Net: e100, fix iomap mem accesses
[linux-2.6/mini2440.git] / mm / mmap.c
blobd2b6d44962b7c7b28b89e20cdbf1af0b0c6ada31
1 /*
2 * mm/mmap.c
4 * Written by obz.
6 * Address space accounting code <alan@redhat.com>
7 */
9 #include <linux/slab.h>
10 #include <linux/backing-dev.h>
11 #include <linux/mm.h>
12 #include <linux/shm.h>
13 #include <linux/mman.h>
14 #include <linux/pagemap.h>
15 #include <linux/swap.h>
16 #include <linux/syscalls.h>
17 #include <linux/capability.h>
18 #include <linux/init.h>
19 #include <linux/file.h>
20 #include <linux/fs.h>
21 #include <linux/personality.h>
22 #include <linux/security.h>
23 #include <linux/hugetlb.h>
24 #include <linux/profile.h>
25 #include <linux/module.h>
26 #include <linux/mount.h>
27 #include <linux/mempolicy.h>
28 #include <linux/rmap.h>
30 #include <asm/uaccess.h>
31 #include <asm/cacheflush.h>
32 #include <asm/tlb.h>
33 #include <asm/mmu_context.h>
35 #ifndef arch_mmap_check
36 #define arch_mmap_check(addr, len, flags) (0)
37 #endif
39 static void unmap_region(struct mm_struct *mm,
40 struct vm_area_struct *vma, struct vm_area_struct *prev,
41 unsigned long start, unsigned long end);
44 * WARNING: the debugging will use recursive algorithms so never enable this
45 * unless you know what you are doing.
47 #undef DEBUG_MM_RB
49 /* description of effects of mapping type and prot in current implementation.
50 * this is due to the limited x86 page protection hardware. The expected
51 * behavior is in parens:
53 * map_type prot
54 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
55 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
56 * w: (no) no w: (no) no w: (yes) yes w: (no) no
57 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
59 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
60 * w: (no) no w: (no) no w: (copy) copy w: (no) no
61 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
64 pgprot_t protection_map[16] = {
65 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
66 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
69 pgprot_t vm_get_page_prot(unsigned long vm_flags)
71 return protection_map[vm_flags &
72 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
74 EXPORT_SYMBOL(vm_get_page_prot);
76 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
77 int sysctl_overcommit_ratio = 50; /* default is 50% */
78 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
79 atomic_t vm_committed_space = ATOMIC_INIT(0);
82 * Check that a process has enough memory to allocate a new virtual
83 * mapping. 0 means there is enough memory for the allocation to
84 * succeed and -ENOMEM implies there is not.
86 * We currently support three overcommit policies, which are set via the
87 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
89 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
90 * Additional code 2002 Jul 20 by Robert Love.
92 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
94 * Note this is a helper function intended to be used by LSMs which
95 * wish to use this logic.
97 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
99 unsigned long free, allowed;
101 vm_acct_memory(pages);
104 * Sometimes we want to use more memory than we have
106 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
107 return 0;
109 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
110 unsigned long n;
112 free = global_page_state(NR_FILE_PAGES);
113 free += nr_swap_pages;
116 * Any slabs which are created with the
117 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
118 * which are reclaimable, under pressure. The dentry
119 * cache and most inode caches should fall into this
121 free += global_page_state(NR_SLAB_RECLAIMABLE);
124 * Leave the last 3% for root
126 if (!cap_sys_admin)
127 free -= free / 32;
129 if (free > pages)
130 return 0;
133 * nr_free_pages() is very expensive on large systems,
134 * only call if we're about to fail.
136 n = nr_free_pages();
139 * Leave reserved pages. The pages are not for anonymous pages.
141 if (n <= totalreserve_pages)
142 goto error;
143 else
144 n -= totalreserve_pages;
147 * Leave the last 3% for root
149 if (!cap_sys_admin)
150 n -= n / 32;
151 free += n;
153 if (free > pages)
154 return 0;
156 goto error;
159 allowed = (totalram_pages - hugetlb_total_pages())
160 * sysctl_overcommit_ratio / 100;
162 * Leave the last 3% for root
164 if (!cap_sys_admin)
165 allowed -= allowed / 32;
166 allowed += total_swap_pages;
168 /* Don't let a single process grow too big:
169 leave 3% of the size of this process for other processes */
170 allowed -= mm->total_vm / 32;
173 * cast `allowed' as a signed long because vm_committed_space
174 * sometimes has a negative value
176 if (atomic_read(&vm_committed_space) < (long)allowed)
177 return 0;
178 error:
179 vm_unacct_memory(pages);
181 return -ENOMEM;
185 * Requires inode->i_mapping->i_mmap_lock
187 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
188 struct file *file, struct address_space *mapping)
190 if (vma->vm_flags & VM_DENYWRITE)
191 atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
192 if (vma->vm_flags & VM_SHARED)
193 mapping->i_mmap_writable--;
195 flush_dcache_mmap_lock(mapping);
196 if (unlikely(vma->vm_flags & VM_NONLINEAR))
197 list_del_init(&vma->shared.vm_set.list);
198 else
199 vma_prio_tree_remove(vma, &mapping->i_mmap);
200 flush_dcache_mmap_unlock(mapping);
204 * Unlink a file-based vm structure from its prio_tree, to hide
205 * vma from rmap and vmtruncate before freeing its page tables.
207 void unlink_file_vma(struct vm_area_struct *vma)
209 struct file *file = vma->vm_file;
211 if (file) {
212 struct address_space *mapping = file->f_mapping;
213 spin_lock(&mapping->i_mmap_lock);
214 __remove_shared_vm_struct(vma, file, mapping);
215 spin_unlock(&mapping->i_mmap_lock);
220 * Close a vm structure and free it, returning the next.
