mmap.c revision 1e624196f43c3a62122959e15c5f03572cdadb5d
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/capability.h> 17#include <linux/init.h> 18#include <linux/file.h> 19#include <linux/fs.h> 20#include <linux/personality.h> 21#include <linux/security.h> 22#include <linux/hugetlb.h> 23#include <linux/profile.h> 24#include <linux/module.h> 25#include <linux/mount.h> 26#include <linux/mempolicy.h> 27#include <linux/rmap.h> 28 29#include <asm/uaccess.h> 30#include <asm/cacheflush.h> 31#include <asm/tlb.h> 32 33static void unmap_region(struct mm_struct *mm, 34 struct vm_area_struct *vma, struct vm_area_struct *prev, 35 unsigned long start, unsigned long end); 36 37/* 38 * WARNING: the debugging will use recursive algorithms so never enable this 39 * unless you know what you are doing. 40 */ 41#undef DEBUG_MM_RB 42 43/* description of effects of mapping type and prot in current implementation. 44 * this is due to the limited x86 page protection hardware. The expected 45 * behavior is in parens: 46 * 47 * map_type prot 48 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 49 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 50 * w: (no) no w: (no) no w: (yes) yes w: (no) no 51 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 52 * 53 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 54 * w: (no) no w: (no) no w: (copy) copy w: (no) no 55 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 56 * 57 */ 58pgprot_t protection_map[16] = { 59 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 60 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 61}; 62 63int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 64int sysctl_overcommit_ratio = 50; /* default is 50% */ 65int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; 66atomic_t vm_committed_space = ATOMIC_INIT(0); 67 68/* 69 * Check that a process has enough memory to allocate a new virtual 70 * mapping. 0 means there is enough memory for the allocation to 71 * succeed and -ENOMEM implies there is not. 72 * 73 * We currently support three overcommit policies, which are set via the 74 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 75 * 76 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 77 * Additional code 2002 Jul 20 by Robert Love. 78 * 79 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 80 * 81 * Note this is a helper function intended to be used by LSMs which 82 * wish to use this logic. 83 */ 84int __vm_enough_memory(long pages, int cap_sys_admin) 85{ 86 unsigned long free, allowed; 87 88 vm_acct_memory(pages); 89 90 /* 91 * Sometimes we want to use more memory than we have 92 */ 93 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 94 return 0; 95 96 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 97 unsigned long n; 98 99 free = get_page_cache_size(); 100 free += nr_swap_pages; 101 102 /* 103 * Any slabs which are created with the 104 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 105 * which are reclaimable, under pressure. The dentry 106 * cache and most inode caches should fall into this 107 */ 108 free += atomic_read(&slab_reclaim_pages); 109 110 /* 111 * Leave the last 3% for root 112 */ 113 if (!cap_sys_admin) 114 free -= free / 32; 115 116 if (free > pages) 117 return 0; 118 119 /* 120 * nr_free_pages() is very expensive on large systems, 121 * only call if we're about to fail. 122 */ 123 n = nr_free_pages(); 124 if (!cap_sys_admin) 125 n -= n / 32; 126 free += n; 127 128 if (free > pages) 129 return 0; 130 vm_unacct_memory(pages); 131 return -ENOMEM; 132 } 133 134 allowed = (totalram_pages - hugetlb_total_pages()) 135 * sysctl_overcommit_ratio / 100; 136 /* 137 * Leave the last 3% for root 138 */ 139 if (!cap_sys_admin) 140 allowed -= allowed / 32; 141 allowed += total_swap_pages; 142 143 /* Don't let a single process grow too big: 144 leave 3% of the size of this process for other processes */ 145 allowed -= current->mm->total_vm / 32; 146 147 /* 148 * cast `allowed' as a signed long because vm_committed_space 149 * sometimes has a negative value 150 */ 151 if (atomic_read(&vm_committed_space) < (long)allowed) 152 return 0; 153 154 vm_unacct_memory(pages); 155 156 return -ENOMEM; 157} 158 159EXPORT_SYMBOL(__vm_enough_memory); 160 161/* 162 * Requires inode->i_mapping->i_mmap_lock 163 */ 164static void __remove_shared_vm_struct(struct vm_area_struct *vma, 165 struct file *file, struct address_space *mapping) 166{ 167 if (vma->vm_flags & VM_DENYWRITE) 168 atomic_inc(&file->f_dentry->d_inode->i_writecount); 169 if (vma->vm_flags & VM_SHARED) 170 mapping->i_mmap_writable--; 171 172 flush_dcache_mmap_lock(mapping); 173 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 174 list_del_init(&vma->shared.vm_set.list); 175 else 176 vma_prio_tree_remove(vma, &mapping->i_mmap); 177 flush_dcache_mmap_unlock(mapping); 178} 179 180/* 181 * Unlink a file-based vm structure from its prio_tree, to hide 182 * vma from rmap and vmtruncate before freeing its page tables. 183 */ 184void unlink_file_vma(struct vm_area_struct *vma) 185{ 186 struct file *file = vma->vm_file; 187 188 if (file) { 189 struct address_space *mapping = file->f_mapping; 190 spin_lock(&mapping->i_mmap_lock); 191 __remove_shared_vm_struct(vma, file, mapping); 192 spin_unlock(&mapping->i_mmap_lock); 193 } 194} 195 196/* 197 * Close a vm structure and free it, returning the next. 198 */ 199static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 200{ 201 struct vm_area_struct *next = vma->vm_next; 202 203 might_sleep(); 204 if (vma->vm_ops && vma->vm_ops->close) 205 vma->vm_ops->close(vma); 206 if (vma->vm_file) 207 fput(vma->vm_file); 208 mpol_free(vma_policy(vma)); 209 kmem_cache_free(vm_area_cachep, vma); 210 return next; 211} 212 213asmlinkage unsigned long sys_brk(unsigned long brk) 214{ 215 unsigned long rlim, retval; 216 unsigned long newbrk, oldbrk; 217 struct mm_struct *mm = current->mm; 218 219 down_write(&mm->mmap_sem); 220 221 if (brk < mm->end_code) 222 goto out; 223 224 /* 225 * Check against rlimit here. If this check is done later after the test 226 * of oldbrk with newbrk then it can escape the test and let the data 227 * segment grow beyond its set limit the in case where the limit is 228 * not page aligned -Ram Gupta 229 */ 230 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 231 if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim) 232 goto out; 233 234 newbrk = PAGE_ALIGN(brk); 235 oldbrk = PAGE_ALIGN(mm->brk); 236 if (oldbrk == newbrk) 237 goto set_brk; 238 239 /* Always allow shrinking brk. */ 240 if (brk <= mm->brk) { 241 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 242 goto set_brk; 243 goto out; 244 } 245 246 /* Check against existing mmap mappings. */ 247 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 248 goto out; 249 250 /* Ok, looks good - let it rip. */ 251 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 252 goto out; 253set_brk: 254 mm->brk = brk; 255out: 256 retval = mm->brk; 257 up_write(&mm->mmap_sem); 258 return retval; 259} 260 261#ifdef DEBUG_MM_RB 262static int browse_rb(struct rb_root *root) 263{ 264 int i = 0, j; 265 struct rb_node *nd, *pn = NULL; 266 unsigned long prev = 0, pend = 0; 267 268 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 269 struct vm_area_struct *vma; 270 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 