1 /* 2 * mm/mmap.c 3 * 4 * Written by obz. 5 * 6 * Address space accounting code <alan@redhat.com> 7 */ 8 9 #include <linux/slab.h> 10 #include <linux/mm.h> 11 #include <linux/shm.h> 12 #include <linux/mman.h> 13 #include <linux/pagemap.h> 14 #include <linux/swap.h> 15 #include <linux/syscalls.h> 16 #include <linux/init.h> 17 #include <linux/file.h> 18 #include <linux/fs.h> 19 #include <linux/personality.h> 20 #include <linux/security.h> 21 #include <linux/hugetlb.h> 22 #include <linux/profile.h> 23 #include <linux/module.h> 24 #include <linux/mount.h> 25 #include <linux/mempolicy.h> 26 #include <linux/rmap.h> 27 28 #include <asm/uaccess.h> 29 #include <asm/cacheflush.h> 30 #include <asm/tlb.h> 31 32 static void unmap_region(struct mm_struct *mm, 33 struct vm_area_struct *vma, struct vm_area_struct *prev, 34 unsigned long start, unsigned long end); 35 36 /* 37 * WARNING: the debugging will use recursive algorithms so never enable this 38 * unless you know what you are doing. 39 */ 40 #undef DEBUG_MM_RB 41 42 /* description of effects of mapping type and prot in current implementation. 43 * this is due to the limited x86 page protection hardware. The expected 44 * behavior is in parens: 45 * 46 * map_type prot 47 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 48 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 49 * w: (no) no w: (no) no w: (yes) yes w: (no) no 50 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 51 * 52 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 53 * w: (no) no w: (no) no w: (copy) copy w: (no) no 54 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 55 * 56 */ 57 pgprot_t protection_map[16] = { 58 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 59 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 60 }; 61 62 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 63 int sysctl_overcommit_ratio = 50; /* default is 50% */ 64 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; 65 atomic_t vm_committed_space = ATOMIC_INIT(0); 66 67 /* 68 * Check that a process has enough memory to allocate a new virtual 69 * mapping. 0 means there is enough memory for the allocation to 70 * succeed and -ENOMEM implies there is not. 71 * 72 * We currently support three overcommit policies, which are set via the 73 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 74 * 75 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 76 * Additional code 2002 Jul 20 by Robert Love. 77 * 78 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 79 * 80 * Note this is a helper function intended to be used by LSMs which 81 * wish to use this logic. 82 */ 83 int __vm_enough_memory(long pages, int cap_sys_admin) 84 { 85 unsigned long free, allowed; 86 87 vm_acct_memory(pages); 88 89 /* 90 * Sometimes we want to use more memory than we have 91 */ 92 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 93 return 0; 94 95 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 96 unsigned long n; 97 98 free = get_page_cache_size(); 99 free += nr_swap_pages; 100 101 /* 102 * Any slabs which are created with the 103 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 104 * which are reclaimable, under pressure. The dentry 105 * cache and most inode caches should fall into this 106 */ 107 free += atomic_read(&slab_reclaim_pages); 108 109 /* 110 * Leave the last 3% for root 111 */ 112 if (!cap_sys_admin) 113 free -= free / 32; 114 115 if (free > pages) 116 return 0; 117 118 /* 119 * nr_free_pages() is very expensive on large systems, 120 * only call if we're about to fail. 121 */ 122 n = nr_free_pages(); 123 if (!cap_sys_admin) 124 n -= n / 32; 125 free += n; 126 127 if (free > pages) 128 return 0; 129 vm_unacct_memory(pages); 130 return -ENOMEM; 131 } 132 133 allowed = (totalram_pages - hugetlb_total_pages()) 134 * sysctl_overcommit_ratio / 100; 135 /* 136 * Leave the last 3% for root 137 */ 138 if (!cap_sys_admin) 139 allowed -= allowed / 32; 140 allowed += total_swap_pages; 141 142 /* Don't let a single process grow too big: 143 leave 3% of the size of this process for other processes */ 144 allowed -= current->mm->total_vm / 32; 145 146 if (atomic_read(&vm_committed_space) < allowed) 147 return 0; 148 149 vm_unacct_memory(pages); 150 151 return -ENOMEM; 152 } 153 154 EXPORT_SYMBOL(sysctl_overcommit_memory); 155 EXPORT_SYMBOL(sysctl_overcommit_ratio); 156 EXPORT_SYMBOL(sysctl_max_map_count); 157 EXPORT_SYMBOL(vm_committed_space); 158 EXPORT_SYMBOL(__vm_enough_memory); 159 160 /* 161 * Requires inode->i_mapping->i_mmap_lock 162 */ 163 static void __remove_shared_vm_struct(struct vm_area_struct *vma, 164 struct file *file, struct address_space *mapping) 165 { 166 if (vma->vm_flags & VM_DENYWRITE) 167 atomic_inc(&file->f_dentry->d_inode->i_writecount); 168 if (vma->vm_flags & VM_SHARED) 169 mapping->i_mmap_writable--; 170 171 flush_dcache_mmap_lock(mapping); 172 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 173 list_del_init(&vma->shared.vm_set.list); 174 else 175 vma_prio_tree_remove(vma, &mapping->i_mmap); 176 flush_dcache_mmap_unlock(mapping); 177 } 178 179 /* 180 * Remove one vm structure and free it. 181 */ 182 static void remove_vm_struct(struct vm_area_struct *vma) 183 { 184 struct file *file = vma->vm_file; 185 186 might_sleep(); 187 if (file) { 188 struct address_space *mapping = file->f_mapping; 189 spin_lock(&mapping->i_mmap_lock); 190 __remove_shared_vm_struct(vma, file, mapping); 191 spin_unlock(&mapping->i_mmap_lock); 192 } 193 if (vma->vm_ops && vma->vm_ops->close) 194 vma->vm_ops->close(vma); 195 if (file) 196 fput(file); 197 anon_vma_unlink(vma); 198 mpol_free(vma_policy(vma)); 199 kmem_cache_free(vm_area_cachep, vma); 200 } 201 202 /* 203 * sys_brk() for the most part doesn't need the global kernel 204 * lock, except when an application is doing something nasty 205 * like trying to un-brk an area that has already been mapped 206 * to a regular file. in this case, the unmapping will need 207 * to invoke file system routines that need the global lock. 208 */ 209 asmlinkage unsigned long sys_brk(unsigned long brk) 210 { 211 unsigned long rlim, retval; 212 unsigned long newbrk, oldbrk; 213 struct mm_struct *mm = current->mm; 214 215 down_write(&mm->mmap_sem); 216 217 if (brk < mm->end_code) 218 goto out; 219 newbrk = PAGE_ALIGN(brk); 220 oldbrk = PAGE_ALIGN(mm->brk); 221 if (oldbrk == newbrk) 222 goto set_brk; 223 224 /* Always allow shrinking brk. */ 225 if (brk <= mm->brk) { 226 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 227 goto set_brk; 228 goto out; 229 } 230 231 /* Check against rlimit.. */ 232 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 233 if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim) 234 goto out; 235 236 /* Check against existing mmap mappings. */ 237 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 238 goto out; 239 240 /* Ok, looks good - let it rip. */ 241 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 242 goto out; 243 set_brk: 244 mm->brk = brk; 245 out: 246 retval = mm->brk; 247 up_write(&mm->mmap_sem); 248 return retval; 249 } 250 251 #ifdef DEBUG_MM_RB 252 static int browse_rb(struct rb_root *root) 253 { 254 int i = 0, j; 255 struct rb_node *nd, *pn = NULL; 256 unsigned long prev = 0, pend = 0; 257 258 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 259 struct vm_area_struct *vma; 260 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 261 if (vma->vm_start < prev) 262 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 263 if (vma->vm_start < pend) 264 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 265 if (vma->vm_start > vma->vm_end) 266 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 267 i++; 268 pn = nd; 269 } 270 j = 0; 271 for (nd = pn; nd; nd = rb_prev(nd)) { 272 j++; 273 } 274 if (i != j) 275 printk("backwards %d, forwards %d\n", j, i), i = 0; 276 return i; 277 } 278 279 void validate_mm(struct mm_struct *mm) 280 { 281 int bug = 0; 282 int i = 0; 283 struct vm_area_struct *tmp = mm->mmap; 284 while (tmp) { 285 tmp = tmp->vm_next; 286 i++; 287 } 288 if (i != mm->map_count) 289 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 290 i = browse_rb(&mm->mm_rb); 291 if (i != mm->map_count) 292 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 293 if (bug) 294 BUG(); 295 } 296 #else 297 #define validate_mm(mm) do { } while (0) 298 #endif 299 300 static struct vm_area_struct * 301 find_vma_prepare(struct mm_struct *mm, unsigned long addr, 302 struct vm_area_struct **pprev, struct rb_node ***rb_link, 303 struct rb_node ** rb_parent) 304 { 305 struct vm_area_struct * vma; 306 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 307 308 __rb_link = &mm->mm_rb.rb_node; 309 rb_prev = __rb_parent = NULL; 310 vma = NULL; 311 312 while (*__rb_link) { 313 struct vm_area_struct *vma_tmp; 314 315 __rb_parent = *__rb_link; 316 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 317 318 if (vma_tmp->vm_end > addr) { 319 vma = vma_tmp; 320 if (vma_tmp->vm_start <= addr) 321 return vma; 322 __rb_link = &__rb_parent->rb_left; 323 } else { 324 rb_prev = __rb_parent; 325 __rb_link = &__rb_parent->rb_right; 326 } 327 } 328 329 *pprev = NULL; 330 if (rb_prev) 331 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 332 *rb_link = __rb_link; 333 *rb_parent = __rb_parent; 334 return vma; 335 } 336 337 static inline void 338 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 339 struct vm_area_struct *prev, struct rb_node *rb_parent) 340 { 341 if (prev) { 342 vma->vm_next = prev->vm_next; 343 prev->vm_next = vma; 344 } else { 345 mm->mmap = vma; 346 if (rb_parent) 347 vma->vm_next = rb_entry(rb_parent, 348 struct vm_area_struct, vm_rb); 349 else 350 vma->vm_next = NULL; 351 } 352 } 353 354 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 355 struct rb_node **rb_link, struct rb_node *rb_parent) 356 { 357 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 358 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 359 } 360 361 static inline void __vma_link_file(struct vm_area_struct *vma) 362 { 363 struct file * file; 364 365 file = vma->vm_file; 366 if (file) { 367 struct address_space *mapping = file->f_mapping; 368 369 if (vma->vm_flags & VM_DENYWRITE) 370 atomic_dec(&file->f_dentry->d_inode->i_writecount); 371 if (vma->vm_flags & VM_SHARED) 372 mapping->i_mmap_writable++; 373 374 flush_dcache_mmap_lock(mapping); 375 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 376 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 377 else 378 vma_prio_tree_insert(vma, &mapping->i_mmap); 379 flush_dcache_mmap_unlock(mapping); 380 } 381 } 382 383 static void 384 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 385 struct vm_area_struct *prev, struct rb_node **rb_link, 386 struct rb_node *rb_parent) 387 { 388 __vma_link_list(mm, vma, prev, rb_parent); 389 __vma_link_rb(mm, vma, rb_link, rb_parent); 390 __anon_vma_link(vma); 391 } 392 393 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 394 struct vm_area_struct *prev, struct rb_node **rb_link, 395 struct rb_node *rb_parent) 396 { 397 struct address_space *mapping = NULL; 398 399 if (vma->vm_file) 400 mapping = vma->vm_file->f_mapping; 401 402 if (mapping) { 403 spin_lock(&mapping->i_mmap_lock); 404 vma->vm_truncate_count = mapping->truncate_count; 405 } 406 anon_vma_lock(vma); 407 408 __vma_link(mm, vma, prev, rb_link, rb_parent); 409 __vma_link_file(vma); 410 411 anon_vma_unlock(vma); 412 if (mapping) 413 spin_unlock(&mapping->i_mmap_lock); 414 415 mm->map_count++; 416 validate_mm(mm); 417 } 418 419 /* 420 * Helper for vma_adjust in the split_vma insert case: 421 * insert vm structure into list and rbtree and anon_vma, 422 * but it has already been inserted into prio_tree earlier. 423 */ 424 static void 425 __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 426 { 427 struct vm_area_struct * __vma, * prev; 428 struct rb_node ** rb_link, * rb_parent; 429 430 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); 431 if (__vma && __vma->vm_start < vma->vm_end) 432 BUG(); 433 __vma_link(mm, vma, prev, rb_link, rb_parent); 434 mm->map_count++; 435 } 436 437 static inline void 438 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 439 struct vm_area_struct *prev) 440 { 441 prev->vm_next = vma->vm_next; 442 rb_erase(&vma->vm_rb, &mm->mm_rb); 443 if (mm->mmap_cache == vma) 444 mm->mmap_cache = prev; 445 } 446 447 /* 448 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 449 * is already present in an i_mmap tree without adjusting the tree. 450 * The following helper function should be used when such adjustments 451 * are necessary. The "insert" vma (if any) is to be inserted 452 * before we drop the necessary locks. 453 */ 454 void vma_adjust(struct vm_area_struct *vma, unsigned long start, 455 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 456 { 457 struct mm_struct *mm = vma->vm_mm; 458 struct vm_area_struct *next = vma->vm_next; 459 struct vm_area_struct *importer = NULL; 460 struct address_space *mapping = NULL; 461 struct prio_tree_root *root = NULL; 462 struct file *file = vma->vm_file; 463 struct anon_vma *anon_vma = NULL; 464 long adjust_next = 0; 465 int remove_next = 0; 466 467 if (next && !insert) { 468 if (end >= next->vm_end) { 469 /* 470 * vma expands, overlapping all the next, and 471 * perhaps the one after too (mprotect case 6). 472 */ 473 again: remove_next = 1 + (end > next->vm_end); 474 end = next->vm_end; 475 anon_vma = next->anon_vma; 476 importer = vma; 477 } else if (end > next->vm_start) { 478 /* 479 * vma expands, overlapping part of the next: 480 * mprotect case 5 shifting the boundary up. 481 */ 482 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 483 anon_vma = next->anon_vma; 484 importer = vma; 485 } else if (end < vma->vm_end) { 486 /* 487 * vma shrinks, and !insert tells it's not 488 * split_vma inserting another: so it must be 489 * mprotect case 4 shifting the boundary down. 490 */ 491 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 492 anon_vma = next->anon_vma; 493 importer = next; 494 } 495 } 496 497 if (file) { 498 mapping = file->f_mapping; 499 if (!(vma->vm_flags & VM_NONLINEAR)) 500 root = &mapping->i_mmap; 501 spin_lock(&mapping->i_mmap_lock); 502 if (importer && 503 vma->vm_truncate_count != next->vm_truncate_count) { 504 /* 505 * unmap_mapping_range might be in progress: 506 * ensure that the expanding vma is rescanned. 507 */ 508 importer->vm_truncate_count = 0; 509 } 510 if (insert) { 511 insert->vm_truncate_count = vma->vm_truncate_count; 512 /* 513 * Put into prio_tree now, so instantiated pages 514 * are visible to arm/parisc __flush_dcache_page 515 * throughout; but we cannot insert into address 516 * space until vma start or end is updated. 