ia64/linux-2.6.18-xen.hg

view mm/mmap.c @ 912:dd42cdb0ab89

[IA64] Build blktap2 driver by default in x86 builds.

add CONFIG_XEN_BLKDEV_TAP2=y to buildconfigs/linux-defconfig_xen_ia64.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
author Isaku Yamahata <yamahata@valinux.co.jp>
date Mon Jun 29 12:09:16 2009 +0900 (2009-06-29)
parents eba6fe6d8d53
children
line source
1 /*
2 * mm/mmap.c
3 *
4 * Written by obz.
5 *
6 * Address space accounting code <alan@redhat.com>
7 */
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>
29 #include <asm/uaccess.h>
30 #include <asm/cacheflush.h>
31 #include <asm/tlb.h>
33 #ifndef arch_mmap_check
34 #define arch_mmap_check(addr, len, flags) (0)
35 #endif
37 static void unmap_region(struct mm_struct *mm,
38 struct vm_area_struct *vma, struct vm_area_struct *prev,
39 unsigned long start, unsigned long end);
41 /*
42 * WARNING: the debugging will use recursive algorithms so never enable this
43 * unless you know what you are doing.
44 */
45 #undef DEBUG_MM_RB
47 /* description of effects of mapping type and prot in current implementation.
48 * this is due to the limited x86 page protection hardware. The expected
49 * behavior is in parens:
50 *
51 * map_type prot
52 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
53 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
54 * w: (no) no w: (no) no w: (yes) yes w: (no) no
55 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
56 *
57 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
58 * w: (no) no w: (no) no w: (copy) copy w: (no) no
59 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
60 *
61 */
62 pgprot_t protection_map[16] = {
63 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
64 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
65 };
67 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
68 int sysctl_overcommit_ratio = 50; /* default is 50% */
69 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
70 atomic_t vm_committed_space = ATOMIC_INIT(0);
72 /*
73 * Check that a process has enough memory to allocate a new virtual
74 * mapping. 0 means there is enough memory for the allocation to
75 * succeed and -ENOMEM implies there is not.
76 *
77 * We currently support three overcommit policies, which are set via the
78 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
79 *
80 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
81 * Additional code 2002 Jul 20 by Robert Love.
82 *
83 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
84 *
85 * Note this is a helper function intended to be used by LSMs which
86 * wish to use this logic.
87 */
88 int __vm_enough_memory(long pages, int cap_sys_admin)
89 {
90 unsigned long free, allowed;
92 vm_acct_memory(pages);
94 /*
95 * Sometimes we want to use more memory than we have
96 */
97 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
98 return 0;
100 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
101 unsigned long n;
103 free = global_page_state(NR_FILE_PAGES);
104 free += nr_swap_pages;
106 /*
107 * Any slabs which are created with the
108 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
109 * which are reclaimable, under pressure. The dentry
110 * cache and most inode caches should fall into this
111 */
112 free += atomic_read(&slab_reclaim_pages);
114 /*
115 * Leave the last 3% for root
116 */
117 if (!cap_sys_admin)
118 free -= free / 32;
120 if (free > pages)
121 return 0;
123 /*
124 * nr_free_pages() is very expensive on large systems,
125 * only call if we're about to fail.
126 */
127 n = nr_free_pages();
129 /*
130 * Leave reserved pages. The pages are not for anonymous pages.
131 */
132 if (n <= totalreserve_pages)
133 goto error;
134 else
135 n -= totalreserve_pages;
137 /*
138 * Leave the last 3% for root
139 */
140 if (!cap_sys_admin)
141 n -= n / 32;
142 free += n;
144 if (free > pages)
145 return 0;
147 goto error;
148 }
150 allowed = (totalram_pages - hugetlb_total_pages())
151 * sysctl_overcommit_ratio / 100;
152 /*
153 * Leave the last 3% for root
154 */
155 if (!cap_sys_admin)
156 allowed -= allowed / 32;
157 allowed += total_swap_pages;
159 /* Don't let a single process grow too big:
160 leave 3% of the size of this process for other processes */
161 allowed -= current->mm->total_vm / 32;
163 /*
164 * cast `allowed' as a signed long because vm_committed_space
165 * sometimes has a negative value
166 */
167 if (atomic_read(&vm_committed_space) < (long)allowed)
168 return 0;
169 error:
170 vm_unacct_memory(pages);
172 return -ENOMEM;
173 }
175 EXPORT_SYMBOL(__vm_enough_memory);
177 /*
178 * Requires inode->i_mapping->i_mmap_lock
179 */
180 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
181 struct file *file, struct address_space *mapping)
182 {
183 if (vma->vm_flags & VM_DENYWRITE)
184 atomic_inc(&file->f_dentry->d_inode->i_writecount);
185 if (vma->vm_flags & VM_SHARED)
186 mapping->i_mmap_writable--;
188 flush_dcache_mmap_lock(mapping);
189 if (unlikely(vma->vm_flags & VM_NONLINEAR))
190 list_del_init(&vma->shared.vm_set.list);
191 else
192 vma_prio_tree_remove(vma, &mapping->i_mmap);
193 flush_dcache_mmap_unlock(mapping);
194 }
196 /*
197 * Unlink a file-based vm structure from its prio_tree, to hide
198 * vma from rmap and vmtruncate before freeing its page tables.
199 */
200 void unlink_file_vma(struct vm_area_struct *vma)
201 {
202 struct file *file = vma->vm_file;
204 if (file) {
205 struct address_space *mapping = file->f_mapping;
206 spin_lock(&mapping->i_mmap_lock);
207 __remove_shared_vm_struct(vma, file, mapping);
208 spin_unlock(&mapping->i_mmap_lock);
209 }
210 }
212 /*
213 * Close a vm structure and free it, returning the next.