222 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
224 struct vm_area_struct *next = vma->vm_next;
226 might_sleep();
227 if (vma->vm_ops && vma->vm_ops->close)
228 vma->vm_ops->close(vma);
229 if (vma->vm_file)
230 fput(vma->vm_file);
231 mpol_free(vma_policy(vma));
232 kmem_cache_free(vm_area_cachep, vma);
233 return next;
236 asmlinkage unsigned long sys_brk(unsigned long brk)
238 unsigned long rlim, retval;
239 unsigned long newbrk, oldbrk;
240 struct mm_struct *mm = current->mm;
242 down_write(&mm->mmap_sem);
244 if (brk < mm->end_code)
245 goto out;
248 * Check against rlimit here. If this check is done later after the test
249 * of oldbrk with newbrk then it can escape the test and let the data
250 * segment grow beyond its set limit the in case where the limit is
251 * not page aligned -Ram Gupta
253 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur;
254 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
255 (mm->end_data - mm->start_data) > rlim)
256 goto out;
258 newbrk = PAGE_ALIGN(brk);
259 oldbrk = PAGE_ALIGN(mm->brk);
260 if (oldbrk == newbrk)
261 goto set_brk;
263 /* Always allow shrinking brk. */
264 if (brk <= mm->brk) {
265 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
266 goto set_brk;
267 goto out;
270 /* Check against existing mmap mappings. */
271 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
272 goto out;
274 /* Ok, looks good - let it rip. */
275 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
276 goto out;
277 set_brk:
278 mm->brk = brk;
279 out:
280 retval = mm->brk;
281 up_write(&mm->mmap_sem);
282 return retval;
285 #ifdef DEBUG_MM_RB
286 static int browse_rb(struct rb_root *root)
288 int i = 0, j;
289 struct rb_node *nd, *pn = NULL;
290 unsigned long prev = 0, pend = 0;
292 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
293 struct vm_area_struct *vma;
294 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
295 if (vma->vm_start < prev)
296 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
297 if (vma->vm_start < pend)
298 printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
299 if (vma->vm_start > vma->vm_end)
300 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
301 i++;
302 pn = nd;
303 prev = vma->vm_start;
304 pend = vma->vm_end;
306 j = 0;
307 for (nd = pn; nd; nd = rb_prev(nd)) {
308 j++;
310 if (i != j)
311 printk("backwards %d, forwards %d\n", j, i), i = 0;
312 return i;
315 void validate_mm(struct mm_struct *mm)
317 int bug = 0;
318 int i = 0;
319 struct vm_area_struct *tmp = mm->mmap;
320 while (tmp) {
321 tmp = tmp->vm_next;
322 i++;
324 if (i != mm->map_count)
325 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
326 i = browse_rb(&mm->mm_rb);
327 if (i != mm->map_count)
328 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
329 BUG_ON(bug);
331 #else
332 #define validate_mm(mm) do { } while (0)
333 #endif
335 static struct vm_area_struct *
336 find_vma_prepare(struct mm_struct *mm, unsigned long addr,
337 struct vm_area_struct **pprev, struct rb_node ***rb_link,
338 struct rb_node ** rb_parent)
340 struct vm_area_struct * vma;
341 struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
343 __rb_link = &mm->mm_rb.rb_node;
344 rb_prev = __rb_parent = NULL;
345 vma = NULL;
347 while (*__rb_link) {
348 struct vm_area_struct *vma_tmp;
350 __rb_parent = *__rb_link;
351 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
353 if (vma_tmp->vm_end > addr) {
354 vma = vma_tmp;
355 if (vma_tmp->vm_start <= addr)
356 return vma;
357 __rb_link = &__rb_parent->rb_left;
358 } else {
359 rb_prev = __rb_parent;
360 __rb_link = &__rb_parent->rb_right;
364 *pprev = NULL;
365 if (rb_prev)
366 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
367 *rb_link = __rb_link;
368 *rb_parent = __rb_parent;
369 return vma;
372 static inline void
373 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
374 struct vm_area_struct *prev, struct rb_node *rb_parent)
376 if (prev) {
377 vma->vm_next = prev->vm_next;
378 prev->vm_next = vma;
379 } else {
380 mm->mmap = vma;
381 if (rb_parent)
382 vma->vm_next = rb_entry(rb_parent,
383 struct vm_area_struct, vm_rb);
384 else
385 vma->vm_next = NULL;
389 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
390 struct rb_node **rb_link, struct rb_node *rb_parent)
392 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
393 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
396 static inline void __vma_link_file(struct vm_area_struct *vma)
398 struct file * file;
400 file = vma->vm_file;
401 if (file) {
402 struct address_space *mapping = file->f_mapping;
404 if (vma->vm_flags & VM_DENYWRITE)
405 atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
406 if (vma->vm_flags & VM_SHARED)
407 mapping->i_mmap_writable++;
409 flush_dcache_mmap_lock(mapping);
410 if (unlikely(vma->vm_flags & VM_NONLINEAR))
411 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
412 else
413 vma_prio_tree_insert(vma, &mapping->i_mmap);
414 flush_dcache_mmap_unlock(mapping);
418 static void
419 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
420 struct vm_area_struct *prev, struct rb_node **rb_link,
421 struct rb_node *rb_parent)
423 __vma_link_list(mm, vma, prev, rb_parent);
424 __vma_link_rb(mm, vma, rb_link, rb_parent);
425 __anon_vma_link(vma);
428 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
429 struct vm_area_struct *prev, struct rb_node **rb_link,
430 struct rb_node *rb_parent)
432 struct address_space *mapping = NULL;
434 if (vma->vm_file)
435 mapping = vma->vm_file->f_mapping;
437 if (mapping) {
438 spin_lock(&mapping->i_mmap_lock);
439 vma->vm_truncate_count = mapping->truncate_count;
441 anon_vma_lock(vma);
443 __vma_link(mm, vma, prev, rb_link, rb_parent);
444 __vma_link_file(vma);
446 anon_vma_unlock(vma);
447 if (mapping)
448 spin_unlock(&mapping->i_mmap_lock);
450 mm->map_count++;
451 validate_mm(mm);
455 * Helper for vma_adjust in the split_vma insert case:
456 * insert vm structure into list and rbtree and anon_vma,
457 * but it has already been inserted into prio_tree earlier.
459 static void
460 __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
462 struct vm_area_struct * __vma, * prev;
463 struct rb_node ** rb_link, * rb_parent;
465 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
466 BUG_ON(__vma && __vma->vm_start < vma->vm_end);
467 __vma_link(mm, vma, prev, rb_link, rb_parent);
468 mm->map_count++;
471 static inline void
472 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
473 struct vm_area_struct *prev)
475 prev->vm_next = vma->vm_next;
476 rb_erase(&vma->vm_rb, &mm->mm_rb);
477 if (mm->mmap_cache == vma)
478 mm->mmap_cache = prev;
482 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
483 * is already present in an i_mmap tree without adjusting the tree.
484 * The following helper function should be used when such adjustments
485 * are necessary. The "insert" vma (if any) is to be inserted
486 * before we drop the necessary locks.
488 void vma_adjust(struct vm_area_struct *vma, unsigned long start,
489 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
491 struct mm_struct *mm = vma->vm_mm;
492 struct vm_area_struct *next = vma->vm_next;
493 struct vm_area_struct *importer = NULL;
494 struct address_space *mapping = NULL;
495 struct prio_tree_root *root = NULL;
496 struct file *file = vma->vm_file;
497 struct anon_vma *anon_vma = NULL;
498 long adjust_next = 0;
499 int remove_next = 0;
501 if (next && !insert) {
502 if (end >= next->vm_end) {
504 * vma expands, overlapping all the next, and
505 * perhaps the one after too (mprotect case 6).
507 again: remove_next = 1 + (end > next->vm_end);
508 end = next->vm_end;
509 anon_vma = next->anon_vma;
510 importer = vma;
511 } else if (end > next->vm_start) {
513 * vma expands, overlapping part of the next:
514 * mprotect case 5 shifting the boundary up.
516 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
517 anon_vma = next->anon_vma;
518 importer = vma;
519 } else if (end < vma->vm_end) {
521 * vma shrinks, and !insert tells it's not
522 * split_vma inserting another: so it must be
523 * mprotect case 4 shifting the boundary down.
525 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
526 anon_vma = next->anon_vma;
527 importer = next;
531 if (file) {
532 mapping = file->f_mapping;
533 if (!(vma->vm_flags & VM_NONLINEAR))
534 root = &mapping->i_mmap;
535 spin_lock(&mapping->i_mmap_lock);
536 if (importer &&
537 vma->vm_truncate_count != next->vm_truncate_count) {
539 * unmap_mapping_range might be in progress:
540 * ensure that the expanding vma is rescanned.
542 importer->vm_truncate_count = 0;
544 if (insert) {
545 insert->vm_truncate_count = vma->vm_truncate_count;
547 * Put into prio_tree now, so instantiated pages
548 * are visible to arm/parisc __flush_dcache_page
549 * throughout; but we cannot insert into address
550 * space until vma start or end is updated.
552 __vma_link_file(insert);
557 * When changing only vma->vm_end, we don't really need
558 * anon_vma lock: but is that case worth optimizing out?
560 if (vma->anon_vma)
561 anon_vma = vma->anon_vma;
562 if (anon_vma) {
563 spin_lock(&anon_vma->lock);
565 * Easily overlooked: when mprotect shifts the boundary,
566 * make sure the expanding vma has anon_vma set if the
567 * shrinking vma had, to cover any anon pages imported.
