_compatible(a, b)) { 1178 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma); 1179 1180 if (anon_vma && list_is_singular(&old->anon_vma_chain)) 1181 return anon_vma; 1182 } 1183 return NULL; 1184 } 1185 1186 /* 1187 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 1188 * neighbouring vmas for a suitable anon_vma, before it goes off 1189 * to allocate a new anon_vma. It checks because a repetitive 1190 * sequence of mprotects and faults may otherwise lead to distinct 1191 * anon_vmas being allocated, preventing vma merge in subsequent 1192 * mprotect. 1193 */ 1194 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 1195 { 1196 struct anon_vma *anon_vma; 1197 struct vm_area_struct *near; 1198 1199 near = vma->vm_next; 1200 if (!near) 1201 goto try_prev; 1202 1203 anon_vma = reusable_anon_vma(near, vma, near); 1204 if (anon_vma) 1205 return anon_vma; 1206 try_prev: 1207 near = vma->vm_prev; 1208 if (!near) 1209 goto none; 1210 1211 anon_vma = reusable_anon_vma(near, near, vma); 1212 if (anon_vma) 1213 return anon_vma; 1214 none: 1215 /* 1216 * There's no absolute need to look only at touching neighbours: 1217 * we could search further afield for "compatible" anon_vmas. 1218 * But it would probably just be a waste of time searching, 1219 * or lead to too many vmas hanging off the same anon_vma. 1220 * We're trying to allow mprotect remerging later on, 1221 * not trying to minimize memory used for anon_vmas. 1222 */ 1223 return NULL; 1224 } 1225 1226 /* 1227 * If a hint addr is less than mmap_min_addr change hint to be as 1228 * low as possible but still greater than mmap_min_addr 1229 */ 1230 static inline unsigned long round_hint_to_min(unsigned long hint) 1231 { 1232 hint &= PAGE_MASK; 1233 if (((void *)hint != NULL) && 1234 (hint < mmap_min_addr)) 1235 return PAGE_ALIGN(mmap_min_addr); 1236 return hint; 1237 } 1238 1239 static inline int mlock_future_check(struct mm_struct *mm, 1240 unsigned long flags, 1241 unsigned long len) 1242 { 1243 unsigned long locked, lock_limit; 1244 1245 /* mlock MCL_FUTURE? */ 1246 if (flags & VM_LOCKED) { 1247 locked = len >> PAGE_SHIFT; 1248 locked += mm->locked_vm; 1249 lock_limit = rlimit(RLIMIT_MEMLOCK); 1250 lock_limit >>= PAGE_SHIFT; 1251 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1252 return -EAGAIN; 1253 } 1254 return 0; 1255 } 1256 1257 /* 1258 * The caller must hold down_write(¤t->mm->mmap_sem). 1259 */ 1260 unsigned long do_mmap(struct file *file, unsigned long addr, 1261 unsigned long len, unsigned long prot, 1262 unsigned long flags, vm_flags_t vm_flags, 1263 unsigned long pgoff, unsigned long *populate) 1264 { 1265 struct mm_struct *mm = current->mm; 1266 1267 *populate = 0; 1268 1269 if (!len) 1270 return -EINVAL; 1271 1272 /* 1273 * Does the application expect PROT_READ to imply PROT_EXEC? 1274 * 1275 * (the exception is when the underlying filesystem is noexec 1276 * mounted, in which case we dont add PROT_EXEC.) 1277 */ 1278 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 1279 if (!(file && path_noexec(&file->f_path))) 1280 prot |= PROT_EXEC; 1281 1282 if (!(flags & MAP_FIXED)) 1283 addr = round_hint_to_min(addr); 1284 1285 /* Careful about overflows.. */ 1286 len = PAGE_ALIGN(len); 1287 if (!len) 1288 return -ENOMEM; 1289 1290 /* offset overflow? */ 1291 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 1292 return -EOVERFLOW; 1293 1294 /* Too many mappings? */ 1295 if (mm->map_count > sysctl_max_map_count) 1296 return -ENOMEM; 1297 1298 /* Obtain the address to map to. we verify (or select) it and ensure 1299 * that it represents a valid section of the address space. 1300 */ 1301 addr = get_unmapped_area(file, addr, len, pgoff, flags); 1302 if (offset_in_page(addr)) 1303 return addr; 1304 1305 /* Do simple checking here so the lower-level routines won't have 1306 * to. we assume access permissions have been handled by the open 1307 * of the memory object, so we don't do any here. 1308 */ 1309 vm_flags |= calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 1310 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 1311 1312 if (flags & MAP_LOCKED) 1313 if (!can_do_mlock()) 1314 return -EPERM; 1315 1316 if (mlock_future_check(mm, vm_flags, len)) 1317 return -EAGAIN; 1318 1319 if (file) { 1320 struct inode *inode = file_inode(file); 1321 1322 switch (flags & MAP_TYPE) { 1323 case MAP_SHARED: 1324 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 1325 return -EACCES; 1326 1327 /* 1328 * Make sure we don't allow writing to an append-only 1329 * file.. 1330 */ 1331 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 1332 return -EACCES; 1333 1334 /* 1335 * Make sure there are no mandatory locks on the file. 1336 */ 1337 if (locks_verify_locked(file)) 1338 return -EAGAIN; 1339 1340 vm_flags |= VM_SHARED | VM_MAYSHARE; 1341 if (!(file->f_mode & FMODE_WRITE)) 1342 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 1343 1344 /* fall through */ 1345 case MAP_PRIVATE: 1346 if (!(file->f_mode & FMODE_READ)) 1347 return -EACCES; 1348 if (path_noexec(&file->f_path)) { 1349 if (vm_flags & VM_EXEC) 1350 return -EPERM; 1351 vm_flags &= ~VM_MAYEXEC; 1352 } 1353 1354 if (!file->f_op->mmap) 1355 return -ENODEV; 1356 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1357 return -EINVAL; 1358 break; 1359 1360 default: 1361 return -EINVAL; 1362 } 1363 } else { 1364 switch (flags & MAP_TYPE) { 1365 case MAP_SHARED: 1366 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1367 return -EINVAL; 1368 /* 1369 * Ignore pgoff. 1370 */ 1371 pgoff = 0; 1372 vm_flags |= VM_SHARED | VM_MAYSHARE; 1373 break; 1374 case MAP_PRIVATE: 1375 /* 1376 * Set pgoff according to addr for anon_vma. 1377 */ 1378 pgoff = addr >> PAGE_SHIFT; 1379 break; 1380 default: 1381 return -EINVAL; 1382 } 1383 } 1384 1385 /* 1386 * Set 'VM_NORESERVE' if we should not account for the 1387 * memory use of this mapping. 1388 */ 1389 if (flags & MAP_NORESERVE) { 1390 /* We honor MAP_NORESERVE if allowed to overcommit */ 1391 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) 1392 vm_flags |= VM_NORESERVE; 1393 1394 /* hugetlb applies strict overcommit unless MAP_NORESERVE */ 1395 if (file && is_file_hugepages(file)) 1396 vm_flags |= VM_NORESERVE; 1397 } 1398 1399 addr = mmap_region(file, addr, len, vm_flags, pgoff); 1400 if (!IS_ERR_VALUE(addr) && 1401 ((vm_flags & VM_LOCKED) || 1402 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) 1403 *populate = len; 1404 return addr; 1405 } 1406 1407 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, 1408 unsigned long, prot, unsigned long, flags, 1409 unsigned long, fd, unsigned long, pgoff) 1410 { 1411 struct file *file = NULL; 1412 unsigned long retval; 1413 1414 if (!(flags & MAP_ANONYMOUS)) { 1415 audit_mmap_fd(fd, flags); 1416 file = fget(fd); 1417 if (!file) 1418 return -EBADF; 1419 if (is_file_hugepages(file)) 1420 len = ALIGN(len, huge_page_size(hstate_file(file))); 1421 retval = -EINVAL; 1422 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file))) 1423 goto out_fput; 1424 } else if (flags & MAP_HUGETLB) { 1425 struct user_struct *user = NULL; 1426 struct hstate *hs; 1427 1428 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK); 1429 if (!hs) 1430 return -EINVAL; 1431 1432 len = ALIGN(len, huge_page_size(hs)); 1433 /* 1434 * VM_NORESERVE is used because the reservations will be 1435 * taken when vm_ops->mmap() is called 1436 * A dummy user value is used because we are not locking 1437 * memory so no accounting is necessary 1438 */ 1439 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, 1440 VM_NORESERVE, 1441 &user, HUGETLB_ANONHUGE_INODE, 1442 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); 1443 if (IS_ERR(file)) 1444 return PTR_ERR(file); 1445 } 1446 1447 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); 1448 1449 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); 1450 out_fput: 1451 if (file) 1452 fput(file); 1453 return retval; 1454 } 1455 1456 #ifdef __ARCH_WANT_SYS_OLD_MMAP 1457 struct mmap_arg_struct { 1458 unsigned long addr; 1459 unsigned long len; 1460 unsigned long prot; 1461 unsigned long flags; 1462 unsigned long fd; 1463 unsigned long offset; 1464 }; 1465 1466 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) 1467 { 1468 struct mmap_arg_struct a; 1469 1470 if (copy_from_user(&a, arg, sizeof(a))) 1471 return -EFAULT; 1472 if (offset_in_page(a.offset)) 1473 return -EINVAL; 1474 1475 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, 1476 a.offset >> PAGE_SHIFT); 1477 } 1478 #endif /* __ARCH_WANT_SYS_OLD_MMAP */ 1479 1480 /* 1481 * Some shared mappigns will want the pages marked read-only 1482 * to track write events. If so, we'll downgrade vm_page_prot 1483 * to the private version (using protection_map[] without the 1484 * VM_SHARED bit). 