517 */ 518 __vma_link_file(insert); 519 } 520 } 521 522 /* 523 * When changing only vma->vm_end, we don't really need 524 * anon_vma lock: but is that case worth optimizing out? 525 */ 526 if (vma->anon_vma) 527 anon_vma = vma->anon_vma; 528 if (anon_vma) { 529 spin_lock(&anon_vma->lock); 530 /* 531 * Easily overlooked: when mprotect shifts the boundary, 532 * make sure the expanding vma has anon_vma set if the 533 * shrinking vma had, to cover any anon pages imported. 534 */ 535 if (importer && !importer->anon_vma) { 536 importer->anon_vma = anon_vma; 537 __anon_vma_link(importer); 538 } 539 } 540 541 if (root) { 542 flush_dcache_mmap_lock(mapping); 543 vma_prio_tree_remove(vma, root); 544 if (adjust_next) 545 vma_prio_tree_remove(next, root); 546 } 547 548 vma->vm_start = start; 549 vma->vm_end = end; 550 vma->vm_pgoff = pgoff; 551 if (adjust_next) { 552 next->vm_start += adjust_next << PAGE_SHIFT; 553 next->vm_pgoff += adjust_next; 554 } 555 556 if (root) { 557 if (adjust_next) 558 vma_prio_tree_insert(next, root); 559 vma_prio_tree_insert(vma, root); 560 flush_dcache_mmap_unlock(mapping); 561 } 562 563 if (remove_next) { 564 /* 565 * vma_merge has merged next into vma, and needs 566 * us to remove next before dropping the locks. 567 */ 568 __vma_unlink(mm, next, vma); 569 if (file) 570 __remove_shared_vm_struct(next, file, mapping); 571 if (next->anon_vma) 572 __anon_vma_merge(vma, next); 573 } else if (insert) { 574 /* 575 * split_vma has split insert from vma, and needs 576 * us to insert it before dropping the locks 577 * (it may either follow vma or precede it). 578 */ 579 __insert_vm_struct(mm, insert); 580 } 581 582 if (anon_vma) 583 spin_unlock(&anon_vma->lock); 584 if (mapping) 585 spin_unlock(&mapping->i_mmap_lock); 586 587 if (remove_next) { 588 if (file) 589 fput(file); 590 mm->map_count--; 591 mpol_free(vma_policy(next)); 592 kmem_cache_free(vm_area_cachep, next); 593 /* 594 * In mprotect's case 6 (see comments on vma_merge), 595 * we must remove another next too. It would clutter 596 * up the code too much to do both in one go. 597 */ 598 if (remove_next == 2) { 599 next = vma->vm_next; 600 goto again; 601 } 602 } 603 604 validate_mm(mm); 605 } 606 607 /* 608 * If the vma has a ->close operation then the driver probably needs to release 609 * per-vma resources, so we don't attempt to merge those. 610 */ 611 #define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED) 612 613 static inline int is_mergeable_vma(struct vm_area_struct *vma, 614 struct file *file, unsigned long vm_flags) 615 { 616 if (vma->vm_flags != vm_flags) 617 return 0; 618 if (vma->vm_file != file) 619 return 0; 620 if (vma->vm_ops && vma->vm_ops->close) 621 return 0; 622 return 1; 623 } 624 625 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 626 struct anon_vma *anon_vma2) 627 { 628 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 629 } 630 631 /* 632 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 633 * in front of (at a lower virtual address and file offset than) the vma. 634 * 635 * We cannot merge two vmas if they have differently assigned (non-NULL) 636 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 637 * 638 * We don't check here for the merged mmap wrapping around the end of pagecache 639 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 640 * wrap, nor mmaps which cover the final page at index -1UL. 641 */ 642 static int 643 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 644 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 645 { 646 if (is_mergeable_vma(vma, file, vm_flags) && 647 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 648 if (vma->vm_pgoff == vm_pgoff) 649 return 1; 650 } 651 return 0; 652 } 653 654 /* 655 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 656 * beyond (at a higher virtual address and file offset than) the vma. 657 * 658 * We cannot merge two vmas if they have differently assigned (non-NULL) 659 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 660 */ 661 static int 662 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 663 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 664 { 665 if (is_mergeable_vma(vma, file, vm_flags) && 666 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 667 pgoff_t vm_pglen; 668 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 669 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 670 return 1; 671 } 672 return 0; 673 } 674 675 /* 676 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 677 * whether that can be merged with its predecessor or its successor. 678 * Or both (it neatly fills a hole). 679 * 680 * In most cases - when called for mmap, brk or mremap - [addr,end) is 681 * certain not to be mapped by the time vma_merge is called; but when 682 * called for mprotect, it is certain to be already mapped (either at 683 * an offset within prev, or at the start of next), and the flags of 684 * this area are about to be changed to vm_flags - and the no-change 685 * case has already been eliminated. 686 * 687 * The following mprotect cases have to be considered, where AAAA is 688 * the area passed down from mprotect_fixup, never extending beyond one 689 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 690 * 691 * AAAA AAAA AAAA AAAA 692 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 693 * cannot merge might become might become might become 694 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 695 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 696 * mremap move: PPPPNNNNNNNN 8 697 * AAAA 698 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 699 * might become case 1 below case 2 below case 3 below 700 * 701 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 702 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 703 */ 704 struct vm_area_struct *vma_merge(struct mm_struct *mm, 705 struct vm_area_struct *prev, unsigned long addr, 706 unsigned long end, unsigned long vm_flags, 707 struct anon_vma *anon_vma, struct file *file, 708 pgoff_t pgoff, struct mempolicy *policy) 709 { 710 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 711 struct vm_area_struct *area, *next; 712 713 /* 714 * We later require that vma->vm_flags == vm_flags, 715 * so this tests vma->vm_flags & VM_SPECIAL, too. 716 */ 717 if (vm_flags & VM_SPECIAL) 718 return NULL; 719 720 if (prev) 721 next = prev->vm_next; 722 else 723 next = mm->mmap; 724 area = next; 725 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 726 next = next->vm_next; 727 728 /* 729 * Can it merge with the predecessor? 730 */ 731 if (prev && prev->vm_end == addr && 732 mpol_equal(vma_policy(prev), policy) && 733 can_vma_merge_after(prev, vm_flags, 734 anon_vma, file, pgoff)) { 735 /* 736 * OK, it can. Can we now merge in the successor as well? 737 */ 738 if (next && end == next->vm_start && 739 mpol_equal(policy, vma_policy(next)) && 740 can_vma_merge_before(next, vm_flags, 741 anon_vma, file, pgoff+pglen) && 742 is_mergeable_anon_vma(prev->anon_vma, 743 next->anon_vma)) { 744 /* cases 1, 6 */ 745 vma_adjust(prev, prev->vm_start, 746 next->vm_end, prev->vm_pgoff, NULL); 747 } else /* cases 2, 5, 7 */ 748 vma_adjust(prev, prev->vm_start, 749 end, prev->vm_pgoff, NULL); 750 return prev; 751 } 752 753 /* 754 * Can this new request be merged in front of next? 755 */ 756 if (next && end == next->vm_start && 757 mpol_equal(policy, vma_policy(next)) && 758 can_vma_merge_before(next, vm_flags, 759 anon_vma, file, pgoff+pglen)) { 760 if (prev && addr < prev->vm_end) /* case 4 */ 761 vma_adjust(prev, prev->vm_start, 762 addr, prev->vm_pgoff, NULL); 763 else /* cases 3, 8 */ 764 vma_adjust(area, addr, next->vm_end, 765 next->vm_pgoff - pglen, NULL); 766 return area; 767 } 768 769 return NULL; 770 } 771 772 /* 773 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 774 * neighbouring vmas for a suitable anon_vma, before it goes off 775 * to allocate a new anon_vma. It checks because a repetitive 776 * sequence of mprotects and faults may otherwise lead to distinct 777 * anon_vmas being allocated, preventing vma merge in subsequent 778 * mprotect. 