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1 /*
2 * mm/mmap.c
3 *
4 * Written by obz.
5 *
6 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
7 */
8
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11 #include <linux/kernel.h>
12 #include <linux/slab.h>
13 #include <linux/backing-dev.h>
14 #include <linux/mm.h>
15 #include <linux/vmacache.h>
16 #include <linux/shm.h>
17 #include <linux/mman.h>
18 #include <linux/pagemap.h>
19 #include <linux/swap.h>
20 #include <linux/syscalls.h>
21 #include <linux/capability.h>
22 #include <linux/init.h>
23 #include <linux/file.h>
24 #include <linux/fs.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/hugetlb.h>
28 #include <linux/profile.h>
29 #include <linux/export.h>
30 #include <linux/mount.h>
31 #include <linux/mempolicy.h>
32 #include <linux/rmap.h>
33 #include <linux/mmu_notifier.h>
34 #include <linux/mmdebug.h>
35 #include <linux/perf_event.h>
36 #include <linux/audit.h>
37 #include <linux/khugepaged.h>
38 #include <linux/uprobes.h>
39 #include <linux/rbtree_augmented.h>
40 #include <linux/sched/sysctl.h>
41 #include <linux/notifier.h>
42 #include <linux/memory.h>
43 #include <linux/printk.h>
44
45 #include <asm/uaccess.h>
46 #include <asm/cacheflush.h>
47 #include <asm/tlb.h>
48 #include <asm/mmu_context.h>
49
50 #include "internal.h"
51
52 #ifndef arch_mmap_check
53 #define arch_mmap_check(addr, len, flags) (0)
54 #endif
55
56 #ifndef arch_rebalance_pgtables
57 #define arch_rebalance_pgtables(addr, len) (addr)
58 #endif
59
60 static void unmap_region(struct mm_struct *mm,
61 struct vm_area_struct *vma, struct vm_area_struct *prev,
62 unsigned long start, unsigned long end);
63
64 /* description of effects of mapping type and prot in current implementation.
65 * this is due to the limited x86 page protection hardware. The expected
66 * behavior is in parens:
67 *
68 * map_type prot
69 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
70 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
71 * w: (no) no w: (no) no w: (yes) yes w: (no) no
72 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
73 *
74 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
75 * w: (no) no w: (no) no w: (copy) copy w: (no) no
76 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
77 *
78 */
79 pgprot_t protection_map[16] = {
80 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
81 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
82 };
83
84 pgprot_t vm_get_page_prot(unsigned long vm_flags)
85 {
86 return __pgprot(pgprot_val(protection_map[vm_flags &
87 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
88 pgprot_val(arch_vm_get_page_prot(vm_flags)));
89 }
90 EXPORT_SYMBOL(vm_get_page_prot);
91
92 static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
93 {
94 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
95 }
96
97 /* Update vma->vm_page_prot to reflect vma->vm_flags. */
98 void vma_set_page_prot(struct vm_area_struct *vma)
99 {
100 unsigned long vm_flags = vma->vm_flags;
101
102 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
103 if (vma_wants_writenotify(vma)) {
104 vm_flags &= ~VM_SHARED;
105 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot,
106 vm_flags);
107 }
108 }
109
110
111 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */
112 int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
113 unsigned long sysctl_overcommit_kbytes __read_mostly;
114 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
115 unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
116 unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
117 /*
118 * Make sure vm_committed_as in one cacheline and not cacheline shared with
119 * other variables. It can be updated by several CPUs frequently.
120 */
121 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
122
123 /*
124 * The global memory commitment made in the system can be a metric
125 * that can be used to drive ballooning decisions when Linux is hosted
126 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
127 * balancing memory across competing virtual machines that are hosted.
128 * Several metrics drive this policy engine including the guest reported
129 * memory commitment.
130 */
131 unsigned long vm_memory_committed(void)
132 {
133 return percpu_counter_read_positive(&vm_committed_as);
134 }
135 EXPORT_SYMBOL_GPL(vm_memory_committed);
136
137 /*
138 * Check that a process has enough memory to allocate a new virtual
139 * mapping. 0 means there is enough memory for the allocation to
140 * succeed and -ENOMEM implies there is not.
141 *
142 * We currently support three overcommit policies, which are set via the
143 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
144 *
145 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
146 * Additional code 2002 Jul 20 by Robert Love.
147 *
148 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
149 *
150 * Note this is a helper function intended to be used by LSMs which
151 * wish to use this logic.
152 */
153 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
154 {
155 long free, allowed, reserve;
156
157 VM_WARN_ONCE(percpu_counter_read(&vm_committed_as) <
158 -(s64)vm_committed_as_batch * num_online_cpus(),
159 "memory commitment underflow");
160
161 vm_acct_memory(pages);
162
163 /*
164 * Sometimes we want to use more memory than we have
165 */
166 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
167 return 0;
168
169 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
170 free = global_page_state(NR_FREE_PAGES);
171 free += global_page_state(NR_FILE_PAGES);
172
173 /*
174 * shmem pages shouldn't be counted as free in this
175 * case, they can't be purged, only swapped out, and
176 * that won't affect the overall amount of available
177 * memory in the system.
178 */
179 free -= global_page_state(NR_SHMEM);
180
181 free += get_nr_swap_pages();
182
183 /*
184 * Any slabs which are created with the
185 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
186 * which are reclaimable, under pressure. The dentry
187 * cache and most inode caches should fall into this
188 */
189 free += global_page_state(NR_SLAB_RECLAIMABLE);
190
191 /*
192 * Leave reserved pages. The pages are not for anonymous pages.
193 */
194 if (free <= totalreserve_pages)
195 goto error;
196 else
197 free -= totalreserve_pages;
198
199 /*
200 * Reserve some for root
201 */
202 if (!cap_sys_admin)
203 free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
204
205 if (free > pages)
206 return 0;
207
208 goto error;
209 }
210
211 allowed = vm_commit_limit();
212 /*
213 * Reserve some for root
214 */
215 if (!cap_sys_admin)
216 allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
217
218 /*
219 * Don't let a single process grow so big a user can't recover
220 */
221 if (mm) {
222 reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
223 allowed -= min_t(long, mm->total_vm / 32, reserve);
224 }
225
226 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
227 return 0;
228 error:
229 vm_unacct_memory(pages);
230
231 return -ENOMEM;
232 }
233
234 /*
235 * Requires inode->i_mapping->i_mmap_rwsem
236 */
237 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
238 struct file *file, struct address_space *mapping)
239 {
240 if (vma->vm_flags & VM_DENYWRITE)
241 atomic_inc(&file_inode(file)->i_writecount);
242 if (vma->vm_flags & VM_SHARED)
243 mapping_unmap_writable(mapping);
244
245 flush_dcache_mmap_lock(mapping);
246 vma_interval_tree_remove(vma, &mapping->i_mmap);
247 flush_dcache_mmap_unlock(mapping);
248 }
249
250 /*
251 * Unlink a file-based vm structure from its interval tree, to hide
252 * vma from rmap and vmtruncate before freeing its page tables.
253 */
254 void unlink_file_vma(struct vm_area_struct *vma)
255 {
256 struct file *file = vma->vm_file;
257
258 if (file) {
259 struct address_space *mapping = file->f_mapping;
260 i_mmap_lock_write(mapping);
261 __remove_shared_vm_struct(vma, file, mapping);
262 i_mmap_unlock_write(mapping);
263 }
264 }
265
266 /*
267 * Close a vm structure and free it, returning the next.