569 if (importer && !importer->anon_vma) {
570 importer->anon_vma = anon_vma;
571 __anon_vma_link(importer);
575 if (root) {
576 flush_dcache_mmap_lock(mapping);
577 vma_prio_tree_remove(vma, root);
578 if (adjust_next)
579 vma_prio_tree_remove(next, root);
582 vma->vm_start = start;
583 vma->vm_end = end;
584 vma->vm_pgoff = pgoff;
585 if (adjust_next) {
586 next->vm_start += adjust_next << PAGE_SHIFT;
587 next->vm_pgoff += adjust_next;
590 if (root) {
591 if (adjust_next)
592 vma_prio_tree_insert(next, root);
593 vma_prio_tree_insert(vma, root);
594 flush_dcache_mmap_unlock(mapping);
597 if (remove_next) {
599 * vma_merge has merged next into vma, and needs
600 * us to remove next before dropping the locks.
602 __vma_unlink(mm, next, vma);
603 if (file)
604 __remove_shared_vm_struct(next, file, mapping);
605 if (next->anon_vma)
606 __anon_vma_merge(vma, next);
607 } else if (insert) {
609 * split_vma has split insert from vma, and needs
610 * us to insert it before dropping the locks
611 * (it may either follow vma or precede it).
613 __insert_vm_struct(mm, insert);
616 if (anon_vma)
617 spin_unlock(&anon_vma->lock);
618 if (mapping)
619 spin_unlock(&mapping->i_mmap_lock);
621 if (remove_next) {
622 if (file)
623 fput(file);
624 mm->map_count--;
625 mpol_free(vma_policy(next));
626 kmem_cache_free(vm_area_cachep, next);
628 * In mprotect's case 6 (see comments on vma_merge),
629 * we must remove another next too. It would clutter
630 * up the code too much to do both in one go.
632 if (remove_next == 2) {
633 next = vma->vm_next;
634 goto again;
638 validate_mm(mm);
642 * If the vma has a ->close operation then the driver probably needs to release
643 * per-vma resources, so we don't attempt to merge those.
645 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
647 static inline int is_mergeable_vma(struct vm_area_struct *vma,
648 struct file *file, unsigned long vm_flags)
650 if (vma->vm_flags != vm_flags)
651 return 0;
652 if (vma->vm_file != file)
653 return 0;
654 if (vma->vm_ops && vma->vm_ops->close)
655 return 0;
656 return 1;
659 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
660 struct anon_vma *anon_vma2)
662 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2);
666 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
667 * in front of (at a lower virtual address and file offset than) the vma.
669 * We cannot merge two vmas if they have differently assigned (non-NULL)
670 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
672 * We don't check here for the merged mmap wrapping around the end of pagecache
673 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
674 * wrap, nor mmaps which cover the final page at index -1UL.
676 static int
677 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
678 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
680 if (is_mergeable_vma(vma, file, vm_flags) &&
681 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
682 if (vma->vm_pgoff == vm_pgoff)
683 return 1;
685 return 0;
689 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
690 * beyond (at a higher virtual address and file offset than) the vma.
692 * We cannot merge two vmas if they have differently assigned (non-NULL)
693 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
695 static int
696 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
697 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
699 if (is_mergeable_vma(vma, file, vm_flags) &&
700 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) {
701 pgoff_t vm_pglen;
702 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
703 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
704 return 1;
706 return 0;
710 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
711 * whether that can be merged with its predecessor or its successor.
712 * Or both (it neatly fills a hole).
714 * In most cases - when called for mmap, brk or mremap - [addr,end) is
715 * certain not to be mapped by the time vma_merge is called; but when
716 * called for mprotect, it is certain to be already mapped (either at
717 * an offset within prev, or at the start of next), and the flags of
718 * this area are about to be changed to vm_flags - and the no-change
719 * case has already been eliminated.
721 * The following mprotect cases have to be considered, where AAAA is
722 * the area passed down from mprotect_fixup, never extending beyond one
723 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
725 * AAAA AAAA AAAA AAAA
726 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
727 * cannot merge might become might become might become
728 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
729 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
730 * mremap move: PPPPNNNNNNNN 8
731 * AAAA
732 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
733 * might become case 1 below case 2 below case 3 below
735 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
736 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
738 struct vm_area_struct *vma_merge(struct mm_struct *mm,
739 struct vm_area_struct *prev, unsigned long addr,
740 unsigned long end, unsigned long vm_flags,
741 struct anon_vma *anon_vma, struct file *file,
742 pgoff_t pgoff, struct mempolicy *policy)
744 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
745 struct vm_area_struct *area, *next;
748 * We later require that vma->vm_flags == vm_flags,
749 * so this tests vma->vm_flags & VM_SPECIAL, too.
751 if (vm_flags & VM_SPECIAL)
752 return NULL;
754 if (prev)
755 next = prev->vm_next;
756 else
757 next = mm->mmap;
758 area = next;
759 if (next && next->vm_end == end) /* cases 6, 7, 8 */
760 next = next->vm_next;
763 * Can it merge with the predecessor?
765 if (prev && prev->vm_end == addr &&
766 mpol_equal(vma_policy(prev), policy) &&
767 can_vma_merge_after(prev, vm_flags,
768 anon_vma, file, pgoff)) {
770 * OK, it can. Can we now merge in the successor as well?
772 if (next && end == next->vm_start &&
773 mpol_equal(policy, vma_policy(next)) &&
774 can_vma_merge_before(next, vm_flags,
775 anon_vma, file, pgoff+pglen) &&
776 is_mergeable_anon_vma(prev->anon_vma,
777 next->anon_vma)) {
778 /* cases 1, 6 */
779 vma_adjust(prev, prev->vm_start,
780 next->vm_end, prev->vm_pgoff, NULL);
781 } else /* cases 2, 5, 7 */
782 vma_adjust(prev, prev->vm_start,
783 end, prev->vm_pgoff, NULL);
784 return prev;
788 * Can this new request be merged in front of next?
790 if (next && end == next->vm_start &&
791 mpol_equal(policy, vma_policy(next)) &&
792 can_vma_merge_before(next, vm_flags,
793 anon_vma, file, pgoff+pglen)) {
794 if (prev && addr < prev->vm_end) /* case 4 */
795 vma_adjust(prev, prev->vm_start,
796 addr, prev->vm_pgoff, NULL);
797 else /* cases 3, 8 */
798 vma_adjust(area, addr, next->vm_end,
799 next->vm_pgoff - pglen, NULL);
800 return area;
803 return NULL;
807 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
808 * neighbouring vmas for a suitable anon_vma, before it goes off
809 * to allocate a new anon_vma. It checks because a repetitive
810 * sequence of mprotects and faults may otherwise lead to distinct
811 * anon_vmas being allocated, preventing vma merge in subsequent
812 * mprotect.
814 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
816 struct vm_area_struct *near;
817 unsigned long vm_flags;
819 near = vma->vm_next;
820 if (!near)
821 goto try_prev;
824 * Since only mprotect tries to remerge vmas, match flags
825 * which might be mprotected into each other later on.
826 * Neither mlock nor madvise tries to remerge at present,
827 * so leave their flags as obstructing a merge.
829 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
830 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
832 if (near->anon_vma && vma->vm_end == near->vm_start &&
833 mpol_equal(vma_policy(vma), vma_policy(near)) &&
834 can_vma_merge_before(near, vm_flags,
835 NULL, vma->vm_file, vma->vm_pgoff +
836 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT)))
837 return near->anon_vma;
838 try_prev:
840 * It is potentially slow to have to call find_vma_prev here.
841 * But it's only on the first write fault on the vma, not
842 * every time, and we could devise a way to avoid it later
843 * (e.g. stash info in next's anon_vma_node when assigning
844 * an anon_vma, or when trying vma_merge). Another time.
846 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma);
847 if (!near)
848 goto none;
850 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC);
851 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC);
853 if (near->anon_vma && near->vm_end == vma->vm_start &&
854 mpol_equal(vma_policy(near), vma_policy(vma)) &&
855 can_vma_merge_after(near, vm_flags,
856 NULL, vma->vm_file, vma->vm_pgoff))
857 return near->anon_vma;
858 none:
860 * There's no absolute need to look only at touching neighbours:
861 * we could search further afield for "compatible" anon_vmas.
