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