268 */
269 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
270 {
271 struct vm_area_struct *next = vma->vm_next;
272
273 might_sleep();
274 if (vma->vm_ops && vma->vm_ops->close)
275 vma->vm_ops->close(vma);
276 if (vma->vm_file)
277 fput(vma->vm_file);
278 mpol_put(vma_policy(vma));
279 kmem_cache_free(vm_area_cachep, vma);
280 return next;
281 }
282
283 static unsigned long do_brk(unsigned long addr, unsigned long len);
284
285 SYSCALL_DEFINE1(brk, unsigned long, brk)
286 {
287 unsigned long retval;
288 unsigned long newbrk, oldbrk;
289 struct mm_struct *mm = current->mm;
290 unsigned long min_brk;
291 bool populate;
292
293 down_write(&mm->mmap_sem);
294
295 #ifdef CONFIG_COMPAT_BRK
296 /*
297 * CONFIG_COMPAT_BRK can still be overridden by setting
298 * randomize_va_space to 2, which will still cause mm->start_brk
299 * to be arbitrarily shifted
300 */
301 if (current->brk_randomized)
302 min_brk = mm->start_brk;
303 else
304 min_brk = mm->end_data;
305 #else
306 min_brk = mm->start_brk;
307 #endif
308 if (brk < min_brk)
309 goto out;
310
311 /*
312 * Check against rlimit here. If this check is done later after the test
313 * of oldbrk with newbrk then it can escape the test and let the data
314 * segment grow beyond its set limit the in case where the limit is
315 * not page aligned -Ram Gupta
316 */
317 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
318 mm->end_data, mm->start_data))
319 goto out;
320
321 newbrk = PAGE_ALIGN(brk);
322 oldbrk = PAGE_ALIGN(mm->brk);
323 if (oldbrk == newbrk)
324 goto set_brk;
325
326 /* Always allow shrinking brk. */
327 if (brk <= mm->brk) {
328 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
329 goto set_brk;
330 goto out;
331 }
332
333 /* Check against existing mmap mappings. */
334 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
335 goto out;
336
337 /* Ok, looks good - let it rip. */
338 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
339 goto out;
340
341 set_brk:
342 mm->brk = brk;
343 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
344 up_write(&mm->mmap_sem);
345 if (populate)
346 mm_populate(oldbrk, newbrk - oldbrk);
347 return brk;
348
349 out:
350 retval = mm->brk;
351 up_write(&mm->mmap_sem);
352 return retval;
353 }
354
355 static long vma_compute_subtree_gap(struct vm_area_struct *vma)
356 {
357 unsigned long max, subtree_gap;
358 max = vma->vm_start;
359 if (vma->vm_prev)
360 max -= vma->vm_prev->vm_end;
361 if (vma->vm_rb.rb_left) {
362 subtree_gap = rb_entry(vma->vm_rb.rb_left,
363 struct vm_area_struct, vm_rb)->rb_subtree_gap;
364 if (subtree_gap > max)
365 max = subtree_gap;
366 }
367 if (vma->vm_rb.rb_right) {
368 subtree_gap = rb_entry(vma->vm_rb.rb_right,
369 struct vm_area_struct, vm_rb)->rb_subtree_gap;
370 if (subtree_gap > max)
371 max = subtree_gap;
372 }
373 return max;
374 }
375
376 #ifdef CONFIG_DEBUG_VM_RB
377 static int browse_rb(struct rb_root *root)
378 {
379 int i = 0, j, bug = 0;
380 struct rb_node *nd, *pn = NULL;
381 unsigned long prev = 0, pend = 0;
382
383 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
384 struct vm_area_struct *vma;
385 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
386 if (vma->vm_start < prev) {
387 pr_emerg("vm_start %lx < prev %lx\n",
388 vma->vm_start, prev);
389 bug = 1;
390 }
391 if (vma->vm_start < pend) {
392 pr_emerg("vm_start %lx < pend %lx\n",
393 vma->vm_start, pend);
394 bug = 1;
395 }
396 if (vma->vm_start > vma->vm_end) {
397 pr_emerg("vm_start %lx > vm_end %lx\n",
398 vma->vm_start, vma->vm_end);
399 bug = 1;
400 }
401 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
402 pr_emerg("free gap %lx, correct %lx\n",
403 vma->rb_subtree_gap,
404 vma_compute_subtree_gap(vma));
405 bug = 1;
406 }
407 i++;
408 pn = nd;
409 prev = vma->vm_start;
410 pend = vma->vm_end;
411 }
412 j = 0;
413 for (nd = pn; nd; nd = rb_prev(nd))
414 j++;
415 if (i != j) {
416 pr_emerg("backwards %d, forwards %d\n", j, i);
417 bug = 1;
418 }
419 return bug ? -1 : i;
420 }
421
422 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
423 {
424 struct rb_node *nd;
425
426 for (nd = rb_first(root); nd; nd = rb_next(nd)) {
427 struct vm_area_struct *vma;
428 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
429 VM_BUG_ON_VMA(vma != ignore &&
430 vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
431 vma);
432 }
433 }
434
435 static void validate_mm(struct mm_struct *mm)
436 {
437 int bug = 0;
438 int i = 0;
439 unsigned long highest_address = 0;
440 struct vm_area_struct *vma = mm->mmap;
441
442 while (vma) {
443 struct anon_vma_chain *avc;
444
445 vma_lock_anon_vma(vma);
446 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
447 anon_vma_interval_tree_verify(avc);
448 vma_unlock_anon_vma(vma);
449 highest_address = vma->vm_end;
450 vma = vma->vm_next;
451 i++;
452 }
453 if (i != mm->map_count) {
454 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
455 bug = 1;
456 }
457 if (highest_address != mm->highest_vm_end) {
458 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
459 mm->highest_vm_end, highest_address);
460 bug = 1;
461 }
462 i = browse_rb(&mm->mm_rb);
463 if (i != mm->map_count) {
464 if (i != -1)
465 pr_emerg("map_count %d rb %d\n", mm->map_count, i);
466 bug = 1;
467 }
468 VM_BUG_ON_MM(bug, mm);
469 }
470 #else
471 #define validate_mm_rb(root, ignore) do { } while (0)
472 #define validate_mm(mm) do { } while (0)
473 #endif
474
475 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
476 unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
477
478 /*
479 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
480 * vma->vm_prev->vm_end values changed, without modifying the vma's position
481 * in the rbtree.
482 */
483 static void vma_gap_update(struct vm_area_struct *vma)
484 {
485 /*
486 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
487 * function that does exacltly what we want.
488 */
489 vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
490 }
491
492 static inline void vma_rb_insert(struct vm_area_struct *vma,
493 struct rb_root *root)
494 {
495 /* All rb_subtree_gap values must be consistent prior to insertion */
496 validate_mm_rb(root, NULL);
497
498 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
499 }
500
501 static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
502 {
503 /*
504 * All rb_subtree_gap values must be consistent prior to erase,
505 * with the possible exception of the vma being erased.
506 */
507 validate_mm_rb(root, vma);
508
509 /*
510 * Note rb_erase_augmented is a fairly large inline function,
511 * so make sure we instantiate it only once with our desired
512 * augmented rbtree callbacks.
513 */
514 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
515 }
516
517 /*
518 * vma has some anon_vma assigned, and is already inserted on that
519 * anon_vma's interval trees.
520 *
521 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
522 * vma must be removed from the anon_vma's interval trees using
523 * anon_vma_interval_tree_pre_update_vma().
524 *
525 * After the update, the vma will be reinserted using
526 * anon_vma_interval_tree_post_update_vma().
527 *
528 * The entire update must be protected by exclusive mmap_sem and by
529 * the root anon_vma's mutex.
530 */
531 static inline void
532 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
533 {
534 struct anon_vma_chain *avc;
535
536 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
537 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
538 }
539
540 static inline void
541 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
542 {
543 struct anon_vma_chain *avc;
544
545 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
546 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
547 }
548
549 static int find_vma_links(struct mm_struct *mm, unsigned long addr,
550 unsigned long end, struct vm_area_struct **pprev,
551 struct rb_node ***rb_link, struct rb_node **rb_parent)
552 {
553 struct rb_node **__rb_link, *__rb_parent, *rb_prev;
554
555 __rb_link = &mm->mm_rb.rb_node;
556 rb_prev = __rb_parent = NULL;
557
558 while (*__rb_link) {
559 struct vm_area_struct *vma_tmp;
560
561 __rb_parent = *__rb_link;
562 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
563
564 if (vma_tmp->vm_end > addr) {
565 /* Fail if an existing vma overlaps the area */
566 if (vma_tmp->vm_start < end)
567 return -ENOMEM;
568 __rb_link = &__rb_parent->rb_left;
569 } else {
570 rb_prev = __rb_parent;
571 __rb_link = &__rb_parent->rb_right;
572 }
573 }
574
575 *pprev = NULL;
576 if (rb_prev)
577 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
578 *rb_link = __rb_link;
579 *rb_parent = __rb_parent;
580 return 0;
581 }
582
583 static unsigned long count_vma_pages_range(struct mm_struct *mm,
584 unsigned long addr, unsigned long end)
585 {
586 unsigned long nr_pages = 0;
587 struct vm_area_struct *vma;
588
589 /* Find first overlaping mapping */
590 vma = find_vma_intersection(mm, addr, end);
591 if (!vma)
592 return 0;
593
594 nr_pages = (min(end, vma->vm_end) -
595 max(addr, vma->vm_start)) >> PAGE_SHIFT;
596
597 /* Iterate over the rest of the overlaps */
598 for (vma = vma->vm_next; vma; vma = vma->vm_next) {
599 unsigned long overlap_len;
600
601 if (vma->vm_start > end)
602 break;
603
604 overlap_len = min(end, vma->vm_end) - vma->vm_start;
605 nr_pages += overlap_len >> PAGE_SHIFT;
606 }
607
608 return nr_pages;
609 }
610
611 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
612 struct rb_node **rb_link, struct rb_node *rb_parent)
613 {
614 /* Update tracking information for the gap following the new vma. */
615 if (vma->vm_next)
616 vma_gap_update(vma->vm_next);
617 else
618 mm->highest_vm_end = vma->vm_end;
619
620 /*
621 * vma->vm_prev wasn't known when we followed the rbtree to find the
622 * correct insertion point for that vma. As a result, we could not
623 * update the vma vm_rb parents rb_subtree_gap values on the way down.
624 * So, we first insert the vma with a zero rb_subtree_gap value
625 * (to be consistent with what we did on the way down), and then
626 * immediately update the gap to the correct value. Finally we
627 * rebalance the rbtree after all augmented values have been set.
628 */
629 rb_link_node(&vma->vm_rb, rb_parent, rb_link);
630 vma->rb_subtree_gap = 0;
631 vma_gap_update(vma);
632 vma_rb_insert(vma, &mm->mm_rb);
633 }
634
635 static void __vma_link_file(struct vm_area_struct *vma)
636 {
637 struct file *file;
638
639 file = vma->vm_file;
640 if (file) {
641 struct address_space *mapping = file->f_mapping;
642
643 if (vma->vm_flags & VM_DENYWRITE)
644 atomic_dec(&file_inode(file)->i_writecount);
645 if (vma->vm_flags & VM_SHARED)
646 atomic_inc(&mapping->i_mmap_writable);
647
648 flush_dcache_mmap_lock(mapping);
649 vma_interval_tree_insert(vma, &mapping->i_mmap);
650 flush_dcache_mmap_unlock(mapping);
651 }
652 }
653
654 static void
655 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
656 struct vm_area_struct *prev, struct rb_node **rb_link,
657 struct rb_node *rb_parent)
658 {
659 __vma_link_list(mm, vma, prev, rb_parent);
660 __vma_link_rb(mm, vma, rb_link, rb_parent);
661 }
662
663 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
664 struct vm_area_struct *prev, struct rb_node **rb_link,
665 struct rb_node *rb_parent)
666 {
667 struct address_space *mapping = NULL;
668
669 if (vma->vm_file) {
670 mapping = vma->vm_file->f_mapping;
671 i_mmap_lock_write(mapping);
672 }
673
674 __vma_link(mm, vma, prev, rb_link, rb_parent);
675 __vma_link_file(vma);
676
677 if (mapping)
678 i_mmap_unlock_write(mapping);
679
680 mm->map_count++;
681 validate_mm(mm);
682 }
683
684 /*
685 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
686 * mm's list and rbtree. It has already been inserted into the interval tree.