779 */ 780 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 781 { 782 struct vm_area_struct *near; 783 unsigned long vm_flags; 784 785 near = vma->vm_next; 786 if (!near) 787 goto try_prev; 788 789 /* 790 * Since only mprotect tries to remerge vmas, match flags 791 * which might be mprotected into each other later on. 792 * Neither mlock nor madvise tries to remerge at present, 793 * so leave their flags as obstructing a merge. 794 */ 795 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 796 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 797 798 if (near->anon_vma && vma->vm_end == near->vm_start && 799 mpol_equal(vma_policy(vma), vma_policy(near)) && 800 can_vma_merge_before(near, vm_flags, 801 NULL, vma->vm_file, vma->vm_pgoff + 802 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 803 return near->anon_vma; 804 try_prev: 805 /* 806 * It is potentially slow to have to call find_vma_prev here. 807 * But it's only on the first write fault on the vma, not 808 * every time, and we could devise a way to avoid it later 809 * (e.g. stash info in next's anon_vma_node when assigning 810 * an anon_vma, or when trying vma_merge). Another time. 811 */ 812 if (find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma) 813 BUG(); 814 if (!near) 815 goto none; 816 817 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 818 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 819 820 if (near->anon_vma && near->vm_end == vma->vm_start && 821 mpol_equal(vma_policy(near), vma_policy(vma)) && 822 can_vma_merge_after(near, vm_flags, 823 NULL, vma->vm_file, vma->vm_pgoff)) 824 return near->anon_vma; 825 none: 826 /* 827 * There's no absolute need to look only at touching neighbours: 828 * we could search further afield for "compatible" anon_vmas. 829 * But it would probably just be a waste of time searching, 830 * or lead to too many vmas hanging off the same anon_vma. 831 * We're trying to allow mprotect remerging later on, 832 * not trying to minimize memory used for anon_vmas. 833 */ 834 return NULL; 835 } 836 837 #ifdef CONFIG_PROC_FS 838 void __vm_stat_account(struct mm_struct *mm, unsigned long flags, 839 struct file *file, long pages) 840 { 841 const unsigned long stack_flags 842 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 843 844 #ifdef CONFIG_HUGETLB 845 if (flags & VM_HUGETLB) { 846 if (!(flags & VM_DONTCOPY)) 847 mm->shared_vm += pages; 848 return; 849 } 850 #endif /* CONFIG_HUGETLB */ 851 852 if (file) { 853 mm->shared_vm += pages; 854 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 855 mm->exec_vm += pages; 856 } else if (flags & stack_flags) 857 mm->stack_vm += pages; 858 if (flags & (VM_RESERVED|VM_IO)) 859 mm->reserved_vm += pages; 860 } 861 #endif /* CONFIG_PROC_FS */ 862 863 /* 864 * The caller must hold down_write(current->mm->mmap_sem). 865 */ 866 867 unsigned long do_mmap_pgoff(struct file * file, unsigned long addr, 868 unsigned long len, unsigned long prot, 869 unsigned long flags, unsigned long pgoff) 870 { 871 struct mm_struct * mm = current->mm; 872 struct vm_area_struct * vma, * prev; 873 struct inode *inode; 874 unsigned int vm_flags; 875 int correct_wcount = 0; 876 int error; 877 struct rb_node ** rb_link, * rb_parent; 878 int accountable = 1; 879 unsigned long charged = 0, reqprot = prot; 880 881 if (file) { 882 if (is_file_hugepages(file)) 883 accountable = 0; 884 885 if (!file->f_op || !file->f_op->mmap) 886 return -ENODEV; 887 888 if ((prot & PROT_EXEC) && 889 (file->f_vfsmnt->mnt_flags & MNT_NOEXEC)) 890 return -EPERM; 891 } 892 /* 893 * Does the application expect PROT_READ to imply PROT_EXEC? 894 * 895 * (the exception is when the underlying filesystem is noexec 896 * mounted, in which case we dont add PROT_EXEC.) 897 */ 898 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 899 if (!(file && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))) 900 prot |= PROT_EXEC; 901 902 if (!len) 903 return -EINVAL; 904 905 /* Careful about overflows.. */ 906 len = PAGE_ALIGN(len); 907 if (!len || len > TASK_SIZE) 908 return -ENOMEM; 909 910 /* offset overflow? */ 911 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 912 return -EOVERFLOW; 913 914 /* Too many mappings? */ 915 if (mm->map_count > sysctl_max_map_count) 916 return -ENOMEM; 917 918 /* Obtain the address to map to. we verify (or select) it and ensure 919 * that it represents a valid section of the address space. 920 */ 921 addr = get_unmapped_area(file, addr, len, pgoff, flags); 922 if (addr & ~PAGE_MASK) 923 return addr; 924 925 /* Do simple checking here so the lower-level routines won't have 926 * to. we assume access permissions have been handled by the open 927 * of the memory object, so we don't do any here. 928 */ 929 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 930 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 931 932 if (flags & MAP_LOCKED) { 933 if (!can_do_mlock()) 934 return -EPERM; 935 vm_flags |= VM_LOCKED; 936 } 937 /* mlock MCL_FUTURE? */ 938 if (vm_flags & VM_LOCKED) { 939 unsigned long locked, lock_limit; 940 locked = len >> PAGE_SHIFT; 941 locked += mm->locked_vm; 942 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 943 lock_limit >>= PAGE_SHIFT; 944 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 945 return -EAGAIN; 946 } 947 948 inode = file ? file->f_dentry->d_inode : NULL; 949 950 if (file) { 951 switch (flags & MAP_TYPE) { 952 case MAP_SHARED: 953 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 954 return -EACCES; 955 956 /* 957 * Make sure we don't allow writing to an append-only 958 * file.. 959 */ 960 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 961 return -EACCES; 962 963 /* 964 * Make sure there are no mandatory locks on the file. 965 */ 966 if (locks_verify_locked(inode)) 967 return -EAGAIN; 968 969 vm_flags |= VM_SHARED | VM_MAYSHARE; 970 if (!(file->f_mode & FMODE_WRITE)) 971 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 972 973 /* fall through */ 974 case MAP_PRIVATE: 975 if (!(file->f_mode & FMODE_READ)) 976 return -EACCES; 977 break; 978 979 default: 980 return -EINVAL; 981 } 982 } else { 983 switch (flags & MAP_TYPE) { 984 case MAP_SHARED: 985 vm_flags |= VM_SHARED | VM_MAYSHARE; 986 break; 987 case MAP_PRIVATE: 988 /* 989 * Set pgoff according to addr for anon_vma. 990 */ 991 pgoff = addr >> PAGE_SHIFT; 992 break; 993 default: 994 return -EINVAL; 995 } 996 } 997 998 error = security_file_mmap(file, reqprot, prot, flags); 999 if (error) 1000 return error; 1001 1002 /* Clear old maps */ 1003 error = -ENOMEM; 1004 munmap_back: 1005 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1006 if (vma && vma->vm_start < addr + len) { 1007 if (do_munmap(mm, addr, len)) 1008 return -ENOMEM; 1009 goto munmap_back; 1010 } 1011 1012 /* Check against address space limit. */ 1013 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1014 return -ENOMEM; 1015 1016 if (accountable && (!