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