687 */
688 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
689 {
690 struct vm_area_struct *prev;
691 struct rb_node **rb_link, *rb_parent;
692
693 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
694 &prev, &rb_link, &rb_parent))
695 BUG();
696 __vma_link(mm, vma, prev, rb_link, rb_parent);
697 mm->map_count++;
698 }
699
700 static inline void
701 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
702 struct vm_area_struct *prev)
703 {
704 struct vm_area_struct *next;
705
706 vma_rb_erase(vma, &mm->mm_rb);
707 prev->vm_next = next = vma->vm_next;
708 if (next)
709 next->vm_prev = prev;
710
711 /* Kill the cache */
712 vmacache_invalidate(mm);
713 }
714
715 /*
716 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
717 * is already present in an i_mmap tree without adjusting the tree.
718 * The following helper function should be used when such adjustments
719 * are necessary. The "insert" vma (if any) is to be inserted
720 * before we drop the necessary locks.
721 */
722 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
723 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
724 {
725 struct mm_struct *mm = vma->vm_mm;
726 struct vm_area_struct *next = vma->vm_next;
727 struct vm_area_struct *importer = NULL;
728 struct address_space *mapping = NULL;
729 struct rb_root *root = NULL;
730 struct anon_vma *anon_vma = NULL;
731 struct file *file = vma->vm_file;
732 bool start_changed = false, end_changed = false;
733 long adjust_next = 0;
734 int remove_next = 0;
735
736 if (next && !insert) {
737 struct vm_area_struct *exporter = NULL;
738
739 if (end >= next->vm_end) {
740 /*
741 * vma expands, overlapping all the next, and
742 * perhaps the one after too (mprotect case 6).
743 */
744 again: remove_next = 1 + (end > next->vm_end);
745 end = next->vm_end;
746 exporter = next;
747 importer = vma;
748 } else if (end > next->vm_start) {
749 /*
750 * vma expands, overlapping part of the next:
751 * mprotect case 5 shifting the boundary up.
752 */
753 adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
754 exporter = next;
755 importer = vma;
756 } else if (end < vma->vm_end) {
757 /*
758 * vma shrinks, and !insert tells it's not
759 * split_vma inserting another: so it must be
760 * mprotect case 4 shifting the boundary down.
761 */
762 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
763 exporter = vma;
764 importer = next;
765 }
766
767 /*
768 * Easily overlooked: when mprotect shifts the boundary,
769 * make sure the expanding vma has anon_vma set if the
770 * shrinking vma had, to cover any anon pages imported.
771 */
772 if (exporter && exporter->anon_vma && !importer->anon_vma) {
773 int error;
774
775 importer->anon_vma = exporter->anon_vma;
776 error = anon_vma_clone(importer, exporter);
777 if (error)
778 return error;
779 }
780 }
781
782 if (file) {
783 mapping = file->f_mapping;
784 root = &mapping->i_mmap;
785 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
786
787 if (adjust_next)
788 uprobe_munmap(next, next->vm_start, next->vm_end);
789
790 i_mmap_lock_write(mapping);
791 if (insert) {
792 /*
793 * Put into interval tree now, so instantiated pages
794 * are visible to arm/parisc __flush_dcache_page
795 * throughout; but we cannot insert into address
796 * space until vma start or end is updated.
797 */
798 __vma_link_file(insert);
799 }
800 }
801
802 vma_adjust_trans_huge(vma, start, end, adjust_next);
803
804 anon_vma = vma->anon_vma;
805 if (!anon_vma && adjust_next)
806 anon_vma = next->anon_vma;
807 if (anon_vma) {
808 VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
809 anon_vma != next->anon_vma, next);
810 anon_vma_lock_write(anon_vma);
811 anon_vma_interval_tree_pre_update_vma(vma);
812 if (adjust_next)
813 anon_vma_interval_tree_pre_update_vma(next);
814 }
815
816 if (root) {
817 flush_dcache_mmap_lock(mapping);
818 vma_interval_tree_remove(vma, root);
819 if (adjust_next)
820 vma_interval_tree_remove(next, root);
821 }
822
823 if (start != vma->vm_start) {
824 vma->vm_start = start;
825 start_changed = true;
826 }
827 if (end != vma->vm_end) {
828 vma->vm_end = end;
829 end_changed = true;
830 }
831 vma->vm_pgoff = pgoff;
832 if (adjust_next) {
833 next->vm_start += adjust_next << PAGE_SHIFT;
834 next->vm_pgoff += adjust_next;
835 }
836
837 if (root) {
838 if (adjust_next)
839 vma_interval_tree_insert(next, root);
840 vma_interval_tree_insert(vma, root);
841 flush_dcache_mmap_unlock(mapping);
842 }
843
844 if (remove_next) {
845 /*
846 * vma_merge has merged next into vma, and needs
847 * us to remove next before dropping the locks.
848 */
849 __vma_unlink(mm, next, vma);
850 if (file)
851 __remove_shared_vm_struct(next, file, mapping);
852 } else if (insert) {
853 /*
854 * split_vma has split insert from vma, and needs
855 * us to insert it before dropping the locks
856 * (it may either follow vma or precede it).
857 */
858 __insert_vm_struct(mm, insert);
859 } else {
860 if (start_changed)
861 vma_gap_update(vma);
862 if (end_changed) {
863 if (!next)
864 mm->highest_vm_end = end;
865 else if (!adjust_next)
866 vma_gap_update(next);
867 }
868 }
869
870 if (anon_vma) {
871 anon_vma_interval_tree_post_update_vma(vma);
872 if (adjust_next)
873 anon_vma_interval_tree_post_update_vma(next);
874 anon_vma_unlock_write(anon_vma);
875 }
876 if (mapping)
877 i_mmap_unlock_write(mapping);
878
879 if (root) {
880 uprobe_mmap(vma);
881
882 if (adjust_next)
883 uprobe_mmap(next);
884 }
885
886 if (remove_next) {
887 if (file) {
888 uprobe_munmap(next, next->vm_start, next->vm_end);
889 fput(file);
890 }
891 if (next->anon_vma)
892 anon_vma_merge(vma, next);
893 mm->map_count--;
894 mpol_put(vma_policy(next));
895 kmem_cache_free(vm_area_cachep, next);
896 /*
897 * In mprotect's case 6 (see comments on vma_merge),
898 * we must remove another next too. It would clutter
899 * up the code too much to do both in one go.
900 */
901 next = vma->vm_next;
902 if (remove_next == 2)
903 goto again;
904 else if (next)
905 vma_gap_update(next);
906 else
907 mm->highest_vm_end = end;
908 }
909 if (insert && file)
910 uprobe_mmap(insert);
911
912 validate_mm(mm);
913
914 return 0;
915 }
916
917 /*
918 * If the vma has a ->close operation then the driver probably needs to release
919 * per-vma resources, so we don't attempt to merge those.
920 */
921 static inline int is_mergeable_vma(struct vm_area_struct *vma,
922 struct file *file, unsigned long vm_flags)
923 {
924 /*
925 * VM_SOFTDIRTY should not prevent from VMA merging, if we
926 * match the flags but dirty bit -- the caller should mark
927 * merged VMA as dirty. If dirty bit won't be excluded from
928 * comparison, we increase pressue on the memory system forcing
929 * the kernel to generate new VMAs when old one could be
930 * extended instead.
931 */
932 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
933 return 0;
934 if (vma->vm_file != file)
935 return 0;
936 if (vma->vm_ops && vma->vm_ops->close)
937 return 0;
938 return 1;
939 }
940
941 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
942 struct anon_vma *anon_vma2,
943 struct vm_area_struct *vma)
944 {
945 /*
946 * The list_is_singular() test is to avoid merging VMA cloned from
947 * parents. This can improve scalability caused by anon_vma lock.
948 */
949 if ((!anon_vma1 || !anon_vma2) && (!vma ||
950 list_is_singular(&vma->anon_vma_chain)))
951 return 1;
952 return anon_vma1 == anon_vma2;
953 }
954
955 /*
956 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
957 * in front of (at a lower virtual address and file offset than) the vma.
958 *
959 * We cannot merge two vmas if they have differently assigned (non-NULL)
960 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
961 *
962 * We don't check here for the merged mmap wrapping around the end of pagecache
963 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
964 * wrap, nor mmaps which cover the final page at index -1UL.
965 */
966 static int
967 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
968 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
969 {
970 if (is_mergeable_vma(vma, file, vm_flags) &&
971 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
972 if (vma->vm_pgoff == vm_pgoff)
973 return 1;
974 }
975 return 0;
976 }
977
978 /*
979 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
980 * beyond (at a higher virtual address and file offset than) the vma.
981 *
982 * We cannot merge two vmas if they have differently assigned (non-NULL)
983 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
984 */
985 static int
986 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
987 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
988 {
989 if (is_mergeable_vma(vma, file, vm_flags) &&
990 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
991 pgoff_t vm_pglen;
992 vm_pglen = vma_pages(vma);
993 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
994 return 1;
995 }
996 return 0;
997 }
998
999 /*
1000 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
1001 * whether that can be merged with its predecessor or its successor.
