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 __read_mostly = 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 /* 147 * cast `allowed' as a signed long because vm_committed_space 148 * sometimes has a negative value 149 */ 150 if (atomic_read(&vm_committed_space) < (long)allowed) 151 return 0; 152 153 vm_unacct_memory(pages); 154 155 return -ENOMEM; 156 } 157 158 EXPORT_SYMBOL(sysctl_overcommit_memory); 159 EXPORT_SYMBOL(sysctl_overcommit_ratio); 160 EXPORT_SYMBOL(sysctl_max_map_count); 161 EXPORT_SYMBOL(vm_committed_space); 162 EXPORT_SYMBOL(__vm_enough_memory); 163 164 /* 165 * Requires inode->i_mapping->i_mmap_lock 166 */ 167 static void __remove_shared_vm_struct(struct vm_area_struct *vma, 168 struct file *file, struct address_space *mapping) 169 { 170 if (vma->vm_flags & VM_DENYWRITE) 171 atomic_inc(&file->f_dentry->d_inode->i_writecount); 172 if (vma->vm_flags & VM_SHARED) 173 mapping->i_mmap_writable--; 174 175 flush_dcache_mmap_lock(mapping); 176 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 177 list_del_init(&vma->shared.vm_set.list); 178 else 179 vma_prio_tree_remove(vma, &mapping->i_mmap); 180 flush_dcache_mmap_unlock(mapping); 181 } 182 183 /* 184 * Unlink a file-based vm structure from its prio_tree, to hide 185 * vma from rmap and vmtruncate before freeing its page tables. 186 */ 187 void unlink_file_vma(struct vm_area_struct *vma) 188 { 189 struct file *file = vma->vm_file; 190 191 if (file) { 192 struct address_space *mapping = file->f_mapping; 193 spin_lock(&mapping->i_mmap_lock); 194 __remove_shared_vm_struct(vma, file, mapping); 195 spin_unlock(&mapping->i_mmap_lock); 196 } 197 } 198 199 /* 200 * Close a vm structure and free it, returning the next. 201 */ 202 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 203 { 204 struct vm_area_struct *next = vma->vm_next; 205 206 might_sleep(); 207 if (vma->vm_ops && vma->vm_ops->close) 208 vma->vm_ops->close(vma); 209 if (vma->vm_file) 210 fput(vma->vm_file); 211 mpol_free(vma_policy(vma)); 212 kmem_cache_free(vm_area_cachep, vma); 213 return next; 214 } 215 216 asmlinkage unsigned long sys_brk(unsigned long brk) 217 { 218 unsigned long rlim, retval; 219 unsigned long newbrk, oldbrk; 220 struct mm_struct *mm = current->mm; 221 222 down_write(&mm->mmap_sem); 223 224 if (brk < mm->end_code) 225 goto out; 226 newbrk = PAGE_ALIGN(brk); 227 oldbrk = PAGE_ALIGN(mm->brk); 228 if (oldbrk == newbrk) 229 goto set_brk; 230 231 /* Always allow shrinking brk. */ 232 if (brk <= mm->brk) { 233 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 234 goto set_brk; 235 goto out; 236 } 237 238 /* Check against rlimit.. */ 239 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 240 if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim) 241 goto out; 242 243 /* Check against existing mmap mappings. */ 244 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 245 goto out; 246 247 /* Ok, looks good - let it rip. */ 248 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 249 goto out; 250 set_brk: 251 mm->brk = brk; 252 out: 253 retval = mm->brk; 254 up_write(&mm->mmap_sem); 255 return retval; 256 } 257 258 #ifdef DEBUG_MM_RB 259 static int browse_rb(struct rb_root *root) 260 { 261 int i = 0, j; 262 struct rb_node *nd, *pn = NULL; 263 unsigned long prev = 0, pend = 0; 264 265 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 266 struct vm_area_struct *vma; 267 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 268 if (vma->vm_start < prev) 269 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 270 if (vma->vm_start < pend) 271 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 272 if (vma->vm_start > vma->vm_end) 273 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 274 i++; 275 pn = nd; 276 } 277 j = 0; 278 for (nd = pn; nd; nd = rb_prev(nd)) { 279 j++; 280 } 281 if (i != j) 282 printk("backwards %d, forwards %d\n", j, i), i = 0; 283 return i; 284 } 285 286 void validate_mm(struct mm_struct *mm) 287 { 288 int bug = 0; 289 int i = 0; 290 struct vm_area_struct *tmp = mm->mmap; 291 while (tmp) { 292 tmp = tmp->vm_next; 293 i++; 294 } 295 if (i != mm->map_count) 296 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 297 i = browse_rb(&mm->mm_rb); 298 if (i != mm->map_count) 299 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 300 if (bug) 301 BUG(); 302 } 303 #else 304 #define validate_mm(mm) do { } while (0) 305 #endif 306 307 static struct vm_area_struct * 308 find_vma_prepare(struct mm_struct *mm, unsigned long addr, 309 struct vm_area_struct **pprev, struct rb_node ***rb_link, 310 struct rb_node ** rb_parent) 311 { 312 struct vm_area_struct * vma; 313 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 314 315 __rb_link = &mm->mm_rb.rb_node; 316 rb_prev = __rb_parent = NULL; 317 vma = NULL; 318 319 while (*__rb_link) { 320 struct vm_area_struct *vma_tmp; 321 322 __rb_parent = *__rb_link; 323 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 324 325 if (vma_tmp->vm_end > addr) { 326 vma = vma_tmp; 327 if (vma_tmp->vm_start <= addr) 328 return vma; 329 __rb_link = &__rb_parent->rb_left; 330 } else { 331 rb_prev = __rb_parent; 332 __rb_link = &__rb_parent->rb_right; 333 } 334 } 335 336 *pprev = NULL; 337 if (rb_prev) 338 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 339 *rb_link = __rb_link; 340 *rb_parent = __rb_parent; 341 return vma; 342 } 343 344 static inline void 345 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 346 struct vm_area_struct *prev, struct rb_node *rb_parent) 347 { 348 if (prev) { 349 vma->vm_next = prev->vm_next; 350 prev->vm_next = vma; 351 } else { 352 mm->mmap = vma; 353 if (rb_parent) 354 vma->vm_next = rb_entry(rb_parent, 355 struct vm_area_struct, vm_rb); 356 else 357 vma->vm_next = NULL; 358 } 359 } 360 361 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 362 struct rb_node **rb_link, struct rb_node *rb_parent) 363 { 364 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 365 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 366 } 367 368 static inline void __vma_link_file(struct vm_area_struct *vma) 369 { 370 struct file * file; 371 372 file = vma->vm_file; 373 if (file) { 374 struct address_space *mapping = file->f_mapping; 375 376 if (vma->vm_flags & VM_DENYWRITE) 377 atomic_dec(&file->f_dentry->d_inode->i_writecount); 378 if (vma->vm_flags & VM_SHARED) 379 mapping->i_mmap_writable++; 380 381 flush_dcache_mmap_lock(mapping); 382 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 383 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 384 else 385 vma_prio_tree_insert(vma, &mapping->i_mmap); 386 flush_dcache_mmap_unlock(mapping); 387 } 388 } 389 390 static void 391 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 392 struct vm_area_struct *prev, struct rb_node **rb_link, 393 struct rb_node *rb_parent) 394 { 395 __vma_link_list(mm, vma, prev, rb_parent); 396 __vma_link_rb(mm, vma, rb_link, rb_parent); 397 __anon_vma_link(vma); 398 } 399 400 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 401 struct vm_area_struct *prev, struct rb_node **rb_link, 402 struct rb_node *rb_parent) 403 { 404 struct address_space *mapping = NULL; 405 406 if (vma->vm_file) 407 mapping = vma->vm_file->f_mapping; 408 409 if (mapping) { 410 spin_lock(&mapping->i_mmap_lock); 411 vma->vm_truncate_count = mapping->truncate_count; 412 } 413 anon_vma_lock(vma); 414 415 __vma_link(mm, vma, prev, rb_link, rb_parent); 416 __vma_link_file(vma); 417 418 anon_vma_unlock(vma); 419 if (mapping) 420 spin_unlock(&mapping->i_mmap_lock); 421 422 mm->map_count++; 423 validate_mm(mm); 424 } 425 426 /* 427 * Helper for vma_adjust in the split_vma insert case: 428 * insert vm structure into list and rbtree and anon_vma, 429 * but it has already been inserted into prio_tree earlier. 