271 if (vma->vm_start < prev) 272 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 273 if (vma->vm_start < pend) 274 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 275 if (vma->vm_start > vma->vm_end) 276 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 277 i++; 278 pn = nd; 279 } 280 j = 0; 281 for (nd = pn; nd; nd = rb_prev(nd)) { 282 j++; 283 } 284 if (i != j) 285 printk("backwards %d, forwards %d\n", j, i), i = 0; 286 return i; 287} 288 289void validate_mm(struct mm_struct *mm) 290{ 291 int bug = 0; 292 int i = 0; 293 struct vm_area_struct *tmp = mm->mmap; 294 while (tmp) { 295 tmp = tmp->vm_next; 296 i++; 297 } 298 if (i != mm->map_count) 299 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 300 i = browse_rb(&mm->mm_rb); 301 if (i != mm->map_count) 302 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 303 BUG_ON(bug); 304} 305#else 306#define validate_mm(mm) do { } while (0) 307#endif 308 309static struct vm_area_struct * 310find_vma_prepare(struct mm_struct *mm, unsigned long addr, 311 struct vm_area_struct **pprev, struct rb_node ***rb_link, 312 struct rb_node ** rb_parent) 313{ 314 struct vm_area_struct * vma; 315 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 316 317 __rb_link = &mm->mm_rb.rb_node; 318 rb_prev = __rb_parent = NULL; 319 vma = NULL; 320 321 while (*__rb_link) { 322 struct vm_area_struct *vma_tmp; 323 324 __rb_parent = *__rb_link; 325 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 326 327 if (vma_tmp->vm_end > addr) { 328 vma = vma_tmp; 329 if (vma_tmp->vm_start <= addr) 330 return vma; 331 __rb_link = &__rb_parent->rb_left; 332 } else { 333 rb_prev = __rb_parent; 334 __rb_link = &__rb_parent->rb_right; 335 } 336 } 337 338 *pprev = NULL; 339 if (rb_prev) 340 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 341 *rb_link = __rb_link; 342 *rb_parent = __rb_parent; 343 return vma; 344} 345 346static inline void 347__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 348 struct vm_area_struct *prev, struct rb_node *rb_parent) 349{ 350 if (prev) { 351 vma->vm_next = prev->vm_next; 352 prev->vm_next = vma; 353 } else { 354 mm->mmap = vma; 355 if (rb_parent) 356 vma->vm_next = rb_entry(rb_parent, 357 struct vm_area_struct, vm_rb); 358 else 359 vma->vm_next = NULL; 360 } 361} 362 363void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 364 struct rb_node **rb_link, struct rb_node *rb_parent) 365{ 366 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 367 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 368} 369 370static inline void __vma_link_file(struct vm_area_struct *vma) 371{ 372 struct file * file; 373 374 file = vma->vm_file; 375 if (file) { 376 struct address_space *mapping = file->f_mapping; 377 378 if (vma->vm_flags & VM_DENYWRITE) 379 atomic_dec(&file->f_dentry->d_inode->i_writecount); 380 if (vma->vm_flags & VM_SHARED) 381 mapping->i_mmap_writable++; 382 383 flush_dcache_mmap_lock(mapping); 384 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 385 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 386 else 387 vma_prio_tree_insert(vma, &mapping->i_mmap); 388 flush_dcache_mmap_unlock(mapping); 389 } 390} 391 392static void 393__vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 394 struct vm_area_struct *prev, struct rb_node **rb_link, 395 struct rb_node *rb_parent) 396{ 397 __vma_link_list(mm, vma, prev, rb_parent); 398 __vma_link_rb(mm, vma, rb_link, rb_parent); 399 __anon_vma_link(vma); 400} 401 402static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 403 struct vm_area_struct *prev, struct rb_node **rb_link, 404 struct rb_node *rb_parent) 405{ 406 struct address_space *mapping = NULL; 407 408 if (vma->vm_file) 409 mapping = vma->vm_file->f_mapping; 410 411 if (mapping) { 412 spin_lock(&mapping->i_mmap_lock); 413 vma->vm_truncate_count = mapping->truncate_count; 414 } 415 anon_vma_lock(vma); 416 417 __vma_link(mm, vma, prev, rb_link, rb_parent); 418 __vma_link_file(vma); 419 420 anon_vma_unlock(vma); 421 if (mapping) 422 spin_unlock(&mapping->i_mmap_lock); 423 424 mm->map_count++; 425 validate_mm(mm); 426} 427 428/* 429 * Helper for vma_adjust in the split_vma insert case: 430 * insert vm structure into list and rbtree and anon_vma, 431 * but it has already been inserted into prio_tree earlier. 432 */ 433static void 434__insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 435{ 436 struct vm_area_struct * __vma, * prev; 437 struct rb_node ** rb_link, * rb_parent; 438 439 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); 440 BUG_ON(__vma && __vma->vm_start < vma->vm_end); 441 __vma_link(mm, vma, prev, rb_link, rb_parent); 442 mm->map_count++; 443} 444 445static inline void 446__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 447 struct vm_area_struct *prev) 448{ 449 prev->vm_next = vma->vm_next; 450 rb_erase(&vma->vm_rb, &mm->mm_rb); 451 if (mm->mmap_cache == vma) 452 mm->mmap_cache = prev; 453} 454 455/* 456 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 457 * is already present in an i_mmap tree without adjusting the tree. 458 * The following helper function should be used when such adjustments 459 * are necessary. The "insert" vma (if any) is to be inserted 460 * before we drop the necessary locks. 461 */ 462void vma_adjust(struct vm_area_struct *vma, unsigned long start, 463 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 464{ 465 struct mm_struct *mm = vma->vm_mm; 466 struct vm_area_struct *next = vma->vm_next; 467 struct vm_area_struct *importer = NULL; 468 struct address_space *mapping = NULL; 469 struct prio_tree_root *root = NULL; 470 struct file *file = vma->vm_file; 471 struct anon_vma *anon_vma = NULL; 472 long adjust_next = 0; 473 int remove_next = 0; 474 475 if (next && !insert) { 476 if (end >= next->vm_end) { 477 /* 478 * vma expands, overlapping all the next, and 479 * perhaps the one after too (mprotect case 6). 480 */ 481again: remove_next = 1 + (end > next->vm_end); 482 end = next->vm_end; 483 anon_vma = next->anon_vma; 484 importer = vma; 485 } else if (end > next->vm_start) { 486 /* 487 * vma expands, overlapping part of the next: 488 * mprotect case 5 shifting the boundary up. 489 */ 490 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 491 anon_vma = next->anon_vma; 492 importer = vma; 493 } else if (end < vma->vm_end) { 494 /* 495 * vma shrinks, and !insert tells it's not 496 * split_vma inserting another: so it must be 497 * mprotect case 4 shifting the boundary down. 498 */ 499 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 500 anon_vma = next->anon_vma; 501 importer = next; 502 } 503 } 504 505 if (file) { 506 mapping = file->f_mapping; 507 if (!(vma->vm_flags & VM_NONLINEAR)) 508 root = &mapping->i_mmap; 509 spin_lock(&mapping->i_mmap_lock); 510 if (importer && 511 vma->vm_truncate_count != next->vm_truncate_count) { 512 /* 513 * unmap_mapping_range might be in progress: 514 * ensure that the expanding vma is rescanned. 515 */ 516 importer->vm_truncate_count = 0; 517 } 518 if (insert) { 519 insert->vm_truncate_count = vma->vm_truncate_count; 520 /* 521 * Put into prio_tree now, so instantiated pages 522 * are visible to arm/parisc __flush_dcache_page 523 * throughout; but we cannot insert into address 524 * space until vma start or end is updated. 