1002 * Or both (it neatly fills a hole).
1003 *
1004 * In most cases - when called for mmap, brk or mremap - [addr,end) is
1005 * certain not to be mapped by the time vma_merge is called; but when
1006 * called for mprotect, it is certain to be already mapped (either at
1007 * an offset within prev, or at the start of next), and the flags of
1008 * this area are about to be changed to vm_flags - and the no-change
1009 * case has already been eliminated.
1010 *
1011 * The following mprotect cases have to be considered, where AAAA is
1012 * the area passed down from mprotect_fixup, never extending beyond one
1013 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
1014 *
1015 * AAAA AAAA AAAA AAAA
1016 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
1017 * cannot merge might become might become might become
1018 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
1019 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
1020 * mremap move: PPPPNNNNNNNN 8
1021 * AAAA
1022 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
1023 * might become case 1 below case 2 below case 3 below
1024 *
1025 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
1026 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
1027 */
1028 struct vm_area_struct *vma_merge(struct mm_struct *mm,
1029 struct vm_area_struct *prev, unsigned long addr,
1030 unsigned long end, unsigned long vm_flags,
1031 struct anon_vma *anon_vma, struct file *file,
1032 pgoff_t pgoff, struct mempolicy *policy)
1033 {
1034 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
1035 struct vm_area_struct *area, *next;
1036 int err;
1037
1038 /*
1039 * We later require that vma->vm_flags == vm_flags,
1040 * so this tests vma->vm_flags & VM_SPECIAL, too.
1041 */
1042 if (vm_flags & VM_SPECIAL)
1043 return NULL;
1044
1045 if (prev)
1046 next = prev->vm_next;
1047 else
1048 next = mm->mmap;
1049 area = next;
1050 if (next && next->vm_end == end) /* cases 6, 7, 8 */
1051 next = next->vm_next;
1052
1053 /*
1054 * Can it merge with the predecessor?
1055 */
1056 if (prev && prev->vm_end == addr &&
1057 mpol_equal(vma_policy(prev), policy) &&
1058 can_vma_merge_after(prev, vm_flags,
1059 anon_vma, file, pgoff)) {
1060 /*
1061 * OK, it can. Can we now merge in the successor as well?
1062 */
1063 if (next && end == next->vm_start &&
1064 mpol_equal(policy, vma_policy(next)) &&
1065 can_vma_merge_before(next, vm_flags,
1066 anon_vma, file, pgoff+pglen) &&
1067 is_mergeable_anon_vma(prev->anon_vma,
1068 next->anon_vma, NULL)) {
1069 /* cases 1, 6 */
1070 err = vma_adjust(prev, prev->vm_start,
1071 next->vm_end, prev->vm_pgoff, NULL);
1072 } else /* cases 2, 5, 7 */
1073 err = vma_adjust(prev, prev->vm_start,
1074 end, prev->vm_pgoff, NULL);
1075 if (err)
1076 return NULL;
1077 khugepaged_enter_vma_merge(prev, vm_flags);
1078 return prev;
1079 }
1080
1081 /*
1082 * Can this new request be merged in front of next?
1083 */
1084 if (next && end == next->vm_start &&
1085 mpol_equal(policy, vma_policy(next)) &&
1086 can_vma_merge_before(next, vm_flags,
1087 anon_vma, file, pgoff+pglen)) {
1088 if (prev && addr < prev->vm_end) /* case 4 */
1089 err = vma_adjust(prev, prev->vm_start,
1090 addr, prev->vm_pgoff, NULL);
1091 else /* cases 3, 8 */
1092 err = vma_adjust(area, addr, next->vm_end,
1093 next->vm_pgoff - pglen, NULL);
1094 if (err)
1095 return NULL;
1096 khugepaged_enter_vma_merge(area, vm_flags);
1097 return area;
1098 }
1099
1100 return NULL;
1101 }
1102
1103 /*
1104 * Rough compatbility check to quickly see if it's even worth looking
1105 * at sharing an anon_vma.
1106 *
1107 * They need to have the same vm_file, and the flags can only differ
1108 * in things that mprotect may change.
1109 *
1110 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1111 * we can merge the two vma's. For example, we refuse to merge a vma if
1112 * there is a vm_ops->close() function, because that indicates that the
1113 * driver is doing some kind of reference counting. But that doesn't
1114 * really matter for the anon_vma sharing case.
1115 */
1116 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1117 {
1118 return a->vm_end == b->vm_start &&
1119 mpol_equal(vma_policy(a), vma_policy(b)) &&
1120 a->vm_file == b->vm_file &&
1121 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1122 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1123 }
1124
1125 /*
1126 * Do some basic sanity checking to see if we can re-use the anon_vma
1127 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1128 * the same as 'old', the other will be the new one that is trying
1129 * to share the anon_vma.
1130 *
1131 * NOTE! This runs with mm_sem held for reading, so it is possible that
1132 * the anon_vma of 'old' is concurrently in the process of being set up
1133 * by another page fault trying to merge _that_. But that's ok: if it
1134 * is being set up, that automatically means that it will be a singleton
1135 * acceptable for merging, so we can do all of this optimistically. But
1136 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1137 *
1138 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1139 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1140 * is to return an anon_vma that is "complex" due to having gone through
1141 * a fork).
1142 *
1143 * We also make sure that the two vma's are compatible (adjacent,
1144 * and with the same memory policies). That's all stable, even with just
1145 * a read lock on the mm_sem.
1146 */
1147 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1148 {
1149 if (anon_vma_compatible(a, b)) {
1150 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1151
1152 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1153 return anon_vma;
1154 }
1155 return NULL;
1156 }
1157
1158 /*
1159 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1160 * neighbouring vmas for a suitable anon_vma, before it goes off
1161 * to allocate a new anon_vma. It checks because a repetitive
1162 * sequence of mprotects and faults may otherwise lead to distinct
1163 * anon_vmas being allocated, preventing vma merge in subsequent
1164 * mprotect.
1165 */
1166 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1167 {
1168 struct anon_vma *anon_vma;
1169 struct vm_area_struct *near;
1170
1171 near = vma->vm_next;
1172 if (!near)
1173 goto try_prev;
1174
1175 anon_vma = reusable_anon_vma(near, vma, near);
1176 if (anon_vma)
1177 return anon_vma;
1178 try_prev:
1179 near = vma->vm_prev;
1180 if (!near)
1181 goto none;
1182
1183 anon_vma = reusable_anon_vma(near, near, vma);
1184 if (anon_vma)
1185 return anon_vma;
1186 none:
1187 /*
1188 * There's no absolute need to look only at touching neighbours:
1189 * we could search further afield for "compatible" anon_vmas.
1190 * But it would probably just be a waste of time searching,
1191 * or lead to too many vmas hanging off the same anon_vma.
1192 * We're trying to allow mprotect remerging later on,
1193 * not trying to minimize memory used for anon_vmas.
1194 */
1195 return NULL;
1196 }
1197
1198 #ifdef CONFIG_PROC_FS
1199 void vm_stat_account(struct mm_struct *mm, unsigned long flags,
1200 struct file *file, long pages)
1201 {
1202 const unsigned long stack_flags
1203 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
1204
1205 mm->total_vm += pages;
1206
1207 if (file) {
1208 mm->shared_vm += pages;
1209 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
1210 mm->exec_vm += pages;
1211 } else if (flags & stack_flags)
1212 mm->stack_vm += pages;
1213 }
1214 #endif /* CONFIG_PROC_FS */
1215
1216 /*
1217 * If a hint addr is less than mmap_min_addr change hint to be as
1218 * low as possible but still greater than mmap_min_addr
1219 */
1220 static inline unsigned long round_hint_to_min(unsigned long hint)
1221 {
1222 hint &= PAGE_MASK;
1223 if (((void *)hint != NULL) &&
1224 (hint < mmap_min_addr))
1225 return PAGE_ALIGN(mmap_min_addr);
1226 return hint;
1227 }
1228
1229 static inline int mlock_future_check(struct mm_struct *mm,
1230 unsigned long flags,
1231 unsigned long len)
1232 {
1233 unsigned long locked, lock_limit;
1234
1235 /* mlock MCL_FUTURE? */
1236 if (flags & VM_LOCKED) {
1237 locked = len >> PAGE_SHIFT;
1238 locked += mm->locked_vm;
1239 lock_limit = rlimit(RLIMIT_MEMLOCK);
1240 lock_limit >>= PAGE_SHIFT;
1241 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1242 return -EAGAIN;
1243 }
1244 return 0;
1245 }
1246
1247 /*
1248 * The caller must hold down_write(&current->mm->mmap_sem).
1249 */
1250
1251 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
1252 unsigned long len, unsigned long prot,
1253 unsigned long flags, unsigned long pgoff,
1254 unsigned long *populate)
1255 {
1256 struct mm_struct *mm = current->mm;
1257 vm_flags_t vm_flags;
1258
1259 *populate = 0;
1260
1261 if (!len)
1262 return -EINVAL;
1263
1264 /*
1265 * Does the application expect PROT_READ to imply PROT_EXEC?
1266 *
1267 * (the exception is when the underlying filesystem is noexec
1268 * mounted, in which case we dont add PROT_EXEC.)
1269 */
1270 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1271 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
1272 prot |= PROT_EXEC;
1273
1274 if (!(flags & MAP_FIXED))
1275 addr = round_hint_to_min(addr);
1276
1277 /* Careful about overflows.. */
1278 len = PAGE_ALIGN(len);
1279 if (!len)
1280 return -ENOMEM;
1281
1282 /* offset overflow? */
1283 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1284 return -EOVERFLOW;
1285
1286 /* Too many mappings? */
1287 if (mm->map_count > sysctl_max_map_count)
1288 return -ENOMEM;
1289
1290 /* Obtain the address to map to. we verify (or select) it and ensure
1291 * that it represents a valid section of the address space.