214 */
215 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
216 {
217 struct vm_area_struct *next = vma->vm_next;
219 might_sleep();
220 if (vma->vm_ops && vma->vm_ops->close)
221 vma->vm_ops->close(vma);
222 if (vma->vm_file)
223 fput(vma->vm_file);
224 mpol_free(vma_policy(vma));
225 kmem_cache_free(vm_area_cachep, vma);
226 return next;
227 }
229 asmlinkage unsigned long sys_brk(unsigned long brk)
230 {
231 unsigned long rlim, retval;
232 unsigned long newbrk, oldbrk;
233 struct mm_struct *mm = current->mm;
235 down_write(&mm->mmap_sem);
237 if (brk < mm->end_code)
238 goto out;
240 /*
241 * Check against rlimit here. If this check is done later after the test
242 * of oldbrk with newbrk then it can escape the test and let the data
243 * segment grow beyond its set limit the in case where the limit is
244 * not page aligned -Ram Gupta
245 */
246 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
247 if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim)
248 goto out;
250 newbrk = PAGE_ALIGN(brk);
251 oldbrk = PAGE_ALIGN(mm->brk);
252 if (oldbrk == newbrk)
253 goto set_brk;
255 /* Always allow shrinking brk. */
256 if (brk <= mm->brk) {
257 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
258 goto set_brk;
259 goto out;
260 }
262 /* Check against existing mmap mappings. */
263 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
264 goto out;
266 /* Ok, looks good - let it rip. */
267 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
268 goto out;
269 set_brk:
270 mm->brk = brk;
271 out:
272 retval = mm->brk;
273 up_write(&mm->mmap_sem);
274 return retval;
275 }
277 #ifdef DEBUG_MM_RB
278 static int browse_rb(struct rb_root *root)
279 {
280 int i = 0, j;
281 struct rb_node *nd, *pn = NULL;
282 unsigned long prev = 0, pend = 0;
284 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
285 struct vm_area_struct *vma;
286 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
287 if (vma->vm_start < prev)
288 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
289 if (vma->vm_start < pend)
290 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
291 if (vma->vm_start > vma->vm_end)
292 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
293 i++;
294 pn = nd;
295 }
296 j = 0;
297 for (nd = pn; nd; nd = rb_prev(nd)) {
298 j++;
299 }
300 if (i != j)
301 printk("backwards %d, forwards %d\n", j, i), i = 0;
302 return i;
303 }
305 void validate_mm(struct mm_struct *mm)
306 {
307 int bug = 0;
308 int i = 0;
309 struct vm_area_struct *tmp = mm->mmap;
310 while (tmp) {
311 tmp = tmp->vm_next;
312 i++;
313 }
314 if (i != mm->map_count)
315 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
316 i = browse_rb(&mm->mm_rb);
317 if (i != mm->map_count)
318 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
319 BUG_ON(bug);
320 }
321 #else
322 #define validate_mm(mm) do { } while (0)
323 #endif
325 static struct vm_area_struct *
326 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
327 struct vm_area_struct **pprev, struct rb_node ***rb_link,
328 struct rb_node ** rb_parent)
329 {
330 struct vm_area_struct * vma;
331 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
333 __rb_link = &mm->mm_rb.rb_node;
334 rb_prev = __rb_parent = NULL;
335 vma = NULL;
337 while (*__rb_link) {
338 struct vm_area_struct *vma_tmp;
340 __rb_parent = *__rb_link;
341 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
343 if (vma_tmp->vm_end > addr) {
344 vma = vma_tmp;
345 if (vma_tmp->vm_start <= addr)
346 return vma;
347 __rb_link = &__rb_parent->rb_left;
348 } else {
349 rb_prev = __rb_parent;
350 __rb_link = &__rb_parent->rb_right;
351 }
352 }
354 *pprev = NULL;
355 if (rb_prev)
356 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
357 *rb_link = __rb_link;
358 *rb_parent = __rb_parent;
359 return vma;
360 }
362 static inline void
363 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
364 struct vm_area_struct *prev, struct rb_node *rb_parent)
365 {
366 if (prev) {
367 vma->vm_next = prev->vm_next;
368 prev->vm_next = vma;
369 } else {
370 mm->mmap = vma;
371 if (rb_parent)
372 vma->vm_next = rb_entry(rb_parent,
373 struct vm_area_struct, vm_rb);
374 else
375 vma->vm_next = NULL;
376 }
377 }
379 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
380 struct rb_node **rb_link, struct rb_node *rb_parent)
381 {
382 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
383 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
384 }
386 static inline void __vma_link_file(struct vm_area_struct *vma)
387 {
388 struct file * file;
390 file = vma->vm_file;
391 if (file) {
392 struct address_space *mapping = file->f_mapping;
394 if (vma->vm_flags & VM_DENYWRITE)
395 atomic_dec(&file->f_dentry->d_inode->i_writecount);
396 if (vma->vm_flags & VM_SHARED)
397 mapping->i_mmap_writable++;
399 flush_dcache_mmap_lock(mapping);
400 if (unlikely(vma->vm_flags & VM_NONLINEAR))
401 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
402 else
403 vma_prio_tree_insert(vma, &mapping->i_mmap);
404 flush_dcache_mmap_unlock(mapping);
405 }
406 }
408 static void
409 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
410 struct vm_area_struct *prev, struct rb_node **rb_link,
411 struct rb_node *rb_parent)
412 {
413 __vma_link_list(mm, vma, prev, rb_parent);
414 __vma_link_rb(mm, vma, rb_link, rb_parent);
415 __anon_vma_link(vma);
416 }
418 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
419 struct vm_area_struct *prev, struct rb_node **rb_link,
420 struct rb_node *rb_parent)
421 {
422 struct address_space *mapping = NULL;
424 if (vma->vm_file)
425 mapping = vma->vm_file->f_mapping;
427 if (mapping) {
428 spin_lock(&mapping->i_mmap_lock);
429 vma->vm_truncate_count = mapping->truncate_count;
430 }
431 anon_vma_lock(vma);
433 __vma_link(mm, vma, prev, rb_link, rb_parent);
434 __vma_link_file(vma);
436 anon_vma_unlock(vma);
437 if (mapping)
438 spin_unlock(&mapping->i_mmap_lock);
440 mm->map_count++;
441 validate_mm(mm);
442 }
444 /*
445 * Helper for vma_adjust in the split_vma insert case:
446 * insert vm structure into list and rbtree and anon_vma,
447 * but it has already been inserted into prio_tree earlier.
448 */
449 static void
450 __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
451 {
452 struct vm_area_struct * __vma, * prev;
453 struct rb_node ** rb_link, * rb_parent;
455 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
456 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
457 __vma_link(mm, vma, prev, rb_link, rb_parent);
458 mm->map_count++;
459 }
461 static inline void
462 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
463 struct vm_area_struct *prev)
464 {
465 prev->vm_next = vma->vm_next;
466 rb_erase(&vma->vm_rb, &mm->mm_rb);
467 if (mm->mmap_cache == vma)
468 mm->mmap_cache = prev;
469 }
471 /*
472 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
473 * is already present in an i_mmap tree without adjusting the tree.
474 * The following helper function should be used when such adjustments
475 * are necessary. The "insert" vma (if any) is to be inserted
476 * before we drop the necessary locks.
477 */
478 void vma_adjust(struct vm_area_struct *vma, unsigned long start,
479 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
480 {
481 struct mm_struct *mm = vma->vm_mm;
482 struct vm_area_struct *next = vma->vm_next;
483 struct vm_area_struct *importer = NULL;
484 struct address_space *mapping = NULL;
485 struct prio_tree_root *root = NULL;
486 struct file *file = vma->vm_file;
487 struct anon_vma *anon_vma = NULL;
488 long adjust_next = 0;
489 int remove_next = 0;
491 if (next && !insert) {
492 if (end >= next->vm_end) {
493 /*
494 * vma expands, overlapping all the next, and
495 * perhaps the one after too (mprotect case 6).
496 */
497 again: remove_next = 1 + (end > next->vm_end);
498 end = next->vm_end;
499 anon_vma = next->anon_vma;
500 importer = vma;
501 } else if (end > next->vm_start) {
502 /*
503 * vma expands, overlapping part of the next:
504 * mprotect case 5 shifting the boundary up.
505 */
506 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
507 anon_vma = next->anon_vma;
508 importer = vma;
509 } else if (end < vma->vm_end) {
510 /*
511 * vma shrinks, and !insert tells it's not
512 * split_vma inserting another: so it must be
513 * mprotect case 4 shifting the boundary down.
514 */
515 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
516 anon_vma = next->anon_vma;
517 importer = next;
518 }
519 }
521 if (file) {
522 mapping = file->f_mapping;
523 if (!(vma->vm_flags & VM_NONLINEAR))
524 root = &mapping->i_mmap;
525 spin_lock(&mapping->i_mmap_lock);
526 if (importer &&
527 vma->vm_truncate_count != next->vm_truncate_count) {
528 /*
529 * unmap_mapping_range might be in progress:
530 * ensure that the expanding vma is rescanned.
531 */
532 importer->vm_truncate_count = 0;
533 }
534 if (insert) {
535 insert->vm_truncate_count = vma->vm_truncate_count;
536 /*
537 * Put into prio_tree now, so instantiated pages
538 * are visible to arm/parisc __flush_dcache_page
539 * throughout; but we cannot insert into address
540 * space until vma start or end is updated.
541 */
542 __vma_link_file(insert);
543 }
544 }
546 /*
547 * When changing only vma->vm_end, we don't really need
548 * anon_vma lock: but is that case worth optimizing out?