525 */ 526 __vma_link_file(insert); 527 } 528 } 529 530 /* 531 * When changing only vma->vm_end, we don't really need 532 * anon_vma lock: but is that case worth optimizing out? 533 */ 534 if (vma->anon_vma) 535 anon_vma = vma->anon_vma; 536 if (anon_vma) { 537 spin_lock(&anon_vma->lock); 538 /* 539 * Easily overlooked: when mprotect shifts the boundary, 540 * make sure the expanding vma has anon_vma set if the 541 * shrinking vma had, to cover any anon pages imported. 542 */ 543 if (importer && !importer->anon_vma) { 544 importer->anon_vma = anon_vma; 545 __anon_vma_link(importer); 546 } 547 } 548 549 if (root) { 550 flush_dcache_mmap_lock(mapping); 551 vma_prio_tree_remove(vma, root); 552 if (adjust_next) 553 vma_prio_tree_remove(next, root); 554 } 555 556 vma->vm_start = start; 557 vma->vm_end = end; 558 vma->vm_pgoff = pgoff; 559 if (adjust_next) { 560 next->vm_start += adjust_next << PAGE_SHIFT; 561 next->vm_pgoff += adjust_next; 562 } 563 564 if (root) { 565 if (adjust_next) 566 vma_prio_tree_insert(next, root); 567 vma_prio_tree_insert(vma, root); 568 flush_dcache_mmap_unlock(mapping); 569 } 570 571 if (remove_next) { 572 /* 573 * vma_merge has merged next into vma, and needs 574 * us to remove next before dropping the locks. 575 */ 576 __vma_unlink(mm, next, vma); 577 if (file) 578 __remove_shared_vm_struct(next, file, mapping); 579 if (next->anon_vma) 580 __anon_vma_merge(vma, next); 581 } else if (insert) { 582 /* 583 * split_vma has split insert from vma, and needs 584 * us to insert it before dropping the locks 585 * (it may either follow vma or precede it). 586 */ 587 __insert_vm_struct(mm, insert); 588 } 589 590 if (anon_vma) 591 spin_unlock(&anon_vma->lock); 592 if (mapping) 593 spin_unlock(&mapping->i_mmap_lock); 594 595 if (remove_next) { 596 if (file) 597 fput(file); 598 mm->map_count--; 599 mpol_free(vma_policy(next)); 600 kmem_cache_free(vm_area_cachep, next); 601 /* 602 * In mprotect's case 6 (see comments on vma_merge), 603 * we must remove another next too. It would clutter 604 * up the code too much to do both in one go. 605 */ 606 if (remove_next == 2) { 607 next = vma->vm_next; 608 goto again; 609 } 610 } 611 612 validate_mm(mm); 613} 614 615/* 616 * If the vma has a ->close operation then the driver probably needs to release 617 * per-vma resources, so we don't attempt to merge those. 618 */ 619#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP) 620 621static inline int is_mergeable_vma(struct vm_area_struct *vma, 622 struct file *file, unsigned long vm_flags) 623{ 624 if (vma->vm_flags != vm_flags) 625 return 0; 626 if (vma->vm_file != file) 627 return 0; 628 if (vma->vm_ops && vma->vm_ops->close) 629 return 0; 630 return 1; 631} 632 633static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 634 struct anon_vma *anon_vma2) 635{ 636 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 637} 638 639/* 640 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 641 * in front of (at a lower virtual address and file offset than) the vma. 642 * 643 * We cannot merge two vmas if they have differently assigned (non-NULL) 644 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 645 * 646 * We don't check here for the merged mmap wrapping around the end of pagecache 647 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 648 * wrap, nor mmaps which cover the final page at index -1UL. 649 */ 650static int 651can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 652 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 653{ 654 if (is_mergeable_vma(vma, file, vm_flags) && 655 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 656 if (vma->vm_pgoff == vm_pgoff) 657 return 1; 658 } 659 return 0; 660} 661 662/* 663 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 664 * beyond (at a higher virtual address and file offset than) the vma. 665 * 666 * We cannot merge two vmas if they have differently assigned (non-NULL) 667 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 668 */ 669static int 670can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 671 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 672{ 673 if (is_mergeable_vma(vma, file, vm_flags) && 674 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 675 pgoff_t vm_pglen; 676 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 677 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 678 return 1; 679 } 680 return 0; 681} 682 683/* 684 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 685 * whether that can be merged with its predecessor or its successor. 686 * Or both (it neatly fills a hole). 687 * 688 * In most cases - when called for mmap, brk or mremap - [addr,end) is 689 * certain not to be mapped by the time vma_merge is called; but when 690 * called for mprotect, it is certain to be already mapped (either at 691 * an offset within prev, or at the start of next), and the flags of 692 * this area are about to be changed to vm_flags - and the no-change 693 * case has already been eliminated. 694 * 695 * The following mprotect cases have to be considered, where AAAA is 696 * the area passed down from mprotect_fixup, never extending beyond one 697 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 698 * 699 * AAAA AAAA AAAA AAAA 700 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 701 * cannot merge might become might become might become 702 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 703 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 704 * mremap move: PPPPNNNNNNNN 8 705 * AAAA 706 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 707 * might become case 1 below case 2 below case 3 below 708 * 709 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 710 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 711 */ 712struct vm_area_struct *vma_merge(struct mm_struct *mm, 713 struct vm_area_struct *prev, unsigned long addr, 714 unsigned long end, unsigned long vm_flags, 715 struct anon_vma *anon_vma, struct file *file, 716 pgoff_t pgoff, struct mempolicy *policy) 717{ 718 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 719 struct vm_area_struct *area, *next; 720 721 /* 722 * We later require that vma->vm_flags == vm_flags, 723 * so this tests vma->vm_flags & VM_SPECIAL, too. 724 */ 725 if (vm_flags & VM_SPECIAL) 726 return NULL; 727 728 if (prev) 729 next = prev->vm_next; 730 else 731 next = mm->mmap; 732 area = next; 733 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 734 next = next->vm_next; 735 736 /* 737 * Can it merge with the predecessor? 738 */ 739 if (prev && prev->vm_end == addr && 740 mpol_equal(vma_policy(prev), policy) && 741 can_vma_merge_after(prev, vm_flags, 742 anon_vma, file, pgoff)) { 743 /* 744 * OK, it can. Can we now merge in the successor as well? 745 */ 746 if (next && end == next->vm_start && 747 mpol_equal(policy, vma_policy(next)) && 748 can_vma_merge_before(next, vm_flags, 749 anon_vma, file, pgoff+pglen) && 750 is_mergeable_anon_vma(prev->anon_vma, 751 next->anon_vma)) { 752 /* cases 1, 6 */ 753 vma_adjust(prev, prev->vm_start, 754 next->vm_end, prev->vm_pgoff, NULL); 755 } else /* cases 2, 5, 7 */ 756 vma_adjust(prev, prev->vm_start, 757 end, prev->vm_pgoff, NULL); 758 return prev; 759 } 760 761 /* 762 * Can this new request be merged in front of next? 763 */ 764 if (next && end == next->vm_start && 765 mpol_equal(policy, vma_policy(next)) && 766 can_vma_merge_before(next, vm_flags, 767 anon_vma, file, pgoff+pglen)) { 768 if (prev && addr < prev->vm_end) /* case 4 */ 769 vma_adjust(prev, prev->vm_start, 770 addr, prev->vm_pgoff, NULL); 771 else /* cases 3, 8 */ 772 vma_adjust(area, addr, next->vm_end, 773 next->vm_pgoff - pglen, NULL); 774 return area; 775 } 776 777 return NULL; 778} 779 780/* 781 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 782 * neighbouring vmas for a suitable anon_vma, before it goes off 783 * to allocate a new anon_vma. It checks because a repetitive 784 * sequence of mprotects and faults may otherwise lead to distinct 785 * anon_vmas being allocated, preventing vma merge in subsequent 786 * mprotect. 