1485 */ 1486 int vma_wants_writenotify(struct vm_area_struct *vma) 1487 { 1488 vm_flags_t vm_flags = vma->vm_flags; 1489 const struct vm_operations_struct *vm_ops = vma->vm_ops; 1490 1491 /* If it was private or non-writable, the write bit is already clear */ 1492 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) 1493 return 0; 1494 1495 /* The backer wishes to know when pages are first written to? */ 1496 if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite)) 1497 return 1; 1498 1499 /* The open routine did something to the protections that pgprot_modify 1500 * won't preserve? */ 1501 if (pgprot_val(vma->vm_page_prot) != 1502 pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags))) 1503 return 0; 1504 1505 /* Do we need to track softdirty? */ 1506 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY)) 1507 return 1; 1508 1509 /* Specialty mapping? */ 1510 if (vm_flags & VM_PFNMAP) 1511 return 0; 1512 1513 /* Can the mapping track the dirty pages? */ 1514 return vma->vm_file && vma->vm_file->f_mapping && 1515 mapping_cap_account_dirty(vma->vm_file->f_mapping); 1516 } 1517 1518 /* 1519 * We account for memory if it's a private writeable mapping, 1520 * not hugepages and VM_NORESERVE wasn't set. 1521 */ 1522 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) 1523 { 1524 /* 1525 * hugetlb has its own accounting separate from the core VM 1526 * VM_HUGETLB may not be set yet so we cannot check for that flag. 1527 */ 1528 if (file && is_file_hugepages(file)) 1529 return 0; 1530 1531 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; 1532 } 1533 1534 unsigned long mmap_region(struct file *file, unsigned long addr, 1535 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff) 1536 { 1537 struct mm_struct *mm = current->mm; 1538 struct vm_area_struct *vma, *prev; 1539 int error; 1540 struct rb_node **rb_link, *rb_parent; 1541 unsigned long charged = 0; 1542 1543 /* Check against address space limit. */ 1544 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) { 1545 unsigned long nr_pages; 1546 1547 /* 1548 * MAP_FIXED may remove pages of mappings that intersects with 1549 * requested mapping. Account for the pages it would unmap. 1550 */ 1551 nr_pages = count_vma_pages_range(mm, addr, addr + len); 1552 1553 if (!may_expand_vm(mm, vm_flags, 1554 (len >> PAGE_SHIFT) - nr_pages)) 1555 return -ENOMEM; 1556 } 1557 1558 /* Clear old maps */ 1559 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, 1560 &rb_parent)) { 1561 if (do_munmap(mm, addr, len)) 1562 return -ENOMEM; 1563 } 1564 1565 /* 1566 * Private writable mapping: check memory availability 1567 */ 1568 if (accountable_mapping(file, vm_flags)) { 1569 charged = len >> PAGE_SHIFT; 1570 if (security_vm_enough_memory_mm(mm, charged)) 1571 return -ENOMEM; 1572 vm_flags |= VM_ACCOUNT; 1573 } 1574 1575 /* 1576 * Can we just expand an old mapping? 1577 */ 1578 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, 1579 NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX); 1580 if (vma) 1581 goto out; 1582 1583 /* 1584 * Determine the object being mapped and call the appropriate 1585 * specific mapper. the address has already been validated, but 1586 * not unmapped, but the maps are removed from the list. 1587 */ 1588 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1589 if (!vma) { 1590 error = -ENOMEM; 1591 goto unacct_error; 1592 } 1593 1594 vma->vm_mm = mm; 1595 vma->vm_start = addr; 1596 vma->vm_end = addr + len; 1597 vma->vm_flags = vm_flags; 1598 vma->vm_page_prot = vm_get_page_prot(vm_flags); 1599 vma->vm_pgoff = pgoff; 1600 INIT_LIST_HEAD(&vma->anon_vma_chain); 1601 1602 if (file) { 1603 if (vm_flags & VM_DENYWRITE) { 1604 error = deny_write_access(file); 1605 if (error) 1606 goto free_vma; 1607 } 1608 if (vm_flags & VM_SHARED) { 1609 error = mapping_map_writable(file->f_mapping); 1610 if (error) 1611 goto allow_write_and_free_vma; 1612 } 1613 1614 /* ->mmap() can change vma->vm_file, but must guarantee that 1615 * vma_link() below can deny write-access if VM_DENYWRITE is set 1616 * and map writably if VM_SHARED is set. This usually means the 1617 * new file must not have been exposed to user-space, yet. 1618 */ 1619 vma->vm_file = get_file(file); 1620 error = file->f_op->mmap(file, vma); 1621 if (error) 1622 goto unmap_and_free_vma; 1623 1624 /* Can addr have changed?? 1625 * 1626 * Answer: Yes, several device drivers can do it in their 1627 * f_op->mmap method. -DaveM 1628 * Bug: If addr is changed, prev, rb_link, rb_parent should 1629 * be updated for vma_link() 1630 */ 1631 WARN_ON_ONCE(addr != vma->vm_start); 1632 1633 addr = vma->vm_start; 1634 vm_flags = vma->vm_flags; 1635 } else if (vm_flags & VM_SHARED) { 1636 error = shmem_zero_setup(vma); 1637 if (error) 1638 goto free_vma; 1639 } 1640 1641 vma_link(mm, vma, prev, rb_link, rb_parent); 1642 /* Once vma denies write, undo our temporary denial count */ 1643 if (file) { 1644 if (vm_flags & VM_SHARED) 1645 mapping_unmap_writable(file->f_mapping); 1646 if (vm_flags & VM_DENYWRITE) 1647 allow_write_access(file); 1648 } 1649 file = vma->vm_file; 1650 out: 1651 perf_event_mmap(vma); 1652 1653 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT); 1654 if (vm_flags & VM_LOCKED) { 1655 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) || 1656 vma == get_gate_vma(current->mm))) 1657 mm->locked_vm += (len >> PAGE_SHIFT); 1658 else 1659 vma->vm_flags &= VM_LOCKED_CLEAR_MASK; 1660 } 1661 1662 if (file) 1663 uprobe_mmap(vma); 1664 1665 /* 1666 * New (or expanded) vma always get soft dirty status. 1667 * Otherwise user-space soft-dirty page tracker won't 1668 * be able to distinguish situation when vma area unmapped, 1669 * then new mapped in-place (which must be aimed as 1670 * a completely new data area). 1671 */ 1672 vma->vm_flags |= VM_SOFTDIRTY; 1673 1674 vma_set_page_prot(vma); 1675 1676 return addr; 1677 1678 unmap_and_free_vma: 1679 vma->vm_file = NULL; 1680 fput(file); 1681 1682 /* Undo any partial mapping done by a device driver. */ 1683 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1684 charged = 0; 1685 if (vm_flags & VM_SHARED) 1686 mapping_unmap_writable(file->f_mapping); 1687 allow_write_and_free_vma: 1688 if (vm_flags & VM_DENYWRITE) 1689 allow_write_access(file); 1690 free_vma: 1691 kmem_cache_free(vm_area_cachep, vma); 1692 unacct_error: 1693 if (charged) 1694 vm_unacct_memory(charged); 1695 return error; 1696 } 1697 1698 unsigned long unmapped_area(struct vm_unmapped_area_info *info) 1699 { 1700 /* 1701 * We implement the search by looking for an rbtree node that 1702 * immediately follows a suitable gap. That is, 1703 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length; 1704 * - gap_end = vma->vm_start >= info->low_limit + length; 1705 * - gap_end - gap_start >= length 1706 */ 1707 1708 struct mm_struct *mm = current->mm; 1709 struct vm_area_struct *vma; 1710 unsigned long length, low_limit, high_limit, gap_start, gap_end; 1711 1712 /* Adjust search length to account for worst case alignment overhead */ 1713 length = info->length + info->align_mask; 1714 if (length < info->length) 1715 return -ENOMEM; 1716 1717 /* Adjust search limits by the desired length */ 1718 if (info->high_limit < length) 1719 return -ENOMEM; 1720 high_limit = info->high_limit - length; 1721 1722 if (info->low_limit > high_limit) 1723 return -ENOMEM; 1724 low_limit = info->low_limit + length; 1725 1726 /* Check if rbtree root looks promising */ 1727 if (RB_EMPTY_ROOT(&mm->mm_rb)) 1728 goto check_highest; 1729 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); 1730 if (vma->rb_subtree_gap < length) 1731 goto check_highest; 1732 1733 while (true) { 1734 /* Visit left subtree if it looks promising */ 1735 gap_end = vma->vm_start; 1736 if (gap_end >= low_limit && vma->vm_rb.rb_left) { 1737 struct vm_area_struct *left = 1738 rb_entry(vma->vm_rb.rb_left, 1739 struct vm_area_struct, vm_rb); 1740 if (left->rb_subtree_gap >= length) { 1741 vma = left; 1742 continue; 1743 } 1744 } 1745 1746 