549 */
550 if (vma->anon_vma)
551 anon_vma = vma->anon_vma;
552 if (anon_vma) {
553 spin_lock(&anon_vma->lock);
554 /*
555 * Easily overlooked: when mprotect shifts the boundary,
556 * make sure the expanding vma has anon_vma set if the
557 * shrinking vma had, to cover any anon pages imported.
558 */
559 if (importer && !importer->anon_vma) {
560 importer->anon_vma = anon_vma;
561 __anon_vma_link(importer);
562 }
563 }
565 if (root) {
566 flush_dcache_mmap_lock(mapping);
567 vma_prio_tree_remove(vma, root);
568 if (adjust_next)
569 vma_prio_tree_remove(next, root);
570 }
572 vma->vm_start = start;
573 vma->vm_end = end;
574 vma->vm_pgoff = pgoff;
575 if (adjust_next) {
576 next->vm_start += adjust_next << PAGE_SHIFT;
577 next->vm_pgoff += adjust_next;
578 }
580 if (root) {
581 if (adjust_next)
582 vma_prio_tree_insert(next, root);
583 vma_prio_tree_insert(vma, root);
584 flush_dcache_mmap_unlock(mapping);
585 }
587 if (remove_next) {
588 /*
589 * vma_merge has merged next into vma, and needs
590 * us to remove next before dropping the locks.
591 */
592 __vma_unlink(mm, next, vma);
593 if (file)
594 __remove_shared_vm_struct(next, file, mapping);
595 if (next->anon_vma)
596 __anon_vma_merge(vma, next);
597 } else if (insert) {
598 /*
599 * split_vma has split insert from vma, and needs
600 * us to insert it before dropping the locks
601 * (it may either follow vma or precede it).
602 */
603 __insert_vm_struct(mm, insert);
604 }
606 if (anon_vma)
607 spin_unlock(&anon_vma->lock);
608 if (mapping)
609 spin_unlock(&mapping->i_mmap_lock);
611 if (remove_next) {
612 if (file)
613 fput(file);
614 mm->map_count--;
615 mpol_free(vma_policy(next));
616 kmem_cache_free(vm_area_cachep, next);
617 /*
618 * In mprotect's case 6 (see comments on vma_merge),
619 * we must remove another next too. It would clutter
620 * up the code too much to do both in one go.
621 */
622 if (remove_next == 2) {
623 next = vma->vm_next;
624 goto again;
625 }
626 }
628 validate_mm(mm);
629 }
631 /*
632 * If the vma has a ->close operation then the driver probably needs to release
633 * per-vma resources, so we don't attempt to merge those.
634 */
635 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
637 static inline int is_mergeable_vma(struct vm_area_struct *vma,
638 struct file *file, unsigned long vm_flags)
639 {
640 if (vma->vm_flags != vm_flags)
641 return 0;
642 if (vma->vm_file != file)
643 return 0;
644 if (vma->vm_ops && vma->vm_ops->close)
645 return 0;
646 return 1;
647 }
649 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
650 struct anon_vma *anon_vma2)
651 {
652 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
653 }
655 /*
656 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
657 * in front of (at a lower virtual address and file offset than) the vma.
658 *
659 * We cannot merge two vmas if they have differently assigned (non-NULL)
660 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
661 *
662 * We don't check here for the merged mmap wrapping around the end of pagecache
663 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
664 * wrap, nor mmaps which cover the final page at index -1UL.
665 */
666 static int
667 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
668 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
669 {
670 if (is_mergeable_vma(vma, file, vm_flags) &&
671 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
672 if (vma->vm_pgoff == vm_pgoff)
673 return 1;
674 }
675 return 0;
676 }
678 /*
679 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
680 * beyond (at a higher virtual address and file offset than) the vma.
681 *
682 * We cannot merge two vmas if they have differently assigned (non-NULL)
683 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
684 */
685 static int
686 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
687 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
688 {
689 if (is_mergeable_vma(vma, file, vm_flags) &&
690 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
691 pgoff_t vm_pglen;
692 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
693 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
694 return 1;
695 }
696 return 0;
697 }
699 /*
700 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
701 * whether that can be merged with its predecessor or its successor.
702 * Or both (it neatly fills a hole).
703 *
704 * In most cases - when called for mmap, brk or mremap - [addr,end) is
705 * certain not to be mapped by the time vma_merge is called; but when
706 * called for mprotect, it is certain to be already mapped (either at
707 * an offset within prev, or at the start of next), and the flags of
708 * this area are about to be changed to vm_flags - and the no-change
709 * case has already been eliminated.
710 *
711 * The following mprotect cases have to be considered, where AAAA is
712 * the area passed down from mprotect_fixup, never extending beyond one
713 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
714 *
715 * AAAA AAAA AAAA AAAA
716 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
717 * cannot merge might become might become might become
718 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
719 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
720 * mremap move: PPPPNNNNNNNN 8
721 * AAAA
722 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
723 * might become case 1 below case 2 below case 3 below
724 *
725 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
726 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
727 */
728 struct vm_area_struct *vma_merge(struct mm_struct *mm,
729 struct vm_area_struct *prev, unsigned long addr,
730 unsigned long end, unsigned long vm_flags,
731 struct anon_vma *anon_vma, struct file *file,
732 pgoff_t pgoff, struct mempolicy *policy)
733 {
734 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
735 struct vm_area_struct *area, *next;
737 /*
738 * We later require that vma->vm_flags == vm_flags,
739 * so this tests vma->vm_flags & VM_SPECIAL, too.
740 */
741 if (vm_flags & VM_SPECIAL)
742 return NULL;
744 if (prev)
745 next = prev->vm_next;
746 else
747 next = mm->mmap;
748 area = next;
749 if (next && next->vm_end == end) /* cases 6, 7, 8 */
750 next = next->vm_next;
752 /*
753 * Can it merge with the predecessor?
754 */
755 if (prev && prev->vm_end == addr &&
756 mpol_equal(vma_policy(prev), policy) &&
757 can_vma_merge_after(prev, vm_flags,
758 anon_vma, file, pgoff)) {
759 /*
760 * OK, it can. Can we now merge in the successor as well?
761 */
762 if (next && end == next->vm_start &&
763 mpol_equal(policy, vma_policy(next)) &&
764 can_vma_merge_before(next, vm_flags,
765 anon_vma, file, pgoff+pglen) &&
766 is_mergeable_anon_vma(prev->anon_vma,
767 next->anon_vma)) {
768 /* cases 1, 6 */
769 vma_adjust(prev, prev->vm_start,
770 next->vm_end, prev->vm_pgoff, NULL);
771 } else /* cases 2, 5, 7 */
772 vma_adjust(prev, prev->vm_start,
773 end, prev->vm_pgoff, NULL);
774 return prev;
775 }
777 /*
778 * Can this new request be merged in front of next?
779 */
780 if (next && end == next->vm_start &&
781 mpol_equal(policy, vma_policy(next)) &&
782 can_vma_merge_before(next, vm_flags,
783 anon_vma, file, pgoff+pglen)) {
784 if (prev && addr < prev->vm_end) /* case 4 */
785 vma_adjust(prev, prev->vm_start,
786 addr, prev->vm_pgoff, NULL);
787 else /* cases 3, 8 */
788 vma_adjust(area, addr, next->vm_end,
789 next->vm_pgoff - pglen, NULL);
790 return area;
791 }
793 return NULL;
794 }
796 /*
797 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
798 * neighbouring vmas for a suitable anon_vma, before it goes off
799 * to allocate a new anon_vma. It checks because a repetitive
800 * sequence of mprotects and faults may otherwise lead to distinct
801 * anon_vmas being allocated, preventing vma merge in subsequent
802 * mprotect.