787 */ 788struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 789{ 790 struct vm_area_struct *near; 791 unsigned long vm_flags; 792 793 near = vma->vm_next; 794 if (!near) 795 goto try_prev; 796 797 /* 798 * Since only mprotect tries to remerge vmas, match flags 799 * which might be mprotected into each other later on. 800 * Neither mlock nor madvise tries to remerge at present, 801 * so leave their flags as obstructing a merge. 802 */ 803 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 804 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 805 806 if (near->anon_vma && vma->vm_end == near->vm_start && 807 mpol_equal(vma_policy(vma), vma_policy(near)) && 808 can_vma_merge_before(near, vm_flags, 809 NULL, vma->vm_file, vma->vm_pgoff + 810 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 811 return near->anon_vma; 812try_prev: 813 /* 814 * It is potentially slow to have to call find_vma_prev here. 815 * But it's only on the first write fault on the vma, not 816 * every time, and we could devise a way to avoid it later 817 * (e.g. stash info in next's anon_vma_node when assigning 818 * an anon_vma, or when trying vma_merge). Another time. 819 */ 820 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); 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; 832none: 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 845void 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 if (file) { 852 mm->shared_vm += pages; 853 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 854 mm->exec_vm += pages; 855 } else if (flags & stack_flags) 856 mm->stack_vm += pages; 857 if (flags & (VM_RESERVED|VM_IO)) 858 mm->reserved_vm += pages; 859} 860#endif /* CONFIG_PROC_FS */ 861 862/* 863 * The caller must hold down_write(current->mm->mmap_sem). 864 */ 865 866unsigned long do_mmap_pgoff(struct file * file, unsigned long addr, 867 unsigned long len, unsigned long prot, 868 unsigned long flags, unsigned long pgoff) 869{ 870 struct mm_struct * mm = current->mm; 871 struct vm_area_struct * vma, * prev; 872 struct inode *inode; 873 unsigned int vm_flags; 874 int correct_wcount = 0; 875 int error; 876 struct rb_node ** rb_link, * rb_parent; 877 int accountable = 1; 878 unsigned long charged = 0, reqprot = prot; 879 880 if (file) { 881 if (is_file_hugepages(file)) 882 accountable = 0; 883 884 if (!file->f_op || !file->f_op->mmap) 885 return -ENODEV; 886 887 if ((prot & PROT_EXEC) && 888 (file->f_vfsmnt->mnt_flags & MNT_NOEXEC)) 889 return -EPERM; 890 } 891 /* 892 * Does the application expect PROT_READ to imply PROT_EXEC? 893 * 894 * (the exception is when the underlying filesystem is noexec 895 * mounted, in which case we dont add PROT_EXEC.) 896 */ 897 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 898 if (!(file && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))) 899 prot |= PROT_EXEC; 900 901 if (!len) 902 return -EINVAL; 903 904 /* Careful about overflows.. */ 905 len = PAGE_ALIGN(len); 906 if (!len || len > TASK_SIZE) 907 return -ENOMEM; 908 909 /* offset overflow? */ 910 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 911 return -EOVERFLOW; 912 913 /* Too many mappings? */ 914 if (mm->map_count > sysctl_max_map_count) 915 return -ENOMEM; 916 917 /* Obtain the address to map to. we verify (or select) it and ensure 918 * that it represents a valid section of the address space. 919 */ 920 addr = get_unmapped_area(file, addr, len, pgoff, flags); 921 if (addr & ~PAGE_MASK) 922 return addr; 923 924 /* Do simple checking here so the lower-level routines won't have 925 * to. we assume access permissions have been handled by the open 926 * of the memory object, so we don't do any here. 927 */ 928 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 929 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 930 931 if (flags & MAP_LOCKED) { 932 if (!can_do_mlock()) 933 return -EPERM; 934 vm_flags |= VM_LOCKED; 935 } 936 /* mlock MCL_FUTURE? */ 937 if (vm_flags & VM_LOCKED) { 938 unsigned long locked, lock_limit; 939 locked = len >> PAGE_SHIFT; 940 locked += mm->locked_vm; 941 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 942 lock_limit >>= PAGE_SHIFT; 943 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 944 return -EAGAIN; 945 } 946 947 inode = file ? file->f_dentry->d_inode : NULL; 948 949 if (file) { 950 switch (flags & MAP_TYPE) { 951 case MAP_SHARED: 952 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 953 return -EACCES; 954 955 /* 956 * Make sure we don't allow writing to an append-only 957 * file.. 958 */ 959 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 960 return -EACCES; 961 962 /* 963 * Make sure there are no mandatory locks on the file. 964 */ 965 if (locks_verify_locked(inode)) 966 return -EAGAIN; 967 968 vm_flags |= VM_SHARED | VM_MAYSHARE; 969 if (!(file->f_mode & FMODE_WRITE)) 970 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 971 972 /* fall through */ 973 case MAP_PRIVATE: 974 if (!(file->f_mode & FMODE_READ)) 975 return -EACCES; 976 break; 977 978 default: 979 return -EINVAL; 980 } 981 } else { 982 switch (flags & MAP_TYPE) { 983 case MAP_SHARED: 984 vm_flags |= VM_SHARED | VM_MAYSHARE; 985 break; 986 case MAP_PRIVATE: 987 /* 988 * Set pgoff according to addr for anon_vma. 989 */ 990 pgoff = addr >> PAGE_SHIFT; 991 break; 992 default: 993 return -EINVAL; 994 } 995 } 996 997 error = security_file_mmap(file, reqprot, prot, flags); 998 if (error) 999 return error; 1000 1001 /* Clear old maps */ 1002 error = -ENOMEM; 1003munmap_back: 1004 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1005 if (vma && vma->vm_start < addr + len) { 1006 if (do_munmap(mm, addr, len)) 1007 return -ENOMEM; 1008 goto munmap_back; 1009 } 1010 1011 /* Check against address space limit. */ 1012 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1013 return -ENOMEM; 1014 1015 if (accountable && (!(flags & MAP_NORESERVE) || 1016 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) { 1017 if (vm_flags & VM_SHARED) { 1018 /* Check memory availability in shmem_file_setup? */ 1019 vm_flags |= VM_ACCOUNT; 1020 } else if (vm_flags & VM_WRITE) { 1021 /* 1022 * Private writable mapping: check memory availability 1023 */ 1024 charged = len >> PAGE_SHIFT; 1025 if (security_vm_enough_memory(charged)) 1026 return -ENOMEM; 1027 vm_flags |= VM_ACCOUNT; 1028 } 1029 } 1030 1031 /* 1032 * Can we just expand an old private anonymous mapping? 1033 * The VM_SHARED test is necessary because shmem_zero_setup 1034 * will create the file object for a shared anonymous map below. 1035 */ 1036 if (!file && !