1292 */
1293 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1294 if (addr & ~PAGE_MASK)
1295 return addr;
1296
1297 /* Do simple checking here so the lower-level routines won't have
1298 * to. we assume access permissions have been handled by the open
1299 * of the memory object, so we don't do any here.
1300 */
1301 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1302 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1303
1304 if (flags & MAP_LOCKED)
1305 if (!can_do_mlock())
1306 return -EPERM;
1307
1308 if (mlock_future_check(mm, vm_flags, len))
1309 return -EAGAIN;
1310
1311 if (file) {
1312 struct inode *inode = file_inode(file);
1313
1314 switch (flags & MAP_TYPE) {
1315 case MAP_SHARED:
1316 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1317 return -EACCES;
1318
1319 /*
1320 * Make sure we don't allow writing to an append-only
1321 * file..
1322 */
1323 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1324 return -EACCES;
1325
1326 /*
1327 * Make sure there are no mandatory locks on the file.
1328 */
1329 if (locks_verify_locked(file))
1330 return -EAGAIN;
1331
1332 vm_flags |= VM_SHARED | VM_MAYSHARE;
1333 if (!(file->f_mode & FMODE_WRITE))
1334 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1335
1336 /* fall through */
1337 case MAP_PRIVATE:
1338 if (!(file->f_mode & FMODE_READ))
1339 return -EACCES;
1340 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1341 if (vm_flags & VM_EXEC)
1342 return -EPERM;
1343 vm_flags &= ~VM_MAYEXEC;
1344 }
1345
1346 if (!file->f_op->mmap)
1347 return -ENODEV;
1348 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1349 return -EINVAL;
1350 break;
1351
1352 default:
1353 return -EINVAL;
1354 }
1355 } else {
1356 switch (flags & MAP_TYPE) {
1357 case MAP_SHARED:
1358 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1359 return -EINVAL;
1360 /*
1361 * Ignore pgoff.
1362 */
1363 pgoff = 0;
1364 vm_flags |= VM_SHARED | VM_MAYSHARE;
1365 break;
1366 case MAP_PRIVATE:
1367 /*
1368 * Set pgoff according to addr for anon_vma.
1369 */
1370 pgoff = addr >> PAGE_SHIFT;
1371 break;
1372 default:
1373 return -EINVAL;
1374 }
1375 }
1376
1377 /*
1378 * Set 'VM_NORESERVE' if we should not account for the
1379 * memory use of this mapping.
1380 */
1381 if (flags & MAP_NORESERVE) {
1382 /* We honor MAP_NORESERVE if allowed to overcommit */
1383 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1384 vm_flags |= VM_NORESERVE;
1385
1386 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1387 if (file && is_file_hugepages(file))
1388 vm_flags |= VM_NORESERVE;
1389 }
1390
1391 addr = mmap_region(file, addr, len, vm_flags, pgoff);
1392 if (!IS_ERR_VALUE(addr) &&
1393 ((vm_flags & VM_LOCKED) ||
1394 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1395 *populate = len;
1396 return addr;
1397 }
1398
1399 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1400 unsigned long, prot, unsigned long, flags,
1401 unsigned long, fd, unsigned long, pgoff)
1402 {
1403 struct file *file = NULL;
1404 unsigned long retval = -EBADF;
1405
1406 if (!(flags & MAP_ANONYMOUS)) {
1407 audit_mmap_fd(fd, flags);
1408 file = fget(fd);
1409 if (!file)
1410 goto out;
1411 if (is_file_hugepages(file))
1412 len = ALIGN(len, huge_page_size(hstate_file(file)));
1413 retval = -EINVAL;
1414 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1415 goto out_fput;
1416 } else if (flags & MAP_HUGETLB) {
1417 struct user_struct *user = NULL;
1418 struct hstate *hs;
1419
1420 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1421 if (!hs)
1422 return -EINVAL;
1423
1424 len = ALIGN(len, huge_page_size(hs));
1425 /*
1426 * VM_NORESERVE is used because the reservations will be
1427 * taken when vm_ops->mmap() is called
1428 * A dummy user value is used because we are not locking
1429 * memory so no accounting is necessary
1430 */
1431 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1432 VM_NORESERVE,
1433 &user, HUGETLB_ANONHUGE_INODE,
1434 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1435 if (IS_ERR(file))
1436 return PTR_ERR(file);
1437 }
1438
1439 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1440
1441 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1442 out_fput:
1443 if (file)
1444 fput(file);
1445 out:
1446 return retval;
1447 }
1448
1449 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1450 struct mmap_arg_struct {
1451 unsigned long addr;
1452 unsigned long len;
1453 unsigned long prot;
1454 unsigned long flags;
1455 unsigned long fd;
1456 unsigned long offset;
1457 };
1458
1459 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1460 {
1461 struct mmap_arg_struct a;
1462
1463 if (copy_from_user(&a, arg, sizeof(a)))
1464 return -EFAULT;
1465 if (a.offset & ~PAGE_MASK)
1466 return -EINVAL;
1467
1468 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1469 a.offset >> PAGE_SHIFT);
1470 }
1471 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1472
1473 /*
1474 * Some shared mappigns will want the pages marked read-only
1475 * to track write events. If so, we'll downgrade vm_page_prot
1476 * to the private version (using protection_map[] without the
1477 * VM_SHARED bit).
1478 */
1479 int vma_wants_writenotify(struct vm_area_struct *vma)
1480 {
1481 vm_flags_t vm_flags = vma->vm_flags;
1482
1483 /* If it was private or non-writable, the write bit is already clear */
1484 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1485 return 0;
1486
1487 /* The backer wishes to know when pages are first written to? */
1488 if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1489 return 1;
1490
1491 /* The open routine did something to the protections that pgprot_modify
1492 * won't preserve? */
1493 if (pgprot_val(vma->vm_page_prot) !=
1494 pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags)))
1495 return 0;
1496
1497 /* Do we need to track softdirty? */
1498 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1499 return 1;
1500
1501 /* Specialty mapping? */
1502 if (vm_flags & VM_PFNMAP)
1503 return 0;
1504
1505 /* Can the mapping track the dirty pages? */
1506 return vma->vm_file && vma->vm_file->f_mapping &&
1507 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1508 }
1509
1510 /*
1511 * We account for memory if it's a private writeable mapping,
1512 * not hugepages and VM_NORESERVE wasn't set.
1513 */
1514 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1515 {
1516 /*
1517 * hugetlb has its own accounting separate from the core VM
1518 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1519 */
1520 if (file && is_file_hugepages(file))
1521 return 0;
1522
1523 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1524 }
1525
1526 unsigned long mmap_region(struct file *file, unsigned long addr,
1527 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1528 {
1529 struct mm_struct *mm = current->mm;
1530 struct vm_area_struct *vma, *prev;
1531 int error;
1532 struct rb_node **rb_link, *rb_parent;
1533 unsigned long charged = 0;
1534
1535 /* Check against address space limit. */
1536 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) {
1537 unsigned long nr_pages;
1538
1539 /*
1540 * MAP_FIXED may remove pages of mappings that intersects with
1541 * requested mapping. Account for the pages it would unmap.
1542 */
1543 if (!(vm_flags & MAP_FIXED))
1544 return -ENOMEM;
1545
1546 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1547
1548 if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages))
1549 return -ENOMEM;
1550 }
1551
1552 /* Clear old maps */
1553 error = -ENOMEM;
1554 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
1555 &rb_parent)) {
1556 if (do_munmap(mm, addr, len))
1557 return -ENOMEM;
1558 }
1559
1560 /*
1561 * Private writable mapping: check memory availability
1562 */
1563 if (accountable_mapping(file, vm_flags)) {
1564 charged = len >> PAGE_SHIFT;
1565 if (security_vm_enough_memory_mm(mm, charged))
1566 return -ENOMEM;
1567 vm_flags |= VM_ACCOUNT;
1568 }
1569
1570 /*
1571 * Can we just expand an old mapping?
1572 */
1573 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff,
1574 NULL);
1575 if (vma)
1576 goto out;
1577
1578 /*
1579 * Determine the object being mapped and call the appropriate
1580 * specific mapper. the address has already been validated, but
1581 * not unmapped, but the maps are removed from the list.
1582 */
1583 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1584 if (!vma) {
1585 error = -ENOMEM;
1586 goto unacct_error;
1587 }
1588
1589 vma->vm_mm = mm;
1590 vma->vm_start = addr;
1591 vma->vm_end = addr + len;
1592 vma->vm_flags = vm_flags;
1593 vma->vm_page_prot = vm_get_page_prot(vm_flags);
1594 vma->vm_pgoff = pgoff;
1595 INIT_LIST_HEAD(&vma->anon_vma_chain);
1596
1597 if (file) {
1598 if (vm_flags & VM_DENYWRITE) {
1599 error = deny_write_access(file);
1600 if (error)
1601 goto free_vma;
1602 }
1603 if (vm_flags & VM_SHARED) {
1604 error = mapping_map_writable(file->f_mapping);
1605 if (error)
1606 goto allow_write_and_free_vma;
1607 }
1608
1609 /* ->mmap() can change vma->vm_file, but must guarantee that
1610 * vma_link() below can deny write-access if VM_DENYWRITE is set
1611 * and map writably if VM_SHARED is set. This usually means the
1612 * new file must not have been exposed to user-space, yet.