(flags & MAP_NORESERVE) || 1017 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) { 1018 if (vm_flags & VM_SHARED) { 1019 /* Check memory availability in shmem_file_setup? */ 1020 vm_flags |= VM_ACCOUNT; 1021 } else if (vm_flags & VM_WRITE) { 1022 /* 1023 * Private writable mapping: check memory availability 1024 */ 1025 charged = len >> PAGE_SHIFT; 1026 if (security_vm_enough_memory(charged)) 1027 return -ENOMEM; 1028 vm_flags |= VM_ACCOUNT; 1029 } 1030 } 1031 1032 /* 1033 * Can we just expand an old private anonymous mapping? 1034 * The VM_SHARED test is necessary because shmem_zero_setup 1035 * will create the file object for a shared anonymous map below. 1036 */ 1037 if (!file && !(vm_flags & VM_SHARED) && 1038 vma_merge(mm, prev, addr, addr + len, vm_flags, 1039 NULL, NULL, pgoff, NULL)) 1040 goto out; 1041 1042 /* 1043 * Determine the object being mapped and call the appropriate 1044 * specific mapper. the address has already been validated, but 1045 * not unmapped, but the maps are removed from the list. 1046 */ 1047 vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 1048 if (!vma) { 1049 error = -ENOMEM; 1050 goto unacct_error; 1051 } 1052 memset(vma, 0, sizeof(*vma)); 1053 1054 vma->vm_mm = mm; 1055 vma->vm_start = addr; 1056 vma->vm_end = addr + len; 1057 vma->vm_flags = vm_flags; 1058 vma->vm_page_prot = protection_map[vm_flags & 0x0f]; 1059 vma->vm_pgoff = pgoff; 1060 1061 if (file) { 1062 error = -EINVAL; 1063 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1064 goto free_vma; 1065 if (vm_flags & VM_DENYWRITE) { 1066 error = deny_write_access(file); 1067 if (error) 1068 goto free_vma; 1069 correct_wcount = 1; 1070 } 1071 vma->vm_file = file; 1072 get_file(file); 1073 error = file->f_op->mmap(file, vma); 1074 if (error) 1075 goto unmap_and_free_vma; 1076 } else if (vm_flags & VM_SHARED) { 1077 error = shmem_zero_setup(vma); 1078 if (error) 1079 goto free_vma; 1080 } 1081 1082 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform 1083 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap) 1084 * that memory reservation must be checked; but that reservation 1085 * belongs to shared memory object, not to vma: so now clear it. 1086 */ 1087 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT)) 1088 vma->vm_flags &= ~VM_ACCOUNT; 1089 1090 /* Can addr have changed?? 1091 * 1092 * Answer: Yes, several device drivers can do it in their 1093 * f_op->mmap method. -DaveM 1094 */ 1095 addr = vma->vm_start; 1096 pgoff = vma->vm_pgoff; 1097 vm_flags = vma->vm_flags; 1098 1099 if (!file || !vma_merge(mm, prev, addr, vma->vm_end, 1100 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) { 1101 file = vma->vm_file; 1102 vma_link(mm, vma, prev, rb_link, rb_parent); 1103 if (correct_wcount) 1104 atomic_inc(&inode->i_writecount); 1105 } else { 1106 if (file) { 1107 if (correct_wcount) 1108 atomic_inc(&inode->i_writecount); 1109 fput(file); 1110 } 1111 mpol_free(vma_policy(vma)); 1112 kmem_cache_free(vm_area_cachep, vma); 1113 } 1114 out: 1115 mm->total_vm += len >> PAGE_SHIFT; 1116 __vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1117 if (vm_flags & VM_LOCKED) { 1118 mm->locked_vm += len >> PAGE_SHIFT; 1119 make_pages_present(addr, addr + len); 1120 } 1121 if (flags & MAP_POPULATE) { 1122 up_write(&mm->mmap_sem); 1123 sys_remap_file_pages(addr, len, 0, 1124 pgoff, flags & MAP_NONBLOCK); 1125 down_write(&mm->mmap_sem); 1126 } 1127 return addr; 1128 1129 unmap_and_free_vma: 1130 if (correct_wcount) 1131 atomic_inc(&inode->i_writecount); 1132 vma->vm_file = NULL; 1133 fput(file); 1134 1135 /* Undo any partial mapping done by a device driver. */ 1136 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1137 charged = 0; 1138 free_vma: 1139 kmem_cache_free(vm_area_cachep, vma); 1140 unacct_error: 1141 if (charged) 1142 vm_unacct_memory(charged); 1143 return error; 1144 } 1145 1146 EXPORT_SYMBOL(do_mmap_pgoff); 1147 1148 /* Get an address range which is currently unmapped. 1149 * For shmat() with addr=0. 1150 * 1151 * Ugly calling convention alert: 1152 * Return value with the low bits set means error value, 1153 * ie 1154 * if (ret & ~PAGE_MASK) 1155 * error = ret; 1156 * 1157 * This function "knows" that -ENOMEM has the bits set. 1158 */ 1159 #ifndef HAVE_ARCH_UNMAPPED_AREA 1160 unsigned long 1161 arch_get_unmapped_area(struct file *filp, unsigned long addr, 1162 unsigned long len, unsigned long pgoff, unsigned long flags) 1163 { 1164 struct mm_struct *mm = current->mm; 1165 struct vm_area_struct *vma; 1166 unsigned long start_addr; 1167 1168 if (len > TASK_SIZE) 1169 return -ENOMEM; 1170 1171 if (addr) { 1172 addr = PAGE_ALIGN(addr); 1173 vma = find_vma(mm, addr); 1174 if (TASK_SIZE - len >= addr && 1175 (!vma || addr + len <= vma->vm_start)) 1176 return addr; 1177 } 1178 start_addr = addr = mm->free_area_cache; 1179 1180 full_search: 1181 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1182 /* At this point: (!vma || addr < vma->vm_end). */ 1183 if (TASK_SIZE - len < addr) { 1184 /* 1185 * Start a new search - just in case we missed 1186 * some holes. 1187 */ 1188 if (start_addr != TASK_UNMAPPED_BASE) { 1189 start_addr = addr = TASK_UNMAPPED_BASE; 1190 goto full_search; 1191 } 1192 return -ENOMEM; 1193 } 1194 if (!vma || addr + len <= vma->vm_start) { 1195 /* 1196 * Remember the place where we stopped the search: 1197 */ 1198 mm->free_area_cache = addr + len; 1199 return addr; 1200 } 1201 addr = vma->vm_end; 1202 } 1203 } 1204 #endif 1205 1206 void arch_unmap_area(struct vm_area_struct *area) 1207 { 1208 /* 1209 * Is this a new hole at the lowest possible address? 1210 */ 1211 if (area->vm_start >= TASK_UNMAPPED_BASE && 1212 area->vm_start < area->vm_mm->free_area_cache) 1213 area->vm_mm->free_area_cache = area->vm_start; 1214 } 1215 1216 /* 1217 * This mmap-allocator allocates new areas top-down from below the 1218 * stack's low limit (the base): 1219 */ 1220 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1221 unsigned long 1222 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1223 const unsigned long len, const unsigned long pgoff, 1224 const unsigned long flags) 1225 { 1226 struct vm_area_struct *vma; 1227 struct mm_struct *mm = current->mm; 1228 unsigned long addr = addr0; 1229 1230 /* requested length too big for entire address space */ 1231 if (len > TASK_SIZE) 1232 return -ENOMEM; 1233 1234 /* requesting a specific address */ 1235 if (addr) { 1236 addr = PAGE_ALIGN(addr); 1237 vma = find_vma(mm, addr); 1238 if (TASK_SIZE - len >= addr && 1239 (!vma || addr + len <= vma->vm_start)) 1240 return addr; 1241 } 1242 1243 /* either no address requested or can't fit in requested address hole */ 1244 addr = mm->free_area_cache; 1245 1246 /* make sure it can fit in the remaining address space */ 1247 if (addr > len) { 1248 vma = find_vma(mm, addr-len); 1249 if (!vma || addr <= vma->vm_start) 1250 /* remember the address as a hint for next time */ 1251 return (mm->free_area_cache = addr-len); 1252 } 1253 1254 addr = mm->mmap_base-len; 1255 1256 do { 1257 /* 1258 * Lookup failure means no vma is above this address, 1259 * else if new region fits below vma->vm_start, 1260 * return with success: 1261 */ 1262 vma = find_vma(mm, addr); 1263 if (!vma || addr+len <= vma->vm_start) 1264 /* remember the address as a hint for next time */ 1265 return (mm->free_area_cache = addr); 1266 1267 /* try just below the current vma->vm_start */ 1268 addr = vma->vm_start-len; 1269 } while (len < vma->vm_start); 1270 1271 /* 1272 * A failed mmap() very likely causes application failure, 1273 * so fall back to the bottom-up function here. This scenario 1274 * can happen with large stack limits and large mmap() 1275 * allocations. 