803 */
804 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
805 {
806 struct vm_area_struct *near;
807 unsigned long vm_flags;
809 near = vma->vm_next;
810 if (!near)
811 goto try_prev;
813 /*
814 * Since only mprotect tries to remerge vmas, match flags
815 * which might be mprotected into each other later on.
816 * Neither mlock nor madvise tries to remerge at present,
817 * so leave their flags as obstructing a merge.
818 */
819 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
820 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
822 if (near->anon_vma && vma->vm_end == near->vm_start &&
823 mpol_equal(vma_policy(vma), vma_policy(near)) &&
824 can_vma_merge_before(near, vm_flags,
825 NULL, vma->vm_file, vma->vm_pgoff +
826 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
827 return near->anon_vma;
828 try_prev:
829 /*
830 * It is potentially slow to have to call find_vma_prev here.
831 * But it's only on the first write fault on the vma, not
832 * every time, and we could devise a way to avoid it later
833 * (e.g. stash info in next's anon_vma_node when assigning
834 * an anon_vma, or when trying vma_merge). Another time.
835 */
836 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
837 if (!near)
838 goto none;
840 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
841 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
843 if (near->anon_vma && near->vm_end == vma->vm_start &&
844 mpol_equal(vma_policy(near), vma_policy(vma)) &&
845 can_vma_merge_after(near, vm_flags,
846 NULL, vma->vm_file, vma->vm_pgoff))
847 return near->anon_vma;
848 none:
849 /*
850 * There's no absolute need to look only at touching neighbours:
851 * we could search further afield for "compatible" anon_vmas.
852 * But it would probably just be a waste of time searching,
853 * or lead to too many vmas hanging off the same anon_vma.
854 * We're trying to allow mprotect remerging later on,
855 * not trying to minimize memory used for anon_vmas.
856 */
857 return NULL;
858 }
860 #ifdef CONFIG_PROC_FS
861 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
862 struct file *file, long pages)
863 {
864 const unsigned long stack_flags
865 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
867 if (file) {
868 mm->shared_vm += pages;
869 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
870 mm->exec_vm += pages;
871 } else if (flags & stack_flags)
872 mm->stack_vm += pages;
873 if (flags & (VM_RESERVED|VM_IO))
874 mm->reserved_vm += pages;
875 }
876 #endif /* CONFIG_PROC_FS */
878 /*
879 * The caller must hold down_write(current->mm->mmap_sem).
880 */
882 unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
883 unsigned long len, unsigned long prot,
884 unsigned long flags, unsigned long pgoff)
885 {
886 struct mm_struct * mm = current->mm;
887 struct vm_area_struct * vma, * prev;
888 struct inode *inode;
889 unsigned int vm_flags;
890 int correct_wcount = 0;
891 int error;
892 struct rb_node ** rb_link, * rb_parent;
893 int accountable = 1;
894 unsigned long charged = 0, reqprot = prot;
896 if (file) {
897 if (is_file_hugepages(file))
898 accountable = 0;
900 if (!file->f_op || !file->f_op->mmap)
901 return -ENODEV;
903 if ((prot & PROT_EXEC) &&
904 (file->f_vfsmnt->mnt_flags & MNT_NOEXEC))
905 return -EPERM;
906 }
907 /*
908 * Does the application expect PROT_READ to imply PROT_EXEC?
909 *
910 * (the exception is when the underlying filesystem is noexec
911 * mounted, in which case we dont add PROT_EXEC.)
912 */
913 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
914 if (!(file && (file->f_vfsmnt->mnt_flags & MNT_NOEXEC)))
915 prot |= PROT_EXEC;
917 if (!len)
918 return -EINVAL;
920 error = arch_mmap_check(addr, len, flags);
921 if (error)
922 return error;
924 /* Careful about overflows.. */
925 len = PAGE_ALIGN(len);
926 if (!len || len > TASK_SIZE)
927 return -ENOMEM;
929 /* offset overflow? */
930 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
931 return -EOVERFLOW;
933 /* Too many mappings? */
934 if (mm->map_count > sysctl_max_map_count)
935 return -ENOMEM;
937 /* Obtain the address to map to. we verify (or select) it and ensure
938 * that it represents a valid section of the address space.
939 */
940 addr = get_unmapped_area(file, addr, len, pgoff, flags);
941 if (addr & ~PAGE_MASK)
942 return addr;
944 /* Do simple checking here so the lower-level routines won't have
945 * to. we assume access permissions have been handled by the open
946 * of the memory object, so we don't do any here.
947 */
948 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
949 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
951 if (flags & MAP_LOCKED) {
952 if (!can_do_mlock())
953 return -EPERM;
954 vm_flags |= VM_LOCKED;
955 }
956 /* mlock MCL_FUTURE? */
957 if (vm_flags & VM_LOCKED) {
958 unsigned long locked, lock_limit;
959 locked = len >> PAGE_SHIFT;
960 locked += mm->locked_vm;
961 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
962 lock_limit >>= PAGE_SHIFT;
963 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
964 return -EAGAIN;
965 }
967 inode = file ? file->f_dentry->d_inode : NULL;
969 if (file) {
970 switch (flags & MAP_TYPE) {
971 case MAP_SHARED:
972 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
973 return -EACCES;
975 /*
976 * Make sure we don't allow writing to an append-only
977 * file..
978 */
979 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
980 return -EACCES;
982 /*
983 * Make sure there are no mandatory locks on the file.
984 */
985 if (locks_verify_locked(inode))
986 return -EAGAIN;
988 vm_flags |= VM_SHARED | VM_MAYSHARE;
989 if (!(file->f_mode & FMODE_WRITE))
990 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
992 /* fall through */
993 case MAP_PRIVATE:
994 if (!(file->f_mode & FMODE_READ))
995 return -EACCES;
996 break;
998 default:
999 return -EINVAL;
1001 } else {
1002 switch (flags & MAP_TYPE) {
1003 case MAP_SHARED:
1004 vm_flags |= VM_SHARED | VM_MAYSHARE;
1005 break;
1006 case MAP_PRIVATE:
1007 /*
1008 * Set pgoff according to addr for anon_vma.
1009 */
1010 pgoff = addr >> PAGE_SHIFT;
1011 break;
1012 default:
1013 return -EINVAL;
1017 error = security_file_mmap(file, reqprot, prot, flags);
1018 if (error)
1019 return error;
1021 /* Clear old maps */
1022 error = -ENOMEM;
1023 munmap_back:
1024 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1025 if (vma && vma->vm_start < addr + len) {
1026 if (do_munmap(mm, addr, len))
1027 return -ENOMEM;
1028 goto munmap_back;
1031 /* Check against address space limit. */
1032 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1033 return -ENOMEM;
1035 if (accountable && (!(flags & MAP_NORESERVE) ||
1036 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
1037 if (vm_flags & VM_SHARED) {
1038 /* Check memory availability in shmem_file_setup? */
1039 vm_flags |= VM_ACCOUNT;
1040 } else if (vm_flags & VM_WRITE) {
1041 /*
1042 * Private writable mapping: check memory availability
1043 */
1044 charged = len >> PAGE_SHIFT;
1045 if (security_vm_enough_memory(charged))
1046 return -ENOMEM;
1047 vm_flags |= VM_ACCOUNT;
1051 /*
1052 * Can we just expand an old private anonymous mapping?
1053 * The VM_SHARED test is necessary because shmem_zero_setup
1054 * will create the file object for a shared anonymous map below.
1055 */
1056 if (!file && !(vm_flags & VM_SHARED) &&
1057 vma_merge(mm, prev, addr, addr + len, vm_flags,
1058 NULL, NULL, pgoff, NULL))
1059 goto out;
1061 /*
1062 * Determine the object being mapped and call the appropriate
1063 * specific mapper. the address has already been validated, but
1064 * not unmapped, but the maps are removed from the list.