1613 */
1614 vma->vm_file = get_file(file);
1615 error = file->f_op->mmap(file, vma);
1616 if (error)
1617 goto unmap_and_free_vma;
1618
1619 /* Can addr have changed??
1620 *
1621 * Answer: Yes, several device drivers can do it in their
1622 * f_op->mmap method. -DaveM
1623 * Bug: If addr is changed, prev, rb_link, rb_parent should
1624 * be updated for vma_link()
1625 */
1626 WARN_ON_ONCE(addr != vma->vm_start);
1627
1628 addr = vma->vm_start;
1629 vm_flags = vma->vm_flags;
1630 } else if (vm_flags & VM_SHARED) {
1631 error = shmem_zero_setup(vma);
1632 if (error)
1633 goto free_vma;
1634 }
1635
1636 vma_link(mm, vma, prev, rb_link, rb_parent);
1637 /* Once vma denies write, undo our temporary denial count */
1638 if (file) {
1639 if (vm_flags & VM_SHARED)
1640 mapping_unmap_writable(file->f_mapping);
1641 if (vm_flags & VM_DENYWRITE)
1642 allow_write_access(file);
1643 }
1644 file = vma->vm_file;
1645 out:
1646 perf_event_mmap(vma);
1647
1648 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1649 if (vm_flags & VM_LOCKED) {
1650 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1651 vma == get_gate_vma(current->mm)))
1652 mm->locked_vm += (len >> PAGE_SHIFT);
1653 else
1654 vma->vm_flags &= ~VM_LOCKED;
1655 }
1656
1657 if (file)
1658 uprobe_mmap(vma);
1659
1660 /*
1661 * New (or expanded) vma always get soft dirty status.
1662 * Otherwise user-space soft-dirty page tracker won't
1663 * be able to distinguish situation when vma area unmapped,
1664 * then new mapped in-place (which must be aimed as
1665 * a completely new data area).
1666 */
1667 vma->vm_flags |= VM_SOFTDIRTY;
1668
1669 vma_set_page_prot(vma);
1670
1671 return addr;
1672
1673 unmap_and_free_vma:
1674 vma->vm_file = NULL;
1675 fput(file);
1676
1677 /* Undo any partial mapping done by a device driver. */
1678 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1679 charged = 0;
1680 if (vm_flags & VM_SHARED)
1681 mapping_unmap_writable(file->f_mapping);
1682 allow_write_and_free_vma:
1683 if (vm_flags & VM_DENYWRITE)
1684 allow_write_access(file);
1685 free_vma:
1686 kmem_cache_free(vm_area_cachep, vma);
1687 unacct_error:
1688 if (charged)
1689 vm_unacct_memory(charged);
1690 return error;
1691 }
1692
1693 unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1694 {
1695 /*
1696 * We implement the search by looking for an rbtree node that
1697 * immediately follows a suitable gap. That is,
1698 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1699 * - gap_end = vma->vm_start >= info->low_limit + length;
1700 * - gap_end - gap_start >= length
1701 */
1702
1703 struct mm_struct *mm = current->mm;
1704 struct vm_area_struct *vma;
1705 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1706
1707 /* Adjust search length to account for worst case alignment overhead */
1708 length = info->length + info->align_mask;
1709 if (length < info->length)
1710 return -ENOMEM;
1711
1712 /* Adjust search limits by the desired length */
1713 if (info->high_limit < length)
1714 return -ENOMEM;
1715 high_limit = info->high_limit - length;
1716
1717 if (info->low_limit > high_limit)
1718 return -ENOMEM;
1719 low_limit = info->low_limit + length;
1720
1721 /* Check if rbtree root looks promising */
1722 if (RB_EMPTY_ROOT(&mm->mm_rb))
1723 goto check_highest;
1724 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1725 if (vma->rb_subtree_gap < length)
1726 goto check_highest;
1727
1728 while (true) {
1729 /* Visit left subtree if it looks promising */
1730 gap_end = vma->vm_start;
1731 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1732 struct vm_area_struct *left =
1733 rb_entry(vma->vm_rb.rb_left,
1734 struct vm_area_struct, vm_rb);
1735 if (left->rb_subtree_gap >= length) {
1736 vma = left;
1737 continue;
1738 }
1739 }
1740
1741 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1742 check_current:
1743 /* Check if current node has a suitable gap */
1744 if (gap_start > high_limit)
1745 return -ENOMEM;
1746 if (gap_end >= low_limit && gap_end - gap_start >= length)
1747 goto found;
1748
1749 /* Visit right subtree if it looks promising */
1750 if (vma->vm_rb.rb_right) {
1751 struct vm_area_struct *right =
1752 rb_entry(vma->vm_rb.rb_right,
1753 struct vm_area_struct, vm_rb);
1754 if (right->rb_subtree_gap >= length) {
1755 vma = right;
1756 continue;
1757 }
1758 }
1759
1760 /* Go back up the rbtree to find next candidate node */
1761 while (true) {
1762 struct rb_node *prev = &vma->vm_rb;
1763 if (!rb_parent(prev))
1764 goto check_highest;
1765 vma = rb_entry(rb_parent(prev),
1766 struct vm_area_struct, vm_rb);
1767 if (prev == vma->vm_rb.rb_left) {
1768 gap_start = vma->vm_prev->vm_end;
1769 gap_end = vma->vm_start;
1770 goto check_current;
1771 }
1772 }
1773 }
1774
1775 check_highest:
1776 /* Check highest gap, which does not precede any rbtree node */
1777 gap_start = mm->highest_vm_end;
1778 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */
1779 if (gap_start > high_limit)
1780 return -ENOMEM;
1781
1782 found:
1783 /* We found a suitable gap. Clip it with the original low_limit. */
1784 if (gap_start < info->low_limit)
1785 gap_start = info->low_limit;
1786
1787 /* Adjust gap address to the desired alignment */
1788 gap_start += (info->align_offset - gap_start) & info->align_mask;
1789
1790 VM_BUG_ON(gap_start + info->length > info->high_limit);
1791 VM_BUG_ON(gap_start + info->length > gap_end);
1792 return gap_start;
1793 }
1794
1795 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1796 {
1797 struct mm_struct *mm = current->mm;
1798 struct vm_area_struct *vma;
1799 unsigned long length, low_limit, high_limit, gap_start, gap_end;
1800
1801 /* Adjust search length to account for worst case alignment overhead */
1802 length = info->length + info->align_mask;
1803 if (length < info->length)
1804 return -ENOMEM;
1805
1806 /*
1807 * Adjust search limits by the desired length.
1808 * See implementation comment at top of unmapped_area().
1809 */
1810 gap_end = info->high_limit;
1811 if (gap_end < length)
1812 return -ENOMEM;
1813 high_limit = gap_end - length;
1814
1815 if (info->low_limit > high_limit)
1816 return -ENOMEM;
1817 low_limit = info->low_limit + length;
1818
1819 /* Check highest gap, which does not precede any rbtree node */
1820 gap_start = mm->highest_vm_end;
1821 if (gap_start <= high_limit)
1822 goto found_highest;
1823
1824 /* Check if rbtree root looks promising */
1825 if (RB_EMPTY_ROOT(&mm->mm_rb))
1826 return -ENOMEM;
1827 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1828 if (vma->rb_subtree_gap < length)
1829 return -ENOMEM;
1830
1831 while (true) {
1832 /* Visit right subtree if it looks promising */
1833 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1834 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1835 struct vm_area_struct *right =
1836 rb_entry(vma->vm_rb.rb_right,
1837 struct vm_area_struct, vm_rb);
1838 if (right->rb_subtree_gap >= length) {
1839 vma = right;
1840 continue;
1841 }
1842 }
1843
1844 check_current:
1845 /* Check if current node has a suitable gap */
1846 gap_end = vma->vm_start;
1847 if (gap_end < low_limit)
1848 return -ENOMEM;
1849 if (gap_start <= high_limit && gap_end - gap_start >= length)
1850 goto found;
1851
1852 /* Visit left subtree if it looks promising */
1853 if (vma->vm_rb.rb_left) {
1854 struct vm_area_struct *left =
1855 rb_entry(vma->vm_rb.rb_left,
1856 struct vm_area_struct, vm_rb);
1857 if (left->rb_subtree_gap >= length) {
1858 vma = left;
1859 continue;
1860 }
1861 }
1862
1863 /* Go back up the rbtree to find next candidate node */
1864 while (true) {
1865 struct rb_node *prev = &vma->vm_rb;
1866 if (!rb_parent(prev))
1867 return -ENOMEM;
1868 vma = rb_entry(rb_parent(prev),
1869 struct vm_area_struct, vm_rb);
1870 if (prev == vma->vm_rb.rb_right) {
1871 gap_start = vma->vm_prev ?
1872 vma->vm_prev->vm_end : 0;
1873 goto check_current;
1874 }
1875 }
1876 }
1877
1878 found:
1879 /* We found a suitable gap. Clip it with the original high_limit. */
1880 if (gap_end > info->high_limit)
1881 gap_end = info->high_limit;
1882
1883 found_highest:
1884 /* Compute highest gap address at the desired alignment */
1885 gap_end -= info->length;
1886 gap_end -= (gap_end - info->align_offset) & info->align_mask;
1887
1888 VM_BUG_ON(gap_end < info->low_limit);
1889 VM_BUG_ON(gap_end < gap_start);
1890 return gap_end;
1891 }
1892
1893 /* Get an address range which is currently unmapped.
1894 * For shmat() with addr=0.
1895 *
1896 * Ugly calling convention alert:
1897 * Return value with the low bits set means error value,
1898 * ie
1899 * if (ret & ~PAGE_MASK)
1900 * error = ret;
1901 *
1902 * This function "knows" that -ENOMEM has the bits set.