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; 1747 check_current: 1748 /* Check if current node has a suitable gap */ 1749 if (gap_start > high_limit) 1750 return -ENOMEM; 1751 if (gap_end >= low_limit && gap_end - gap_start >= length) 1752 goto found; 1753 1754 /* Visit right subtree if it looks promising */ 1755 if (vma->vm_rb.rb_right) { 1756 struct vm_area_struct *right = 1757 rb_entry(vma->vm_rb.rb_right, 1758 struct vm_area_struct, vm_rb); 1759 if (right->rb_subtree_gap >= length) { 1760 vma = right; 1761 continue; 1762 } 1763 } 1764 1765 /* Go back up the rbtree to find next candidate node */ 1766 while (true) { 1767 struct rb_node *prev = &vma->vm_rb; 1768 if (!rb_parent(prev)) 1769 goto check_highest; 1770 vma = rb_entry(rb_parent(prev), 1771 struct vm_area_struct, vm_rb); 1772 if (prev == vma->vm_rb.rb_left) { 1773 gap_start = vma->vm_prev->vm_end; 1774 gap_end = vma->vm_start; 1775 goto check_current; 1776 } 1777 } 1778 } 1779 1780 check_highest: 1781 /* Check highest gap, which does not precede any rbtree node */ 1782 gap_start = mm->highest_vm_end; 1783 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */ 1784 if (gap_start > high_limit) 1785 return -ENOMEM; 1786 1787 found: 1788 /* We found a suitable gap. Clip it with the original low_limit. */ 1789 if (gap_start < info->low_limit) 1790 gap_start = info->low_limit; 1791 1792 /* Adjust gap address to the desired alignment */ 1793 gap_start += (info->align_offset - gap_start) & info->align_mask; 1794 1795 VM_BUG_ON(gap_start + info->length > info->high_limit); 1796 VM_BUG_ON(gap_start + info->length > gap_end); 1797 return gap_start; 1798 } 1799 1800 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) 1801 { 1802 struct mm_struct *mm = current->mm; 1803 struct vm_area_struct *vma; 1804 unsigned long length, low_limit, high_limit, gap_start, gap_end; 1805 1806 /* Adjust search length to account for worst case alignment overhead */ 1807 length = info->length + info->align_mask; 1808 if (length < info->length) 1809 return -ENOMEM; 1810 1811 /* 1812 * Adjust search limits by the desired length. 1813 * See implementation comment at top of unmapped_area(). 1814 */ 1815 gap_end = info->high_limit; 1816 if (gap_end < length) 1817 return -ENOMEM; 1818 high_limit = gap_end - length; 1819 1820 if (info->low_limit > high_limit) 1821 return -ENOMEM; 1822 low_limit = info->low_limit + length; 1823 1824 /* Check highest gap, which does not precede any rbtree node */ 1825 gap_start = mm->highest_vm_end; 1826 if (gap_start <= high_limit) 1827 goto found_highest; 1828 1829 /* Check if rbtree root looks promising */ 1830 if (RB_EMPTY_ROOT(&mm->mm_rb)) 1831 return -ENOMEM; 1832 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); 1833 if (vma->rb_subtree_gap < length) 1834 return -ENOMEM; 1835 1836 while (true) { 1837 /* Visit right subtree if it looks promising */ 1838 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; 1839 if (gap_start <= high_limit && vma->vm_rb.rb_right) { 1840 struct vm_area_struct *right = 1841 rb_entry(vma->vm_rb.rb_right, 1842 struct vm_area_struct, vm_rb); 1843 if (right->rb_subtree_gap >= length) { 1844 vma = right; 1845 continue; 1846 } 1847 } 1848 1849 check_current: 1850 /* Check if current node has a suitable gap */ 1851 gap_end = vma->vm_start; 1852 if (gap_end < low_limit) 1853 return -ENOMEM; 1854 if (gap_start <= high_limit && gap_end - gap_start >= length) 1855 goto found; 1856 1857 /* Visit left subtree if it looks promising */ 1858 if (vma->vm_rb.rb_left) { 1859 struct vm_area_struct *left = 1860 rb_entry(vma->vm_rb.rb_left, 1861 struct vm_area_struct, vm_rb); 1862 if (left->rb_subtree_gap >= length) { 1863 vma = left; 1864 continue; 1865 } 1866 } 1867 1868 /* Go back up the rbtree to find next candidate node */ 1869 while (true) { 1870 struct rb_node *prev = &vma->vm_rb; 1871 if (!rb_parent(prev)) 1872 return -ENOMEM; 1873 vma = rb_entry(rb_parent(prev), 1874 struct vm_area_struct, vm_rb); 1875 if (prev == vma->vm_rb.rb_right) { 1876 gap_start = vma->vm_prev ? 1877 vma->vm_prev->vm_end : 0; 1878 goto check_current; 1879 } 1880 } 1881 } 1882 1883 found: 1884 /* We found a suitable gap. Clip it with the original high_limit. */ 1885 if (gap_end > info->high_limit) 1886 gap_end = info->high_limit; 1887 1888 found_highest: 1889 /* Compute highest gap address at the desired alignment */ 1890 gap_end -= info->length; 1891 gap_end -= (gap_end - info->align_offset) & info->align_mask; 1892 1893 VM_BUG_ON(gap_end < info->low_limit); 1894 VM_BUG_ON(gap_end < gap_start); 1895 return gap_end; 1896 } 1897 1898 /* Get an address range which is currently unmapped. 1899 * For shmat() with addr=0. 1900 * 1901 * Ugly calling convention alert: 1902 * Return value with the low bits set means error value, 1903 * ie 1904 * if (ret & ~PAGE_MASK) 1905 * error = ret; 1906 * 1907 * This function "knows" that -ENOMEM has the bits set. 1908 */ 1909 #ifndef HAVE_ARCH_UNMAPPED_AREA 1910 unsigned long 1911 arch_get_unmapped_area(struct file *filp, unsigned long addr, 1912 unsigned long len, unsigned long pgoff, unsigned long flags) 1913 { 1914 struct mm_struct *mm = current->mm; 1915 struct vm_area_struct *vma; 1916 struct vm_unmapped_area_info info; 1917 1918 if (len > TASK_SIZE - mmap_min_addr) 1919 return -ENOMEM; 1920 1921 if (flags & MAP_FIXED) 1922 return addr; 1923 1924 if (addr) { 1925 addr = PAGE_ALIGN(addr); 1926 vma = find_vma(mm, addr); 1927 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && 1928 (!vma || addr + len <= vma->vm_start)) 1929 return addr; 1930 } 1931 1932 info.flags = 0; 1933 info.length = len; 1934 info.low_limit = mm->mmap_base; 1935 info.high_limit = TASK_SIZE; 1936 info.align_mask = 0; 1937 return vm_unmapped_area(&info); 1938 } 1939 #endif 1940 1941 /* 1942 * This mmap-allocator allocates new areas top-down from below the 1943 * stack's low limit (the base): 1944 */ 1945 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1946 unsigned long 1947 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1948 const unsigned long len, const unsigned long pgoff, 1949 const unsigned long flags) 1950 { 1951 struct vm_area_struct *vma; 1952 struct mm_struct *mm = current->mm; 1953 unsigned long addr = addr0; 1954 struct vm_unmapped_area_info info; 1955 1956 /* requested length too big for entire address space */ 1957 if (len > TASK_SIZE - mmap_min_addr) 1958 return -ENOMEM; 1959 1960 if (flags & MAP_FIXED) 1961 return addr; 1962 1963 /* requesting a specific address */ 1964 if (addr) { 1965 addr = PAGE_ALIGN(addr); 1966 vma = find_vma(mm, addr); 1967 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr && 1968 (!vma || addr + len <= vma->vm_start)) 1969 return addr; 1970 } 1971 1972 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 1973 info.length = len; 1974 info.low_limit = max(PAGE_SIZE, mmap_min_addr); 1975 info.high_limit = mm->mmap_base; 1976 info.align_mask = 0; 1977 addr = vm_unmapped_area(&info); 1978 1979 /* 1980 * A failed mmap() very likely causes application failure, 1981 * so fall back to the bottom-up function here. This scenario 1982 * can happen with large stack limits and large mmap() 1983 * allocations. 1984 */ 1985 if (offset_in_page(addr)) { 1986 VM_BUG_ON(addr != -ENOMEM); 1987 info.flags = 0; 1988 info.low_limit = TASK_UNMAPPED_BASE; 1989 info.high_limit = TASK_SIZE; 1990 addr = vm_unmapped_area(&info); 1991 } 1992 1993 return addr; 1994 } 1995 #endif 1996 1997 unsigned long 1998 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1999 unsigned long pgoff, unsigned long flags) 2000 { 2001 unsigned long (*get_area)(struct file *, unsigned long, 2002 unsigned long, unsigned long, unsigned long); 2003 2004 unsigned long error = arch_mmap_check(addr, len, flags); 2005 if (error) 2006 return error; 2007 2008 /* Careful about overflows.. */ 2009 if (len > TASK_SIZE) 2010 return -ENOMEM; 2011 2012 get_area = current->mm->get_unmapped_area; 2013 if (file && file->f_op->get_unmapped_area) 2014 get_area = file->f_op->get_unmapped_area; 2015 addr = get_area(file, addr, len, pgoff, flags); 2016 if (IS_ERR_VALUE(addr)) 2017 return addr; 2018 2019 if (addr > TASK_SIZE - len) 2020 return -ENOMEM; 2021 if (offset_in_page(addr)) 2022 return -EINVAL; 2023 2024 addr = arch_rebalance_pgtables(addr, len); 2025 error = security_mmap_addr(addr); 2026 return error ? error : addr; 2027 } 2028 2029 EXPORT_SYMBOL(get_unmapped_area); 2030 2031 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 2032 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 2033 { 2034 struct rb_node *rb_node; 2035 struct vm_area_struct *vma; 2036 2037 /* Check the cache first. */ 2038 vma = vmacache_find(mm, addr); 2039 if (likely(vma)) 2040 return vma; 2041 2042 rb_node = mm->mm_rb.rb_node; 2043 2044 while (rb_node) { 2045 struct vm_area_struct *tmp; 2046 2047 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 2048 2049 if (tmp->vm_end > addr) { 2050 vma = tmp; 2051 if (tmp->vm_start <= addr) 2052 break; 2053 rb_node = rb_node->rb_left; 2054 } else 2055 rb_node = rb_node->rb_right; 2056 } 2057 2058 if (vma) 2059 vmacache_update(addr, vma); 2060 return vma; 2061 } 2062 2063 EXPORT_SYMBOL(find_vma); 2064 2065 /* 2066 * Same as find_vma, but also return a pointer to the previous VMA in *pprev. 