862 * But it would probably just be a waste of time searching,
863 * or lead to too many vmas hanging off the same anon_vma.
864 * We're trying to allow mprotect remerging later on,
865 * not trying to minimize memory used for anon_vmas.
867 return NULL;
870 #ifdef CONFIG_PROC_FS
871 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
872 struct file *file, long pages)
874 const unsigned long stack_flags
875 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
877 if (file) {
878 mm->shared_vm += pages;
879 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
880 mm->exec_vm += pages;
881 } else if (flags & stack_flags)
882 mm->stack_vm += pages;
883 if (flags & (VM_RESERVED|VM_IO))
884 mm->reserved_vm += pages;
886 #endif /* CONFIG_PROC_FS */
889 * The caller must hold down_write(current->mm->mmap_sem).
892 unsigned long do_mmap_pgoff(struct file * file, unsigned long addr,
893 unsigned long len, unsigned long prot,
894 unsigned long flags, unsigned long pgoff)
896 struct mm_struct * mm = current->mm;
897 struct inode *inode;
898 unsigned int vm_flags;
899 int error;
900 int accountable = 1;
901 unsigned long reqprot = prot;
904 * Does the application expect PROT_READ to imply PROT_EXEC?
906 * (the exception is when the underlying filesystem is noexec
907 * mounted, in which case we dont add PROT_EXEC.)
909 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
910 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
911 prot |= PROT_EXEC;
913 if (!len)
914 return -EINVAL;
916 if (!(flags & MAP_FIXED))
917 addr = round_hint_to_min(addr);
919 error = arch_mmap_check(addr, len, flags);
920 if (error)
921 return error;
923 /* Careful about overflows.. */
924 len = PAGE_ALIGN(len);
925 if (!len || len > TASK_SIZE)
926 return -ENOMEM;
928 /* offset overflow? */
929 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
930 return -EOVERFLOW;
932 /* Too many mappings? */
933 if (mm->map_count > sysctl_max_map_count)
934 return -ENOMEM;
936 /* Obtain the address to map to. we verify (or select) it and ensure
937 * that it represents a valid section of the address space.
939 addr = get_unmapped_area(file, addr, len, pgoff, flags);
940 if (addr & ~PAGE_MASK)
941 return addr;
943 /* Do simple checking here so the lower-level routines won't have
944 * to. we assume access permissions have been handled by the open
945 * of the memory object, so we don't do any here.
947 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
948 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
950 if (flags & MAP_LOCKED) {
951 if (!can_do_mlock())
952 return -EPERM;
953 vm_flags |= VM_LOCKED;
955 /* mlock MCL_FUTURE? */
956 if (vm_flags & VM_LOCKED) {
957 unsigned long locked, lock_limit;
958 locked = len >> PAGE_SHIFT;
959 locked += mm->locked_vm;
960 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
961 lock_limit >>= PAGE_SHIFT;
962 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
963 return -EAGAIN;
966 inode = file ? file->f_path.dentry->d_inode : NULL;
968 if (file) {
969 switch (flags & MAP_TYPE) {
970 case MAP_SHARED:
971 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
972 return -EACCES;
975 * Make sure we don't allow writing to an append-only
976 * file..
978 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
979 return -EACCES;
982 * Make sure there are no mandatory locks on the file.
984 if (locks_verify_locked(inode))
985 return -EAGAIN;
987 vm_flags |= VM_SHARED | VM_MAYSHARE;
988 if (!(file->f_mode & FMODE_WRITE))
989 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
991 /* fall through */
992 case MAP_PRIVATE:
993 if (!(file->f_mode & FMODE_READ))
994 return -EACCES;
995 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
996 if (vm_flags & VM_EXEC)
997 return -EPERM;
998 vm_flags &= ~VM_MAYEXEC;
1000 if (is_file_hugepages(file))
1001 accountable = 0;
1003 if (!file->f_op || !file->f_op->mmap)
1004 return -ENODEV;
1005 break;
1007 default:
1008 return -EINVAL;
1010 } else {
1011 switch (flags & MAP_TYPE) {
1012 case MAP_SHARED:
1013 vm_flags |= VM_SHARED | VM_MAYSHARE;
1014 break;
1015 case MAP_PRIVATE:
1017 * Set pgoff according to addr for anon_vma.
1019 pgoff = addr >> PAGE_SHIFT;
1020 break;
1021 default:
1022 return -EINVAL;
1026 error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1027 if (error)
1028 return error;
1030 return mmap_region(file, addr, len, flags, vm_flags, pgoff,
1031 accountable);
1033 EXPORT_SYMBOL(do_mmap_pgoff);
1036 * Some shared mappigns will want the pages marked read-only
1037 * to track write events. If so, we'll downgrade vm_page_prot
1038 * to the private version (using protection_map[] without the
1039 * VM_SHARED bit).
1041 int vma_wants_writenotify(struct vm_area_struct *vma)
1043 unsigned int vm_flags = vma->vm_flags;
1045 /* If it was private or non-writable, the write bit is already clear */
1046 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1047 return 0;
1049 /* The backer wishes to know when pages are first written to? */
1050 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1051 return 1;
1053 /* The open routine did something to the protections already? */
1054 if (pgprot_val(vma->vm_page_prot) !=
1055 pgprot_val(vm_get_page_prot(vm_flags)))
1056 return 0;
1058 /* Specialty mapping? */
1059 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1060 return 0;
1062 /* Can the mapping track the dirty pages? */
1063 return vma->vm_file && vma->vm_file->f_mapping &&
1064 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1068 unsigned long mmap_region(struct file *file, unsigned long addr,
1069 unsigned long len, unsigned long flags,
1070 unsigned int vm_flags, unsigned long pgoff,
1071 int accountable)
1073 struct mm_struct *mm = current->mm;
1074 struct vm_area_struct *vma, *prev;
1075 int correct_wcount = 0;
1076 int error;
1077 struct rb_node **rb_link, *rb_parent;
1078 unsigned long charged = 0;
1079 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1081 /* Clear old maps */
1082 error = -ENOMEM;
1083 munmap_back:
1084 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1085 if (vma && vma->vm_start < addr + len) {
1086 if (do_munmap(mm, addr, len))
1087 return -ENOMEM;
1088 goto munmap_back;
1091 /* Check against address space limit. */
1092 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1093 return -ENOMEM;
1095 if (accountable && (!(flags & MAP_NORESERVE) ||
1096 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) {
1097 if (vm_flags & VM_SHARED) {
1098 /* Check memory availability in shmem_file_setup? */
1099 vm_flags |= VM_ACCOUNT;
1100 } else if (vm_flags & VM_WRITE) {
1102 * Private writable mapping: check memory availability
1104 charged = len >> PAGE_SHIFT;
1105 if (security_vm_enough_memory(charged))
1106 return -ENOMEM;
1107 vm_flags |= VM_ACCOUNT;
1112 * Can we just expand an old private anonymous mapping?
1113 * The VM_SHARED test is necessary because shmem_zero_setup
1114 * will create the file object for a shared anonymous map below.
1116 if (!file && !(vm_flags & VM_SHARED) &&
1117 vma_merge(mm, prev, addr, addr + len, vm_flags,
1118 NULL, NULL, pgoff, NULL))
1119 goto out;
1122 * Determine the object being mapped and call the appropriate
1123 * specific mapper. the address has already been validated, but
1124 * not unmapped, but the maps are removed from the list.