1903 */
1904 #ifndef HAVE_ARCH_UNMAPPED_AREA
1905 unsigned long
1906 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1907 unsigned long len, unsigned long pgoff, unsigned long flags)
1908 {
1909 struct mm_struct *mm = current->mm;
1910 struct vm_area_struct *vma;
1911 struct vm_unmapped_area_info info;
1912
1913 if (len > TASK_SIZE - mmap_min_addr)
1914 return -ENOMEM;
1915
1916 if (flags & MAP_FIXED)
1917 return addr;
1918
1919 if (addr) {
1920 addr = PAGE_ALIGN(addr);
1921 vma = find_vma(mm, addr);
1922 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1923 (!vma || addr + len <= vma->vm_start))
1924 return addr;
1925 }
1926
1927 info.flags = 0;
1928 info.length = len;
1929 info.low_limit = mm->mmap_base;
1930 info.high_limit = TASK_SIZE;
1931 info.align_mask = 0;
1932 return vm_unmapped_area(&info);
1933 }
1934 #endif
1935
1936 /*
1937 * This mmap-allocator allocates new areas top-down from below the
1938 * stack's low limit (the base):
1939 */
1940 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1941 unsigned long
1942 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1943 const unsigned long len, const unsigned long pgoff,
1944 const unsigned long flags)
1945 {
1946 struct vm_area_struct *vma;
1947 struct mm_struct *mm = current->mm;
1948 unsigned long addr = addr0;
1949 struct vm_unmapped_area_info info;
1950
1951 /* requested length too big for entire address space */
1952 if (len > TASK_SIZE - mmap_min_addr)
1953 return -ENOMEM;
1954
1955 if (flags & MAP_FIXED)
1956 return addr;
1957
1958 /* requesting a specific address */
1959 if (addr) {
1960 addr = PAGE_ALIGN(addr);
1961 vma = find_vma(mm, addr);
1962 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1963 (!vma || addr + len <= vma->vm_start))
1964 return addr;
1965 }
1966
1967 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1968 info.length = len;
1969 info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1970 info.high_limit = mm->mmap_base;
1971 info.align_mask = 0;
1972 addr = vm_unmapped_area(&info);
1973
1974 /*
1975 * A failed mmap() very likely causes application failure,
1976 * so fall back to the bottom-up function here. This scenario
1977 * can happen with large stack limits and large mmap()
1978 * allocations.
1979 */
1980 if (addr & ~PAGE_MASK) {
1981 VM_BUG_ON(addr != -ENOMEM);
1982 info.flags = 0;
1983 info.low_limit = TASK_UNMAPPED_BASE;
1984 info.high_limit = TASK_SIZE;
1985 addr = vm_unmapped_area(&info);
1986 }
1987
1988 return addr;
1989 }
1990 #endif
1991
1992 unsigned long
1993 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1994 unsigned long pgoff, unsigned long flags)
1995 {
1996 unsigned long (*get_area)(struct file *, unsigned long,
1997 unsigned long, unsigned long, unsigned long);
1998
1999 unsigned long error = arch_mmap_check(addr, len, flags);
2000 if (error)
2001 return error;
2002
2003 /* Careful about overflows.. */
2004 if (len > TASK_SIZE)
2005 return -ENOMEM;
2006
2007 get_area = current->mm->get_unmapped_area;
2008 if (file && file->f_op->get_unmapped_area)
2009 get_area = file->f_op->get_unmapped_area;
2010 addr = get_area(file, addr, len, pgoff, flags);
2011 if (IS_ERR_VALUE(addr))
2012 return addr;
2013
2014 if (addr > TASK_SIZE - len)
2015 return -ENOMEM;
2016 if (addr & ~PAGE_MASK)
2017 return -EINVAL;
2018
2019 addr = arch_rebalance_pgtables(addr, len);
2020 error = security_mmap_addr(addr);
2021 return error ? error : addr;
2022 }
2023
2024 EXPORT_SYMBOL(get_unmapped_area);
2025
2026 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
2027 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
2028 {
2029 struct rb_node *rb_node;
2030 struct vm_area_struct *vma;
2031
2032 /* Check the cache first. */
2033 vma = vmacache_find(mm, addr);
2034 if (likely(vma))
2035 return vma;
2036
2037 rb_node = mm->mm_rb.rb_node;
2038 vma = NULL;
2039
2040 while (rb_node) {
2041 struct vm_area_struct *tmp;
2042
2043 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2044
2045 if (tmp->vm_end > addr) {
2046 vma = tmp;
2047 if (tmp->vm_start <= addr)
2048 break;
2049 rb_node = rb_node->rb_left;
2050 } else
2051 rb_node = rb_node->rb_right;
2052 }
2053
2054 if (vma)
2055 vmacache_update(addr, vma);
2056 return vma;
2057 }
2058
2059 EXPORT_SYMBOL(find_vma);
2060
2061 /*
2062 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
2063 */
2064 struct vm_area_struct *
2065 find_vma_prev(struct mm_struct *mm, unsigned long addr,
2066 struct vm_area_struct **pprev)
2067 {
2068 struct vm_area_struct *vma;
2069
2070 vma = find_vma(mm, addr);
2071 if (vma) {
2072 *pprev = vma->vm_prev;
2073 } else {
2074 struct rb_node *rb_node = mm->mm_rb.rb_node;
2075 *pprev = NULL;
2076 while (rb_node) {
2077 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
2078 rb_node = rb_node->rb_right;
2079 }
2080 }
2081 return vma;
2082 }
2083
2084 /*
2085 * Verify that the stack growth is acceptable and
2086 * update accounting. This is shared with both the
2087 * grow-up and grow-down cases.
2088 */
2089 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
2090 {
2091 struct mm_struct *mm = vma->vm_mm;
2092 struct rlimit *rlim = current->signal->rlim;
2093 unsigned long new_start, actual_size;
2094
2095 /* address space limit tests */
2096 if (!may_expand_vm(mm, grow))
2097 return -ENOMEM;
2098
2099 /* Stack limit test */
2100 actual_size = size;
2101 if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
2102 actual_size -= PAGE_SIZE;
2103 if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
2104 return -ENOMEM;
2105
2106 /* mlock limit tests */
2107 if (vma->vm_flags & VM_LOCKED) {
2108 unsigned long locked;
2109 unsigned long limit;
2110 locked = mm->locked_vm + grow;
2111 limit = READ_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
2112 limit >>= PAGE_SHIFT;
2113 if (locked > limit && !capable(CAP_IPC_LOCK))
2114 return -ENOMEM;
2115 }
2116
2117 /* Check to ensure the stack will not grow into a hugetlb-only region */
2118 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2119 vma->vm_end - size;
2120 if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2121 return -EFAULT;
2122
2123 /*
2124 * Overcommit.. This must be the final test, as it will
2125 * update security statistics.
2126 */
2127 if (security_vm_enough_memory_mm(mm, grow))
2128 return -ENOMEM;
2129
2130 /* Ok, everything looks good - let it rip */
2131 if (vma->vm_flags & VM_LOCKED)
2132 mm->locked_vm += grow;
2133 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
2134 return 0;
2135 }
2136
2137 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2138 /*
2139 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2140 * vma is the last one with address > vma->vm_end. Have to extend vma.
2141 */
2142 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2143 {
2144 int error;
2145
2146 if (!(vma->vm_flags & VM_GROWSUP))
2147 return -EFAULT;
2148
2149 /*
2150 * We must make sure the anon_vma is allocated
2151 * so that the anon_vma locking is not a noop.
2152 */
2153 if (unlikely(anon_vma_prepare(vma)))
2154 return -ENOMEM;
2155 vma_lock_anon_vma(vma);
2156
2157 /*
2158 * vma->vm_start/vm_end cannot change under us because the caller
2159 * is required to hold the mmap_sem in read mode. We need the
2160 * anon_vma lock to serialize against concurrent expand_stacks.
2161 * Also guard against wrapping around to address 0.
2162 */
2163 if (address < PAGE_ALIGN(address+4))
2164 address = PAGE_ALIGN(address+4);
2165 else {
2166 vma_unlock_anon_vma(vma);
2167 return -ENOMEM;
2168 }
2169 error = 0;
2170
2171 /* Somebody else might have raced and expanded it already */
2172 if (address > vma->vm_end) {
2173 unsigned long size, grow;
2174
2175 size = address - vma->vm_start;
2176 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2177
2178 error = -ENOMEM;
2179 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2180 error = acct_stack_growth(vma, size, grow);
2181 if (!error) {
2182 /*
2183 * vma_gap_update() doesn't support concurrent
2184 * updates, but we only hold a shared mmap_sem
2185 * lock here, so we need to protect against
2186 * concurrent vma expansions.
2187 * vma_lock_anon_vma() doesn't help here, as
2188 * we don't guarantee that all growable vmas
2189 * in a mm share the same root anon vma.
2190 * So, we reuse mm->page_table_lock to guard
2191 * against concurrent vma expansions.
2192 */
2193 spin_lock(&vma->vm_mm->page_table_lock);
2194 anon_vma_interval_tree_pre_update_vma(vma);
2195 vma->vm_end = address;
2196 anon_vma_interval_tree_post_update_vma(vma);
2197 if (vma->vm_next)
2198 vma_gap_update(vma->vm_next);
2199 else
2200 vma->vm_mm->highest_vm_end = address;
2201 spin_unlock(&vma->vm_mm->page_table_lock);
2202
2203 perf_event_mmap(vma);
2204 }
2205 }
2206 }
2207 vma_unlock_anon_vma(vma);
2208 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2209 validate_mm(vma->vm_mm);
2210 return error;
2211 }
2212 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2213
2214 /*
2215 * vma is the first one with address < vma->vm_start. Have to extend vma.