1065 */
1066 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1067 if (!vma) {
1068 error = -ENOMEM;
1069 goto unacct_error;
1072 vma->vm_mm = mm;
1073 vma->vm_start = addr;
1074 vma->vm_end = addr + len;
1075 vma->vm_flags = vm_flags;
1076 vma->vm_page_prot = protection_map[vm_flags &
1077 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
1078 vma->vm_pgoff = pgoff;
1080 if (file) {
1081 error = -EINVAL;
1082 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1083 goto free_vma;
1084 if (vm_flags & VM_DENYWRITE) {
1085 error = deny_write_access(file);
1086 if (error)
1087 goto free_vma;
1088 correct_wcount = 1;
1090 vma->vm_file = file;
1091 get_file(file);
1092 error = file->f_op->mmap(file, vma);
1093 if (error)
1094 goto unmap_and_free_vma;
1095 } else if (vm_flags & VM_SHARED) {
1096 error = shmem_zero_setup(vma);
1097 if (error)
1098 goto free_vma;
1101 /* Don't make the VMA automatically writable if it's shared, but the
1102 * backer wishes to know when pages are first written to */
1103 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1104 vma->vm_page_prot =
1105 protection_map[vm_flags & (VM_READ|VM_WRITE|VM_EXEC)];
1107 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
1108 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
1109 * that memory reservation must be checked; but that reservation
1110 * belongs to shared memory object, not to vma: so now clear it.
1111 */
1112 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
1113 vma->vm_flags &= ~VM_ACCOUNT;
1115 /* Can addr have changed??
1117 * Answer: Yes, several device drivers can do it in their
1118 * f_op->mmap method. -DaveM
1119 */
1120 addr = vma->vm_start;
1121 pgoff = vma->vm_pgoff;
1122 vm_flags = vma->vm_flags;
1124 if (!file || !vma_merge(mm, prev, addr, vma->vm_end,
1125 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
1126 file = vma->vm_file;
1127 vma_link(mm, vma, prev, rb_link, rb_parent);
1128 if (correct_wcount)
1129 atomic_inc(&inode->i_writecount);
1130 } else {
1131 if (file) {
1132 if (correct_wcount)
1133 atomic_inc(&inode->i_writecount);
1134 fput(file);
1136 mpol_free(vma_policy(vma));
1137 kmem_cache_free(vm_area_cachep, vma);
1139 out:
1140 mm->total_vm += len >> PAGE_SHIFT;
1141 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1142 if (vm_flags & VM_LOCKED) {
1143 mm->locked_vm += len >> PAGE_SHIFT;
1144 make_pages_present(addr, addr + len);
1146 if (flags & MAP_POPULATE) {
1147 up_write(&mm->mmap_sem);
1148 sys_remap_file_pages(addr, len, 0,
1149 pgoff, flags & MAP_NONBLOCK);
1150 down_write(&mm->mmap_sem);
1152 return addr;
1154 unmap_and_free_vma:
1155 if (correct_wcount)
1156 atomic_inc(&inode->i_writecount);
1157 vma->vm_file = NULL;
1158 fput(file);
1160 /* Undo any partial mapping done by a device driver. */
1161 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1162 charged = 0;
1163 free_vma:
1164 kmem_cache_free(vm_area_cachep, vma);
1165 unacct_error:
1166 if (charged)
1167 vm_unacct_memory(charged);
1168 return error;
1171 EXPORT_SYMBOL(do_mmap_pgoff);
1173 /* Get an address range which is currently unmapped.
1174 * For shmat() with addr=0.
1176 * Ugly calling convention alert:
1177 * Return value with the low bits set means error value,
1178 * ie
1179 * if (ret & ~PAGE_MASK)
1180 * error = ret;
1182 * This function "knows" that -ENOMEM has the bits set.
1183 */
1184 #ifndef HAVE_ARCH_UNMAPPED_AREA
1185 unsigned long
1186 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1187 unsigned long len, unsigned long pgoff, unsigned long flags)
1189 struct mm_struct *mm = current->mm;
1190 struct vm_area_struct *vma;
1191 unsigned long start_addr;
1193 if (len > TASK_SIZE)
1194 return -ENOMEM;
1196 if (addr) {
1197 addr = PAGE_ALIGN(addr);
1198 vma = find_vma(mm, addr);
1199 if (TASK_SIZE - len >= addr &&
1200 (!vma || addr + len <= vma->vm_start))
1201 return addr;
1203 if (len > mm->cached_hole_size) {
1204 start_addr = addr = mm->free_area_cache;
1205 } else {
1206 start_addr = addr = TASK_UNMAPPED_BASE;
1207 mm->cached_hole_size = 0;
1210 full_search:
1211 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1212 /* At this point: (!vma || addr < vma->vm_end). */
1213 if (TASK_SIZE - len < addr) {
1214 /*
1215 * Start a new search - just in case we missed
1216 * some holes.
1217 */
1218 if (start_addr != TASK_UNMAPPED_BASE) {
1219 addr = TASK_UNMAPPED_BASE;
1220 start_addr = addr;
1221 mm->cached_hole_size = 0;
1222 goto full_search;
1224 return -ENOMEM;
1226 if (!vma || addr + len <= vma->vm_start) {
1227 /*
1228 * Remember the place where we stopped the search:
1229 */
1230 mm->free_area_cache = addr + len;
1231 return addr;
1233 if (addr + mm->cached_hole_size < vma->vm_start)
1234 mm->cached_hole_size = vma->vm_start - addr;
1235 addr = vma->vm_end;
1238 #endif
1240 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1242 /*
1243 * Is this a new hole at the lowest possible address?
1244 */
1245 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1246 mm->free_area_cache = addr;
1247 mm->cached_hole_size = ~0UL;
1251 /*
1252 * This mmap-allocator allocates new areas top-down from below the
1253 * stack's low limit (the base):
1254 */
1255 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1256 unsigned long
1257 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1258 const unsigned long len, const unsigned long pgoff,
1259 const unsigned long flags)
1261 struct vm_area_struct *vma;
1262 struct mm_struct *mm = current->mm;
1263 unsigned long addr = addr0;
1265 /* requested length too big for entire address space */
1266 if (len > TASK_SIZE)
1267 return -ENOMEM;
1269 /* requesting a specific address */
1270 if (addr) {
1271 addr = PAGE_ALIGN(addr);
1272 vma = find_vma(mm, addr);
1273 if (TASK_SIZE - len >= addr &&
1274 (!vma || addr + len <= vma->vm_start))
1275 return addr;
1278 /* check if free_area_cache is useful for us */
1279 if (len <= mm->cached_hole_size) {
1280 mm->cached_hole_size = 0;
1281 mm->free_area_cache = mm->mmap_base;
1284 /* either no address requested or can't fit in requested address hole */
1285 addr = mm->free_area_cache;
1287 /* make sure it can fit in the remaining address space */
1288 if (addr > len) {
1289 vma = find_vma(mm, addr-len);
1290 if (!vma || addr <= vma->vm_start)
1291 /* remember the address as a hint for next time */
1292 return (mm->free_area_cache = addr-len);
1295 if (mm->mmap_base < len)
1296 goto bottomup;
1298 addr = mm->mmap_base-len;
1300 do {
1301 /*
1302 * Lookup failure means no vma is above this address,
1303 * else if new region fits below vma->vm_start,
1304 * return with success:
1305 */
1306 vma = find_vma(mm, addr);
1307 if (!vma || addr+len <= vma->vm_start)
1308 /* remember the address as a hint for next time */
1309 return (mm->free_area_cache = addr);
1311 /* remember the largest hole we saw so far */
1312 if (addr + mm->cached_hole_size < vma->vm_start)
1313 mm->cached_hole_size = vma->vm_start - addr;
1315 /* try just below the current vma->vm_start */
1316 addr = vma->vm_start-len;
1317 } while (len < vma->vm_start);
1319 bottomup:
1320 /*
1321 * A failed mmap() very likely causes application failure,
1322 * so fall back to the bottom-up function here. This scenario
1323 * can happen with large stack limits and large mmap()
1324 * allocations.