2067 */ 2068 struct vm_area_struct * 2069 find_vma_prev(struct mm_struct *mm, unsigned long addr, 2070 struct vm_area_struct **pprev) 2071 { 2072 struct vm_area_struct *vma; 2073 2074 vma = find_vma(mm, addr); 2075 if (vma) { 2076 *pprev = vma->vm_prev; 2077 } else { 2078 struct rb_node *rb_node = mm->mm_rb.rb_node; 2079 *pprev = NULL; 2080 while (rb_node) { 2081 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb); 2082 rb_node = rb_node->rb_right; 2083 } 2084 } 2085 return vma; 2086 } 2087 2088 /* 2089 * Verify that the stack growth is acceptable and 2090 * update accounting. This is shared with both the 2091 * grow-up and grow-down cases. 2092 */ 2093 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow) 2094 { 2095 struct mm_struct *mm = vma->vm_mm; 2096 struct rlimit *rlim = current->signal->rlim; 2097 unsigned long new_start, actual_size; 2098 2099 /* address space limit tests */ 2100 if (!may_expand_vm(mm, vma->vm_flags, grow)) 2101 return -ENOMEM; 2102 2103 /* Stack limit test */ 2104 actual_size = size; 2105 if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN))) 2106 actual_size -= PAGE_SIZE; 2107 if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur)) 2108 return -ENOMEM; 2109 2110 /* mlock limit tests */ 2111 if (vma->vm_flags & VM_LOCKED) { 2112 unsigned long locked; 2113 unsigned long limit; 2114 locked = mm->locked_vm + grow; 2115 limit = READ_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur); 2116 limit >>= PAGE_SHIFT; 2117 if (locked > limit && !capable(CAP_IPC_LOCK)) 2118 return -ENOMEM; 2119 } 2120 2121 /* Check to ensure the stack will not grow into a hugetlb-only region */ 2122 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 2123 vma->vm_end - size; 2124 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 2125 return -EFAULT; 2126 2127 /* 2128 * Overcommit.. This must be the final test, as it will 2129 * update security statistics. 2130 */ 2131 if (security_vm_enough_memory_mm(mm, grow)) 2132 return -ENOMEM; 2133 2134 return 0; 2135 } 2136 2137 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 2138 /* 2139 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 2140 * vma is the last one with address > vma->vm_end. Have to extend vma. 2141 */ 2142 int expand_upwards(struct vm_area_struct *vma, unsigned long address) 2143 { 2144 struct mm_struct *mm = vma->vm_mm; 2145 int error; 2146 2147 if (!(vma->vm_flags & VM_GROWSUP)) 2148 return -EFAULT; 2149 2150 /* 2151 * We must make sure the anon_vma is allocated 2152 * so that the anon_vma locking is not a noop. 2153 */ 2154 if (unlikely(anon_vma_prepare(vma))) 2155 return -ENOMEM; 2156 vma_lock_anon_vma(vma); 2157 2158 /* 2159 * vma->vm_start/vm_end cannot change under us because the caller 2160 * is required to hold the mmap_sem in read mode. We need the 2161 * anon_vma lock to serialize against concurrent expand_stacks. 2162 * Also guard against wrapping around to address 0. 2163 */ 2164 if (address < PAGE_ALIGN(address+4)) 2165 address = PAGE_ALIGN(address+4); 2166 else { 2167 vma_unlock_anon_vma(vma); 2168 return -ENOMEM; 2169 } 2170 error = 0; 2171 2172 /* Somebody else might have raced and expanded it already */ 2173 if (address > vma->vm_end) { 2174 unsigned long size, grow; 2175 2176 size = address - vma->vm_start; 2177 grow = (address - vma->vm_end) >> PAGE_SHIFT; 2178 2179 error = -ENOMEM; 2180 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { 2181 error = acct_stack_growth(vma, size, grow); 2182 if (!error) { 2183 /* 2184 * vma_gap_update() doesn't support concurrent 2185 * updates, but we only hold a shared mmap_sem 2186 * lock here, so we need to protect against 2187 * concurrent vma expansions. 2188 * vma_lock_anon_vma() doesn't help here, as 2189 * we don't guarantee that all growable vmas 2190 * in a mm share the same root anon vma. 2191 * So, we reuse mm->page_table_lock to guard 2192 * against concurrent vma expansions. 2193 */ 2194 spin_lock(&mm->page_table_lock); 2195 if (vma->vm_flags & VM_LOCKED) 2196 mm->locked_vm += grow; 2197 vm_stat_account(mm, vma->vm_flags, grow); 2198 anon_vma_interval_tree_pre_update_vma(vma); 2199 vma->vm_end = address; 2200 anon_vma_interval_tree_post_update_vma(vma); 2201 if (vma->vm_next) 2202 vma_gap_update(vma->vm_next); 2203 else 2204 mm->highest_vm_end = address; 2205 spin_unlock(&mm->page_table_lock); 2206 2207 perf_event_mmap(vma); 2208 } 2209 } 2210 } 2211 vma_unlock_anon_vma(vma); 2212 khugepaged_enter_vma_merge(vma, vma->vm_flags); 2213 validate_mm(mm); 2214 return error; 2215 } 2216 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 2217 2218 /* 2219 * vma is the first one with address < vma->vm_start. Have to extend vma. 2220 */ 2221 int expand_downwards(struct vm_area_struct *vma, 2222 unsigned long address) 2223 { 2224 struct mm_struct *mm = vma->vm_mm; 2225 int error; 2226 2227 /* 2228 * We must make sure the anon_vma is allocated 2229 * so that the anon_vma locking is not a noop. 2230 */ 2231 if (unlikely(anon_vma_prepare(vma))) 2232 return -ENOMEM; 2233 2234 address &= PAGE_MASK; 2235 error = security_mmap_addr(address); 2236 if (error) 2237 return error; 2238 2239 vma_lock_anon_vma(vma); 2240 2241 /* 2242 * vma->vm_start/vm_end cannot change under us because the caller 2243 * is required to hold the mmap_sem in read mode. We need the 2244 * anon_vma lock to serialize against concurrent expand_stacks. 2245 */ 2246 2247 /* Somebody else might have raced and expanded it already */ 2248 if (address < vma->vm_start) { 2249 unsigned long size, grow; 2250 2251 size = vma->vm_end - address; 2252 grow = (vma->vm_start - address) >> PAGE_SHIFT; 2253 2254 error = -ENOMEM; 2255 if (grow <= vma->vm_pgoff) { 2256 error = acct_stack_growth(vma, size, grow); 2257 if (!error) { 2258 /* 2259 * vma_gap_update() doesn't support concurrent 2260 * updates, but we only hold a shared mmap_sem 2261 * lock here, so we need to protect against 2262 * concurrent vma expansions. 2263 * vma_lock_anon_vma() doesn't help here, as 2264 * we don't guarantee that all growable vmas 2265 * in a mm share the same root anon vma. 2266 * So, we reuse mm->page_table_lock to guard 2267 * against concurrent vma expansions. 2268 */ 2269 spin_lock(&mm->page_table_lock); 2270 if (vma->vm_flags & VM_LOCKED) 2271 mm->locked_vm += grow; 2272 vm_stat_account(mm, vma->vm_flags, grow); 2273 anon_vma_interval_tree_pre_update_vma(vma); 2274 vma->vm_start = address; 2275 vma->vm_pgoff -= grow; 2276 anon_vma_interval_tree_post_update_vma(vma); 2277 vma_gap_update(vma); 2278 spin_unlock(&mm->page_table_lock); 2279 2280 perf_event_mmap(vma); 2281 } 2282 } 2283 } 2284 vma_unlock_anon_vma(vma); 2285 khugepaged_enter_vma_merge(vma, vma->vm_flags); 2286 validate_mm(mm); 2287 return error; 2288 } 2289 2290 /* 2291 * Note how expand_stack() refuses to expand the stack all the way to 2292 * abut the next virtual mapping, *unless* that mapping itself is also 2293 * a stack mapping. We want to leave room for a guard page, after all 2294 * (the guard page itself is not added here, that is done by the 2295 * actual page faulting logic) 2296 * 2297 * This matches the behavior of the guard page logic (see mm/memory.c: 2298 * check_stack_guard_page()), which only allows the guard page to be 2299 * removed under these circumstances. 2300 */ 2301 #ifdef CONFIG_STACK_GROWSUP 2302 int expand_stack(struct vm_area_struct *vma, unsigned long address) 2303 { 2304 struct vm_area_struct *next; 2305 2306 address &= PAGE_MASK; 2307 next = vma->vm_next; 2308 if (next && next->vm_start == address + PAGE_SIZE) { 2309 if (!