1276 */ 1277 mm->free_area_cache = TASK_UNMAPPED_BASE; 1278 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1279 /* 1280 * Restore the topdown base: 1281 */ 1282 mm->free_area_cache = mm->mmap_base; 1283 1284 return addr; 1285 } 1286 #endif 1287 1288 void arch_unmap_area_topdown(struct vm_area_struct *area) 1289 { 1290 /* 1291 * Is this a new hole at the highest possible address? 1292 */ 1293 if (area->vm_end > area->vm_mm->free_area_cache) 1294 area->vm_mm->free_area_cache = area->vm_end; 1295 1296 /* dont allow allocations above current base */ 1297 if (area->vm_mm->free_area_cache > area->vm_mm->mmap_base) 1298 area->vm_mm->free_area_cache = area->vm_mm->mmap_base; 1299 } 1300 1301 unsigned long 1302 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1303 unsigned long pgoff, unsigned long flags) 1304 { 1305 unsigned long ret; 1306 1307 if (!(flags & MAP_FIXED)) { 1308 unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); 1309 1310 get_area = current->mm->get_unmapped_area; 1311 if (file && file->f_op && file->f_op->get_unmapped_area) 1312 get_area = file->f_op->get_unmapped_area; 1313 addr = get_area(file, addr, len, pgoff, flags); 1314 if (IS_ERR_VALUE(addr)) 1315 return addr; 1316 } 1317 1318 if (addr > TASK_SIZE - len) 1319 return -ENOMEM; 1320 if (addr & ~PAGE_MASK) 1321 return -EINVAL; 1322 if (file && is_file_hugepages(file)) { 1323 /* 1324 * Check if the given range is hugepage aligned, and 1325 * can be made suitable for hugepages. 1326 */ 1327 ret = prepare_hugepage_range(addr, len); 1328 } else { 1329 /* 1330 * Ensure that a normal request is not falling in a 1331 * reserved hugepage range. For some archs like IA-64, 1332 * there is a separate region for hugepages. 1333 */ 1334 ret = is_hugepage_only_range(current->mm, addr, len); 1335 } 1336 if (ret) 1337 return -EINVAL; 1338 return addr; 1339 } 1340 1341 EXPORT_SYMBOL(get_unmapped_area); 1342 1343 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1344 struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr) 1345 { 1346 struct vm_area_struct *vma = NULL; 1347 1348 if (mm) { 1349 /* Check the cache first. */ 1350 /* (Cache hit rate is typically around 35%.) */ 1351 vma = mm->mmap_cache; 1352 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1353 struct rb_node * rb_node; 1354 1355 rb_node = mm->mm_rb.rb_node; 1356 vma = NULL; 1357 1358 while (rb_node) { 1359 struct vm_area_struct * vma_tmp; 1360 1361 vma_tmp = rb_entry(rb_node, 1362 struct vm_area_struct, vm_rb); 1363 1364 if (vma_tmp->vm_end > addr) { 1365 vma = vma_tmp; 1366 if (vma_tmp->vm_start <= addr) 1367 break; 1368 rb_node = rb_node->rb_left; 1369 } else 1370 rb_node = rb_node->rb_right; 1371 } 1372 if (vma) 1373 mm->mmap_cache = vma; 1374 } 1375 } 1376 return vma; 1377 } 1378 1379 EXPORT_SYMBOL(find_vma); 1380 1381 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1382 struct vm_area_struct * 1383 find_vma_prev(struct mm_struct *mm, unsigned long addr, 1384 struct vm_area_struct **pprev) 1385 { 1386 struct vm_area_struct *vma = NULL, *prev = NULL; 1387 struct rb_node * rb_node; 1388 if (!mm) 1389 goto out; 1390 1391 /* Guard against addr being lower than the first VMA */ 1392 vma = mm->mmap; 1393 1394 /* Go through the RB tree quickly. */ 1395 rb_node = mm->mm_rb.rb_node; 1396 1397 while (rb_node) { 1398 struct vm_area_struct *vma_tmp; 1399 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1400 1401 if (addr < vma_tmp->vm_end) { 1402 rb_node = rb_node->rb_left; 1403 } else { 1404 prev = vma_tmp; 1405 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1406 break; 1407 rb_node = rb_node->rb_right; 1408 } 1409 } 1410 1411 out: 1412 *pprev = prev; 1413 return prev ? prev->vm_next : vma; 1414 } 1415 1416 /* 1417 * Verify that the stack growth is acceptable and 1418 * update accounting. This is shared with both the 1419 * grow-up and grow-down cases. 1420 */ 1421 static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow) 1422 { 1423 struct mm_struct *mm = vma->vm_mm; 1424 struct rlimit *rlim = current->signal->rlim; 1425 1426 /* address space limit tests */ 1427 if (!may_expand_vm(mm, grow)) 1428 return -ENOMEM; 1429 1430 /* Stack limit test */ 1431 if (size > rlim[RLIMIT_STACK].rlim_cur) 1432 return -ENOMEM; 1433 1434 /* mlock limit tests */ 1435 if (vma->vm_flags & VM_LOCKED) { 1436 unsigned long locked; 1437 unsigned long limit; 1438 locked = mm->locked_vm + grow; 1439 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1440 if (locked > limit && !capable(CAP_IPC_LOCK)) 1441 return -ENOMEM; 1442 } 1443 1444 /* 1445 * Overcommit.. This must be the final test, as it will 1446 * update security statistics. 1447 */ 1448 if (security_vm_enough_memory(grow)) 1449 return -ENOMEM; 1450 1451 /* Ok, everything looks good - let it rip */ 1452 mm->total_vm += grow; 1453 if (vma->vm_flags & VM_LOCKED) 1454 mm->locked_vm += grow; 1455 __vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1456 return 0; 1457 } 1458 1459 #ifdef CONFIG_STACK_GROWSUP 1460 /* 1461 * vma is the first one with address > vma->vm_end. Have to extend vma. 1462 */ 1463 int expand_stack(struct vm_area_struct * vma, unsigned long address) 1464 { 1465 int error; 1466 1467 if (!(vma->vm_flags & VM_GROWSUP)) 1468 return -EFAULT; 1469 1470 /* 1471 * We must make sure the anon_vma is allocated 1472 * so that the anon_vma locking is not a noop. 1473 */ 1474 if (unlikely(anon_vma_prepare(vma))) 1475 return -ENOMEM; 1476 anon_vma_lock(vma); 1477 1478 /* 1479 * vma->vm_start/vm_end cannot change under us because the caller 1480 * is required to hold the mmap_sem in read mode. We need the 1481 * anon_vma lock to serialize against concurrent expand_stacks. 1482 */ 1483 address += 4 + PAGE_SIZE - 1; 1484 address &= PAGE_MASK; 1485 error = 0; 1486 1487 /* Somebody else might have raced and expanded it already */ 1488 if (address > vma->vm_end) { 1489 unsigned long size, grow; 1490 1491 size = address - vma->vm_start; 1492 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1493 1494 error = acct_stack_growth(vma, size, grow); 1495 if (!error) 1496 vma->vm_end = address; 1497 } 1498 anon_vma_unlock(vma); 1499 return error; 1500 } 1501 1502 struct vm_area_struct * 1503 find_extend_vma(struct mm_struct *mm, unsigned long addr) 1504 { 1505 struct vm_area_struct *vma, *prev; 1506 1507 addr &= PAGE_MASK; 1508 vma = find_vma_prev(mm, addr, &prev); 1509 if (vma && (vma->vm_start <= addr)) 1510 return vma; 1511 if (!prev || expand_stack(prev, addr)) 1512 return NULL; 1513 if (prev->vm_flags & VM_LOCKED) { 1514 make_pages_present(addr, prev->vm_end); 1515 } 1516 return prev; 1517 } 1518 #else 1519 /* 1520 * vma is the first one with address < vma->vm_start. Have to extend vma. 1521 */ 1522 int expand_stack(struct vm_area_struct *vma, unsigned long address) 1523 { 1524 int error; 1525 1526 /* 1527 * We must make sure the anon_vma is allocated 1528 * so that the anon_vma locking is not a noop. 1529 */ 1530 if (unlikely(anon_vma_prepare(vma))) 1531 return -ENOMEM; 1532 anon_vma_lock(vma); 1533 1534 /* 1535 * vma->vm_start/vm_end cannot change under us because the caller 1536 * is required to hold the mmap_sem in read mode. We need the 1537 * anon_vma lock to serialize against concurrent expand_stacks. 