1126 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1127 if (!vma) {
1128 error = -ENOMEM;
1129 goto unacct_error;
1132 vma->vm_mm = mm;
1133 vma->vm_start = addr;
1134 vma->vm_end = addr + len;
1135 vma->vm_flags = vm_flags;
1136 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1137 vma->vm_pgoff = pgoff;
1139 if (file) {
1140 error = -EINVAL;
1141 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1142 goto free_vma;
1143 if (vm_flags & VM_DENYWRITE) {
1144 error = deny_write_access(file);
1145 if (error)
1146 goto free_vma;
1147 correct_wcount = 1;
1149 vma->vm_file = file;
1150 get_file(file);
1151 error = file->f_op->mmap(file, vma);
1152 if (error)
1153 goto unmap_and_free_vma;
1154 } else if (vm_flags & VM_SHARED) {
1155 error = shmem_zero_setup(vma);
1156 if (error)
1157 goto free_vma;
1160 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform
1161 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap)
1162 * that memory reservation must be checked; but that reservation
1163 * belongs to shared memory object, not to vma: so now clear it.
1165 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT))
1166 vma->vm_flags &= ~VM_ACCOUNT;
1168 /* Can addr have changed??
1170 * Answer: Yes, several device drivers can do it in their
1171 * f_op->mmap method. -DaveM
1173 addr = vma->vm_start;
1174 pgoff = vma->vm_pgoff;
1175 vm_flags = vma->vm_flags;
1177 if (vma_wants_writenotify(vma))
1178 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1180 if (!file || !vma_merge(mm, prev, addr, vma->vm_end,
1181 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) {
1182 file = vma->vm_file;
1183 vma_link(mm, vma, prev, rb_link, rb_parent);
1184 if (correct_wcount)
1185 atomic_inc(&inode->i_writecount);
1186 } else {
1187 if (file) {
1188 if (correct_wcount)
1189 atomic_inc(&inode->i_writecount);
1190 fput(file);
1192 mpol_free(vma_policy(vma));
1193 kmem_cache_free(vm_area_cachep, vma);
1195 out:
1196 mm->total_vm += len >> PAGE_SHIFT;
1197 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1198 if (vm_flags & VM_LOCKED) {
1199 mm->locked_vm += len >> PAGE_SHIFT;
1200 make_pages_present(addr, addr + len);
1202 if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1203 make_pages_present(addr, addr + len);
1204 return addr;
1206 unmap_and_free_vma:
1207 if (correct_wcount)
1208 atomic_inc(&inode->i_writecount);
1209 vma->vm_file = NULL;
1210 fput(file);
1212 /* Undo any partial mapping done by a device driver. */
1213 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1214 charged = 0;
1215 free_vma:
1216 kmem_cache_free(vm_area_cachep, vma);
1217 unacct_error:
1218 if (charged)
1219 vm_unacct_memory(charged);
1220 return error;
1223 /* Get an address range which is currently unmapped.
1224 * For shmat() with addr=0.
1226 * Ugly calling convention alert:
1227 * Return value with the low bits set means error value,
1228 * ie
1229 * if (ret & ~PAGE_MASK)
1230 * error = ret;
1232 * This function "knows" that -ENOMEM has the bits set.
1234 #ifndef HAVE_ARCH_UNMAPPED_AREA
1235 unsigned long
1236 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1237 unsigned long len, unsigned long pgoff, unsigned long flags)
1239 struct mm_struct *mm = current->mm;
1240 struct vm_area_struct *vma;
1241 unsigned long start_addr;
1243 if (len > TASK_SIZE)
1244 return -ENOMEM;
1246 if (flags & MAP_FIXED)
1247 return addr;
1249 if (addr) {
1250 addr = PAGE_ALIGN(addr);
1251 vma = find_vma(mm, addr);
1252 if (TASK_SIZE - len >= addr &&
1253 (!vma || addr + len <= vma->vm_start))
1254 return addr;
1256 if (len > mm->cached_hole_size) {
1257 start_addr = addr = mm->free_area_cache;
1258 } else {
1259 start_addr = addr = TASK_UNMAPPED_BASE;
1260 mm->cached_hole_size = 0;
1263 full_search:
1264 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1265 /* At this point: (!vma || addr < vma->vm_end). */
1266 if (TASK_SIZE - len < addr) {
1268 * Start a new search - just in case we missed
1269 * some holes.
1271 if (start_addr != TASK_UNMAPPED_BASE) {
1272 addr = TASK_UNMAPPED_BASE;
1273 start_addr = addr;
1274 mm->cached_hole_size = 0;
1275 goto full_search;
1277 return -ENOMEM;
1279 if (!vma || addr + len <= vma->vm_start) {
1281 * Remember the place where we stopped the search:
1283 mm->free_area_cache = addr + len;
1284 return addr;
1286 if (addr + mm->cached_hole_size < vma->vm_start)
1287 mm->cached_hole_size = vma->vm_start - addr;
1288 addr = vma->vm_end;
1291 #endif
1293 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1296 * Is this a new hole at the lowest possible address?
1298 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) {
1299 mm->free_area_cache = addr;
1300 mm->cached_hole_size = ~0UL;
1305 * This mmap-allocator allocates new areas top-down from below the
1306 * stack's low limit (the base):
1308 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1309 unsigned long
1310 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1311 const unsigned long len, const unsigned long pgoff,
1312 const unsigned long flags)
1314 struct vm_area_struct *vma;
1315 struct mm_struct *mm = current->mm;
1316 unsigned long addr = addr0;
1318 /* requested length too big for entire address space */
1319 if (len > TASK_SIZE)
1320 return -ENOMEM;
1322 if (flags & MAP_FIXED)
1323 return addr;
1325 /* requesting a specific address */
1326 if (addr) {
1327 addr = PAGE_ALIGN(addr);
1328 vma = find_vma(mm, addr);
1329 if (TASK_SIZE - len >= addr &&
1330 (!vma || addr + len <= vma->vm_start))
1331 return addr;
1334 /* check if free_area_cache is useful for us */
1335 if (len <= mm->cached_hole_size) {
1336 mm->cached_hole_size = 0;
1337 mm->free_area_cache = mm->mmap_base;
1340 /* either no address requested or can't fit in requested address hole */
1341 addr = mm->free_area_cache;
1343 /* make sure it can fit in the remaining address space */
1344 if (addr > len) {
1345 vma = find_vma(mm, addr-len);
1346 if (!vma || addr <= vma->vm_start)
1347 /* remember the address as a hint for next time */
1348 return (mm->free_area_cache = addr-len);
1351 if (mm->mmap_base < len)
1352 goto bottomup;
1354 addr = mm->mmap_base-len;
1356 do {
1358 * Lookup failure means no vma is above this address,
1359 * else if new region fits below vma->vm_start,
1360 * return with success:
1362 vma = find_vma(mm, addr);
1363 if (!vma || addr+len <= vma->vm_start)
1364 /* remember the address as a hint for next time */
1365 return (mm->free_area_cache = addr);
1367 /* remember the largest hole we saw so far */
1368 if (addr + mm->cached_hole_size < vma->vm_start)
1369 mm->cached_hole_size = vma->vm_start - addr;
1371 /* try just below the current vma->vm_start */
1372 addr = vma->vm_start-len;
1373 } while (len < vma->vm_start);
1375 bottomup:
1377 * A failed mmap() very likely causes application failure,
1378 * so fall back to the bottom-up function here. This scenario
1379 * can happen with large stack limits and large mmap()
1380 * allocations.
1382 mm->cached_hole_size = ~0UL;
1383 mm->free_area_cache = TASK_UNMAPPED_BASE;
1384 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1386 * Restore the topdown base:
1388 mm->free_area_cache = mm->mmap_base;
1389 mm->cached_hole_size = ~0UL;
1391 return addr;
1393 #endif
1395 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1398 * Is this a new hole at the highest possible address?