430 */ 431 static void 432 __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 433 { 434 struct vm_area_struct * __vma, * prev; 435 struct rb_node ** rb_link, * rb_parent; 436 437 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); 438 if (__vma && __vma->vm_start < vma->vm_end) 439 BUG(); 440 __vma_link(mm, vma, prev, rb_link, rb_parent); 441 mm->map_count++; 442 } 443 444 static inline void 445 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 446 struct vm_area_struct *prev) 447 { 448 prev->vm_next = vma->vm_next; 449 rb_erase(&vma->vm_rb, &mm->mm_rb); 450 if (mm->mmap_cache == vma) 451 mm->mmap_cache = prev; 452 } 453 454 /* 455 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 456 * is already present in an i_mmap tree without adjusting the tree. 457 * The following helper function should be used when such adjustments 458 * are necessary. The "insert" vma (if any) is to be inserted 459 * before we drop the necessary locks. 460 */ 461 void vma_adjust(struct vm_area_struct *vma, unsigned long start, 462 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 463 { 464 struct mm_struct *mm = vma->vm_mm; 465 struct vm_area_struct *next = vma->vm_next; 466 struct vm_area_struct *importer = NULL; 467 struct address_space *mapping = NULL; 468 struct prio_tree_root *root = NULL; 469 struct file *file = vma->vm_file; 470 struct anon_vma *anon_vma = NULL; 471 long adjust_next = 0; 472 int remove_next = 0; 473 474 if (next && !insert) { 475 if (end >= next->vm_end) { 476 /* 477 * vma expands, overlapping all the next, and 478 * perhaps the one after too (mprotect case 6). 479 */ 480 again: remove_next = 1 + (end > next->vm_end); 481 end = next->vm_end; 482 anon_vma = next->anon_vma; 483 importer = vma; 484 } else if (end > next->vm_start) { 485 /* 486 * vma expands, overlapping part of the next: 487 * mprotect case 5 shifting the boundary up. 488 */ 489 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 490 anon_vma = next->anon_vma; 491 importer = vma; 492 } else if (end < vma->vm_end) { 493 /* 494 * vma shrinks, and !insert tells it's not 495 * split_vma inserting another: so it must be 496 * mprotect case 4 shifting the boundary down. 497 */ 498 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 499 anon_vma = next->anon_vma; 500 importer = next; 501 } 502 } 503 504 if (file) { 505 mapping = file->f_mapping; 506 if (!(vma->vm_flags & VM_NONLINEAR)) 507 root = &mapping->i_mmap; 508 spin_lock(&mapping->i_mmap_lock); 509 if (importer && 510 vma->vm_truncate_count != next->vm_truncate_count) { 511 /* 512 * unmap_mapping_range might be in progress: 513 * ensure that the expanding vma is rescanned. 514 */ 515 importer->vm_truncate_count = 0; 516 } 517 if (insert) { 518 insert->vm_truncate_count = vma->vm_truncate_count; 519 /* 520 * Put into prio_tree now, so instantiated pages 521 * are visible to arm/parisc __flush_dcache_page 522 * throughout; but we cannot insert into address 523 * space until vma start or end is updated. 524 */ 525 __vma_link_file(insert); 526 } 527 } 528 529 /* 530 * When changing only vma->vm_end, we don't really need 531 * anon_vma lock: but is that case worth optimizing out? 532 */ 533 if (vma->anon_vma) 534 anon_vma = vma->anon_vma; 535 if (anon_vma) { 536 spin_lock(&anon_vma->lock); 537 /* 538 * Easily overlooked: when mprotect shifts the boundary, 539 * make sure the expanding vma has anon_vma set if the 540 * shrinking vma had, to cover any anon pages imported. 541 */ 542 if (importer && !importer->anon_vma) { 543 importer->anon_vma = anon_vma; 544 __anon_vma_link(importer); 545 } 546 } 547 548 if (root) { 549 flush_dcache_mmap_lock(mapping); 550 vma_prio_tree_remove(vma, root); 551 if (adjust_next) 552 vma_prio_tree_remove(next, root); 553 } 554 555 vma->vm_start = start; 556 vma->vm_end = end; 557 vma->vm_pgoff = pgoff; 558 if (adjust_next) { 559 next->vm_start += adjust_next << PAGE_SHIFT; 560 next->vm_pgoff += adjust_next; 561 } 562 563 if (root) { 564 if (adjust_next) 565 vma_prio_tree_insert(next, root); 566 vma_prio_tree_insert(vma, root); 567 flush_dcache_mmap_unlock(mapping); 568 } 569 570 if (remove_next) { 571 /* 572 * vma_merge has merged next into vma, and needs 573 * us to remove next before dropping the locks. 574 */ 575 __vma_unlink(mm, next, vma); 576 if (file) 577 __remove_shared_vm_struct(next, file, mapping); 578 if (next->anon_vma) 579 __anon_vma_merge(vma, next); 580 } else if (insert) { 581 /* 582 * split_vma has split insert from vma, and needs 583 * us to insert it before dropping the locks 584 * (it may either follow vma or precede it). 585 */ 586 __insert_vm_struct(mm, insert); 587 } 588 589 if (anon_vma) 590 spin_unlock(&anon_vma->lock); 591 if (mapping) 592 spin_unlock(&mapping->i_mmap_lock); 593 594 if (remove_next) { 595 if (file) 596 fput(file); 597 mm->map_count--; 598 mpol_free(vma_policy(next)); 599 kmem_cache_free(vm_area_cachep, next); 600 /* 601 * In mprotect's case 6 (see comments on vma_merge), 602 * we must remove another next too. It would clutter 603 * up the code too much to do both in one go. 604 */ 605 if (remove_next == 2) { 606 next = vma->vm_next; 607 goto again; 608 } 609 } 610 611 validate_mm(mm); 612 } 613 614 /* 615 * If the vma has a ->close operation then the driver probably needs to release 616 * per-vma resources, so we don't attempt to merge those. 