(next->vm_flags & VM_GROWSUP)) 2310 return -ENOMEM; 2311 } 2312 return expand_upwards(vma, address); 2313 } 2314 2315 struct vm_area_struct * 2316 find_extend_vma(struct mm_struct *mm, unsigned long addr) 2317 { 2318 struct vm_area_struct *vma, *prev; 2319 2320 addr &= PAGE_MASK; 2321 vma = find_vma_prev(mm, addr, &prev); 2322 if (vma && (vma->vm_start <= addr)) 2323 return vma; 2324 if (!prev || expand_stack(prev, addr)) 2325 return NULL; 2326 if (prev->vm_flags & VM_LOCKED) 2327 populate_vma_page_range(prev, addr, prev->vm_end, NULL); 2328 return prev; 2329 } 2330 #else 2331 int expand_stack(struct vm_area_struct *vma, unsigned long address) 2332 { 2333 struct vm_area_struct *prev; 2334 2335 address &= PAGE_MASK; 2336 prev = vma->vm_prev; 2337 if (prev && prev->vm_end == address) { 2338 if (!(prev->vm_flags & VM_GROWSDOWN)) 2339 return -ENOMEM; 2340 } 2341 return expand_downwards(vma, address); 2342 } 2343 2344 struct vm_area_struct * 2345 find_extend_vma(struct mm_struct *mm, unsigned long addr) 2346 { 2347 struct vm_area_struct *vma; 2348 unsigned long start; 2349 2350 addr &= PAGE_MASK; 2351 vma = find_vma(mm, addr); 2352 if (!vma) 2353 return NULL; 2354 if (vma->vm_start <= addr) 2355 return vma; 2356 if (!(vma->vm_flags & VM_GROWSDOWN)) 2357 return NULL; 2358 start = vma->vm_start; 2359 if (expand_stack(vma, addr)) 2360 return NULL; 2361 if (vma->vm_flags & VM_LOCKED) 2362 populate_vma_page_range(vma, addr, start, NULL); 2363 return vma; 2364 } 2365 #endif 2366 2367 EXPORT_SYMBOL_GPL(find_extend_vma); 2368 2369 /* 2370 * Ok - we have the memory areas we should free on the vma list, 2371 * so release them, and do the vma updates. 2372 * 2373 * Called with the mm semaphore held. 2374 */ 2375 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 2376 { 2377 unsigned long nr_accounted = 0; 2378 2379 /* Update high watermark before we lower total_vm */ 2380 update_hiwater_vm(mm); 2381 do { 2382 long nrpages = vma_pages(vma); 2383 2384 if (vma->vm_flags & VM_ACCOUNT) 2385 nr_accounted += nrpages; 2386 vm_stat_account(mm, vma->vm_flags, -nrpages); 2387 vma = remove_vma(vma); 2388 } while (vma); 2389 vm_unacct_memory(nr_accounted); 2390 validate_mm(mm); 2391 } 2392 2393 /* 2394 * Get rid of page table information in the indicated region. 2395 * 2396 * Called with the mm semaphore held. 2397 */ 2398 static void unmap_region(struct mm_struct *mm, 2399 struct vm_area_struct *vma, struct vm_area_struct *prev, 2400 unsigned long start, unsigned long end) 2401 { 2402 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap; 2403 struct mmu_gather tlb; 2404 2405 lru_add_drain(); 2406 tlb_gather_mmu(&tlb, mm, start, end); 2407 update_hiwater_rss(mm); 2408 unmap_vmas(&tlb, vma, start, end); 2409 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, 2410 next ? next->vm_start : USER_PGTABLES_CEILING); 2411 tlb_finish_mmu(&tlb, start, end); 2412 } 2413 2414 /* 2415 * Create a list of vma's touched by the unmap, removing them from the mm's 2416 * vma list as we go.. 2417 */ 2418 static void 2419 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 2420 struct vm_area_struct *prev, unsigned long end) 2421 { 2422 struct vm_area_struct **insertion_point; 2423 struct vm_area_struct *tail_vma = NULL; 2424 2425 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 2426 vma->vm_prev = NULL; 2427 do { 2428 vma_rb_erase(vma, &mm->mm_rb); 2429 mm->map_count--; 2430 tail_vma = vma; 2431 vma = vma->vm_next; 2432 } while (vma && vma->vm_start < end); 2433 *insertion_point = vma; 2434 if (vma) { 2435 vma->vm_prev = prev; 2436 vma_gap_update(vma); 2437 } else 2438 mm->highest_vm_end = prev ? prev->vm_end : 0; 2439 tail_vma->vm_next = NULL; 2440 2441 /* Kill the cache */ 2442 vmacache_invalidate(mm); 2443 } 2444 2445 /* 2446 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the 2447 * munmap path where it doesn't make sense to fail. 2448 */ 2449 static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 2450 unsigned long addr, int new_below) 2451 { 2452 struct vm_area_struct *new; 2453 int err; 2454 2455 if (is_vm_hugetlb_page(vma) && (addr & 2456 ~(huge_page_mask(hstate_vma(vma))))) 2457 return -EINVAL; 2458 2459 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2460 if (!new) 2461 return -ENOMEM; 2462 2463 /* most fields are the same, copy all, and then fixup */ 2464 *new = *vma; 2465 2466 INIT_LIST_HEAD(&new->anon_vma_chain); 2467 2468 if (new_below) 2469 new->vm_end = addr; 2470 else { 2471 new->vm_start = addr; 2472 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 2473 } 2474 2475 err = vma_dup_policy(vma, new); 2476 if (err) 2477 goto out_free_vma; 2478 2479 err = anon_vma_clone(new, vma); 2480 if (err) 2481 goto out_free_mpol; 2482 2483 if (new->vm_file) 2484 get_file(new->vm_file); 2485 2486 if (new->vm_ops && new->vm_ops->open) 2487 new->vm_ops->open(new); 2488 2489 if (new_below) 2490 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 2491 ((addr - new->vm_start) >> PAGE_SHIFT), new); 2492 else 2493 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 2494 2495 /* Success. */ 2496 if (!err) 2497 return 0; 2498 2499 /* Clean everything up if vma_adjust failed. */ 2500 if (new->vm_ops && new->vm_ops->close) 2501 new->vm_ops->close(new); 2502 if (new->vm_file) 2503 fput(new->vm_file); 2504 unlink_anon_vmas(new); 2505 out_free_mpol: 2506 mpol_put(vma_policy(new)); 2507 out_free_vma: 2508 kmem_cache_free(vm_area_cachep, new); 2509 return err; 2510 } 2511 2512 /* 2513 * Split a vma into two pieces at address 'addr', a new vma is allocated 2514 * either for the first part or the tail. 2515 */ 2516 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 2517 unsigned long addr, int new_below) 2518 { 2519 if (mm->map_count >= sysctl_max_map_count) 2520 return -ENOMEM; 2521 2522 return __split_vma(mm, vma, addr, new_below); 2523 } 2524 2525 /* Munmap is split into 2 main parts -- this part which finds 2526 * what needs doing, and the areas themselves, which do the 2527 * work. This now handles partial unmappings. 2528 * Jeremy Fitzhardinge <jeremy@goop.org> 2529 */ 2530 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 2531 { 2532 unsigned long end; 2533 struct vm_area_struct *vma, *prev, *last; 2534 2535 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) 2536 return -EINVAL; 2537 2538 len = PAGE_ALIGN(len); 2539 if (len == 0) 2540 return -EINVAL; 2541 2542 /* Find the first overlapping VMA */ 2543 vma = find_vma(mm, start); 2544 if (!vma) 2545 return 0; 2546 prev = vma->vm_prev; 2547 /* we have start < vma->vm_end */ 2548 2549 /* if it doesn't overlap, we have nothing.. */ 2550 end = start + len; 2551 if (vma->vm_start >= end) 2552 return 0; 2553 2554 /* 2555 * If we need to split any vma, do it now to save pain later. 2556 * 2557 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 2558 * unmapped vm_area_struct will remain in use: so lower split_vma 2559 * places tmp vma above, and higher split_vma places tmp vma below. 2560 */ 2561 if (start > vma->vm_start) { 2562 int error; 2563 2564 /* 2565 * Make sure that map_count on return from munmap() will 2566 * not exceed its limit; but let map_count go just above 2567 * its limit temporarily, to help free resources as expected. 2568 */ 2569 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) 2570 return -ENOMEM; 2571 2572 error = __split_vma(mm, vma, start, 0); 2573 if (error) 2574 return error; 2575 prev = vma; 2576 } 2577 2578 /* Does it split the last one? */ 2579 last = find_vma(mm, end); 2580 if (last && end > last->vm_start) { 2581 int error = __split_vma(mm, last, end, 1); 2582 if (error) 2583 return error; 2584 } 2585 vma = prev ? prev->vm_next : mm->mmap; 2586 2587 /* 2588 * unlock any mlock()ed ranges before detaching vmas 2589 */ 2590 if (mm->locked_vm) { 2591 struct vm_area_struct *tmp = vma; 2592 while (tmp && tmp->vm_start < end) { 2593 if (tmp->vm_flags & VM_LOCKED) { 2594 mm->locked_vm -= vma_pages(tmp); 2595 munlock_vma_pages_all(tmp); 2596 } 2597 tmp = tmp->vm_next; 2598 } 2599 } 2600 2601 /* 2602 * Remove the vma's, and unmap the actual pages 2603 */ 2604 detach_vmas_to_be_unmapped(mm, vma, prev, end); 2605 unmap_region(mm, vma, prev, start, end); 2606 2607 arch_unmap(mm, vma, start, end); 2608 2609 /* Fix up all other VM information */ 2610 remove_vma_list(mm, vma); 2611 2612 return 0; 2613 } 2614 2615 int vm_munmap(unsigned long start, size_t len) 2616 { 2617 int ret; 2618 struct mm_struct *mm = current->mm; 2619 2620 down_write(&mm->mmap_sem); 2621 ret = do_munmap(mm, start, len); 2622 up_write(&mm->mmap_sem); 2623 return ret; 2624 } 2625 EXPORT_SYMBOL(vm_munmap); 2626 2627 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 2628 { 2629 profile_munmap(addr); 2630 return vm_munmap(addr, len); 2631 } 2632 2633 2634 /* 2635 * Emulation of deprecated remap_file_pages() syscall. 