(vm_flags & VM_SHARED) && 1037 vma_merge(mm, prev, addr, addr + len, vm_flags, 1038 NULL, NULL, pgoff, NULL)) 1039 goto out; 1040 1041 /* 1042 * Determine the object being mapped and call the appropriate 1043 * specific mapper. the address has already been validated, but 1044 * not unmapped, but the maps are removed from the list. 1045 */ 1046 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1047 if (!vma) { 1048 error = -ENOMEM; 1049 goto unacct_error; 1050 } 1051 1052 vma->vm_mm = mm; 1053 vma->vm_start = addr; 1054 vma->vm_end = addr + len; 1055 vma->vm_flags = vm_flags; 1056 vma->vm_page_prot = protection_map[vm_flags & 0x0f]; 1057 vma->vm_pgoff = pgoff; 1058 1059 if (file) { 1060 error = -EINVAL; 1061 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1062 goto free_vma; 1063 if (vm_flags & VM_DENYWRITE) { 1064 error = deny_write_access(file); 1065 if (error) 1066 goto free_vma; 1067 correct_wcount = 1; 1068 } 1069 vma->vm_file = file; 1070 get_file(file); 1071 error = file->f_op->mmap(file, vma); 1072 if (error) 1073 goto unmap_and_free_vma; 1074 } else if (vm_flags & VM_SHARED) { 1075 error = shmem_zero_setup(vma); 1076 if (error) 1077 goto free_vma; 1078 } 1079 1080 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform 1081 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap) 1082 * that memory reservation must be checked; but that reservation 1083 * belongs to shared memory object, not to vma: so now clear it. 1084 */ 1085 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT)) 1086 vma->vm_flags &= ~VM_ACCOUNT; 1087 1088 /* Can addr have changed?? 1089 * 1090 * Answer: Yes, several device drivers can do it in their 1091 * f_op->mmap method. -DaveM 1092 */ 1093 addr = vma->vm_start; 1094 pgoff = vma->vm_pgoff; 1095 vm_flags = vma->vm_flags; 1096 1097 if (!file || !vma_merge(mm, prev, addr, vma->vm_end, 1098 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) { 1099 file = vma->vm_file; 1100 vma_link(mm, vma, prev, rb_link, rb_parent); 1101 if (correct_wcount) 1102 atomic_inc(&inode->i_writecount); 1103 } else { 1104 if (file) { 1105 if (correct_wcount) 1106 atomic_inc(&inode->i_writecount); 1107 fput(file); 1108 } 1109 mpol_free(vma_policy(vma)); 1110 kmem_cache_free(vm_area_cachep, vma); 1111 } 1112out: 1113 mm->total_vm += len >> PAGE_SHIFT; 1114 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1115 if (vm_flags & VM_LOCKED) { 1116 mm->locked_vm += len >> PAGE_SHIFT; 1117 make_pages_present(addr, addr + len); 1118 } 1119 if (flags & MAP_POPULATE) { 1120 up_write(&mm->mmap_sem); 1121 sys_remap_file_pages(addr, len, 0, 1122 pgoff, flags & MAP_NONBLOCK); 1123 down_write(&mm->mmap_sem); 1124 } 1125 return addr; 1126 1127unmap_and_free_vma: 1128 if (correct_wcount) 1129 atomic_inc(&inode->i_writecount); 1130 vma->vm_file = NULL; 1131 fput(file); 1132 1133 /* Undo any partial mapping done by a device driver. */ 1134 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1135 charged = 0; 1136free_vma: 1137 kmem_cache_free(vm_area_cachep, vma); 1138unacct_error: 1139 if (charged) 1140 vm_unacct_memory(charged); 1141 return error; 1142} 1143 1144EXPORT_SYMBOL(do_mmap_pgoff); 1145 1146/* Get an address range which is currently unmapped. 1147 * For shmat() with addr=0. 1148 * 1149 * Ugly calling convention alert: 1150 * Return value with the low bits set means error value, 1151 * ie 1152 * if (ret & ~PAGE_MASK) 1153 * error = ret; 1154 * 1155 * This function "knows" that -ENOMEM has the bits set. 1156 */ 1157#ifndef HAVE_ARCH_UNMAPPED_AREA 1158unsigned long 1159arch_get_unmapped_area(struct file *filp, unsigned long addr, 1160 unsigned long len, unsigned long pgoff, unsigned long flags) 1161{ 1162 struct mm_struct *mm = current->mm; 1163 struct vm_area_struct *vma; 1164 unsigned long start_addr; 1165 1166 if (len > TASK_SIZE) 1167 return -ENOMEM; 1168 1169 if (addr) { 1170 addr = PAGE_ALIGN(addr); 1171 vma = find_vma(mm, addr); 1172 if (TASK_SIZE - len >= addr && 1173 (!vma || addr + len <= vma->vm_start)) 1174 return addr; 1175 } 1176 if (len > mm->cached_hole_size) { 1177 start_addr = addr = mm->free_area_cache; 1178 } else { 1179 start_addr = addr = TASK_UNMAPPED_BASE; 1180 mm->cached_hole_size = 0; 1181 } 1182 1183full_search: 1184 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1185 /* At this point: (!vma || addr < vma->vm_end). */ 1186 if (TASK_SIZE - len < addr) { 1187 /* 1188 * Start a new search - just in case we missed 1189 * some holes. 1190 */ 1191 if (start_addr != TASK_UNMAPPED_BASE) { 1192 addr = TASK_UNMAPPED_BASE; 1193 start_addr = addr; 1194 mm->cached_hole_size = 0; 1195 goto full_search; 1196 } 1197 return -ENOMEM; 1198 } 1199 if (!vma || addr + len <= vma->vm_start) { 1200 /* 1201 * Remember the place where we stopped the search: 1202 */ 1203 mm->free_area_cache = addr + len; 1204 return addr; 1205 } 1206 if (addr + mm->cached_hole_size < vma->vm_start) 1207 mm->cached_hole_size = vma->vm_start - addr; 1208 addr = vma->vm_end; 1209 } 1210} 1211#endif 1212 1213void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1214{ 1215 /* 1216 * Is this a new hole at the lowest possible address? 1217 */ 1218 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { 1219 mm->free_area_cache = addr; 1220 mm->cached_hole_size = ~0UL; 1221 } 1222} 1223 1224/* 1225 * This mmap-allocator allocates new areas top-down from below the 1226 * stack's low limit (the base): 1227 */ 1228#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1229unsigned long 1230arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1231 const unsigned long len, const unsigned long pgoff, 1232 const unsigned long flags) 1233{ 1234 struct vm_area_struct *vma; 1235 struct mm_struct *mm = current->mm; 1236 unsigned long addr = addr0; 1237 1238 /* requested length too big for entire address space */ 1239 if (len > TASK_SIZE) 1240 return -ENOMEM; 1241 1242 /* requesting a specific address */ 1243 if (addr) { 1244 addr = PAGE_ALIGN(addr); 1245 vma = find_vma(mm, addr); 1246 if (TASK_SIZE - len >= addr && 1247 (!vma || addr + len <= vma->vm_start)) 1248 return addr; 1249 } 1250 1251 /* check if free_area_cache is useful for us */ 1252 if (len <= mm->cached_hole_size) { 1253 mm->cached_hole_size = 0; 1254 mm->free_area_cache = mm->mmap_base; 1255 } 1256 1257 /* either no address requested or can't fit in requested address hole */ 1258 addr = mm->free_area_cache; 1259 1260 /* make sure it can fit in the remaining address space */ 1261 if (addr > len) { 1262 vma = find_vma(mm, addr-len); 1263 if (!vma || addr <= vma->vm_start) 1264 /* remember the address as a hint for next time */ 1265 return (mm->free_area_cache = addr-len); 1266 } 1267 1268 if (mm->mmap_base < len) 1269 goto bottomup; 1270 1271 addr = mm->mmap_base-len; 1272 1273 do { 1274 /* 1275 * Lookup failure means no vma is above this address, 1276 * else if new region fits below vma->vm_start, 1277 * return with success: 1278 */ 1279 vma = find_vma(mm, addr); 1280 if (!vma || addr+len <= vma->vm_start) 1281 /* remember the address as a hint for next time */ 1282 return (mm->free_area_cache = addr); 1283 1284 /* remember the largest hole we saw so far */ 1285 if (addr + mm->cached_hole_size < vma->vm_start) 1286 mm->cached_hole_size = vma->vm_start - addr; 1287 1288 /* try just below the current vma->vm_start */ 1289 addr = vma->vm_start-len; 1290 } while (len < vma->vm_start); 1291 1292bottomup: 1293 /* 1294 * A failed mmap() very likely causes application failure, 1295 * so fall back to the bottom-up function here. This scenario 1296 * can happen with large stack limits and large mmap() 1297 * allocations. 