617 */ 618 #define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED) 619 620 static inline int is_mergeable_vma(struct vm_area_struct *vma, 621 struct file *file, unsigned long vm_flags) 622 { 623 if (vma->vm_flags != vm_flags) 624 return 0; 625 if (vma->vm_file != file) 626 return 0; 627 if (vma->vm_ops && vma->vm_ops->close) 628 return 0; 629 return 1; 630 } 631 632 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 633 struct anon_vma *anon_vma2) 634 { 635 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 636 } 637 638 /* 639 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 640 * in front of (at a lower virtual address and file offset than) the vma. 641 * 642 * We cannot merge two vmas if they have differently assigned (non-NULL) 643 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 644 * 645 * We don't check here for the merged mmap wrapping around the end of pagecache 646 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 647 * wrap, nor mmaps which cover the final page at index -1UL. 648 */ 649 static int 650 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 651 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 652 { 653 if (is_mergeable_vma(vma, file, vm_flags) && 654 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 655 if (vma->vm_pgoff == vm_pgoff) 656 return 1; 657 } 658 return 0; 659 } 660 661 /* 662 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 663 * beyond (at a higher virtual address and file offset than) the vma. 664 * 665 * We cannot merge two vmas if they have differently assigned (non-NULL) 666 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 667 */ 668 static int 669 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 670 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 671 { 672 if (is_mergeable_vma(vma, file, vm_flags) && 673 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 674 pgoff_t vm_pglen; 675 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 676 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 677 return 1; 678 } 679 return 0; 680 } 681 682 /* 683 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 684 * whether that can be merged with its predecessor or its successor. 685 * Or both (it neatly fills a hole). 686 * 687 * In most cases - when called for mmap, brk or mremap - [addr,end) is 688 * certain not to be mapped by the time vma_merge is called; but when 689 * called for mprotect, it is certain to be already mapped (either at 690 * an offset within prev, or at the start of next), and the flags of 691 * this area are about to be changed to vm_flags - and the no-change 692 * case has already been eliminated. 693 * 694 * The following mprotect cases have to be considered, where AAAA is 695 * the area passed down from mprotect_fixup, never extending beyond one 696 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 697 * 698 * AAAA AAAA AAAA AAAA 699 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 700 * cannot merge might become might become might become 701 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 702 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 703 * mremap move: PPPPNNNNNNNN 8 704 * AAAA 705 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 706 * might become case 1 below case 2 below case 3 below 707 * 708 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 709 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 710 */ 711 struct vm_area_struct *vma_merge(struct mm_struct *mm, 712 struct vm_area_struct *prev, unsigned long addr, 713 unsigned long end, unsigned long vm_flags, 714 struct anon_vma *anon_vma, struct file *file, 715 pgoff_t pgoff, struct mempolicy *policy) 716 { 717 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 718 struct vm_area_struct *area, *next; 719 720 /* 721 * We later require that vma->vm_flags == vm_flags, 722 * so this tests vma->vm_flags & VM_SPECIAL, too. 723 */ 724 if (vm_flags & VM_SPECIAL) 725 return NULL; 726 727 if (prev) 728 next = prev->vm_next; 729 else 730 next = mm->mmap; 731 area = next; 732 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 733 next = next->vm_next; 734 735 /* 736 * Can it merge with the predecessor? 737 */ 738 if (prev && prev->vm_end == addr && 739 mpol_equal(vma_policy(prev), policy) && 740 can_vma_merge_after(prev, vm_flags, 741 anon_vma, file, pgoff)) { 742 /* 743 * OK, it can. Can we now merge in the successor as well? 744 */ 745 if (next && end == next->vm_start && 746 mpol_equal(policy, vma_policy(next)) && 747 can_vma_merge_before(next, vm_flags, 748 anon_vma, file, pgoff+pglen) && 749 is_mergeable_anon_vma(prev->anon_vma, 750 next->anon_vma)) { 751 /* cases 1, 6 */ 752 vma_adjust(prev, prev->vm_start, 753 next->vm_end, prev->vm_pgoff, NULL); 754 } else /* cases 2, 5, 7 */ 755 vma_adjust(prev, prev->vm_start, 756 end, prev->vm_pgoff, NULL); 757 return prev; 758 } 759 760 /* 761 * Can this new request be merged in front of next? 762 */ 763 if (next && end == next->vm_start && 764 mpol_equal(policy, vma_policy(next)) && 765 can_vma_merge_before(next, vm_flags, 766 anon_vma, file, pgoff+pglen)) { 767 if (prev && addr < prev->vm_end) /* case 4 */ 768 vma_adjust(prev, prev->vm_start, 769 addr, prev->vm_pgoff, NULL); 770 else /* cases 3, 8 */ 771 vma_adjust(area, addr, next->vm_end, 772 next->vm_pgoff - pglen, NULL); 773 return area; 774 } 775 776 return NULL; 777 } 778 779 /* 780 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 781 * neighbouring vmas for a suitable anon_vma, before it goes off 782 * to allocate a new anon_vma. It checks because a repetitive 783 * sequence of mprotects and faults may otherwise lead to distinct 784 * anon_vmas being allocated, preventing vma merge in subsequent 785 * mprotect. 786 */ 787 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 788 { 789 struct vm_area_struct *near; 790 unsigned long vm_flags; 791 792 near = vma->vm_next; 793 if (!near) 794 goto try_prev; 795 796 /* 797 * Since only mprotect tries to remerge vmas, match flags 798 * which might be mprotected into each other later on. 799 * Neither mlock nor madvise tries to remerge at present, 800 * so leave their flags as obstructing a merge. 801 */ 802 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 803 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 804 805 if (near->anon_vma && vma->vm_end == near->vm_start && 806 mpol_equal(vma_policy(vma), vma_policy(near)) && 807 can_vma_merge_before(near, vm_flags, 808 NULL, vma->vm_file, vma->vm_pgoff + 809 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 810 return near->anon_vma; 811 try_prev: 812 /* 813 * It is potentially slow to have to call find_vma_prev here. 814 * But it's only on the first write fault on the vma, not 815 * every time, and we could devise a way to avoid it later 816 * (e.g. stash info in next's anon_vma_node when assigning 817 * an anon_vma, or when trying vma_merge). Another time. 818 */ 819 if (find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma) 820 BUG(); 821 if (!near) 822 goto none; 823 824 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 825 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 826 827 if (near->anon_vma && near->vm_end == vma->vm_start && 828 mpol_equal(vma_policy(near), vma_policy(vma)) && 829 can_vma_merge_after(near, vm_flags, 830 NULL, vma->vm_file, vma->vm_pgoff)) 831 return near->anon_vma; 832 none: 833 /* 834 * There's no absolute need to look only at touching neighbours: 835 * we could search further afield for "compatible" anon_vmas. 836 * But it would probably just be a waste of time searching, 837 * or lead to too many vmas hanging off the same anon_vma. 838 * We're trying to allow mprotect remerging later on, 839 * not trying to minimize memory used for anon_vmas. 840 */ 841 return NULL; 842 } 843 844 #ifdef CONFIG_PROC_FS 845 void vm_stat_account(struct mm_struct *mm, unsigned long flags, 846 struct file *file, long pages) 847 { 848 const unsigned long stack_flags 849 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 850 851 #ifdef CONFIG_HUGETLB 852 if (flags & VM_HUGETLB) { 853 if (!