1400 if (addr > mm->free_area_cache)
1401 mm->free_area_cache = addr;
1403 /* dont allow allocations above current base */
1404 if (mm->free_area_cache > mm->mmap_base)
1405 mm->free_area_cache = mm->mmap_base;
1408 unsigned long
1409 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1410 unsigned long pgoff, unsigned long flags)
1412 unsigned long (*get_area)(struct file *, unsigned long,
1413 unsigned long, unsigned long, unsigned long);
1415 get_area = current->mm->get_unmapped_area;
1416 if (file && file->f_op && file->f_op->get_unmapped_area)
1417 get_area = file->f_op->get_unmapped_area;
1418 addr = get_area(file, addr, len, pgoff, flags);
1419 if (IS_ERR_VALUE(addr))
1420 return addr;
1422 if (addr > TASK_SIZE - len)
1423 return -ENOMEM;
1424 if (addr & ~PAGE_MASK)
1425 return -EINVAL;
1427 return addr;
1430 EXPORT_SYMBOL(get_unmapped_area);
1432 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1433 struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr)
1435 struct vm_area_struct *vma = NULL;
1437 if (mm) {
1438 /* Check the cache first. */
1439 /* (Cache hit rate is typically around 35%.) */
1440 vma = mm->mmap_cache;
1441 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1442 struct rb_node * rb_node;
1444 rb_node = mm->mm_rb.rb_node;
1445 vma = NULL;
1447 while (rb_node) {
1448 struct vm_area_struct * vma_tmp;
1450 vma_tmp = rb_entry(rb_node,
1451 struct vm_area_struct, vm_rb);
1453 if (vma_tmp->vm_end > addr) {
1454 vma = vma_tmp;
1455 if (vma_tmp->vm_start <= addr)
1456 break;
1457 rb_node = rb_node->rb_left;
1458 } else
1459 rb_node = rb_node->rb_right;
1461 if (vma)
1462 mm->mmap_cache = vma;
1465 return vma;
1468 EXPORT_SYMBOL(find_vma);
1470 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */
1471 struct vm_area_struct *
1472 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1473 struct vm_area_struct **pprev)
1475 struct vm_area_struct *vma = NULL, *prev = NULL;
1476 struct rb_node * rb_node;
1477 if (!mm)
1478 goto out;
1480 /* Guard against addr being lower than the first VMA */
1481 vma = mm->mmap;
1483 /* Go through the RB tree quickly. */
1484 rb_node = mm->mm_rb.rb_node;
1486 while (rb_node) {
1487 struct vm_area_struct *vma_tmp;
1488 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1490 if (addr < vma_tmp->vm_end) {
1491 rb_node = rb_node->rb_left;
1492 } else {
1493 prev = vma_tmp;
1494 if (!prev->vm_next || (addr < prev->vm_next->vm_end))
1495 break;
1496 rb_node = rb_node->rb_right;
1500 out:
1501 *pprev = prev;
1502 return prev ? prev->vm_next : vma;
1506 * Verify that the stack growth is acceptable and
1507 * update accounting. This is shared with both the
1508 * grow-up and grow-down cases.
1510 static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow)
1512 struct mm_struct *mm = vma->vm_mm;
1513 struct rlimit *rlim = current->signal->rlim;
1514 unsigned long new_start;
1516 /* address space limit tests */
1517 if (!may_expand_vm(mm, grow))
1518 return -ENOMEM;
1520 /* Stack limit test */
1521 if (size > rlim[RLIMIT_STACK].rlim_cur)
1522 return -ENOMEM;
1524 /* mlock limit tests */
1525 if (vma->vm_flags & VM_LOCKED) {
1526 unsigned long locked;
1527 unsigned long limit;
1528 locked = mm->locked_vm + grow;
1529 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT;
1530 if (locked > limit && !capable(CAP_IPC_LOCK))
1531 return -ENOMEM;
1534 /* Check to ensure the stack will not grow into a hugetlb-only region */
1535 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1536 vma->vm_end - size;
1537 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1538 return -EFAULT;
1541 * Overcommit.. This must be the final test, as it will
1542 * update security statistics.
1544 if (security_vm_enough_memory(grow))
1545 return -ENOMEM;
1547 /* Ok, everything looks good - let it rip */
1548 mm->total_vm += grow;
1549 if (vma->vm_flags & VM_LOCKED)
1550 mm->locked_vm += grow;
1551 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1552 return 0;
1555 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1557 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1558 * vma is the last one with address > vma->vm_end. Have to extend vma.
1560 #ifndef CONFIG_IA64
1561 static inline
1562 #endif
1563 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1565 int error;
1567 if (!(vma->vm_flags & VM_GROWSUP))
1568 return -EFAULT;
1571 * We must make sure the anon_vma is allocated
1572 * so that the anon_vma locking is not a noop.
1574 if (unlikely(anon_vma_prepare(vma)))
1575 return -ENOMEM;
1576 anon_vma_lock(vma);
1579 * vma->vm_start/vm_end cannot change under us because the caller
1580 * is required to hold the mmap_sem in read mode. We need the
1581 * anon_vma lock to serialize against concurrent expand_stacks.
1582 * Also guard against wrapping around to address 0.
1584 if (address < PAGE_ALIGN(address+4))
1585 address = PAGE_ALIGN(address+4);
1586 else {
1587 anon_vma_unlock(vma);
1588 return -ENOMEM;
1590 error = 0;
1592 /* Somebody else might have raced and expanded it already */
1593 if (address > vma->vm_end) {
1594 unsigned long size, grow;
1596 size = address - vma->vm_start;
1597 grow = (address - vma->vm_end) >> PAGE_SHIFT;
1599 error = acct_stack_growth(vma, size, grow);
1600 if (!error)
1601 vma->vm_end = address;
1603 anon_vma_unlock(vma);
1604 return error;
1606 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1609 * vma is the first one with address < vma->vm_start. Have to extend vma.
1611 static inline int expand_downwards(struct vm_area_struct *vma,
1612 unsigned long address)
1614 int error;
1617 * We must make sure the anon_vma is allocated
1618 * so that the anon_vma locking is not a noop.
1620 if (unlikely(anon_vma_prepare(vma)))
1621 return -ENOMEM;
1623 address &= PAGE_MASK;
1624 error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1625 if (error)
1626 return error;
1628 anon_vma_lock(vma);
1631 * vma->vm_start/vm_end cannot change under us because the caller
1632 * is required to hold the mmap_sem in read mode. We need the
1633 * anon_vma lock to serialize against concurrent expand_stacks.
1636 /* Somebody else might have raced and expanded it already */
1637 if (address < vma->vm_start) {
1638 unsigned long size, grow;
1640 size = vma->vm_end - address;
1641 grow = (vma->vm_start - address) >> PAGE_SHIFT;
1643 error = acct_stack_growth(vma, size, grow);
1644 if (!error) {
1645 vma->vm_start = address;
1646 vma->vm_pgoff -= grow;
1649 anon_vma_unlock(vma);
1650 return error;
1653 int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address)
1655 return expand_downwards(vma, address);
1658 #ifdef CONFIG_STACK_GROWSUP
1659 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1661 return expand_upwards(vma, address);
1664 struct vm_area_struct *
1665 find_extend_vma(struct mm_struct *mm, unsigned long addr)
1667 struct vm_area_struct *vma, *prev;
1669 addr &= PAGE_MASK;
1670 vma = find_vma_prev(mm, addr, &prev);
1671 if (vma && (vma->vm_start <= addr))
1672 return vma;
1673 if (!prev || expand_stack(prev, addr))
1674 return NULL;
1675 if (prev->vm_flags & VM_LOCKED)
1676 make_pages_present(addr, prev->vm_end);
1677 return prev;
1679 #else
1680 int expand_stack(struct vm_area_struct *vma, unsigned long address)
1682 return expand_downwards(vma, address);
1685 struct vm_area_struct *
1686 find_extend_vma(struct mm_struct * mm, unsigned long addr)
1688 struct vm_area_struct * vma;
1689 unsigned long start;
1691 addr &= PAGE_MASK;
1692 vma = find_vma(mm,addr);
1693 if (!vma)
1694 return NULL;
1695 if (vma->vm_start <= addr)
1696 return vma;
1697 if (!(vma->vm_flags & VM_GROWSDOWN))
1698 return NULL;
1699 start = vma->vm_start;
1700 if (expand_stack(vma, addr))
1701 return NULL;
1702 if (vma->vm_flags & VM_LOCKED)
1703 make_pages_present(addr, start);
1704 return vma;
1706 #endif
1709 * Ok - we have the memory areas we should free on the vma list,
1710 * so release them, and do the vma updates.