1298 */ 1299 mm->cached_hole_size = ~0UL; 1300 mm->free_area_cache = TASK_UNMAPPED_BASE; 1301 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1302 /* 1303 * Restore the topdown base: 1304 */ 1305 mm->free_area_cache = mm->mmap_base; 1306 mm->cached_hole_size = ~0UL; 1307 1308 return addr; 1309} 1310#endif 1311 1312void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1313{ 1314 /* 1315 * Is this a new hole at the highest possible address? 1316 */ 1317 if (addr > mm->free_area_cache) 1318 mm->free_area_cache = addr; 1319 1320 /* dont allow allocations above current base */ 1321 if (mm->free_area_cache > mm->mmap_base) 1322 mm->free_area_cache = mm->mmap_base; 1323} 1324 1325unsigned long 1326get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1327 unsigned long pgoff, unsigned long flags) 1328{ 1329 unsigned long ret; 1330 1331 if (!(flags & MAP_FIXED)) { 1332 unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long); 1333 1334 get_area = current->mm->get_unmapped_area; 1335 if (file && file->f_op && file->f_op->get_unmapped_area) 1336 get_area = file->f_op->get_unmapped_area; 1337 addr = get_area(file, addr, len, pgoff, flags); 1338 if (IS_ERR_VALUE(addr)) 1339 return addr; 1340 } 1341 1342 if (addr > TASK_SIZE - len) 1343 return -ENOMEM; 1344 if (addr & ~PAGE_MASK) 1345 return -EINVAL; 1346 if (file && is_file_hugepages(file)) { 1347 /* 1348 * Check if the given range is hugepage aligned, and 1349 * can be made suitable for hugepages. 1350 */ 1351 ret = prepare_hugepage_range(addr, len); 1352 } else { 1353 /* 1354 * Ensure that a normal request is not falling in a 1355 * reserved hugepage range. For some archs like IA-64, 1356 * there is a separate region for hugepages. 1357 */ 1358 ret = is_hugepage_only_range(current->mm, addr, len); 1359 } 1360 if (ret) 1361 return -EINVAL; 1362 return addr; 1363} 1364 1365EXPORT_SYMBOL(get_unmapped_area); 1366 1367/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1368struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr) 1369{ 1370 struct vm_area_struct *vma = NULL; 1371 1372 if (mm) { 1373 /* Check the cache first. */ 1374 /* (Cache hit rate is typically around 35%.) */ 1375 vma = mm->mmap_cache; 1376 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1377 struct rb_node * rb_node; 1378 1379 rb_node = mm->mm_rb.rb_node; 1380 vma = NULL; 1381 1382 while (rb_node) { 1383 struct vm_area_struct * vma_tmp; 1384 1385 vma_tmp = rb_entry(rb_node, 1386 struct vm_area_struct, vm_rb); 1387 1388 if (vma_tmp->vm_end > addr) { 1389 vma = vma_tmp; 1390 if (vma_tmp->vm_start <= addr) 1391 break; 1392 rb_node = rb_node->rb_left; 1393 } else 1394 rb_node = rb_node->rb_right; 1395 } 1396 if (vma) 1397 mm->mmap_cache = vma; 1398 } 1399 } 1400 return vma; 1401} 1402 1403EXPORT_SYMBOL(find_vma); 1404 1405/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1406struct vm_area_struct * 1407find_vma_prev(struct mm_struct *mm, unsigned long addr, 1408 struct vm_area_struct **pprev) 1409{ 1410 struct vm_area_struct *vma = NULL, *prev = NULL; 1411 struct rb_node * rb_node; 1412 if (!mm) 1413 goto out; 1414 1415 /* Guard against addr being lower than the first VMA */ 1416 vma = mm->mmap; 1417 1418 /* Go through the RB tree quickly. */ 1419 rb_node = mm->mm_rb.rb_node; 1420 1421 while (rb_node) { 1422 struct vm_area_struct *vma_tmp; 1423 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1424 1425 if (addr < vma_tmp->vm_end) { 1426 rb_node = rb_node->rb_left; 1427 } else { 1428 prev = vma_tmp; 1429 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1430 break; 1431 rb_node = rb_node->rb_right; 1432 } 1433 } 1434 1435out: 1436 *pprev = prev; 1437 return prev ? prev->vm_next : vma; 1438} 1439 1440/* 1441 * Verify that the stack growth is acceptable and 1442 * update accounting. This is shared with both the 1443 * grow-up and grow-down cases. 1444 */ 1445static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow) 1446{ 1447 struct mm_struct *mm = vma->vm_mm; 1448 struct rlimit *rlim = current->signal->rlim; 1449 1450 /* address space limit tests */ 1451 if (!may_expand_vm(mm, grow)) 1452 return -ENOMEM; 1453 1454 /* Stack limit test */ 1455 if (size > rlim[RLIMIT_STACK].rlim_cur) 1456 return -ENOMEM; 1457 1458 /* mlock limit tests */ 1459 if (vma->vm_flags & VM_LOCKED) { 1460 unsigned long locked; 1461 unsigned long limit; 1462 locked = mm->locked_vm + grow; 1463 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1464 if (locked > limit && !capable(CAP_IPC_LOCK)) 1465 return -ENOMEM; 1466 } 1467 1468 /* 1469 * Overcommit.. This must be the final test, as it will 1470 * update security statistics. 1471 */ 1472 if (security_vm_enough_memory(grow)) 1473 return -ENOMEM; 1474 1475 /* Ok, everything looks good - let it rip */ 1476 mm->total_vm += grow; 1477 if (vma->vm_flags & VM_LOCKED) 1478 mm->locked_vm += grow; 1479 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1480 return 0; 1481} 1482 1483#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 1484/* 1485 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 1486 * vma is the last one with address > vma->vm_end. Have to extend vma. 1487 */ 1488#ifndef CONFIG_IA64 1489static inline 1490#endif 1491int expand_upwards(struct vm_area_struct *vma, unsigned long address) 1492{ 1493 int error; 1494 1495 if (!(vma->vm_flags & VM_GROWSUP)) 1496 return -EFAULT; 1497 1498 /* 1499 * We must make sure the anon_vma is allocated 1500 * so that the anon_vma locking is not a noop. 1501 */ 1502 if (unlikely(anon_vma_prepare(vma))) 1503 return -ENOMEM; 1504 anon_vma_lock(vma); 1505 1506 /* 1507 * vma->vm_start/vm_end cannot change under us because the caller 1508 * is required to hold the mmap_sem in read mode. We need the 1509 * anon_vma lock to serialize against concurrent expand_stacks. 1510 */ 1511 address += 4 + PAGE_SIZE - 1; 1512 address &= PAGE_MASK; 1513 error = 0; 1514 1515 /* Somebody else might have raced and expanded it already */ 1516 if (address > vma->vm_end) { 1517 unsigned long size, grow; 1518 1519 size = address - vma->vm_start; 1520 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1521 1522 error = acct_stack_growth(vma, size, grow); 1523 if (!error) 1524 vma->vm_end = address; 1525 } 1526 anon_vma_unlock(vma); 1527 return error; 1528} 1529#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 1530 1531#ifdef CONFIG_STACK_GROWSUP 1532int expand_stack(struct vm_area_struct *vma, unsigned long address) 1533{ 1534 return expand_upwards(vma, address); 1535} 1536 1537struct vm_area_struct * 1538find_extend_vma(struct mm_struct *mm, unsigned long addr) 1539{ 1540 struct vm_area_struct *vma, *prev; 1541 1542 addr &= PAGE_MASK; 1543 vma = find_vma_prev(mm, addr, &prev); 1544 if (vma && (vma->vm_start <= addr)) 1545 return vma; 1546 if (!prev || expand_stack(prev, addr)) 1547 return NULL; 1548 if (prev->vm_flags & VM_LOCKED) { 1549 make_pages_present(addr, prev->vm_end); 1550 } 1551 return prev; 1552} 1553#else 1554/* 1555 * vma is the first one with address < vma->vm_start. Have to extend vma. 1556 */ 1557int expand_stack(struct vm_area_struct *vma, unsigned long address) 1558{ 1559 int error; 1560 1561 /* 1562 * We must make sure the anon_vma is allocated 1563 * so that the anon_vma locking is not a noop. 1564 */ 1565 if (unlikely(anon_vma_prepare(vma))) 1566 return -ENOMEM; 1567 anon_vma_lock(vma); 1568 1569 /* 1570 * vma->vm_start/vm_end cannot change under us because the caller 1571 * is required to hold the mmap_sem in read mode. We need the 1572 * anon_vma lock to serialize against concurrent expand_stacks. 