(flags & VM_DONTCOPY)) 854 mm->shared_vm += pages; 855 return; 856 } 857 #endif /* CONFIG_HUGETLB */ 858 859 if (file) { 860 mm->shared_vm += pages; 861 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 862 mm->exec_vm += pages; 863 } else if (flags & stack_flags) 864 mm->stack_vm += pages; 865 if (flags & (VM_RESERVED|VM_IO)) 866 mm->reserved_vm += pages; 867 } 868 #endif /* CONFIG_PROC_FS */ 869 870 /* 871 * The caller must hold down_write(current->mm->mmap_sem). 872 */ 873 874 unsigned long do_mmap_pgoff(struct file * file, unsigned long addr, 875 unsigned long len, unsigned long prot, 876 unsigned long flags, unsigned long pgoff) 877 { 878 struct mm_struct * mm = current->mm; 879 struct vm_area_struct * vma, * prev; 880 struct inode *inode; 881 unsigned int vm_flags; 882 int correct_wcount = 0; 883 int error; 884 struct rb_node ** rb_link, * rb_parent; 885 int accountable = 1; 886 unsigned long charged = 0, reqprot = prot; 887 888 if (file) { 889 if (is_file_hugepages(file)) 890 accountable = 0; 891 892 if (!file->f_op || !file->f_op->mmap) 893 return -ENODEV; 894 895 if ((prot & PROT_EXEC) && 896 (file->f_vfsmnt->mnt_flags & MNT_NOEXEC)) 897 return -EPERM; 898 } 899 /* 900 * Does the application expect PROT_READ to imply PROT_EXEC? 901 * 902 * (the exception is when the underlying filesystem is noexec 903 * mounted, in which case we dont add PROT_EXEC.) 904 */ 905 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 906 if (!(file && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))) 907 prot |= PROT_EXEC; 908 909 if (!len) 910 return -EINVAL; 911 912 /* Careful about overflows.. */ 913 len = PAGE_ALIGN(len); 914 if (!len || len > TASK_SIZE) 915 return -ENOMEM; 916 917 /* offset overflow? */ 918 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 919 return -EOVERFLOW; 920 921 /* Too many mappings? */ 922 if (mm->map_count > sysctl_max_map_count) 923 return -ENOMEM; 924 925 /* Obtain the address to map to. we verify (or select) it and ensure 926 * that it represents a valid section of the address space. 927 */ 928 addr = get_unmapped_area(file, addr, len, pgoff, flags); 929 if (addr & ~PAGE_MASK) 930 return addr; 931 932 /* Do simple checking here so the lower-level routines won't have 933 * to. we assume access permissions have been handled by the open 934 * of the memory object, so we don't do any here. 935 */ 936 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 937 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 938 939 if (flags & MAP_LOCKED) { 940 if (!can_do_mlock()) 941 return -EPERM; 942 vm_flags |= VM_LOCKED; 943 } 944 /* mlock MCL_FUTURE? */ 945 if (vm_flags & VM_LOCKED) { 946 unsigned long locked, lock_limit; 947 locked = len >> PAGE_SHIFT; 948 locked += mm->locked_vm; 949 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 950 lock_limit >>= PAGE_SHIFT; 951 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 952 return -EAGAIN; 953 } 954 955 inode = file ? file->f_dentry->d_inode : NULL; 956 957 if (file) { 958 switch (flags & MAP_TYPE) { 959 case MAP_SHARED: 960 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 961 return -EACCES; 962 963 /* 964 * Make sure we don't allow writing to an append-only 965 * file.. 966 */ 967 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 968 return -EACCES; 969 970 /* 971 * Make sure there are no mandatory locks on the file. 972 */ 973 if (locks_verify_locked(inode)) 974 return -EAGAIN; 975 976 vm_flags |= VM_SHARED | VM_MAYSHARE; 977 if (!(file->f_mode & FMODE_WRITE)) 978 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 979 980 /* fall through */ 981 case MAP_PRIVATE: 982 if (!(file->f_mode & FMODE_READ)) 983 return -EACCES; 984 break; 985 986 default: 987 return -EINVAL; 988 } 989 } else { 990 switch (flags & MAP_TYPE) { 991 case MAP_SHARED: 992 vm_flags |= VM_SHARED | VM_MAYSHARE; 993 break; 994 case MAP_PRIVATE: 995 /* 996 * Set pgoff according to addr for anon_vma. 997 */ 998 pgoff = addr >> PAGE_SHIFT; 999 break; 1000 default: 1001 return -EINVAL; 1002 } 1003 } 1004 1005 error = security_file_mmap(file, reqprot, prot, flags); 1006 if (error) 1007 return error; 1008 1009 /* Clear old maps */ 1010 error = -ENOMEM; 1011 munmap_back: 1012 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1013 if (vma && vma->vm_start < addr + len) { 1014 if (do_munmap(mm, addr, len)) 1015 return -ENOMEM; 1016 goto munmap_back; 1017 } 1018 1019 /* Check against address space limit. */ 1020 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1021 return -ENOMEM; 1022 1023 if (accountable && (!(flags & MAP_NORESERVE) || 1024 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) { 1025 if (vm_flags & VM_SHARED) { 1026 /* Check memory availability in shmem_file_setup? */ 1027 vm_flags |= VM_ACCOUNT; 1028 } else if (vm_flags & VM_WRITE) { 1029 /* 1030 * Private writable mapping: check memory availability 1031 */ 1032 charged = len >> PAGE_SHIFT; 1033 if (security_vm_enough_memory(charged)) 1034 return -ENOMEM; 1035 vm_flags |= VM_ACCOUNT; 1036 } 1037 } 1038 1039 /* 1040 * Can we just expand an old private anonymous mapping? 1041 * The VM_SHARED test is necessary because shmem_zero_setup 1042 * will create the file object for a shared anonymous map below. 1043 */ 1044 if (!file && !(vm_flags & VM_SHARED) && 1045 vma_merge(mm, prev, addr, addr + len, vm_flags, 1046 NULL, NULL, pgoff, NULL)) 1047 goto out; 1048 1049 /* 1050 * Determine the object being mapped and call the appropriate 1051 * specific mapper. the address has already been validated, but 1052 * not unmapped, but the maps are removed from the list. 1053 */ 1054 vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 1055 if (!vma) { 1056 error = -ENOMEM; 1057 goto unacct_error; 1058 } 1059 memset(vma, 0, sizeof(*vma)); 1060 1061 vma->vm_mm = mm; 1062 vma->vm_start = addr; 1063 vma->vm_end = addr + len; 1064 vma->vm_flags = vm_flags; 1065 vma->vm_page_prot = protection_map[vm_flags & 0x0f]; 1066 vma->vm_pgoff = pgoff; 1067 1068 if (file) { 1069 error = -EINVAL; 1070 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1071 goto free_vma; 1072 if (vm_flags & VM_DENYWRITE) { 1073 error = deny_write_access(file); 1074 if (error) 1075 goto free_vma; 1076 correct_wcount = 1; 1077 } 1078 vma->vm_file = file; 1079 get_file(file); 1080 error = file->f_op->mmap(file, vma); 1081 if (error) 1082 goto unmap_and_free_vma; 1083 if ((vma->vm_flags & (VM_SHARED | VM_WRITE | VM_RESERVED)) 1084 == (VM_WRITE | VM_RESERVED)) { 1085 printk(KERN_WARNING "program %s is using MAP_PRIVATE, " 1086 "PROT_WRITE mmap of VM_RESERVED memory, which " 1087 "is deprecated. Please report this to " 1088 "linux-kernel@vger.kernel.org\n",current->comm); 1089 if (vma->vm_ops && vma->vm_ops->close) 1090 vma->vm_ops->close(vma); 1091 error = -EACCES; 1092 goto unmap_and_free_vma; 1093 } 1094 } else if (vm_flags & VM_SHARED) { 1095 error = shmem_zero_setup(vma); 1096 if (error) 1097 goto free_vma; 1098 } 1099 1100 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform 1101 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap) 1102 * that memory reservation must be checked; but that reservation 1103 * belongs to shared memory object, not to vma: so now clear it. 1104 */ 1105 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT)) 1106 vma->vm_flags &= ~VM_ACCOUNT; 1107 1108 /* Can addr have changed?? 