1712 * Called with the mm semaphore held.
1714 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1716 /* Update high watermark before we lower total_vm */
1717 update_hiwater_vm(mm);
1718 do {
1719 long nrpages = vma_pages(vma);
1721 mm->total_vm -= nrpages;
1722 if (vma->vm_flags & VM_LOCKED)
1723 mm->locked_vm -= nrpages;
1724 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1725 vma = remove_vma(vma);
1726 } while (vma);
1727 validate_mm(mm);
1731 * Get rid of page table information in the indicated region.
1733 * Called with the mm semaphore held.
1735 static void unmap_region(struct mm_struct *mm,
1736 struct vm_area_struct *vma, struct vm_area_struct *prev,
1737 unsigned long start, unsigned long end)
1739 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1740 struct mmu_gather *tlb;
1741 unsigned long nr_accounted = 0;
1743 lru_add_drain();
1744 tlb = tlb_gather_mmu(mm, 0);
1745 update_hiwater_rss(mm);
1746 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1747 vm_unacct_memory(nr_accounted);
1748 free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
1749 next? next->vm_start: 0);
1750 tlb_finish_mmu(tlb, start, end);
1754 * Create a list of vma's touched by the unmap, removing them from the mm's
1755 * vma list as we go..
1757 static void
1758 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1759 struct vm_area_struct *prev, unsigned long end)
1761 struct vm_area_struct **insertion_point;
1762 struct vm_area_struct *tail_vma = NULL;
1763 unsigned long addr;
1765 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1766 do {
1767 rb_erase(&vma->vm_rb, &mm->mm_rb);
1768 mm->map_count--;
1769 tail_vma = vma;
1770 vma = vma->vm_next;
1771 } while (vma && vma->vm_start < end);
1772 *insertion_point = vma;
1773 tail_vma->vm_next = NULL;
1774 if (mm->unmap_area == arch_unmap_area)
1775 addr = prev ? prev->vm_end : mm->mmap_base;
1776 else
1777 addr = vma ? vma->vm_start : mm->mmap_base;
1778 mm->unmap_area(mm, addr);
1779 mm->mmap_cache = NULL; /* Kill the cache. */
1783 * Split a vma into two pieces at address 'addr', a new vma is allocated
1784 * either for the first part or the tail.
1786 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1787 unsigned long addr, int new_below)
1789 struct mempolicy *pol;
1790 struct vm_area_struct *new;
1792 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK))
1793 return -EINVAL;
1795 if (mm->map_count >= sysctl_max_map_count)
1796 return -ENOMEM;
1798 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1799 if (!new)
1800 return -ENOMEM;
1802 /* most fields are the same, copy all, and then fixup */
1803 *new = *vma;
1805 if (new_below)
1806 new->vm_end = addr;
1807 else {
1808 new->vm_start = addr;
1809 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1812 pol = mpol_copy(vma_policy(vma));
1813 if (IS_ERR(pol)) {
1814 kmem_cache_free(vm_area_cachep, new);
1815 return PTR_ERR(pol);
1817 vma_set_policy(new, pol);
1819 if (new->vm_file)
1820 get_file(new->vm_file);
1822 if (new->vm_ops && new->vm_ops->open)
1823 new->vm_ops->open(new);
1825 if (new_below)
1826 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
1827 ((addr - new->vm_start) >> PAGE_SHIFT), new);
1828 else
1829 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
1831 return 0;
1834 /* Munmap is split into 2 main parts -- this part which finds
1835 * what needs doing, and the areas themselves, which do the
1836 * work. This now handles partial unmappings.
1837 * Jeremy Fitzhardinge <jeremy@goop.org>
1839 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1841 unsigned long end;
1842 struct vm_area_struct *vma, *prev, *last;
1844 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
1845 return -EINVAL;
1847 if ((len = PAGE_ALIGN(len)) == 0)
1848 return -EINVAL;
1850 /* Find the first overlapping VMA */
1851 vma = find_vma_prev(mm, start, &prev);
1852 if (!vma)
1853 return 0;
1854 /* we have start < vma->vm_end */
1856 /* if it doesn't overlap, we have nothing.. */
1857 end = start + len;
1858 if (vma->vm_start >= end)
1859 return 0;
1862 * If we need to split any vma, do it now to save pain later.
1864 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
1865 * unmapped vm_area_struct will remain in use: so lower split_vma
1866 * places tmp vma above, and higher split_vma places tmp vma below.
1868 if (start > vma->vm_start) {
1869 int error = split_vma(mm, vma, start, 0);
1870 if (error)
1871 return error;
1872 prev = vma;
1875 /* Does it split the last one? */
1876 last = find_vma(mm, end);
1877 if (last && end > last->vm_start) {
1878 int error = split_vma(mm, last, end, 1);
1879 if (error)
1880 return error;
1882 vma = prev? prev->vm_next: mm->mmap;
1885 * Remove the vma's, and unmap the actual pages
1887 detach_vmas_to_be_unmapped(mm, vma, prev, end);
1888 unmap_region(mm, vma, prev, start, end);
1890 /* Fix up all other VM information */
1891 remove_vma_list(mm, vma);
1893 return 0;
1896 EXPORT_SYMBOL(do_munmap);
1898 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1900 int ret;
1901 struct mm_struct *mm = current->mm;
1903 profile_munmap(addr);
1905 down_write(&mm->mmap_sem);
1906 ret = do_munmap(mm, addr, len);
1907 up_write(&mm->mmap_sem);
1908 return ret;
1911 static inline void verify_mm_writelocked(struct mm_struct *mm)
1913 #ifdef CONFIG_DEBUG_VM
1914 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
1915 WARN_ON(1);
1916 up_read(&mm->mmap_sem);
1918 #endif
1922 * this is really a simplified "do_mmap". it only handles
1923 * anonymous maps. eventually we may be able to do some
1924 * brk-specific accounting here.
1926 unsigned long do_brk(unsigned long addr, unsigned long len)
1928 struct mm_struct * mm = current->mm;
1929 struct vm_area_struct * vma, * prev;
1930 unsigned long flags;
1931 struct rb_node ** rb_link, * rb_parent;
1932 pgoff_t pgoff = addr >> PAGE_SHIFT;
1933 int error;
1935 len = PAGE_ALIGN(len);
1936 if (!len)
1937 return addr;
1939 if ((addr + len) > TASK_SIZE || (addr + len) < addr)
1940 return -EINVAL;
1942 if (is_hugepage_only_range(mm, addr, len))
1943 return -EINVAL;
1945 error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
1946 if (error)
1947 return error;
1949 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
1951 error = arch_mmap_check(addr, len, flags);
1952 if (error)
1953 return error;
1956 * mlock MCL_FUTURE?
1958 if (mm->def_flags & VM_LOCKED) {
1959 unsigned long locked, lock_limit;
1960 locked = len >> PAGE_SHIFT;
1961 locked += mm->locked_vm;
1962 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur;
1963 lock_limit >>= PAGE_SHIFT;
1964 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1965 return -EAGAIN;
1969 * mm->mmap_sem is required to protect against another thread
1970 * changing the mappings in case we sleep.