2636 */ 2637 SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, 2638 unsigned long, prot, unsigned long, pgoff, unsigned long, flags) 2639 { 2640 2641 struct mm_struct *mm = current->mm; 2642 struct vm_area_struct *vma; 2643 unsigned long populate = 0; 2644 unsigned long ret = -EINVAL; 2645 struct file *file; 2646 2647 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. " 2648 "See Documentation/vm/remap_file_pages.txt.\n", 2649 current->comm, current->pid); 2650 2651 if (prot) 2652 return ret; 2653 start = start & PAGE_MASK; 2654 size = size & PAGE_MASK; 2655 2656 if (start + size <= start) 2657 return ret; 2658 2659 /* Does pgoff wrap? */ 2660 if (pgoff + (size >> PAGE_SHIFT) < pgoff) 2661 return ret; 2662 2663 down_write(&mm->mmap_sem); 2664 vma = find_vma(mm, start); 2665 2666 if (!vma || !(vma->vm_flags & VM_SHARED)) 2667 goto out; 2668 2669 if (start < vma->vm_start || start + size > vma->vm_end) 2670 goto out; 2671 2672 if (pgoff == linear_page_index(vma, start)) { 2673 ret = 0; 2674 goto out; 2675 } 2676 2677 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; 2678 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0; 2679 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0; 2680 2681 flags &= MAP_NONBLOCK; 2682 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE; 2683 if (vma->vm_flags & VM_LOCKED) { 2684 flags |= MAP_LOCKED; 2685 /* drop PG_Mlocked flag for over-mapped range */ 2686 munlock_vma_pages_range(vma, start, start + size); 2687 } 2688 2689 file = get_file(vma->vm_file); 2690 ret = do_mmap_pgoff(vma->vm_file, start, size, 2691 prot, flags, pgoff, &populate); 2692 fput(file); 2693 out: 2694 up_write(&mm->mmap_sem); 2695 if (populate) 2696 mm_populate(ret, populate); 2697 if (!IS_ERR_VALUE(ret)) 2698 ret = 0; 2699 return ret; 2700 } 2701 2702 static inline void verify_mm_writelocked(struct mm_struct *mm) 2703 { 2704 #ifdef CONFIG_DEBUG_VM 2705 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 2706 WARN_ON(1); 2707 up_read(&mm->mmap_sem); 2708 } 2709 #endif 2710 } 2711 2712 /* 2713 * this is really a simplified "do_mmap". it only handles 2714 * anonymous maps. eventually we may be able to do some 2715 * brk-specific accounting here. 2716 */ 2717 static unsigned long do_brk(unsigned long addr, unsigned long len) 2718 { 2719 struct mm_struct *mm = current->mm; 2720 struct vm_area_struct *vma, *prev; 2721 unsigned long flags; 2722 struct rb_node **rb_link, *rb_parent; 2723 pgoff_t pgoff = addr >> PAGE_SHIFT; 2724 int error; 2725 2726 len = PAGE_ALIGN(len); 2727 if (!len) 2728 return addr; 2729 2730 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 2731 2732 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); 2733 if (offset_in_page(error)) 2734 return error; 2735 2736 error = mlock_future_check(mm, mm->def_flags, len); 2737 if (error) 2738 return error; 2739 2740 /* 2741 * mm->mmap_sem is required to protect against another thread 2742 * changing the mappings in case we sleep. 2743 */ 2744 verify_mm_writelocked(mm); 2745 2746 /* 2747 * Clear old maps. this also does some error checking for us 2748 */ 2749 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, 2750 &rb_parent)) { 2751 if (do_munmap(mm, addr, len)) 2752 return -ENOMEM; 2753 } 2754 2755 /* Check against address space limits *after* clearing old maps... */ 2756 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT)) 2757 return -ENOMEM; 2758 2759 if (mm->map_count > sysctl_max_map_count) 2760 return -ENOMEM; 2761 2762 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) 2763 return -ENOMEM; 2764 2765 /* Can we just expand an old private anonymous mapping? */ 2766 vma = vma_merge(mm, prev, addr, addr + len, flags, 2767 NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX); 2768 if (vma) 2769 goto out; 2770 2771 /* 2772 * create a vma struct for an anonymous mapping 2773 */ 2774 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2775 if (!vma) { 2776 vm_unacct_memory(len >> PAGE_SHIFT); 2777 return -ENOMEM; 2778 } 2779 2780 INIT_LIST_HEAD(&vma->anon_vma_chain); 2781 vma->vm_mm = mm; 2782 vma->vm_start = addr; 2783 vma->vm_end = addr + len; 2784 vma->vm_pgoff = pgoff; 2785 vma->vm_flags = flags; 2786 vma->vm_page_prot = vm_get_page_prot(flags); 2787 vma_link(mm, vma, prev, rb_link, rb_parent); 2788 out: 2789 perf_event_mmap(vma); 2790 mm->total_vm += len >> PAGE_SHIFT; 2791 mm->data_vm += len >> PAGE_SHIFT; 2792 if (flags & VM_LOCKED) 2793 mm->locked_vm += (len >> PAGE_SHIFT); 2794 vma->vm_flags |= VM_SOFTDIRTY; 2795 return addr; 2796 } 2797 2798 unsigned long vm_brk(unsigned long addr, unsigned long len) 2799 { 2800 struct mm_struct *mm = current->mm; 2801 unsigned long ret; 2802 bool populate; 2803 2804 down_write(&mm->mmap_sem); 2805 ret = do_brk(addr, len); 2806 populate = ((mm->def_flags & VM_LOCKED) != 0); 2807 up_write(&mm->mmap_sem); 2808 if (populate) 2809 mm_populate(addr, len); 2810 return ret; 2811 } 2812 EXPORT_SYMBOL(vm_brk); 2813 2814 /* Release all mmaps. */ 2815 void exit_mmap(struct mm_struct *mm) 2816 { 2817 struct mmu_gather tlb; 2818 struct vm_area_struct *vma; 2819 unsigned long nr_accounted = 0; 2820 2821 /* mm's last user has gone, and its about to be pulled down */ 2822 mmu_notifier_release(mm); 2823 2824 if (mm->locked_vm) { 2825 vma = mm->mmap; 2826 while (vma) { 2827 if (vma->vm_flags & VM_LOCKED) 2828 munlock_vma_pages_all(vma); 2829 vma = vma->vm_next; 2830 } 2831 } 2832 2833 arch_exit_mmap(mm); 2834 2835 vma = mm->mmap; 2836 if (!vma) /* Can happen if dup_mmap() received an OOM */ 2837 return; 2838 2839 lru_add_drain(); 2840 flush_cache_mm(mm); 2841 tlb_gather_mmu(&tlb, mm, 0, -1); 2842 /* update_hiwater_rss(mm) here? but nobody should be looking */ 2843 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 2844 unmap_vmas(&tlb, vma, 0, -1); 2845 2846 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); 2847 tlb_finish_mmu(&tlb, 0, -1); 2848 2849 /* 2850 * Walk the list again, actually closing and freeing it, 2851 * with preemption enabled, without holding any MM locks. 2852 */ 2853 while (vma) { 2854 if (vma->vm_flags & VM_ACCOUNT) 2855 nr_accounted += vma_pages(vma); 2856 vma = remove_vma(vma); 2857 } 2858 vm_unacct_memory(nr_accounted); 2859 } 2860 2861 /* Insert vm structure into process list sorted by address 2862 * and into the inode's i_mmap tree. If vm_file is non-NULL 2863 * then i_mmap_rwsem is taken here. 2864 */ 2865 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) 2866 { 2867 struct vm_area_struct *prev; 2868 struct rb_node **rb_link, *rb_parent; 2869 2870 if (find_vma_links(mm, vma->vm_start, vma->vm_end, 2871 &prev, &rb_link, &rb_parent)) 2872 return -ENOMEM; 2873 if ((vma->vm_flags & VM_ACCOUNT) && 2874 security_vm_enough_memory_mm(mm, vma_pages(vma))) 2875 return -ENOMEM; 2876 2877 /* 2878 * The vm_pgoff of a purely anonymous vma should be irrelevant 2879 * until its first write fault, when page's anon_vma and index 2880 * are set. But now set the vm_pgoff it will almost certainly 2881 * end up with (unless mremap moves it elsewhere before that 2882 * first wfault), so /proc/pid/maps tells a consistent story. 2883 * 2884 * By setting it to reflect the virtual start address of the 2885 * vma, merges and splits can happen in a seamless way, just 2886 * using the existing file pgoff checks and manipulations. 2887 * Similarly in do_mmap_pgoff and in do_brk. 2888 */ 2889 if (vma_is_anonymous(vma)) { 2890 BUG_ON(vma->anon_vma); 2891 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 2892 } 2893 2894 vma_link(mm, vma, prev, rb_link, rb_parent); 2895 return 0; 2896 } 2897 2898 /* 2899 * Copy the vma structure to a new location in the same mm, 2900 * prior to moving page table entries, to effect an mremap move. 2901 */ 2902 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2903 unsigned long addr, unsigned long len, pgoff_t pgoff, 2904 bool *need_rmap_locks) 2905 { 2906 struct vm_area_struct *vma = *vmap; 2907 unsigned long vma_start = vma->vm_start; 2908 struct mm_struct *mm = vma->vm_mm; 2909 struct vm_area_struct *new_vma, *prev; 2910 struct rb_node **rb_link, *rb_parent; 2911 bool faulted_in_anon_vma = true; 2912 2913 /* 2914 * If anonymous vma has not yet been faulted, update new pgoff 2915 * to match new location, to increase its chance of merging. 