1109 * 1110 * Answer: Yes, several device drivers can do it in their 1111 * f_op->mmap method. -DaveM 1112 */ 1113 addr = vma->vm_start; 1114 pgoff = vma->vm_pgoff; 1115 vm_flags = vma->vm_flags; 1116 1117 if (!file || !vma_merge(mm, prev, addr, vma->vm_end, 1118 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) { 1119 file = vma->vm_file; 1120 vma_link(mm, vma, prev, rb_link, rb_parent); 1121 if (correct_wcount) 1122 atomic_inc(&inode->i_writecount); 1123 } else { 1124 if (file) { 1125 if (correct_wcount) 1126 atomic_inc(&inode->i_writecount); 1127 fput(file); 1128 } 1129 mpol_free(vma_policy(vma)); 1130 kmem_cache_free(vm_area_cachep, vma); 1131 } 1132 out: 1133 mm->total_vm += len >> PAGE_SHIFT; 1134 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1135 if (vm_flags & VM_LOCKED) { 1136 mm->locked_vm += len >> PAGE_SHIFT; 1137 make_pages_present(addr, addr + len); 1138 } 1139 if (flags & MAP_POPULATE) { 1140 up_write(&mm->mmap_sem); 1141 sys_remap_file_pages(addr, len, 0, 1142 pgoff, flags & MAP_NONBLOCK); 1143 down_write(&mm->mmap_sem); 1144 } 1145 return addr; 1146 1147 unmap_and_free_vma: 1148 if (correct_wcount) 1149 atomic_inc(&inode->i_writecount); 1150 vma->vm_file = NULL; 1151 fput(file); 1152 1153 /* Undo any partial mapping done by a device driver. */ 1154 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1155 charged = 0; 1156 free_vma: 1157 kmem_cache_free(vm_area_cachep, vma); 1158 unacct_error: 1159 if (charged) 1160 vm_unacct_memory(charged); 1161 return error; 1162 } 1163 1164 EXPORT_SYMBOL(do_mmap_pgoff); 1165 1166 /* Get an address range which is currently unmapped. 1167 * For shmat() with addr=0. 1168 * 1169 * Ugly calling convention alert: 1170 * Return value with the low bits set means error value, 1171 * ie 1172 * if (ret & ~PAGE_MASK) 1173 * error = ret; 1174 * 1175 * This function "knows" that -ENOMEM has the bits set. 1176 */ 1177 #ifndef HAVE_ARCH_UNMAPPED_AREA 1178 unsigned long 1179 arch_get_unmapped_area(struct file *filp, unsigned long addr, 1180 unsigned long len, unsigned long pgoff, unsigned long flags) 1181 { 1182 struct mm_struct *mm = current->mm; 1183 struct vm_area_struct *vma; 1184 unsigned long start_addr; 1185 1186 if (len > TASK_SIZE) 1187 return -ENOMEM; 1188 1189 if (addr) { 1190 addr = PAGE_ALIGN(addr); 1191 vma = find_vma(mm, addr); 1192 if (TASK_SIZE - len >= addr && 1193 (!vma || addr + len <= vma->vm_start)) 1194 return addr; 1195 } 1196 if (len > mm->cached_hole_size) { 1197 start_addr = addr = mm->free_area_cache; 1198 } else { 1199 start_addr = addr = TASK_UNMAPPED_BASE; 1200 mm->cached_hole_size = 0; 1201 } 1202 1203 full_search: 1204 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1205 /* At this point: (!vma || addr < vma->vm_end). */ 1206 if (TASK_SIZE - len < addr) { 1207 /* 1208 * Start a new search - just in case we missed 1209 * some holes. 1210 */ 1211 if (start_addr != TASK_UNMAPPED_BASE) { 1212 addr = TASK_UNMAPPED_BASE; 1213 start_addr = addr; 1214 mm->cached_hole_size = 0; 1215 goto full_search; 1216 } 1217 return -ENOMEM; 1218 } 1219 if (!vma || addr + len <= vma->vm_start) { 1220 /* 1221 * Remember the place where we stopped the search: 1222 */ 1223 mm->free_area_cache = addr + len; 1224 return addr; 1225 } 1226 if (addr + mm->cached_hole_size < vma->vm_start) 1227 mm->cached_hole_size = vma->vm_start - addr; 1228 addr = vma->vm_end; 1229 } 1230 } 1231 #endif 1232 1233 void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1234 { 1235 /* 1236 * Is this a new hole at the lowest possible address? 1237 */ 1238 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { 1239 mm->free_area_cache = addr; 1240 mm->cached_hole_size = ~0UL; 1241 } 1242 } 1243 1244 /* 1245 * This mmap-allocator allocates new areas top-down from below the 1246 * stack's low limit (the base): 1247 */ 1248 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1249 unsigned long 1250 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1251 const unsigned long len, const unsigned long pgoff, 1252 const unsigned long flags) 1253 { 1254 struct vm_area_struct *vma; 1255 struct mm_struct *mm = current->mm; 1256 unsigned long addr = addr0; 1257 1258 /* requested length too big for entire address space */ 1259 if (len > TASK_SIZE) 1260 return -ENOMEM; 1261 1262 /* requesting a specific address */ 1263 if (addr) { 1264 addr = PAGE_ALIGN(addr); 1265 vma = find_vma(mm, addr); 1266 if (TASK_SIZE - len >= addr && 1267 (!vma || addr + len <= vma->vm_start)) 1268 return addr; 1269 } 1270 1271 /* check if free_area_cache is useful for us */ 1272 if (len <= mm->cached_hole_size) { 1273 mm->cached_hole_size = 0; 1274 mm->free_area_cache = mm->mmap_base; 1275 } 1276 1277 /* either no address requested or can't fit in requested address hole */ 1278 addr = mm->free_area_cache; 1279 1280 /* make sure it can fit in the remaining address space */ 1281 if (addr > len) { 1282 vma = find_vma(mm, addr-len); 1283 if (!vma || addr <= vma->vm_start) 1284 /* remember the address as a hint for next time */ 1285 return (mm->free_area_cache = addr-len); 1286 } 1287 1288 if (mm->mmap_base < len) 1289 goto bottomup; 1290 1291 addr = mm->mmap_base-len; 1292 1293 do { 1294 /* 1295 * Lookup failure means no vma is above this address, 1296 * else if new region fits below vma->vm_start, 1297 * return with success: 1298 */ 1299 vma = find_vma(mm, addr); 1300 if (!vma || addr+len <= vma->vm_start) 1301 /* remember the address as a hint for next time */ 1302 return (mm->free_area_cache = addr); 1303 1304 /* remember the largest hole we saw so far */ 1305 if (addr + mm->cached_hole_size < vma->vm_start) 1306 mm->cached_hole_size = vma->vm_start - addr; 1307 1308 /* try just below the current vma->vm_start */ 1309 addr = vma->vm_start-len; 1310 } while (len < vma->vm_start); 1311 1312 bottomup: 1313 /* 1314 * A failed mmap() very likely causes application failure, 1315 * so fall back to the bottom-up function here. This scenario 1316 * can happen with large stack limits and large mmap() 1317 * allocations. 1318 */ 1319 mm->cached_hole_size = ~0UL; 1320 mm->free_area_cache = TASK_UNMAPPED_BASE; 1321 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1322 /* 1323 * Restore the topdown base: 1324 */ 1325 mm->free_area_cache = mm->mmap_base; 1326 mm->cached_hole_size = ~0UL; 1327 1328 return addr; 1329 } 1330 #endif 1331 1332 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1333 { 1334 /* 1335 * Is this a new hole at the highest possible address? 