1573 */ 1574 address &= PAGE_MASK; 1575 error = 0; 1576 1577 /* Somebody else might have raced and expanded it already */ 1578 if (address < vma->vm_start) { 1579 unsigned long size, grow; 1580 1581 size = vma->vm_end - address; 1582 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1583 1584 error = acct_stack_growth(vma, size, grow); 1585 if (!error) { 1586 vma->vm_start = address; 1587 vma->vm_pgoff -= grow; 1588 } 1589 } 1590 anon_vma_unlock(vma); 1591 return error; 1592} 1593 1594struct vm_area_struct * 1595find_extend_vma(struct mm_struct * mm, unsigned long addr) 1596{ 1597 struct vm_area_struct * vma; 1598 unsigned long start; 1599 1600 addr &= PAGE_MASK; 1601 vma = find_vma(mm,addr); 1602 if (!vma) 1603 return NULL; 1604 if (vma->vm_start <= addr) 1605 return vma; 1606 if (!(vma->vm_flags & VM_GROWSDOWN)) 1607 return NULL; 1608 start = vma->vm_start; 1609 if (expand_stack(vma, addr)) 1610 return NULL; 1611 if (vma->vm_flags & VM_LOCKED) { 1612 make_pages_present(addr, start); 1613 } 1614 return vma; 1615} 1616#endif 1617 1618/* 1619 * Ok - we have the memory areas we should free on the vma list, 1620 * so release them, and do the vma updates. 1621 * 1622 * Called with the mm semaphore held. 1623 */ 1624static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1625{ 1626 /* Update high watermark before we lower total_vm */ 1627 update_hiwater_vm(mm); 1628 do { 1629 long nrpages = vma_pages(vma); 1630 1631 mm->total_vm -= nrpages; 1632 if (vma->vm_flags & VM_LOCKED) 1633 mm->locked_vm -= nrpages; 1634 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 1635 vma = remove_vma(vma); 1636 } while (vma); 1637 validate_mm(mm); 1638} 1639 1640/* 1641 * Get rid of page table information in the indicated region. 1642 * 1643 * Called with the mm semaphore held. 1644 */ 1645static void unmap_region(struct mm_struct *mm, 1646 struct vm_area_struct *vma, struct vm_area_struct *prev, 1647 unsigned long start, unsigned long end) 1648{ 1649 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1650 struct mmu_gather *tlb; 1651 unsigned long nr_accounted = 0; 1652 1653 lru_add_drain(); 1654 tlb = tlb_gather_mmu(mm, 0); 1655 update_hiwater_rss(mm); 1656 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); 1657 vm_unacct_memory(nr_accounted); 1658 free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1659 next? next->vm_start: 0); 1660 tlb_finish_mmu(tlb, start, end); 1661} 1662 1663/* 1664 * Create a list of vma's touched by the unmap, removing them from the mm's 1665 * vma list as we go.. 1666 */ 1667static void 1668detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1669 struct vm_area_struct *prev, unsigned long end) 1670{ 1671 struct vm_area_struct **insertion_point; 1672 struct vm_area_struct *tail_vma = NULL; 1673 unsigned long addr; 1674 1675 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1676 do { 1677 rb_erase(&vma->vm_rb, &mm->mm_rb); 1678 mm->map_count--; 1679 tail_vma = vma; 1680 vma = vma->vm_next; 1681 } while (vma && vma->vm_start < end); 1682 *insertion_point = vma; 1683 tail_vma->vm_next = NULL; 1684 if (mm->unmap_area == arch_unmap_area) 1685 addr = prev ? prev->vm_end : mm->mmap_base; 1686 else 1687 addr = vma ? vma->vm_start : mm->mmap_base; 1688 mm->unmap_area(mm, addr); 1689 mm->mmap_cache = NULL; /* Kill the cache. */ 1690} 1691 1692/* 1693 * Split a vma into two pieces at address 'addr', a new vma is allocated 1694 * either for the first part or the the tail. 1695 */ 1696int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1697 unsigned long addr, int new_below) 1698{ 1699 struct mempolicy *pol; 1700 struct vm_area_struct *new; 1701 1702 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK)) 1703 return -EINVAL; 1704 1705 if (mm->map_count >= sysctl_max_map_count) 1706 return -ENOMEM; 1707 1708 new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 1709 if (!new) 1710 return -ENOMEM; 1711 1712 /* most fields are the same, copy all, and then fixup */ 1713 *new = *vma; 1714 1715 if (new_below) 1716 new->vm_end = addr; 1717 else { 1718 new->vm_start = addr; 1719 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1720 } 1721 1722 pol = mpol_copy(vma_policy(vma)); 1723 if (IS_ERR(pol)) { 1724 kmem_cache_free(vm_area_cachep, new); 1725 return PTR_ERR(pol); 1726 } 1727 vma_set_policy(new, pol); 1728 1729 if (new->vm_file) 1730 get_file(new->vm_file); 1731 1732 if (new->vm_ops && new->vm_ops->open) 1733 new->vm_ops->open(new); 1734 1735 if (new_below) 1736 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1737 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1738 else 1739 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1740 1741 return 0; 1742} 1743 1744/* Munmap is split into 2 main parts -- this part which finds 1745 * what needs doing, and the areas themselves, which do the 1746 * work. This now handles partial unmappings. 1747 * Jeremy Fitzhardinge <jeremy@goop.org> 1748 */ 1749int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1750{ 1751 unsigned long end; 1752 struct vm_area_struct *vma, *prev, *last; 1753 1754 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1755 return -EINVAL; 1756 1757 if ((len = PAGE_ALIGN(len)) == 0) 1758 return -EINVAL; 1759 1760 /* Find the first overlapping VMA */ 1761 vma = find_vma_prev(mm, start, &prev); 1762 if (!vma) 1763 return 0; 1764 /* we have start < vma->vm_end */ 1765 1766 /* if it doesn't overlap, we have nothing.. */ 1767 end = start + len; 1768 if (vma->vm_start >= end) 1769 return 0; 1770 1771 /* 1772 * If we need to split any vma, do it now to save pain later. 1773 * 1774 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1775 * unmapped vm_area_struct will remain in use: so lower split_vma 1776 * places tmp vma above, and higher split_vma places tmp vma below. 1777 */ 1778 if (start > vma->vm_start) { 1779 int error = split_vma(mm, vma, start, 0); 1780 if (error) 1781 return error; 1782 prev = vma; 1783 } 1784 1785 /* Does it split the last one? */ 1786 last = find_vma(mm, end); 1787 if (last && end > last->vm_start) { 1788 int error = split_vma(mm, last, end, 1); 1789 if (error) 1790 return error; 1791 } 1792 vma = prev? prev->vm_next: mm->mmap; 1793 1794 /* 1795 * Remove the vma's, and unmap the actual pages 1796 */ 1797 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1798 unmap_region(mm, vma, prev, start, end); 1799 1800 /* Fix up all other VM information */ 1801 remove_vma_list(mm, vma); 1802 1803 return 0; 1804} 1805 1806EXPORT_SYMBOL(do_munmap); 1807 1808asmlinkage long sys_munmap(unsigned long addr, size_t len) 1809{ 1810 int ret; 1811 struct mm_struct *mm = current->mm; 1812 1813 profile_munmap(addr); 1814 1815 down_write(&mm->mmap_sem); 1816 ret = do_munmap(mm, addr, len); 1817 up_write(&mm->mmap_sem); 1818 return ret; 1819} 1820 1821static inline void verify_mm_writelocked(struct mm_struct *mm) 1822{ 1823#ifdef CONFIG_DEBUG_VM 1824 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1825 WARN_ON(1); 1826 up_read(&mm->mmap_sem); 1827 } 1828#endif 1829} 1830 1831/* 1832 * this is really a simplified "do_mmap". it only handles 1833 * anonymous maps. eventually we may be able to do some 1834 * brk-specific accounting here. 1835 */ 1836unsigned long do_brk(unsigned long addr, unsigned long len) 1837{ 1838 struct mm_struct * mm = current->mm; 1839 struct vm_area_struct * vma, * prev; 1840 unsigned long flags; 1841 struct rb_node ** rb_link, * rb_parent; 1842 pgoff_t pgoff = addr >> PAGE_SHIFT; 1843 1844 len = PAGE_ALIGN(len); 1845 if (!len) 1846 return addr; 1847 1848 if ((addr + len) > TASK_SIZE || (addr + len) < addr) 1849 return -EINVAL; 1850 1851 /* 1852 * mlock MCL_FUTURE? 