1972 verify_mm_writelocked(mm);
1975 * Clear old maps. this also does some error checking for us
1977 munmap_back:
1978 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1979 if (vma && vma->vm_start < addr + len) {
1980 if (do_munmap(mm, addr, len))
1981 return -ENOMEM;
1982 goto munmap_back;
1985 /* Check against address space limits *after* clearing old maps... */
1986 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1987 return -ENOMEM;
1989 if (mm->map_count > sysctl_max_map_count)
1990 return -ENOMEM;
1992 if (security_vm_enough_memory(len >> PAGE_SHIFT))
1993 return -ENOMEM;
1995 /* Can we just expand an old private anonymous mapping? */
1996 if (vma_merge(mm, prev, addr, addr + len, flags,
1997 NULL, NULL, pgoff, NULL))
1998 goto out;
2001 * create a vma struct for an anonymous mapping
2003 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2004 if (!vma) {
2005 vm_unacct_memory(len >> PAGE_SHIFT);
2006 return -ENOMEM;
2009 vma->vm_mm = mm;
2010 vma->vm_start = addr;
2011 vma->vm_end = addr + len;
2012 vma->vm_pgoff = pgoff;
2013 vma->vm_flags = flags;
2014 vma->vm_page_prot = vm_get_page_prot(flags);
2015 vma_link(mm, vma, prev, rb_link, rb_parent);
2016 out:
2017 mm->total_vm += len >> PAGE_SHIFT;
2018 if (flags & VM_LOCKED) {
2019 mm->locked_vm += len >> PAGE_SHIFT;
2020 make_pages_present(addr, addr + len);
2022 return addr;
2025 EXPORT_SYMBOL(do_brk);
2027 /* Release all mmaps. */
2028 void exit_mmap(struct mm_struct *mm)
2030 struct mmu_gather *tlb;
2031 struct vm_area_struct *vma = mm->mmap;
2032 unsigned long nr_accounted = 0;
2033 unsigned long end;
2035 /* mm's last user has gone, and its about to be pulled down */
2036 arch_exit_mmap(mm);
2038 lru_add_drain();
2039 flush_cache_mm(mm);
2040 tlb = tlb_gather_mmu(mm, 1);
2041 /* Don't update_hiwater_rss(mm) here, do_exit already did */
2042 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2043 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2044 vm_unacct_memory(nr_accounted);
2045 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
2046 tlb_finish_mmu(tlb, 0, end);
2049 * Walk the list again, actually closing and freeing it,
2050 * with preemption enabled, without holding any MM locks.
2052 while (vma)
2053 vma = remove_vma(vma);
2055 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2058 /* Insert vm structure into process list sorted by address
2059 * and into the inode's i_mmap tree. If vm_file is non-NULL
2060 * then i_mmap_lock is taken here.
2062 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2064 struct vm_area_struct * __vma, * prev;
2065 struct rb_node ** rb_link, * rb_parent;
2068 * The vm_pgoff of a purely anonymous vma should be irrelevant
2069 * until its first write fault, when page's anon_vma and index
2070 * are set. But now set the vm_pgoff it will almost certainly
2071 * end up with (unless mremap moves it elsewhere before that
2072 * first wfault), so /proc/pid/maps tells a consistent story.
2074 * By setting it to reflect the virtual start address of the
2075 * vma, merges and splits can happen in a seamless way, just
2076 * using the existing file pgoff checks and manipulations.
2077 * Similarly in do_mmap_pgoff and in do_brk.
2079 if (!vma->vm_file) {
2080 BUG_ON(vma->anon_vma);
2081 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2083 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2084 if (__vma && __vma->vm_start < vma->vm_end)
2085 return -ENOMEM;
2086 if ((vma->vm_flags & VM_ACCOUNT) &&
2087 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2088 return -ENOMEM;
2089 vma_link(mm, vma, prev, rb_link, rb_parent);
2090 return 0;
2094 * Copy the vma structure to a new location in the same mm,
2095 * prior to moving page table entries, to effect an mremap move.
2097 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2098 unsigned long addr, unsigned long len, pgoff_t pgoff)
2100 struct vm_area_struct *vma = *vmap;
2101 unsigned long vma_start = vma->vm_start;
2102 struct mm_struct *mm = vma->vm_mm;
2103 struct vm_area_struct *new_vma, *prev;
2104 struct rb_node **rb_link, *rb_parent;
2105 struct mempolicy *pol;
2108 * If anonymous vma has not yet been faulted, update new pgoff
2109 * to match new location, to increase its chance of merging.
2111 if (!vma->vm_file && !vma->anon_vma)
2112 pgoff = addr >> PAGE_SHIFT;
2114 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2115 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2116 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2117 if (new_vma) {
2119 * Source vma may have been merged into new_vma
2121 if (vma_start >= new_vma->vm_start &&
2122 vma_start < new_vma->vm_end)
2123 *vmap = new_vma;
2124 } else {
2125 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2126 if (new_vma) {
2127 *new_vma = *vma;
2128 pol = mpol_copy(vma_policy(vma));
2129 if (IS_ERR(pol)) {
2130 kmem_cache_free(vm_area_cachep, new_vma);
2131 return NULL;
2133 vma_set_policy(new_vma, pol);
2134 new_vma->vm_start = addr;
2135 new_vma->vm_end = addr + len;
2136 new_vma->vm_pgoff = pgoff;
2137 if (new_vma->vm_file)
2138 get_file(new_vma->vm_file);
2139 if (new_vma->vm_ops && new_vma->vm_ops->open)
2140 new_vma->vm_ops->open(new_vma);
2141 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2144 return new_vma;
2148 * Return true if the calling process may expand its vm space by the passed
2149 * number of pages
2151 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2153 unsigned long cur = mm->total_vm; /* pages */
2154 unsigned long lim;
2156 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT;
2158 if (cur + npages > lim)
2159 return 0;
2160 return 1;
2164 static struct page *special_mapping_nopage(struct vm_area_struct *vma,
2165 unsigned long address, int *type)
2167 struct page **pages;
2169 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
2171 address -= vma->vm_start;
2172 for (pages = vma->vm_private_data; address > 0 && *pages; ++pages)
2173 address -= PAGE_SIZE;
2175 if (*pages) {
2176 struct page *page = *pages;
2177 get_page(page);
2178 return page;
2181 return NOPAGE_SIGBUS;
2185 * Having a close hook prevents vma merging regardless of flags.
2187 static void special_mapping_close(struct vm_area_struct *vma)
2191 static struct vm_operations_struct special_mapping_vmops = {
2192 .close = special_mapping_close,
2193 .nopage = special_mapping_nopage,
2197 * Called with mm->mmap_sem held for writing.
2198 * Insert a new vma covering the given region, with the given flags.
2199 * Its pages are supplied by the given array of struct page *.
2200 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2201 * The region past the last page supplied will always produce SIGBUS.
2202 * The array pointer and the pages it points to are assumed to stay alive
2203 * for as long as this mapping might exist.
2205 int install_special_mapping(struct mm_struct *mm,
2206 unsigned long addr, unsigned long len,
2207 unsigned long vm_flags, struct page **pages)
2209 struct vm_area_struct *vma;
2211 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2212 if (unlikely(vma == NULL))
2213 return -ENOMEM;
2215 vma->vm_mm = mm;
2216 vma->vm_start = addr;
2217 vma->vm_end = addr + len;
2219 vma->vm_flags = vm_flags | mm->def_flags;
2220 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2222 vma->vm_ops = &special_mapping_vmops;
2223 vma->vm_private_data = pages;
2225 if (unlikely(insert_vm_struct(mm, vma))) {
2226 kmem_cache_free(vm_area_cachep, vma);
2227 return -ENOMEM;
2230 mm->total_vm += len >> PAGE_SHIFT;
2232 return 0;