1336 */ 1337 if (addr > mm->free_area_cache) 1338 mm->free_area_cache = addr; 1339 1340 /* dont allow allocations above current base */ 1341 if (mm->free_area_cache > mm->mmap_base) 1342 mm->free_area_cache = mm->mmap_base; 1343 } 1344 1345 unsigned long 1346 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1347 unsigned long pgoff, unsigned long flags) 1348 { 1349 unsigned long ret; 1350 1351 if (!(flags & MAP_FIXED)) { 1352 unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); 1353 1354 get_area = current->mm->get_unmapped_area; 1355 if (file && file->f_op && file->f_op->get_unmapped_area) 1356 get_area = file->f_op->get_unmapped_area; 1357 addr = get_area(file, addr, len, pgoff, flags); 1358 if (IS_ERR_VALUE(addr)) 1359 return addr; 1360 } 1361 1362 if (addr > TASK_SIZE - len) 1363 return -ENOMEM; 1364 if (addr & ~PAGE_MASK) 1365 return -EINVAL; 1366 if (file && is_file_hugepages(file)) { 1367 /* 1368 * Check if the given range is hugepage aligned, and 1369 * can be made suitable for hugepages. 1370 */ 1371 ret = prepare_hugepage_range(addr, len); 1372 } else { 1373 /* 1374 * Ensure that a normal request is not falling in a 1375 * reserved hugepage range. For some archs like IA-64, 1376 * there is a separate region for hugepages. 1377 */ 1378 ret = is_hugepage_only_range(current->mm, addr, len); 1379 } 1380 if (ret) 1381 return -EINVAL; 1382 return addr; 1383 } 1384 1385 EXPORT_SYMBOL(get_unmapped_area); 1386 1387 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1388 struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr) 1389 { 1390 struct vm_area_struct *vma = NULL; 1391 1392 if (mm) { 1393 /* Check the cache first. */ 1394 /* (Cache hit rate is typically around 35%.) */ 1395 vma = mm->mmap_cache; 1396 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1397 struct rb_node * rb_node; 1398 1399 rb_node = mm->mm_rb.rb_node; 1400 vma = NULL; 1401 1402 while (rb_node) { 1403 struct vm_area_struct * vma_tmp; 1404 1405 vma_tmp = rb_entry(rb_node, 1406 struct vm_area_struct, vm_rb); 1407 1408 if (vma_tmp->vm_end > addr) { 1409 vma = vma_tmp; 1410 if (vma_tmp->vm_start <= addr) 1411 break; 1412 rb_node = rb_node->rb_left; 1413 } else 1414 rb_node = rb_node->rb_right; 1415 } 1416 if (vma) 1417 mm->mmap_cache = vma; 1418 } 1419 } 1420 return vma; 1421 } 1422 1423 EXPORT_SYMBOL(find_vma); 1424 1425 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1426 struct vm_area_struct * 1427 find_vma_prev(struct mm_struct *mm, unsigned long addr, 1428 struct vm_area_struct **pprev) 1429 { 1430 struct vm_area_struct *vma = NULL, *prev = NULL; 1431 struct rb_node * rb_node; 1432 if (!mm) 1433 goto out; 1434 1435 /* Guard against addr being lower than the first VMA */ 1436 vma = mm->mmap; 1437 1438 /* Go through the RB tree quickly. */ 1439 rb_node = mm->mm_rb.rb_node; 1440 1441 while (rb_node) { 1442 struct vm_area_struct *vma_tmp; 1443 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1444 1445 if (addr < vma_tmp->vm_end) { 1446 rb_node = rb_node->rb_left; 1447 } else { 1448 prev = vma_tmp; 1449 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1450 break; 1451 rb_node = rb_node->rb_right; 1452 } 1453 } 1454 1455 out: 1456 *pprev = prev; 1457 return prev ? prev->vm_next : vma; 1458 } 1459 1460 /* 1461 * Verify that the stack growth is acceptable and 1462 * update accounting. This is shared with both the 1463 * grow-up and grow-down cases. 1464 */ 1465 static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow) 1466 { 1467 struct mm_struct *mm = vma->vm_mm; 1468 struct rlimit *rlim = current->signal->rlim; 1469 1470 /* address space limit tests */ 1471 if (!may_expand_vm(mm, grow)) 1472 return -ENOMEM; 1473 1474 /* Stack limit test */ 1475 if (size > rlim[RLIMIT_STACK].rlim_cur) 1476 return -ENOMEM; 1477 1478 /* mlock limit tests */ 1479 if (vma->vm_flags & VM_LOCKED) { 1480 unsigned long locked; 1481 unsigned long limit; 1482 locked = mm->locked_vm + grow; 1483 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1484 if (locked > limit && !capable(CAP_IPC_LOCK)) 1485 return -ENOMEM; 1486 } 1487 1488 /* 1489 * Overcommit.. This must be the final test, as it will 1490 * update security statistics. 1491 */ 1492 if (security_vm_enough_memory(grow)) 1493 return -ENOMEM; 1494 1495 /* Ok, everything looks good - let it rip */ 1496 mm->total_vm += grow; 1497 if (vma->vm_flags & VM_LOCKED) 1498 mm->locked_vm += grow; 1499 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1500 return 0; 1501 } 1502 1503 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 1504 /* 1505 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 1506 * vma is the last one with address > vma->vm_end. Have to extend vma. 1507 */ 1508 #ifdef CONFIG_STACK_GROWSUP 1509 static inline 1510 #endif 1511 int expand_upwards(struct vm_area_struct *vma, unsigned long address) 1512 { 1513 int error; 1514 1515 if (!(vma->vm_flags & VM_GROWSUP)) 1516 return -EFAULT; 1517 1518 /* 1519 * We must make sure the anon_vma is allocated 1520 * so that the anon_vma locking is not a noop. 1521 */ 1522 if (unlikely(anon_vma_prepare(vma))) 1523 return -ENOMEM; 1524 anon_vma_lock(vma); 1525 1526 /* 1527 * vma->vm_start/vm_end cannot change under us because the caller 1528 * is required to hold the mmap_sem in read mode. We need the 1529 * anon_vma lock to serialize against concurrent expand_stacks. 1530 */ 1531 address += 4 + PAGE_SIZE - 1; 1532 address &= PAGE_MASK; 1533 error = 0; 1534 1535 /* Somebody else might have raced and expanded it already */ 1536 if (address > vma->vm_end) { 1537 unsigned long size, grow; 1538 1539 size = address - vma->vm_start; 1540 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1541 1542 error = acct_stack_growth(vma, size, grow); 1543 if (!error) 1544 vma->vm_end = address; 1545 } 1546 anon_vma_unlock(vma); 1547 return error; 1548 } 1549 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 1550 1551 #ifdef CONFIG_STACK_GROWSUP 1552 int expand_stack(struct vm_area_struct *vma, unsigned long address) 1553 { 1554 return expand_upwards(vma, address); 1555 } 1556 1557 struct vm_area_struct * 1558 find_extend_vma(struct mm_struct *mm, unsigned long addr) 1559 { 1560 struct vm_area_struct *vma, *prev; 1561 1562 addr &= PAGE_MASK; 1563 vma = find_vma_prev(mm, addr, &prev); 1564 if (vma && (vma->vm_start <= addr)) 1565 return vma; 1566 if (!prev || expand_stack(prev, addr)) 1567 return NULL; 1568 if (prev->vm_flags & VM_LOCKED) { 1569 make_pages_present(addr, prev->vm_end); 1570 } 1571 return prev; 1572 } 1573 #else 1574 /* 1575 * vma is the first one with address < vma->vm_start. Have to extend vma. 1576 */ 1577 int expand_stack(struct vm_area_struct *vma, unsigned long address) 1578 { 1579 int error; 1580 1581 /* 1582 * We must make sure the anon_vma is allocated 1583 * so that the anon_vma locking is not a noop. 1584 */ 1585 if (unlikely(anon_vma_prepare(vma))) 1586 return -ENOMEM; 1587 anon_vma_lock(vma); 1588 1589 /* 1590 * vma->vm_start/vm_end cannot change under us because the caller 1591 * is required to hold the mmap_sem in read mode. We need the 1592 * anon_vma lock to serialize against concurrent expand_stacks. 