2916 */ 2917 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { 2918 pgoff = addr >> PAGE_SHIFT; 2919 faulted_in_anon_vma = false; 2920 } 2921 2922 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) 2923 return NULL; /* should never get here */ 2924 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2925 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), 2926 vma->vm_userfaultfd_ctx); 2927 if (new_vma) { 2928 /* 2929 * Source vma may have been merged into new_vma 2930 */ 2931 if (unlikely(vma_start >= new_vma->vm_start && 2932 vma_start < new_vma->vm_end)) { 2933 /* 2934 * The only way we can get a vma_merge with 2935 * self during an mremap is if the vma hasn't 2936 * been faulted in yet and we were allowed to 2937 * reset the dst vma->vm_pgoff to the 2938 * destination address of the mremap to allow 2939 * the merge to happen. mremap must change the 2940 * vm_pgoff linearity between src and dst vmas 2941 * (in turn preventing a vma_merge) to be 2942 * safe. It is only safe to keep the vm_pgoff 2943 * linear if there are no pages mapped yet. 2944 */ 2945 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma); 2946 *vmap = vma = new_vma; 2947 } 2948 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); 2949 } else { 2950 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2951 if (!new_vma) 2952 goto out; 2953 *new_vma = *vma; 2954 new_vma->vm_start = addr; 2955 new_vma->vm_end = addr + len; 2956 new_vma->vm_pgoff = pgoff; 2957 if (vma_dup_policy(vma, new_vma)) 2958 goto out_free_vma; 2959 INIT_LIST_HEAD(&new_vma->anon_vma_chain); 2960 if (anon_vma_clone(new_vma, vma)) 2961 goto out_free_mempol; 2962 if (new_vma->vm_file) 2963 get_file(new_vma->vm_file); 2964 if (new_vma->vm_ops && new_vma->vm_ops->open) 2965 new_vma->vm_ops->open(new_vma); 2966 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2967 *need_rmap_locks = false; 2968 } 2969 return new_vma; 2970 2971 out_free_mempol: 2972 mpol_put(vma_policy(new_vma)); 2973 out_free_vma: 2974 kmem_cache_free(vm_area_cachep, new_vma); 2975 out: 2976 return NULL; 2977 } 2978 2979 /* 2980 * Return true if the calling process may expand its vm space by the passed 2981 * number of pages 2982 */ 2983 bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) 2984 { 2985 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) 2986 return false; 2987 2988 if (is_data_mapping(flags) && 2989 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) { 2990 if (ignore_rlimit_data) 2991 pr_warn_once("%s (%d): VmData %lu exceed data ulimit " 2992 "%lu. Will be forbidden soon.\n", 2993 current->comm, current->pid, 2994 (mm->data_vm + npages) << PAGE_SHIFT, 2995 rlimit(RLIMIT_DATA)); 2996 else 2997 return false; 2998 } 2999 3000 return true; 3001 } 3002 3003 void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) 3004 { 3005 mm->total_vm += npages; 3006 3007 if (is_exec_mapping(flags)) 3008 mm->exec_vm += npages; 3009 else if (is_stack_mapping(flags)) 3010 mm->stack_vm += npages; 3011 else if (is_data_mapping(flags)) 3012 mm->data_vm += npages; 3013 } 3014 3015 static int special_mapping_fault(struct vm_area_struct *vma, 3016 struct vm_fault *vmf); 3017 3018 /* 3019 * Having a close hook prevents vma merging regardless of flags. 3020 */ 3021 static void special_mapping_close(struct vm_area_struct *vma) 3022 { 3023 } 3024 3025 static const char *special_mapping_name(struct vm_area_struct *vma) 3026 { 3027 return ((struct vm_special_mapping *)vma->vm_private_data)->name; 3028 } 3029 3030 static const struct vm_operations_struct special_mapping_vmops = { 3031 .close = special_mapping_close, 3032 .fault = special_mapping_fault, 3033 .name = special_mapping_name, 3034 }; 3035 3036 static const struct vm_operations_struct legacy_special_mapping_vmops = { 3037 .close = special_mapping_close, 3038 .fault = special_mapping_fault, 3039 }; 3040 3041 static int special_mapping_fault(struct vm_area_struct *vma, 3042 struct vm_fault *vmf) 3043 { 3044 pgoff_t pgoff; 3045 struct page **pages; 3046 3047 if (vma->vm_ops == &legacy_special_mapping_vmops) 3048 pages = vma->vm_private_data; 3049 else 3050 pages = ((struct vm_special_mapping *)vma->vm_private_data)-> 3051 pages; 3052 3053 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages) 3054 pgoff--; 3055 3056 if (*pages) { 3057 struct page *page = *pages; 3058 get_page(page); 3059 vmf->page = page; 3060 return 0; 3061 } 3062 3063 return VM_FAULT_SIGBUS; 3064 } 3065 3066 static struct vm_area_struct *__install_special_mapping( 3067 struct mm_struct *mm, 3068 unsigned long addr, unsigned long len, 3069 unsigned long vm_flags, void *priv, 3070 const struct vm_operations_struct *ops) 3071 { 3072 int ret; 3073 struct vm_area_struct *vma; 3074 3075 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 3076 if (unlikely(vma == NULL)) 3077 return ERR_PTR(-ENOMEM); 3078 3079 INIT_LIST_HEAD(&vma->anon_vma_chain); 3080 vma->vm_mm = mm; 3081 vma->vm_start = addr; 3082 vma->vm_end = addr + len; 3083 3084 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY; 3085 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 3086 3087 vma->vm_ops = ops; 3088 vma->vm_private_data = priv; 3089 3090 ret = insert_vm_struct(mm, vma); 3091 if (ret) 3092 goto out; 3093 3094 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT); 3095 3096 perf_event_mmap(vma); 3097 3098 return vma; 3099 3100 out: 3101 kmem_cache_free(vm_area_cachep, vma); 3102 return ERR_PTR(ret); 3103 } 3104 3105 /* 3106 * Called with mm->mmap_sem held for writing. 3107 * Insert a new vma covering the given region, with the given flags. 3108 * Its pages are supplied by the given array of struct page *. 3109 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 3110 * The region past the last page supplied will always produce SIGBUS. 3111 * The array pointer and the pages it points to are assumed to stay alive 3112 * for as long as this mapping might exist. 3113 */ 3114 struct vm_area_struct *_install_special_mapping( 3115 struct mm_struct *mm, 3116 unsigned long addr, unsigned long len, 3117 unsigned long vm_flags, const struct vm_special_mapping *spec) 3118 { 3119 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec, 3120 &special_mapping_vmops); 3121 } 3122 3123 int install_special_mapping(struct mm_struct *mm, 3124 unsigned long addr, unsigned long len, 3125 unsigned long vm_flags, struct page **pages) 3126 { 3127 struct vm_area_struct *vma = __install_special_mapping( 3128 mm, addr, len, vm_flags, (void *)pages, 3129 &legacy_special_mapping_vmops); 3130 3131 return PTR_ERR_OR_ZERO(vma); 3132 } 3133 3134 static DEFINE_MUTEX(mm_all_locks_mutex); 3135 3136 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) 3137 { 3138 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) { 3139 /* 3140 * The LSB of head.next can't change from under us 3141 * because we hold the mm_all_locks_mutex. 3142 */ 3143 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem); 3144 /* 3145 * We can safely modify head.next after taking the 3146 * anon_vma->root->rwsem. If some other vma in this mm shares 3147 * the same anon_vma we won't take it again. 3148 * 3149 * No need of atomic instructions here, head.next 3150 * can't change from under us thanks to the 3151 * anon_vma->root->rwsem. 3152 */ 3153 if (__test_and_set_bit(0, (unsigned long *) 3154 &anon_vma->root->rb_root.rb_node)) 3155 BUG(); 3156 } 3157 } 3158 3159 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) 3160 { 3161 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 3162 /* 3163 * AS_MM_ALL_LOCKS can't change from under us because 3164 * we hold the mm_all_locks_mutex. 3165 * 3166 * Operations on ->flags have to be atomic because 3167 * even if AS_MM_ALL_LOCKS is stable thanks to the 3168 * mm_all_locks_mutex, there may be other cpus 3169 * changing other bitflags in parallel to us. 3170 */ 3171 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) 3172 BUG(); 3173 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem); 3174 } 3175 } 3176 3177 /* 3178 * This operation locks against the VM for all pte/vma/mm related 3179 * operations that could ever happen on a certain mm. This includes 3180 * vmtruncate, try_to_unmap, and all page faults. 