1538 */ 1539 address &= PAGE_MASK; 1540 error = 0; 1541 1542 /* Somebody else might have raced and expanded it already */ 1543 if (address < vma->vm_start) { 1544 unsigned long size, grow; 1545 1546 size = vma->vm_end - address; 1547 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1548 1549 error = acct_stack_growth(vma, size, grow); 1550 if (!error) { 1551 vma->vm_start = address; 1552 vma->vm_pgoff -= grow; 1553 } 1554 } 1555 anon_vma_unlock(vma); 1556 return error; 1557 } 1558 1559 struct vm_area_struct * 1560 find_extend_vma(struct mm_struct * mm, unsigned long addr) 1561 { 1562 struct vm_area_struct * vma; 1563 unsigned long start; 1564 1565 addr &= PAGE_MASK; 1566 vma = find_vma(mm,addr); 1567 if (!vma) 1568 return NULL; 1569 if (vma->vm_start <= addr) 1570 return vma; 1571 if (!(vma->vm_flags & VM_GROWSDOWN)) 1572 return NULL; 1573 start = vma->vm_start; 1574 if (expand_stack(vma, addr)) 1575 return NULL; 1576 if (vma->vm_flags & VM_LOCKED) { 1577 make_pages_present(addr, start); 1578 } 1579 return vma; 1580 } 1581 #endif 1582 1583 /* Normal function to fix up a mapping 1584 * This function is the default for when an area has no specific 1585 * function. This may be used as part of a more specific routine. 1586 * 1587 * By the time this function is called, the area struct has been 1588 * removed from the process mapping list. 1589 */ 1590 static void unmap_vma(struct mm_struct *mm, struct vm_area_struct *area) 1591 { 1592 size_t len = area->vm_end - area->vm_start; 1593 1594 area->vm_mm->total_vm -= len >> PAGE_SHIFT; 1595 if (area->vm_flags & VM_LOCKED) 1596 area->vm_mm->locked_vm -= len >> PAGE_SHIFT; 1597 vm_stat_unaccount(area); 1598 area->vm_mm->unmap_area(area); 1599 remove_vm_struct(area); 1600 } 1601 1602 /* 1603 * Update the VMA and inode share lists. 1604 * 1605 * Ok - we have the memory areas we should free on the 'free' list, 1606 * so release them, and do the vma updates. 1607 */ 1608 static void unmap_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1609 { 1610 do { 1611 struct vm_area_struct *next = vma->vm_next; 1612 unmap_vma(mm, vma); 1613 vma = next; 1614 } while (vma); 1615 validate_mm(mm); 1616 } 1617 1618 /* 1619 * Get rid of page table information in the indicated region. 1620 * 1621 * Called with the page table lock held. 1622 */ 1623 static void unmap_region(struct mm_struct *mm, 1624 struct vm_area_struct *vma, struct vm_area_struct *prev, 1625 unsigned long start, unsigned long end) 1626 { 1627 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1628 struct mmu_gather *tlb; 1629 unsigned long nr_accounted = 0; 1630 1631 lru_add_drain(); 1632 spin_lock(&mm->page_table_lock); 1633 tlb = tlb_gather_mmu(mm, 0); 1634 unmap_vmas(&tlb, mm, vma, start, end, &nr_accounted, NULL); 1635 vm_unacct_memory(nr_accounted); 1636 free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1637 next? next->vm_start: 0); 1638 tlb_finish_mmu(tlb, start, end); 1639 spin_unlock(&mm->page_table_lock); 1640 } 1641 1642 /* 1643 * Create a list of vma's touched by the unmap, removing them from the mm's 1644 * vma list as we go.. 1645 */ 1646 static void 1647 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1648 struct vm_area_struct *prev, unsigned long end) 1649 { 1650 struct vm_area_struct **insertion_point; 1651 struct vm_area_struct *tail_vma = NULL; 1652 1653 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1654 do { 1655 rb_erase(&vma->vm_rb, &mm->mm_rb); 1656 mm->map_count--; 1657 tail_vma = vma; 1658 vma = vma->vm_next; 1659 } while (vma && vma->vm_start < end); 1660 *insertion_point = vma; 1661 tail_vma->vm_next = NULL; 1662 mm->mmap_cache = NULL; /* Kill the cache. */ 1663 } 1664 1665 /* 1666 * Split a vma into two pieces at address 'addr', a new vma is allocated 1667 * either for the first part or the the tail. 1668 */ 1669 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1670 unsigned long addr, int new_below) 1671 { 1672 struct mempolicy *pol; 1673 struct vm_area_struct *new; 1674 1675 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK)) 1676 return -EINVAL; 1677 1678 if (mm->map_count >= sysctl_max_map_count) 1679 return -ENOMEM; 1680 1681 new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 1682 if (!new) 1683 return -ENOMEM; 1684 1685 /* most fields are the same, copy all, and then fixup */ 1686 *new = *vma; 1687 1688 if (new_below) 1689 new->vm_end = addr; 1690 else { 1691 new->vm_start = addr; 1692 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1693 } 1694 1695 pol = mpol_copy(vma_policy(vma)); 1696 if (IS_ERR(pol)) { 1697 kmem_cache_free(vm_area_cachep, new); 1698 return PTR_ERR(pol); 1699 } 1700 vma_set_policy(new, pol); 1701 1702 if (new->vm_file) 1703 get_file(new->vm_file); 1704 1705 if (new->vm_ops && new->vm_ops->open) 1706 new->vm_ops->open(new); 1707 1708 if (new_below) 1709 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1710 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1711 else 1712 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1713 1714 return 0; 1715 } 1716 1717 /* Munmap is split into 2 main parts -- this part which finds 1718 * what needs doing, and the areas themselves, which do the 1719 * work. This now handles partial unmappings. 1720 * Jeremy Fitzhardinge <jeremy@goop.org> 1721 */ 1722 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1723 { 1724 unsigned long end; 1725 struct vm_area_struct *vma, *prev, *last; 1726 1727 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1728 return -EINVAL; 1729 1730 if ((len = PAGE_ALIGN(len)) == 0) 1731 return -EINVAL; 1732 1733 /* Find the first overlapping VMA */ 1734 vma = find_vma_prev(mm, start, &prev); 1735 if (!vma) 1736 return 0; 1737 /* we have start < vma->vm_end */ 1738 1739 /* if it doesn't overlap, we have nothing.. */ 1740 end = start + len; 1741 if (vma->vm_start >= end) 1742 return 0; 1743 1744 /* 1745 * If we need to split any vma, do it now to save pain later. 1746 * 1747 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1748 * unmapped vm_area_struct will remain in use: so lower split_vma 1749 * places tmp vma above, and higher split_vma places tmp vma below. 1750 */ 1751 if (start > vma->vm_start) { 1752 int error = split_vma(mm, vma, start, 0); 1753 if (error) 1754 return error; 1755 prev = vma; 1756 } 1757 1758 /* Does it split the last one? */ 1759 last = find_vma(mm, end); 1760 if (last && end > last->vm_start) { 1761 int error = split_vma(mm, last, end, 1); 1762 if (error) 1763 return error; 1764 } 1765 vma = prev? prev->vm_next: mm->mmap; 1766 1767 /* 1768 * Remove the vma's, and unmap the actual pages 1769 */ 1770 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1771 unmap_region(mm, vma, prev, start, end); 1772 1773 /* Fix up all other VM information */ 1774 unmap_vma_list(mm, vma); 1775 1776 return 0; 1777 } 1778 1779 EXPORT_SYMBOL(do_munmap); 1780 1781 asmlinkage long sys_munmap(unsigned long addr, size_t len) 1782 { 1783 int ret; 1784 struct mm_struct *mm = current->mm; 1785 1786 profile_munmap(addr); 1787 1788 down_write(&mm->mmap_sem); 1789 ret = do_munmap(mm, addr, len); 1790 up_write(&mm->mmap_sem); 1791 return ret; 1792 } 1793 1794 static inline void verify_mm_writelocked(struct mm_struct *mm) 1795 { 1796 #ifdef CONFIG_DEBUG_KERNEL 1797 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1798 WARN_ON(1); 1799 up_read(&mm->mmap_sem); 1800 } 1801 #endif 1802 } 1803 1804 /* 1805 * this is really a simplified "do_mmap". it only handles 1806 * anonymous maps. eventually we may be able to do some 1807 * brk-specific accounting here. 1808 */ 1809 unsigned long do_brk(unsigned long addr, unsigned long len) 1810 { 1811 struct mm_struct * mm = current->mm; 1812 struct vm_area_struct * vma, * prev; 1813 unsigned long flags; 1814 struct rb_node ** rb_link, * rb_parent; 1815 pgoff_t pgoff = addr >> PAGE_SHIFT; 1816 1817 len = PAGE_ALIGN(len); 1818 if (!len) 1819 return addr; 1820 1821 if ((addr + len) > TASK_SIZE || (addr + len) < addr) 1822 return -EINVAL; 1823 1824 /* 1825 * mlock MCL_FUTURE? 