1593 */ 1594 address &= PAGE_MASK; 1595 error = 0; 1596 1597 /* Somebody else might have raced and expanded it already */ 1598 if (address < vma->vm_start) { 1599 unsigned long size, grow; 1600 1601 size = vma->vm_end - address; 1602 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1603 1604 error = acct_stack_growth(vma, size, grow); 1605 if (!error) { 1606 vma->vm_start = address; 1607 vma->vm_pgoff -= grow; 1608 } 1609 } 1610 anon_vma_unlock(vma); 1611 return error; 1612 } 1613 1614 struct vm_area_struct * 1615 find_extend_vma(struct mm_struct * mm, unsigned long addr) 1616 { 1617 struct vm_area_struct * vma; 1618 unsigned long start; 1619 1620 addr &= PAGE_MASK; 1621 vma = find_vma(mm,addr); 1622 if (!vma) 1623 return NULL; 1624 if (vma->vm_start <= addr) 1625 return vma; 1626 if (!(vma->vm_flags & VM_GROWSDOWN)) 1627 return NULL; 1628 start = vma->vm_start; 1629 if (expand_stack(vma, addr)) 1630 return NULL; 1631 if (vma->vm_flags & VM_LOCKED) { 1632 make_pages_present(addr, start); 1633 } 1634 return vma; 1635 } 1636 #endif 1637 1638 /* 1639 * Ok - we have the memory areas we should free on the vma list, 1640 * so release them, and do the vma updates. 1641 * 1642 * Called with the mm semaphore held. 1643 */ 1644 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1645 { 1646 /* Update high watermark before we lower total_vm */ 1647 update_hiwater_vm(mm); 1648 do { 1649 long nrpages = vma_pages(vma); 1650 1651 mm->total_vm -= nrpages; 1652 if (vma->vm_flags & VM_LOCKED) 1653 mm->locked_vm -= nrpages; 1654 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 1655 vma = remove_vma(vma); 1656 } while (vma); 1657 validate_mm(mm); 1658 } 1659 1660 /* 1661 * Get rid of page table information in the indicated region. 1662 * 1663 * Called with the mm semaphore held. 1664 */ 1665 static void unmap_region(struct mm_struct *mm, 1666 struct vm_area_struct *vma, struct vm_area_struct *prev, 1667 unsigned long start, unsigned long end) 1668 { 1669 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1670 struct mmu_gather *tlb; 1671 unsigned long nr_accounted = 0; 1672 1673 lru_add_drain(); 1674 tlb = tlb_gather_mmu(mm, 0); 1675 update_hiwater_rss(mm); 1676 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); 1677 vm_unacct_memory(nr_accounted); 1678 free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1679 next? next->vm_start: 0); 1680 tlb_finish_mmu(tlb, start, end); 1681 } 1682 1683 /* 1684 * Create a list of vma's touched by the unmap, removing them from the mm's 1685 * vma list as we go.. 1686 */ 1687 static void 1688 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1689 struct vm_area_struct *prev, unsigned long end) 1690 { 1691 struct vm_area_struct **insertion_point; 1692 struct vm_area_struct *tail_vma = NULL; 1693 unsigned long addr; 1694 1695 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1696 do { 1697 rb_erase(&vma->vm_rb, &mm->mm_rb); 1698 mm->map_count--; 1699 tail_vma = vma; 1700 vma = vma->vm_next; 1701 } while (vma && vma->vm_start < end); 1702 *insertion_point = vma; 1703 tail_vma->vm_next = NULL; 1704 if (mm->unmap_area == arch_unmap_area) 1705 addr = prev ? prev->vm_end : mm->mmap_base; 1706 else 1707 addr = vma ? vma->vm_start : mm->mmap_base; 1708 mm->unmap_area(mm, addr); 1709 mm->mmap_cache = NULL; /* Kill the cache. */ 1710 } 1711 1712 /* 1713 * Split a vma into two pieces at address 'addr', a new vma is allocated 1714 * either for the first part or the the tail. 1715 */ 1716 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1717 unsigned long addr, int new_below) 1718 { 1719 struct mempolicy *pol; 1720 struct vm_area_struct *new; 1721 1722 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK)) 1723 return -EINVAL; 1724 1725 if (mm->map_count >= sysctl_max_map_count) 1726 return -ENOMEM; 1727 1728 new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 1729 if (!new) 1730 return -ENOMEM; 1731 1732 /* most fields are the same, copy all, and then fixup */ 1733 *new = *vma; 1734 1735 if (new_below) 1736 new->vm_end = addr; 1737 else { 1738 new->vm_start = addr; 1739 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1740 } 1741 1742 pol = mpol_copy(vma_policy(vma)); 1743 if (IS_ERR(pol)) { 1744 kmem_cache_free(vm_area_cachep, new); 1745 return PTR_ERR(pol); 1746 } 1747 vma_set_policy(new, pol); 1748 1749 if (new->vm_file) 1750 get_file(new->vm_file); 1751 1752 if (new->vm_ops && new->vm_ops->open) 1753 new->vm_ops->open(new); 1754 1755 if (new_below) 1756 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1757 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1758 else 1759 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1760 1761 return 0; 1762 } 1763 1764 /* Munmap is split into 2 main parts -- this part which finds 1765 * what needs doing, and the areas themselves, which do the 1766 * work. This now handles partial unmappings. 1767 * Jeremy Fitzhardinge <jeremy@goop.org> 1768 */ 1769 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1770 { 1771 unsigned long end; 1772 struct vm_area_struct *vma, *prev, *last; 1773 1774 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1775 return -EINVAL; 1776 1777 if ((len = PAGE_ALIGN(len)) == 0) 1778 return -EINVAL; 1779 1780 /* Find the first overlapping VMA */ 1781 vma = find_vma_prev(mm, start, &prev); 1782 if (!vma) 1783 return 0; 1784 /* we have start < vma->vm_end */ 1785 1786 /* if it doesn't overlap, we have nothing.. */ 1787 end = start + len; 1788 if (vma->vm_start >= end) 1789 return 0; 1790 1791 /* 1792 * If we need to split any vma, do it now to save pain later. 1793 * 1794 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1795 * unmapped vm_area_struct will remain in use: so lower split_vma 1796 * places tmp vma above, and higher split_vma places tmp vma below. 1797 */ 1798 if (start > vma->vm_start) { 1799 int error = split_vma(mm, vma, start, 0); 1800 if (error) 1801 return error; 1802 prev = vma; 1803 } 1804 1805 /* Does it split the last one? */ 1806 last = find_vma(mm, end); 1807 if (last && end > last->vm_start) { 1808 int error = split_vma(mm, last, end, 1); 1809 if (error) 1810 return error; 1811 } 1812 vma = prev? prev->vm_next: mm->mmap; 1813 1814 /* 1815 * Remove the vma's, and unmap the actual pages 1816 */ 1817 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1818 unmap_region(mm, vma, prev, start, end); 1819 1820 /* Fix up all other VM information */ 1821 remove_vma_list(mm, vma); 1822 1823 return 0; 1824 } 1825 1826 EXPORT_SYMBOL(do_munmap); 1827 1828 asmlinkage long sys_munmap(unsigned long addr, size_t len) 1829 { 1830 int ret; 1831 struct mm_struct *mm = current->mm; 1832 1833 profile_munmap(addr); 1834 1835 down_write(&mm->mmap_sem); 1836 ret = do_munmap(mm, addr, len); 1837 up_write(&mm->mmap_sem); 1838 return ret; 1839 } 1840 1841 static inline void verify_mm_writelocked(struct mm_struct *mm) 1842 { 1843 #ifdef CONFIG_DEBUG_VM 1844 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1845 WARN_ON(1); 1846 up_read(&mm->mmap_sem); 1847 } 1848 #endif 1849 } 1850 1851 /* 1852 * this is really a simplified "do_mmap". it only handles 1853 * anonymous maps. eventually we may be able to do some 1854 * brk-specific accounting here. 1855 */ 1856 unsigned long do_brk(unsigned long addr, unsigned long len) 1857 { 1858 struct mm_struct * mm = current->mm; 1859 struct vm_area_struct * vma, * prev; 1860 unsigned long flags; 1861 struct rb_node ** rb_link, * rb_parent; 1862 pgoff_t pgoff = addr >> PAGE_SHIFT; 1863 1864 len = PAGE_ALIGN(len); 1865 if (!len) 1866 return addr; 1867 1868 if ((addr + len) > TASK_SIZE || (addr + len) < addr) 1869 return -EINVAL; 1870 1871 /* 1872 * mlock MCL_FUTURE? 