3181 * 3182 * The caller must take the mmap_sem in write mode before calling 3183 * mm_take_all_locks(). The caller isn't allowed to release the 3184 * mmap_sem until mm_drop_all_locks() returns. 3185 * 3186 * mmap_sem in write mode is required in order to block all operations 3187 * that could modify pagetables and free pages without need of 3188 * altering the vma layout. It's also needed in write mode to avoid new 3189 * anon_vmas to be associated with existing vmas. 3190 * 3191 * A single task can't take more than one mm_take_all_locks() in a row 3192 * or it would deadlock. 3193 * 3194 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in 3195 * mapping->flags avoid to take the same lock twice, if more than one 3196 * vma in this mm is backed by the same anon_vma or address_space. 3197 * 3198 * We take locks in following order, accordingly to comment at beginning 3199 * of mm/rmap.c: 3200 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for 3201 * hugetlb mapping); 3202 * - all i_mmap_rwsem locks; 3203 * - all anon_vma->rwseml 3204 * 3205 * We can take all locks within these types randomly because the VM code 3206 * doesn't nest them and we protected from parallel mm_take_all_locks() by 3207 * mm_all_locks_mutex. 3208 * 3209 * mm_take_all_locks() and mm_drop_all_locks are expensive operations 3210 * that may have to take thousand of locks. 3211 * 3212 * mm_take_all_locks() can fail if it's interrupted by signals. 3213 */ 3214 int mm_take_all_locks(struct mm_struct *mm) 3215 { 3216 struct vm_area_struct *vma; 3217 struct anon_vma_chain *avc; 3218 3219 BUG_ON(down_read_trylock(&mm->mmap_sem)); 3220 3221 mutex_lock(&mm_all_locks_mutex); 3222 3223 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3224 if (signal_pending(current)) 3225 goto out_unlock; 3226 if (vma->vm_file && vma->vm_file->f_mapping && 3227 is_vm_hugetlb_page(vma)) 3228 vm_lock_mapping(mm, vma->vm_file->f_mapping); 3229 } 3230 3231 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3232 if (signal_pending(current)) 3233 goto out_unlock; 3234 if (vma->vm_file && vma->vm_file->f_mapping && 3235 !is_vm_hugetlb_page(vma)) 3236 vm_lock_mapping(mm, vma->vm_file->f_mapping); 3237 } 3238 3239 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3240 if (signal_pending(current)) 3241 goto out_unlock; 3242 if (vma->anon_vma) 3243 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 3244 vm_lock_anon_vma(mm, avc->anon_vma); 3245 } 3246 3247 return 0; 3248 3249 out_unlock: 3250 mm_drop_all_locks(mm); 3251 return -EINTR; 3252 } 3253 3254 static void vm_unlock_anon_vma(struct anon_vma *anon_vma) 3255 { 3256 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) { 3257 /* 3258 * The LSB of head.next can't change to 0 from under 3259 * us because we hold the mm_all_locks_mutex. 3260 * 3261 * We must however clear the bitflag before unlocking 3262 * the vma so the users using the anon_vma->rb_root will 3263 * never see our bitflag. 3264 * 3265 * No need of atomic instructions here, head.next 3266 * can't change from under us until we release the 3267 * anon_vma->root->rwsem. 3268 */ 3269 if (!__test_and_clear_bit(0, (unsigned long *) 3270 &anon_vma->root->rb_root.rb_node)) 3271 BUG(); 3272 anon_vma_unlock_write(anon_vma); 3273 } 3274 } 3275 3276 static void vm_unlock_mapping(struct address_space *mapping) 3277 { 3278 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 3279 /* 3280 * AS_MM_ALL_LOCKS can't change to 0 from under us 3281 * because we hold the mm_all_locks_mutex. 3282 */ 3283 i_mmap_unlock_write(mapping); 3284 if (!test_and_clear_bit(AS_MM_ALL_LOCKS, 3285 &mapping->flags)) 3286 BUG(); 3287 } 3288 } 3289 3290 /* 3291 * The mmap_sem cannot be released by the caller until 3292 * mm_drop_all_locks() returns. 3293 */ 3294 void mm_drop_all_locks(struct mm_struct *mm) 3295 { 3296 struct vm_area_struct *vma; 3297 struct anon_vma_chain *avc; 3298 3299 BUG_ON(down_read_trylock(&mm->mmap_sem)); 3300 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); 3301 3302 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3303 if (vma->anon_vma) 3304 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 3305 vm_unlock_anon_vma(avc->anon_vma); 3306 if (vma->vm_file && vma->vm_file->f_mapping) 3307 vm_unlock_mapping(vma->vm_file->f_mapping); 3308 } 3309 3310 mutex_unlock(&mm_all_locks_mutex); 3311 } 3312 3313 /* 3314 * initialise the VMA slab 3315 */ 3316 void __init mmap_init(void) 3317 { 3318 int ret; 3319 3320 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); 3321 VM_BUG_ON(ret); 3322 } 3323 3324 /* 3325 * Initialise sysctl_user_reserve_kbytes. 3326 * 3327 * This is intended to prevent a user from starting a single memory hogging 3328 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER 3329 * mode. 3330 * 3331 * The default value is min(3% of free memory, 128MB) 3332 * 128MB is enough to recover with sshd/login, bash, and top/kill. 3333 */ 3334 static int init_user_reserve(void) 3335 { 3336 unsigned long free_kbytes; 3337 3338 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); 3339 3340 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); 3341 return 0; 3342 } 3343 subsys_initcall(init_user_reserve); 3344 3345 /* 3346 * Initialise sysctl_admin_reserve_kbytes. 3347 * 3348 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin 3349 * to log in and kill a memory hogging process. 3350 * 3351 * Systems with more than 256MB will reserve 8MB, enough to recover 3352 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will 3353 * only reserve 3% of free pages by default. 3354 */ 3355 static int init_admin_reserve(void) 3356 { 3357 unsigned long free_kbytes; 3358 3359 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); 3360 3361 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); 3362 return 0; 3363 } 3364 subsys_initcall(init_admin_reserve); 3365 3366 /* 3367 * Reinititalise user and admin reserves if memory is added or removed. 3368 * 3369 * The default user reserve max is 128MB, and the default max for the 3370 * admin reserve is 8MB. These are usually, but not always, enough to 3371 * enable recovery from a memory hogging process using login/sshd, a shell, 3372 * and tools like top. It may make sense to increase or even disable the 3373 * reserve depending on the existence of swap or variations in the recovery 3374 * tools. So, the admin may have changed them. 3375 * 3376 * If memory is added and the reserves have been eliminated or increased above 3377 * the default max, then we'll trust the admin. 3378 * 3379 * If memory is removed and there isn't enough free memory, then we 3380 * need to reset the reserves. 3381 * 3382 * Otherwise keep the reserve set by the admin. 3383 */ 3384 static int reserve_mem_notifier(struct notifier_block *nb, 3385 unsigned long action, void *data) 3386 { 3387 unsigned long tmp, free_kbytes; 3388 3389 switch (action) { 3390 case MEM_ONLINE: 3391 /* Default max is 128MB. Leave alone if modified by operator. */ 3392 tmp = sysctl_user_reserve_kbytes; 3393 if (0 < tmp && tmp < (1UL << 17)) 3394 init_user_reserve(); 3395 3396 /* Default max is 8MB. Leave alone if modified by operator. */ 3397 tmp = sysctl_admin_reserve_kbytes; 3398 if (0 < tmp && tmp < (1UL << 13)) 3399 init_admin_reserve(); 3400 3401 break; 3402 case MEM_OFFLINE: 3403 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); 3404 3405 if (sysctl_user_reserve_kbytes > free_kbytes) { 3406 init_user_reserve(); 3407 pr_info("vm.user_reserve_kbytes reset to %lu\n", 3408 sysctl_user_reserve_kbytes); 3409 } 3410 3411 if (sysctl_admin_reserve_kbytes > free_kbytes) { 3412 init_admin_reserve(); 3413 pr_info("vm.admin_reserve_kbytes reset to %lu\n", 3414 sysctl_admin_reserve_kbytes); 3415 } 3416 break; 3417 default: 3418 break; 3419 } 3420 return NOTIFY_OK; 3421 } 3422 3423 static struct notifier_block reserve_mem_nb = { 3424 .notifier_call = reserve_mem_notifier, 3425 }; 3426 3427 static int __meminit init_reserve_notifier(void) 3428 { 3429 if (register_hotmemory_notifier(&reserve_mem_nb)) 3430 pr_err("Failed registering memory add/remove notifier for admin reserve\n"); 3431 3432 return 0; 3433 } 3434 subsys_initcall(init_reserve_notifier); 3435