1325 */
1326 mm->cached_hole_size = ~0UL;
1327 mm->free_area_cache = TASK_UNMAPPED_BASE;
1328 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1329 /*
1330 * Restore the topdown base:
1331 */
1332 mm->free_area_cache = mm->mmap_base;
1333 mm->cached_hole_size = ~0UL;
1335 return addr;
1337 #endif
1339 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1341 /*
1342 * Is this a new hole at the highest possible address?
1343 */
1344 if (addr > mm->free_area_cache)
1345 mm->free_area_cache = addr;
1347 /* dont allow allocations above current base */
1348 if (mm->free_area_cache > mm->mmap_base)
1349 mm->free_area_cache = mm->mmap_base;
1352 unsigned long
1353 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1354 unsigned long pgoff, unsigned long flags)
1356 unsigned long ret;
1358 if (!(flags & MAP_FIXED)) {
1359 unsigned long (*get_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
1361 get_area = current->mm->get_unmapped_area;
1362 if (file && file->f_op && file->f_op->get_unmapped_area)
1363 get_area = file->f_op->get_unmapped_area;
1364 addr = get_area(file, addr, len, pgoff, flags);
1365 if (IS_ERR_VALUE(addr))
1366 return addr;
1369 if (addr > TASK_SIZE - len)
1370 return -ENOMEM;
1371 if (addr & ~PAGE_MASK)
1372 return -EINVAL;
1373 if (file && is_file_hugepages(file)) {
1374 /*
1375 * Check if the given range is hugepage aligned, and
1376 * can be made suitable for hugepages.
1377 */
1378 ret = prepare_hugepage_range(addr, len);
1379 } else {
1380 /*
1381 * Ensure that a normal request is not falling in a
1382 * reserved hugepage range. For some archs like IA-64,
1383 * there is a separate region for hugepages.
1384 */
1385 ret = is_hugepage_only_range(current->mm, addr, len);
1387 if (ret)
1388 return -EINVAL;
1389 return addr;
1392 EXPORT_SYMBOL(get_unmapped_area);
1394 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1395 struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
1397 struct vm_area_struct *vma = NULL;
1399 if (mm) {
1400 /* Check the cache first. */
1401 /* (Cache hit rate is typically around 35%.) */
1402 vma = mm->mmap_cache;
1403 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1404 struct rb_node * rb_node;
1406 rb_node = mm->mm_rb.rb_node;
1407 vma = NULL;
1409 while (rb_node) {
1410 struct vm_area_struct * vma_tmp;
1412 vma_tmp = rb_entry(rb_node,
1413 struct vm_area_struct, vm_rb);
1415 if (vma_tmp->vm_end > addr) {
1416 vma = vma_tmp;
1417 if (vma_tmp->vm_start <= addr)
1418 break;
1419 rb_node = rb_node->rb_left;
1420 } else
1421 rb_node = rb_node->rb_right;
1423 if (vma)
1424 mm->mmap_cache = vma;
1427 return vma;
1430 EXPORT_SYMBOL(find_vma);
1432 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1433 struct vm_area_struct *
1434 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1435 struct vm_area_struct **pprev)
1437 struct vm_area_struct *vma = NULL, *prev = NULL;
1438 struct rb_node * rb_node;
1439 if (!mm)
1440 goto out;
1442 /* Guard against addr being lower than the first VMA */
1443 vma = mm->mmap;
1445 /* Go through the RB tree quickly. */
1446 rb_node = mm->mm_rb.rb_node;
1448 while (rb_node) {
1449 struct vm_area_struct *vma_tmp;
1450 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1452 if (addr < vma_tmp->vm_end) {
1453 rb_node = rb_node->rb_left;
1454 } else {
1455 prev = vma_tmp;
1456 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1457 break;
1458 rb_node = rb_node->rb_right;
1462 out:
1463 *pprev = prev;
1464 return prev ? prev->vm_next : vma;
1467 /*
1468 * Verify that the stack growth is acceptable and
1469 * update accounting. This is shared with both the
1470 * grow-up and grow-down cases.
1471 */
1472 static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
1474 struct mm_struct *mm = vma->vm_mm;
1475 struct rlimit *rlim = current->signal->rlim;
1477 /* address space limit tests */
1478 if (!may_expand_vm(mm, grow))
1479 return -ENOMEM;
1481 /* Stack limit test */
1482 if (size > rlim[RLIMIT_STACK].rlim_cur)
1483 return -ENOMEM;
1485 /* mlock limit tests */
1486 if (vma->vm_flags & VM_LOCKED) {
1487 unsigned long locked;
1488 unsigned long limit;
1489 locked = mm->locked_vm + grow;
1490 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1491 if (locked > limit && !capable(CAP_IPC_LOCK))
1492 return -ENOMEM;
1495 /*
1496 * Overcommit.. This must be the final test, as it will
1497 * update security statistics.
1498 */
1499 if (security_vm_enough_memory(grow))
1500 return -ENOMEM;
1502 /* Ok, everything looks good - let it rip */
1503 mm->total_vm += grow;
1504 if (vma->vm_flags & VM_LOCKED)
1505 mm->locked_vm += grow;
1506 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1507 return 0;
1510 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1511 /*
1512 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1513 * vma is the last one with address > vma->vm_end. Have to extend vma.
1514 */
1515 #ifndef CONFIG_IA64
1516 static inline
1517 #endif
1518 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1520 int error;
1522 if (!(vma->vm_flags & VM_GROWSUP))
1523 return -EFAULT;
1525 /*
1526 * We must make sure the anon_vma is allocated
1527 * so that the anon_vma locking is not a noop.
1528 */
1529 if (unlikely(anon_vma_prepare(vma)))
1530 return -ENOMEM;
1531 anon_vma_lock(vma);
1533 /*
1534 * vma->vm_start/vm_end cannot change under us because the caller
1535 * is required to hold the mmap_sem in read mode. We need the
1536 * anon_vma lock to serialize against concurrent expand_stacks.
1537 */
1538 address += 4 + PAGE_SIZE - 1;
1539 address &= PAGE_MASK;
1540 error = 0;
1542 /* Somebody else might have raced and expanded it already */
1543 if (address > vma->vm_end) {
1544 unsigned long size, grow;
1546 size = address - vma->vm_start;
1547 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1549 error = acct_stack_growth(vma, size, grow);
1550 if (!error)
1551 vma->vm_end = address;
1553 anon_vma_unlock(vma);
1554 return error;
1556 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1558 #ifdef CONFIG_STACK_GROWSUP
1559 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1561 return expand_upwards(vma, address);
1564 struct vm_area_struct *
1565 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1567 struct vm_area_struct *vma, *prev;
1569 addr &= PAGE_MASK;
1570 vma = find_vma_prev(mm, addr, &prev);
1571 if (vma && (vma->vm_start <= addr))
1572 return vma;
1573 if (!prev || expand_stack(prev, addr))
1574 return NULL;
1575 if (prev->vm_flags & VM_LOCKED) {
1576 make_pages_present(addr, prev->vm_end);
1578 return prev;
1580 #else
1581 /*
1582 * vma is the first one with address < vma->vm_start. Have to extend vma.
1583 */
1584 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1586 int error;
1588 /*
1589 * We must make sure the anon_vma is allocated
1590 * so that the anon_vma locking is not a noop.