1873 */ 1874 if (mm->def_flags & VM_LOCKED) { 1875 unsigned long locked, lock_limit; 1876 locked = len >> PAGE_SHIFT; 1877 locked += mm->locked_vm; 1878 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 1879 lock_limit >>= PAGE_SHIFT; 1880 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1881 return -EAGAIN; 1882 } 1883 1884 /* 1885 * mm->mmap_sem is required to protect against another thread 1886 * changing the mappings in case we sleep. 1887 */ 1888 verify_mm_writelocked(mm); 1889 1890 /* 1891 * Clear old maps. this also does some error checking for us 1892 */ 1893 munmap_back: 1894 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1895 if (vma && vma->vm_start < addr + len) { 1896 if (do_munmap(mm, addr, len)) 1897 return -ENOMEM; 1898 goto munmap_back; 1899 } 1900 1901 /* Check against address space limits *after* clearing old maps... */ 1902 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1903 return -ENOMEM; 1904 1905 if (mm->map_count > sysctl_max_map_count) 1906 return -ENOMEM; 1907 1908 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 1909 return -ENOMEM; 1910 1911 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 1912 1913 /* Can we just expand an old private anonymous mapping? */ 1914 if (vma_merge(mm, prev, addr, addr + len, flags, 1915 NULL, NULL, pgoff, NULL)) 1916 goto out; 1917 1918 /* 1919 * create a vma struct for an anonymous mapping 1920 */ 1921 vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 1922 if (!vma) { 1923 vm_unacct_memory(len >> PAGE_SHIFT); 1924 return -ENOMEM; 1925 } 1926 memset(vma, 0, sizeof(*vma)); 1927 1928 vma->vm_mm = mm; 1929 vma->vm_start = addr; 1930 vma->vm_end = addr + len; 1931 vma->vm_pgoff = pgoff; 1932 vma->vm_flags = flags; 1933 vma->vm_page_prot = protection_map[flags & 0x0f]; 1934 vma_link(mm, vma, prev, rb_link, rb_parent); 1935 out: 1936 mm->total_vm += len >> PAGE_SHIFT; 1937 if (flags & VM_LOCKED) { 1938 mm->locked_vm += len >> PAGE_SHIFT; 1939 make_pages_present(addr, addr + len); 1940 } 1941 return addr; 1942 } 1943 1944 EXPORT_SYMBOL(do_brk); 1945 1946 /* Release all mmaps. */ 1947 void exit_mmap(struct mm_struct *mm) 1948 { 1949 struct mmu_gather *tlb; 1950 struct vm_area_struct *vma = mm->mmap; 1951 unsigned long nr_accounted = 0; 1952 unsigned long end; 1953 1954 lru_add_drain(); 1955 flush_cache_mm(mm); 1956 tlb = tlb_gather_mmu(mm, 1); 1957 /* Don't update_hiwater_rss(mm) here, do_exit already did */ 1958 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 1959 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); 1960 vm_unacct_memory(nr_accounted); 1961 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); 1962 tlb_finish_mmu(tlb, 0, end); 1963 1964 /* 1965 * Walk the list again, actually closing and freeing it, 1966 * with preemption enabled, without holding any MM locks. 1967 */ 1968 while (vma) 1969 vma = remove_vma(vma); 1970 1971 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 1972 } 1973 1974 /* Insert vm structure into process list sorted by address 1975 * and into the inode's i_mmap tree. If vm_file is non-NULL 1976 * then i_mmap_lock is taken here. 1977 */ 1978 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 1979 { 1980 struct vm_area_struct * __vma, * prev; 1981 struct rb_node ** rb_link, * rb_parent; 1982 1983 /* 1984 * The vm_pgoff of a purely anonymous vma should be irrelevant 1985 * until its first write fault, when page's anon_vma and index 1986 * are set. But now set the vm_pgoff it will almost certainly 1987 * end up with (unless mremap moves it elsewhere before that 1988 * first wfault), so /proc/pid/maps tells a consistent story. 1989 * 1990 * By setting it to reflect the virtual start address of the 1991 * vma, merges and splits can happen in a seamless way, just 1992 * using the existing file pgoff checks and manipulations. 1993 * Similarly in do_mmap_pgoff and in do_brk. 1994 */ 1995 if (!vma->vm_file) { 1996 BUG_ON(vma->anon_vma); 1997 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 1998 } 1999 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 2000 if (__vma && __vma->vm_start < vma->vm_end) 2001 return -ENOMEM; 2002 if ((vma->vm_flags & VM_ACCOUNT) && 2003 security_vm_enough_memory(vma_pages(vma))) 2004 return -ENOMEM; 2005 vma_link(mm, vma, prev, rb_link, rb_parent); 2006 return 0; 2007 } 2008 2009 /* 2010 * Copy the vma structure to a new location in the same mm, 2011 * prior to moving page table entries, to effect an mremap move. 2012 */ 2013 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2014 unsigned long addr, unsigned long len, pgoff_t pgoff) 2015 { 2016 struct vm_area_struct *vma = *vmap; 2017 unsigned long vma_start = vma->vm_start; 2018 struct mm_struct *mm = vma->vm_mm; 2019 struct vm_area_struct *new_vma, *prev; 2020 struct rb_node **rb_link, *rb_parent; 2021 struct mempolicy *pol; 2022 2023 /* 2024 * If anonymous vma has not yet been faulted, update new pgoff 2025 * to match new location, to increase its chance of merging. 2026 */ 2027 if (!vma->vm_file && !vma->anon_vma) 2028 pgoff = addr >> PAGE_SHIFT; 2029 2030 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2031 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2032 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2033 if (new_vma) { 2034 /* 2035 * Source vma may have been merged into new_vma 2036 */ 2037 if (vma_start >= new_vma->vm_start && 2038 vma_start < new_vma->vm_end) 2039 *vmap = new_vma; 2040 } else { 2041 new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 2042 if (new_vma) { 2043 *new_vma = *vma; 2044 pol = mpol_copy(vma_policy(vma)); 2045 if (IS_ERR(pol)) { 2046 kmem_cache_free(vm_area_cachep, new_vma); 2047 return NULL; 2048 } 2049 vma_set_policy(new_vma, pol); 2050 new_vma->vm_start = addr; 2051 new_vma->vm_end = addr + len; 2052 new_vma->vm_pgoff = pgoff; 2053 if (new_vma->vm_file) 2054 get_file(new_vma->vm_file); 2055 if (new_vma->vm_ops && new_vma->vm_ops->open) 2056 new_vma->vm_ops->open(new_vma); 2057 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2058 } 2059 } 2060 return new_vma; 2061 } 2062 2063 /* 2064 * Return true if the calling process may expand its vm space by the passed 2065 * number of pages 2066 */ 2067 int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2068 { 2069 unsigned long cur = mm->total_vm; /* pages */ 2070 unsigned long lim; 2071 2072 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2073 2074 if (cur + npages > lim) 2075 return 0; 2076 return 1; 2077 } 2078