1853 */ 1854 if (mm->def_flags & VM_LOCKED) { 1855 unsigned long locked, lock_limit; 1856 locked = len >> PAGE_SHIFT; 1857 locked += mm->locked_vm; 1858 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 1859 lock_limit >>= PAGE_SHIFT; 1860 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1861 return -EAGAIN; 1862 } 1863 1864 /* 1865 * mm->mmap_sem is required to protect against another thread 1866 * changing the mappings in case we sleep. 1867 */ 1868 verify_mm_writelocked(mm); 1869 1870 /* 1871 * Clear old maps. this also does some error checking for us 1872 */ 1873 munmap_back: 1874 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1875 if (vma && vma->vm_start < addr + len) { 1876 if (do_munmap(mm, addr, len)) 1877 return -ENOMEM; 1878 goto munmap_back; 1879 } 1880 1881 /* Check against address space limits *after* clearing old maps... */ 1882 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1883 return -ENOMEM; 1884 1885 if (mm->map_count > sysctl_max_map_count) 1886 return -ENOMEM; 1887 1888 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 1889 return -ENOMEM; 1890 1891 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 1892 1893 /* Can we just expand an old private anonymous mapping? */ 1894 if (vma_merge(mm, prev, addr, addr + len, flags, 1895 NULL, NULL, pgoff, NULL)) 1896 goto out; 1897 1898 /* 1899 * create a vma struct for an anonymous mapping 1900 */ 1901 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1902 if (!vma) { 1903 vm_unacct_memory(len >> PAGE_SHIFT); 1904 return -ENOMEM; 1905 } 1906 1907 vma->vm_mm = mm; 1908 vma->vm_start = addr; 1909 vma->vm_end = addr + len; 1910 vma->vm_pgoff = pgoff; 1911 vma->vm_flags = flags; 1912 vma->vm_page_prot = protection_map[flags & 0x0f]; 1913 vma_link(mm, vma, prev, rb_link, rb_parent); 1914out: 1915 mm->total_vm += len >> PAGE_SHIFT; 1916 if (flags & VM_LOCKED) { 1917 mm->locked_vm += len >> PAGE_SHIFT; 1918 make_pages_present(addr, addr + len); 1919 } 1920 return addr; 1921} 1922 1923EXPORT_SYMBOL(do_brk); 1924 1925/* Release all mmaps. */ 1926void exit_mmap(struct mm_struct *mm) 1927{ 1928 struct mmu_gather *tlb; 1929 struct vm_area_struct *vma = mm->mmap; 1930 unsigned long nr_accounted = 0; 1931 unsigned long end; 1932 1933 lru_add_drain(); 1934 flush_cache_mm(mm); 1935 tlb = tlb_gather_mmu(mm, 1); 1936 /* Don't update_hiwater_rss(mm) here, do_exit already did */ 1937 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 1938 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); 1939 vm_unacct_memory(nr_accounted); 1940 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); 1941 tlb_finish_mmu(tlb, 0, end); 1942 1943 /* 1944 * Walk the list again, actually closing and freeing it, 1945 * with preemption enabled, without holding any MM locks. 1946 */ 1947 while (vma) 1948 vma = remove_vma(vma); 1949 1950 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 1951} 1952 1953/* Insert vm structure into process list sorted by address 1954 * and into the inode's i_mmap tree. If vm_file is non-NULL 1955 * then i_mmap_lock is taken here. 1956 */ 1957int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 1958{ 1959 struct vm_area_struct * __vma, * prev; 1960 struct rb_node ** rb_link, * rb_parent; 1961 1962 /* 1963 * The vm_pgoff of a purely anonymous vma should be irrelevant 1964 * until its first write fault, when page's anon_vma and index 1965 * are set. But now set the vm_pgoff it will almost certainly 1966 * end up with (unless mremap moves it elsewhere before that 1967 * first wfault), so /proc/pid/maps tells a consistent story. 1968 * 1969 * By setting it to reflect the virtual start address of the 1970 * vma, merges and splits can happen in a seamless way, just 1971 * using the existing file pgoff checks and manipulations. 1972 * Similarly in do_mmap_pgoff and in do_brk. 1973 */ 1974 if (!vma->vm_file) { 1975 BUG_ON(vma->anon_vma); 1976 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 1977 } 1978 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 1979 if (__vma && __vma->vm_start < vma->vm_end) 1980 return -ENOMEM; 1981 if ((vma->vm_flags & VM_ACCOUNT) && 1982 security_vm_enough_memory(vma_pages(vma))) 1983 return -ENOMEM; 1984 vma_link(mm, vma, prev, rb_link, rb_parent); 1985 return 0; 1986} 1987 1988/* 1989 * Copy the vma structure to a new location in the same mm, 1990 * prior to moving page table entries, to effect an mremap move. 1991 */ 1992struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 1993 unsigned long addr, unsigned long len, pgoff_t pgoff) 1994{ 1995 struct vm_area_struct *vma = *vmap; 1996 unsigned long vma_start = vma->vm_start; 1997 struct mm_struct *mm = vma->vm_mm; 1998 struct vm_area_struct *new_vma, *prev; 1999 struct rb_node **rb_link, *rb_parent; 2000 struct mempolicy *pol; 2001 2002 /* 2003 * If anonymous vma has not yet been faulted, update new pgoff 2004 * to match new location, to increase its chance of merging. 2005 */ 2006 if (!vma->vm_file && !vma->anon_vma) 2007 pgoff = addr >> PAGE_SHIFT; 2008 2009 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2010 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2011 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2012 if (new_vma) { 2013 /* 2014 * Source vma may have been merged into new_vma 2015 */ 2016 if (vma_start >= new_vma->vm_start && 2017 vma_start < new_vma->vm_end) 2018 *vmap = new_vma; 2019 } else { 2020 new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); 2021 if (new_vma) { 2022 *new_vma = *vma; 2023 pol = mpol_copy(vma_policy(vma)); 2024 if (IS_ERR(pol)) { 2025 kmem_cache_free(vm_area_cachep, new_vma); 2026 return NULL; 2027 } 2028 vma_set_policy(new_vma, pol); 2029 new_vma->vm_start = addr; 2030 new_vma->vm_end = addr + len; 2031 new_vma->vm_pgoff = pgoff; 2032 if (new_vma->vm_file) 2033 get_file(new_vma->vm_file); 2034 if (new_vma->vm_ops && new_vma->vm_ops->open) 2035 new_vma->vm_ops->open(new_vma); 2036 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2037 } 2038 } 2039 return new_vma; 2040} 2041 2042/* 2043 * Return true if the calling process may expand its vm space by the passed 2044 * number of pages 2045 */ 2046int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2047{ 2048 unsigned long cur = mm->total_vm; /* pages */ 2049 unsigned long lim; 2050 2051 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2052 2053 if (cur + npages > lim) 2054 return 0; 2055 return 1; 2056} 2057