1591 */
1592 if (unlikely(anon_vma_prepare(vma)))
1593 return -ENOMEM;
1594 anon_vma_lock(vma);
1596 /*
1597 * vma->vm_start/vm_end cannot change under us because the caller
1598 * is required to hold the mmap_sem in read mode. We need the
1599 * anon_vma lock to serialize against concurrent expand_stacks.
1600 */
1601 address &= PAGE_MASK;
1602 error = 0;
1604 /* Somebody else might have raced and expanded it already */
1605 if (address < vma->vm_start) {
1606 unsigned long size, grow;
1608 size = vma->vm_end - address;
1609 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1611 error = acct_stack_growth(vma, size, grow);
1612 if (!error) {
1613 vma->vm_start = address;
1614 vma->vm_pgoff -= grow;
1617 anon_vma_unlock(vma);
1618 return error;
1621 struct vm_area_struct *
1622 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1624 struct vm_area_struct * vma;
1625 unsigned long start;
1627 addr &= PAGE_MASK;
1628 vma = find_vma(mm,addr);
1629 if (!vma)
1630 return NULL;
1631 if (vma->vm_start <= addr)
1632 return vma;
1633 if (!(vma->vm_flags & VM_GROWSDOWN))
1634 return NULL;
1635 start = vma->vm_start;
1636 if (expand_stack(vma, addr))
1637 return NULL;
1638 if (vma->vm_flags & VM_LOCKED) {
1639 make_pages_present(addr, start);
1641 return vma;
1643 #endif
1645 /*
1646 * Ok - we have the memory areas we should free on the vma list,
1647 * so release them, and do the vma updates.
1649 * Called with the mm semaphore held.
1650 */
1651 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1653 /* Update high watermark before we lower total_vm */
1654 update_hiwater_vm(mm);
1655 do {
1656 long nrpages = vma_pages(vma);
1658 mm->total_vm -= nrpages;
1659 if (vma->vm_flags & VM_LOCKED)
1660 mm->locked_vm -= nrpages;
1661 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1662 vma = remove_vma(vma);
1663 } while (vma);
1664 validate_mm(mm);
1667 /*
1668 * Get rid of page table information in the indicated region.
1670 * Called with the mm semaphore held.
1671 */
1672 static void unmap_region(struct mm_struct *mm,
1673 struct vm_area_struct *vma, struct vm_area_struct *prev,
1674 unsigned long start, unsigned long end)
1676 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1677 struct mmu_gather *tlb;
1678 unsigned long nr_accounted = 0;
1680 lru_add_drain();
1681 tlb = tlb_gather_mmu(mm, 0);
1682 update_hiwater_rss(mm);
1683 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1684 vm_unacct_memory(nr_accounted);
1685 free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1686 next? next->vm_start: 0);
1687 tlb_finish_mmu(tlb, start, end);
1690 static inline void unmap_vma(struct vm_area_struct *vma)
1692 if (unlikely(vma->vm_ops && vma->vm_ops->unmap))
1693 vma->vm_ops->unmap(vma);
1696 /*
1697 * Create a list of vma's touched by the unmap, removing them from the mm's
1698 * vma list as we go..
1699 */
1700 static void
1701 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1702 struct vm_area_struct *prev, unsigned long end)
1704 struct vm_area_struct **insertion_point;
1705 struct vm_area_struct *tail_vma = NULL;
1706 unsigned long addr;
1708 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1709 do {
1710 rb_erase(&vma->vm_rb, &mm->mm_rb);
1711 unmap_vma(vma);
1712 mm->map_count--;
1713 tail_vma = vma;
1714 vma = vma->vm_next;
1715 } while (vma && vma->vm_start < end);
1716 *insertion_point = vma;
1717 tail_vma->vm_next = NULL;
1718 if (mm->unmap_area == arch_unmap_area)
1719 addr = prev ? prev->vm_end : mm->mmap_base;
1720 else
1721 addr = vma ? vma->vm_start : mm->mmap_base;
1722 mm->unmap_area(mm, addr);
1723 mm->mmap_cache = NULL; /* Kill the cache. */
1726 /*
1727 * Split a vma into two pieces at address 'addr', a new vma is allocated
1728 * either for the first part or the the tail.
1729 */
1730 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1731 unsigned long addr, int new_below)
1733 struct mempolicy *pol;
1734 struct vm_area_struct *new;
1736 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK))
1737 return -EINVAL;
1739 if (mm->map_count >= sysctl_max_map_count)
1740 return -ENOMEM;
1742 new = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
1743 if (!new)
1744 return -ENOMEM;
1746 /* most fields are the same, copy all, and then fixup */
1747 *new = *vma;
1749 if (new_below)
1750 new->vm_end = addr;
1751 else {
1752 new->vm_start = addr;
1753 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1756 pol = mpol_copy(vma_policy(vma));
1757 if (IS_ERR(pol)) {
1758 kmem_cache_free(vm_area_cachep, new);
1759 return PTR_ERR(pol);
1761 vma_set_policy(new, pol);
1763 if (new->vm_file)
1764 get_file(new->vm_file);
1766 if (new->vm_ops && new->vm_ops->open)
1767 new->vm_ops->open(new);
1769 if (new_below)
1770 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1771 ((addr - new->vm_start) >> PAGE_SHIFT), new);
1772 else
1773 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1775 return 0;
1778 /* Munmap is split into 2 main parts -- this part which finds
1779 * what needs doing, and the areas themselves, which do the
1780 * work. This now handles partial unmappings.
1781 * Jeremy Fitzhardinge <jeremy@goop.org>
1782 */
1783 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1785 unsigned long end;
1786 struct vm_area_struct *vma, *prev, *last;
1788 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1789 return -EINVAL;
1791 if ((len = PAGE_ALIGN(len)) == 0)
1792 return -EINVAL;
1794 /* Find the first overlapping VMA */
1795 vma = find_vma_prev(mm, start, &prev);
1796 if (!vma)
1797 return 0;
1798 /* we have start < vma->vm_end */
1800 /* if it doesn't overlap, we have nothing.. */
1801 end = start + len;
1802 if (vma->vm_start >= end)
1803 return 0;
1805 /*
1806 * If we need to split any vma, do it now to save pain later.
1808 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1809 * unmapped vm_area_struct will remain in use: so lower split_vma
1810 * places tmp vma above, and higher split_vma places tmp vma below.
1811 */
1812 if (start > vma->vm_start) {
1813 int error = split_vma(mm, vma, start, 0);
1814 if (error)
1815 return error;
1816 prev = vma;
1819 /* Does it split the last one? */
1820 last = find_vma(mm, end);
1821 if (last && end > last->vm_start) {
1822 int error = split_vma(mm, last, end, 1);
1823 if (error)
1824 return error;
1826 vma = prev? prev->vm_next: mm->mmap;
1828 /*
1829 * Remove the vma's, and unmap the actual pages
1830 */
1831 detach_vmas_to_be_unmapped(mm, vma, prev, end);
1832 unmap_region(mm, vma, prev, start, end);
1834 /* Fix up all other VM information */
1835 remove_vma_list(mm, vma);
1837 return 0;
1840 EXPORT_SYMBOL(do_munmap);
1842 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1844 int ret;
1845 struct mm_struct *mm = current->mm;
1847 profile_munmap(addr);
1849 down_write(&mm->mmap_sem);
1850 ret = do_munmap(mm, addr, len);
1851 up_write(&mm->mmap_sem);
1852 return ret;
1855 static inline void verify_mm_writelocked(struct mm_struct *mm)
1857 #ifdef CONFIG_DEBUG_VM
1858 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1859 WARN_ON(1);
1860 up_read(&mm->mmap_sem);
1862 #endif
1865 /*
1866 * this is really a simplified "do_mmap". it only handles
1867 * anonymous maps. eventually we may be able to do some
1868 * brk-specific accounting here.