1826 */ 1827 if (mm->def_flags & VM_LOCKED) { 1828 unsigned long locked, lock_limit; 1829 locked = len >> PAGE_SHIFT; 1830 locked += mm->locked_vm; 1831 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 1832 lock_limit >>= PAGE_SHIFT; 1833 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1834 return -EAGAIN; 1835 } 1836 1837 /* 1838 * mm->mmap_sem is required to protect against another thread 1839 * changing the mappings in case we sleep. 1840 */ 1841 verify_mm_writelocked(mm); 1842 1843 /* 1844 * Clear old maps. this also does some error checking for us 1845 */ 1846 munmap_back: 1847 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1848 if (vma && vma->vm_start < addr + len) { 1849 if (do_munmap(mm, addr, len)) 1850 return -ENOMEM; 1851 goto munmap_back; 1852 } 1853 1854 /* Check against address space limits *after* clearing old maps... */ 1855 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1856 return -ENOMEM; 1857 1858 if (mm->map_count > sysctl_max_map_count) 1859 return -ENOMEM; 1860 1861 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 1862 return -ENOMEM; 1863 1864 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 1865 1866 /* Can we just expand an old private anonymous mapping? */ 1867 if (vma_merge(mm, prev, addr, addr + len, flags, 1868 NULL, NULL, pgoff, NULL)) 1869 goto out; 1870 1871 /* 1872 * create a vma struct for an anonymous mapping 1873 */ 1874 vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 1875 if (!vma) { 1876 vm_unacct_memory(len >> PAGE_SHIFT); 1877 return -ENOMEM; 1878 } 1879 memset(vma, 0, sizeof(*vma)); 1880 1881 vma->vm_mm = mm; 1882 vma->vm_start = addr; 1883 vma->vm_end = addr + len; 1884 vma->vm_pgoff = pgoff; 1885 vma->vm_flags = flags; 1886 vma->vm_page_prot = protection_map[flags & 0x0f]; 1887 vma_link(mm, vma, prev, rb_link, rb_parent); 1888 out: 1889 mm->total_vm += len >> PAGE_SHIFT; 1890 if (flags & VM_LOCKED) { 1891 mm->locked_vm += len >> PAGE_SHIFT; 1892 make_pages_present(addr, addr + len); 1893 } 1894 return addr; 1895 } 1896 1897 EXPORT_SYMBOL(do_brk); 1898 1899 /* Release all mmaps. */ 1900 void exit_mmap(struct mm_struct *mm) 1901 { 1902 struct mmu_gather *tlb; 1903 struct vm_area_struct *vma = mm->mmap; 1904 unsigned long nr_accounted = 0; 1905 unsigned long end; 1906 1907 lru_add_drain(); 1908 1909 spin_lock(&mm->page_table_lock); 1910 1911 flush_cache_mm(mm); 1912 tlb = tlb_gather_mmu(mm, 1); 1913 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 1914 end = unmap_vmas(&tlb, mm, vma, 0, -1, &nr_accounted, NULL); 1915 vm_unacct_memory(nr_accounted); 1916 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); 1917 tlb_finish_mmu(tlb, 0, end); 1918 1919 mm->mmap = mm->mmap_cache = NULL; 1920 mm->mm_rb = RB_ROOT; 1921 set_mm_counter(mm, rss, 0); 1922 mm->total_vm = 0; 1923 mm->locked_vm = 0; 1924 1925 spin_unlock(&mm->page_table_lock); 1926 1927 /* 1928 * Walk the list again, actually closing and freeing it 1929 * without holding any MM locks. 1930 */ 1931 while (vma) { 1932 struct vm_area_struct *next = vma->vm_next; 1933 remove_vm_struct(vma); 1934 vma = next; 1935 } 1936 1937 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 1938 } 1939 1940 /* Insert vm structure into process list sorted by address 1941 * and into the inode's i_mmap tree. If vm_file is non-NULL 1942 * then i_mmap_lock is taken here. 1943 */ 1944 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 1945 { 1946 struct vm_area_struct * __vma, * prev; 1947 struct rb_node ** rb_link, * rb_parent; 1948 1949 /* 1950 * The vm_pgoff of a purely anonymous vma should be irrelevant 1951 * until its first write fault, when page's anon_vma and index 1952 * are set. But now set the vm_pgoff it will almost certainly 1953 * end up with (unless mremap moves it elsewhere before that 1954 * first wfault), so /proc/pid/maps tells a consistent story. 1955 * 1956 * By setting it to reflect the virtual start address of the 1957 * vma, merges and splits can happen in a seamless way, just 1958 * using the existing file pgoff checks and manipulations. 1959 * Similarly in do_mmap_pgoff and in do_brk. 1960 */ 1961 if (!vma->vm_file) { 1962 BUG_ON(vma->anon_vma); 1963 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 1964 } 1965 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 1966 if (__vma && __vma->vm_start < vma->vm_end) 1967 return -ENOMEM; 1968 vma_link(mm, vma, prev, rb_link, rb_parent); 1969 return 0; 1970 } 1971 1972 /* 1973 * Copy the vma structure to a new location in the same mm, 1974 * prior to moving page table entries, to effect an mremap move. 1975 */ 1976 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 1977 unsigned long addr, unsigned long len, pgoff_t pgoff) 1978 { 1979 struct vm_area_struct *vma = *vmap; 1980 unsigned long vma_start = vma->vm_start; 1981 struct mm_struct *mm = vma->vm_mm; 1982 struct vm_area_struct *new_vma, *prev; 1983 struct rb_node **rb_link, *rb_parent; 1984 struct mempolicy *pol; 1985 1986 /* 1987 * If anonymous vma has not yet been faulted, update new pgoff 1988 * to match new location, to increase its chance of merging. 1989 */ 1990 if (!vma->vm_file && !vma->anon_vma) 1991 pgoff = addr >> PAGE_SHIFT; 1992 1993 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1994 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 1995 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 1996 if (new_vma) { 1997 /* 1998 * Source vma may have been merged into new_vma 1999 */ 2000 if (vma_start >= new_vma->vm_start && 2001 vma_start < new_vma->vm_end) 2002 *vmap = new_vma; 2003 } else { 2004 new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 2005 if (new_vma) { 2006 *new_vma = *vma; 2007 pol = mpol_copy(vma_policy(vma)); 2008 if (IS_ERR(pol)) { 2009 kmem_cache_free(vm_area_cachep, new_vma); 2010 return NULL; 2011 } 2012 vma_set_policy(new_vma, pol); 2013 new_vma->vm_start = addr; 2014 new_vma->vm_end = addr + len; 2015 new_vma->vm_pgoff = pgoff; 2016 if (new_vma->vm_file) 2017 get_file(new_vma->vm_file); 2018 if (new_vma->vm_ops && new_vma->vm_ops->open) 2019 new_vma->vm_ops->open(new_vma); 2020 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2021 } 2022 } 2023 return new_vma; 2024 } 2025 2026 /* 2027 * Return true if the calling process may expand its vm space by the passed 2028 * number of pages 2029 */ 2030 int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2031 { 2032 unsigned long cur = mm->total_vm; /* pages */ 2033 unsigned long lim; 2034 2035 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2036 2037 if (cur + npages > lim) 2038 return 0; 2039 return 1; 2040 } 2041