1869 */
1870 unsigned long do_brk(unsigned long addr, unsigned long len)
1872 struct mm_struct * mm = current->mm;
1873 struct vm_area_struct * vma, * prev;
1874 unsigned long flags;
1875 struct rb_node ** rb_link, * rb_parent;
1876 pgoff_t pgoff = addr >> PAGE_SHIFT;
1877 int error;
1879 len = PAGE_ALIGN(len);
1880 if (!len)
1881 return addr;
1883 if ((addr + len) > TASK_SIZE || (addr + len) < addr)
1884 return -EINVAL;
1886 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
1888 error = arch_mmap_check(addr, len, flags);
1889 if (error)
1890 return error;
1892 /*
1893 * mlock MCL_FUTURE?
1894 */
1895 if (mm->def_flags & VM_LOCKED) {
1896 unsigned long locked, lock_limit;
1897 locked = len >> PAGE_SHIFT;
1898 locked += mm->locked_vm;
1899 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
1900 lock_limit >>= PAGE_SHIFT;
1901 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1902 return -EAGAIN;
1905 /*
1906 * mm->mmap_sem is required to protect against another thread
1907 * changing the mappings in case we sleep.
1908 */
1909 verify_mm_writelocked(mm);
1911 /*
1912 * Clear old maps. this also does some error checking for us
1913 */
1914 munmap_back:
1915 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1916 if (vma && vma->vm_start < addr + len) {
1917 if (do_munmap(mm, addr, len))
1918 return -ENOMEM;
1919 goto munmap_back;
1922 /* Check against address space limits *after* clearing old maps... */
1923 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1924 return -ENOMEM;
1926 if (mm->map_count > sysctl_max_map_count)
1927 return -ENOMEM;
1929 if (security_vm_enough_memory(len >> PAGE_SHIFT))
1930 return -ENOMEM;
1932 /* Can we just expand an old private anonymous mapping? */
1933 if (vma_merge(mm, prev, addr, addr + len, flags,
1934 NULL, NULL, pgoff, NULL))
1935 goto out;
1937 /*
1938 * create a vma struct for an anonymous mapping
1939 */
1940 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1941 if (!vma) {
1942 vm_unacct_memory(len >> PAGE_SHIFT);
1943 return -ENOMEM;
1946 vma->vm_mm = mm;
1947 vma->vm_start = addr;
1948 vma->vm_end = addr + len;
1949 vma->vm_pgoff = pgoff;
1950 vma->vm_flags = flags;
1951 vma->vm_page_prot = protection_map[flags &
1952 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
1953 vma_link(mm, vma, prev, rb_link, rb_parent);
1954 out:
1955 mm->total_vm += len >> PAGE_SHIFT;
1956 if (flags & VM_LOCKED) {
1957 mm->locked_vm += len >> PAGE_SHIFT;
1958 make_pages_present(addr, addr + len);
1960 return addr;
1963 EXPORT_SYMBOL(do_brk);
1965 /* Release all mmaps. */
1966 void exit_mmap(struct mm_struct *mm)
1968 struct mmu_gather *tlb;
1969 struct vm_area_struct *vma_tmp, *vma = mm->mmap;
1970 unsigned long nr_accounted = 0;
1971 unsigned long end;
1973 #ifdef arch_exit_mmap
1974 arch_exit_mmap(mm);
1975 #endif
1977 for (vma_tmp = mm->mmap; vma_tmp; vma_tmp = vma_tmp->vm_next)
1978 unmap_vma(vma_tmp);
1980 lru_add_drain();
1981 flush_cache_mm(mm);
1982 tlb = tlb_gather_mmu(mm, 1);
1983 /* Don't update_hiwater_rss(mm) here, do_exit already did */
1984 /* Use -1 here to ensure all VMAs in the mm are unmapped */
1985 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
1986 vm_unacct_memory(nr_accounted);
1987 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
1988 tlb_finish_mmu(tlb, 0, end);
1990 /*
1991 * Walk the list again, actually closing and freeing it,
1992 * with preemption enabled, without holding any MM locks.
1993 */
1994 while (vma)
1995 vma = remove_vma(vma);
1997 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2000 /* Insert vm structure into process list sorted by address
2001 * and into the inode's i_mmap tree. If vm_file is non-NULL
2002 * then i_mmap_lock is taken here.
2003 */
2004 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2006 struct vm_area_struct * __vma, * prev;
2007 struct rb_node ** rb_link, * rb_parent;
2009 /*
2010 * The vm_pgoff of a purely anonymous vma should be irrelevant
2011 * until its first write fault, when page's anon_vma and index
2012 * are set. But now set the vm_pgoff it will almost certainly
2013 * end up with (unless mremap moves it elsewhere before that
2014 * first wfault), so /proc/pid/maps tells a consistent story.
2016 * By setting it to reflect the virtual start address of the
2017 * vma, merges and splits can happen in a seamless way, just
2018 * using the existing file pgoff checks and manipulations.
2019 * Similarly in do_mmap_pgoff and in do_brk.
2020 */
2021 if (!vma->vm_file) {
2022 BUG_ON(vma->anon_vma);
2023 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2025 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2026 if (__vma && __vma->vm_start < vma->vm_end)
2027 return -ENOMEM;
2028 if ((vma->vm_flags & VM_ACCOUNT) &&
2029 security_vm_enough_memory(vma_pages(vma)))
2030 return -ENOMEM;
2031 vma_link(mm, vma, prev, rb_link, rb_parent);
2032 return 0;
2035 /*
2036 * Copy the vma structure to a new location in the same mm,
2037 * prior to moving page table entries, to effect an mremap move.
2038 */
2039 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2040 unsigned long addr, unsigned long len, pgoff_t pgoff)
2042 struct vm_area_struct *vma = *vmap;
2043 unsigned long vma_start = vma->vm_start;
2044 struct mm_struct *mm = vma->vm_mm;
2045 struct vm_area_struct *new_vma, *prev;
2046 struct rb_node **rb_link, *rb_parent;
2047 struct mempolicy *pol;
2049 /*
2050 * If anonymous vma has not yet been faulted, update new pgoff
2051 * to match new location, to increase its chance of merging.
2052 */
2053 if (!vma->vm_file && !vma->anon_vma)
2054 pgoff = addr >> PAGE_SHIFT;
2056 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2057 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2058 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2059 if (new_vma) {
2060 /*
2061 * Source vma may have been merged into new_vma
2062 */
2063 if (vma_start >= new_vma->vm_start &&
2064 vma_start < new_vma->vm_end)
2065 *vmap = new_vma;
2066 } else {
2067 new_vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
2068 if (new_vma) {
2069 *new_vma = *vma;
2070 pol = mpol_copy(vma_policy(vma));
2071 if (IS_ERR(pol)) {
2072 kmem_cache_free(vm_area_cachep, new_vma);
2073 return NULL;
2075 vma_set_policy(new_vma, pol);
2076 new_vma->vm_start = addr;
2077 new_vma->vm_end = addr + len;
2078 new_vma->vm_pgoff = pgoff;
2079 if (new_vma->vm_file)
2080 get_file(new_vma->vm_file);
2081 if (new_vma->vm_ops && new_vma->vm_ops->open)
2082 new_vma->vm_ops->open(new_vma);
2083 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2086 return new_vma;
2089 /*
2090 * Return true if the calling process may expand its vm space by the passed
2091 * number of pages
2092 */
2093 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2095 unsigned long cur = mm->total_vm; /* pages */
2096 unsigned long lim;
2098 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2100 if (cur + npages > lim)
2101 return 0;
2102 return 1;