2216 */
2217 int expand_downwards(struct vm_area_struct *vma,
2218 unsigned long address)
2219 {
2220 int error;
2221
2222 /*
2223 * We must make sure the anon_vma is allocated
2224 * so that the anon_vma locking is not a noop.
2225 */
2226 if (unlikely(anon_vma_prepare(vma)))
2227 return -ENOMEM;
2228
2229 address &= PAGE_MASK;
2230 error = security_mmap_addr(address);
2231 if (error)
2232 return error;
2233
2234 vma_lock_anon_vma(vma);
2235
2236 /*
2237 * vma->vm_start/vm_end cannot change under us because the caller
2238 * is required to hold the mmap_sem in read mode. We need the
2239 * anon_vma lock to serialize against concurrent expand_stacks.
2240 */
2241
2242 /* Somebody else might have raced and expanded it already */
2243 if (address < vma->vm_start) {
2244 unsigned long size, grow;
2245
2246 size = vma->vm_end - address;
2247 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2248
2249 error = -ENOMEM;
2250 if (grow <= vma->vm_pgoff) {
2251 error = acct_stack_growth(vma, size, grow);
2252 if (!error) {
2253 /*
2254 * vma_gap_update() doesn't support concurrent
2255 * updates, but we only hold a shared mmap_sem
2256 * lock here, so we need to protect against
2257 * concurrent vma expansions.
2258 * vma_lock_anon_vma() doesn't help here, as
2259 * we don't guarantee that all growable vmas
2260 * in a mm share the same root anon vma.
2261 * So, we reuse mm->page_table_lock to guard
2262 * against concurrent vma expansions.
2263 */
2264 spin_lock(&vma->vm_mm->page_table_lock);
2265 anon_vma_interval_tree_pre_update_vma(vma);
2266 vma->vm_start = address;
2267 vma->vm_pgoff -= grow;
2268 anon_vma_interval_tree_post_update_vma(vma);
2269 vma_gap_update(vma);
2270 spin_unlock(&vma->vm_mm->page_table_lock);
2271
2272 perf_event_mmap(vma);
2273 }
2274 }
2275 }
2276 vma_unlock_anon_vma(vma);
2277 khugepaged_enter_vma_merge(vma, vma->vm_flags);
2278 validate_mm(vma->vm_mm);
2279 return error;
2280 }
2281
2282 /*
2283 * Note how expand_stack() refuses to expand the stack all the way to
2284 * abut the next virtual mapping, *unless* that mapping itself is also
2285 * a stack mapping. We want to leave room for a guard page, after all
2286 * (the guard page itself is not added here, that is done by the
2287 * actual page faulting logic)
2288 *
2289 * This matches the behavior of the guard page logic (see mm/memory.c:
2290 * check_stack_guard_page()), which only allows the guard page to be
2291 * removed under these circumstances.
2292 */
2293 #ifdef CONFIG_STACK_GROWSUP
2294 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2295 {
2296 struct vm_area_struct *next;
2297
2298 address &= PAGE_MASK;
2299 next = vma->vm_next;
2300 if (next && next->vm_start == address + PAGE_SIZE) {
2301 if (!(next->vm_flags & VM_GROWSUP))
2302 return -ENOMEM;
2303 }
2304 return expand_upwards(vma, address);
2305 }
2306
2307 struct vm_area_struct *
2308 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2309 {
2310 struct vm_area_struct *vma, *prev;
2311
2312 addr &= PAGE_MASK;
2313 vma = find_vma_prev(mm, addr, &prev);
2314 if (vma && (vma->vm_start <= addr))
2315 return vma;
2316 if (!prev || expand_stack(prev, addr))
2317 return NULL;
2318 if (prev->vm_flags & VM_LOCKED)
2319 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2320 return prev;
2321 }
2322 #else
2323 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2324 {
2325 struct vm_area_struct *prev;
2326
2327 address &= PAGE_MASK;
2328 prev = vma->vm_prev;
2329 if (prev && prev->vm_end == address) {
2330 if (!(prev->vm_flags & VM_GROWSDOWN))
2331 return -ENOMEM;
2332 }
2333 return expand_downwards(vma, address);
2334 }
2335
2336 struct vm_area_struct *
2337 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2338 {
2339 struct vm_area_struct *vma;
2340 unsigned long start;
2341
2342 addr &= PAGE_MASK;
2343 vma = find_vma(mm, addr);
2344 if (!vma)
2345 return NULL;
2346 if (vma->vm_start <= addr)
2347 return vma;
2348 if (!(vma->vm_flags & VM_GROWSDOWN))
2349 return NULL;
2350 start = vma->vm_start;
2351 if (expand_stack(vma, addr))
2352 return NULL;
2353 if (vma->vm_flags & VM_LOCKED)
2354 populate_vma_page_range(vma, addr, start, NULL);
2355 return vma;
2356 }
2357 #endif
2358
2359 EXPORT_SYMBOL_GPL(find_extend_vma);
2360
2361 /*
2362 * Ok - we have the memory areas we should free on the vma list,
2363 * so release them, and do the vma updates.
2364 *
2365 * Called with the mm semaphore held.
2366 */
2367 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2368 {
2369 unsigned long nr_accounted = 0;
2370
2371 /* Update high watermark before we lower total_vm */
2372 update_hiwater_vm(mm);
2373 do {
2374 long nrpages = vma_pages(vma);
2375
2376 if (vma->vm_flags & VM_ACCOUNT)
2377 nr_accounted += nrpages;
2378 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
2379 vma = remove_vma(vma);
2380 } while (vma);
2381 vm_unacct_memory(nr_accounted);
2382 validate_mm(mm);
2383 }
2384
2385 /*
2386 * Get rid of page table information in the indicated region.
2387 *
2388 * Called with the mm semaphore held.
2389 */
2390 static void unmap_region(struct mm_struct *mm,
2391 struct vm_area_struct *vma, struct vm_area_struct *prev,
2392 unsigned long start, unsigned long end)
2393 {
2394 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2395 struct mmu_gather tlb;
2396
2397 lru_add_drain();
2398 tlb_gather_mmu(&tlb, mm, start, end);
2399 update_hiwater_rss(mm);
2400 unmap_vmas(&tlb, vma, start, end);
2401 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2402 next ? next->vm_start : USER_PGTABLES_CEILING);
2403 tlb_finish_mmu(&tlb, start, end);
2404 }
2405
2406 /*
2407 * Create a list of vma's touched by the unmap, removing them from the mm's
2408 * vma list as we go..
2409 */
2410 static void
2411 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2412 struct vm_area_struct *prev, unsigned long end)
2413 {
2414 struct vm_area_struct **insertion_point;
2415 struct vm_area_struct *tail_vma = NULL;
2416
2417 insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2418 vma->vm_prev = NULL;
2419 do {
2420 vma_rb_erase(vma, &mm->mm_rb);
2421 mm->map_count--;
2422 tail_vma = vma;
2423 vma = vma->vm_next;
2424 } while (vma && vma->vm_start < end);
2425 *insertion_point = vma;
2426 if (vma) {
2427 vma->vm_prev = prev;
2428 vma_gap_update(vma);
2429 } else
2430 mm->highest_vm_end = prev ? prev->vm_end : 0;
2431 tail_vma->vm_next = NULL;
2432
2433 /* Kill the cache */
2434 vmacache_invalidate(mm);
2435 }
2436
2437 /*
2438 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
2439 * munmap path where it doesn't make sense to fail.
2440 */
2441 static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2442 unsigned long addr, int new_below)
2443 {
2444 struct vm_area_struct *new;
2445 int err = -ENOMEM;
2446
2447 if (is_vm_hugetlb_page(vma) && (addr &
2448 ~(huge_page_mask(hstate_vma(vma)))))
2449 return -EINVAL;
2450
2451 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2452 if (!new)
2453 goto out_err;
2454
2455 /* most fields are the same, copy all, and then fixup */
2456 *new = *vma;
2457
2458 INIT_LIST_HEAD(&new->anon_vma_chain);
2459
2460 if (new_below)
2461 new->vm_end = addr;
2462 else {
2463 new->vm_start = addr;
2464 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2465 }
2466
2467 err = vma_dup_policy(vma, new);
2468 if (err)
2469 goto out_free_vma;
2470
2471 err = anon_vma_clone(new, vma);
2472 if (err)
2473 goto out_free_mpol;
2474
2475 if (new->vm_file)
2476 get_file(new->vm_file);
2477
2478 if (new->vm_ops && new->vm_ops->open)
2479 new->vm_ops->open(new);
2480
2481 if (new_below)
2482 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2483 ((addr - new->vm_start) >> PAGE_SHIFT), new);
2484 else
2485 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2486
2487 /* Success. */
2488 if (!err)
2489 return 0;
2490
2491 /* Clean everything up if vma_adjust failed. */
2492 if (new->vm_ops && new->vm_ops->close)
2493 new->vm_ops->close(new);
2494 if (new->vm_file)
2495 fput(new->vm_file);
2496 unlink_anon_vmas(new);
2497 out_free_mpol:
2498 mpol_put(vma_policy(new));
2499 out_free_vma:
2500 kmem_cache_free(vm_area_cachep, new);
2501 out_err:
2502 return err;
2503 }
2504
2505 /*
2506 * Split a vma into two pieces at address 'addr', a new vma is allocated
2507 * either for the first part or the tail.
2508 */
2509 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2510 unsigned long addr, int new_below)
2511 {
2512 if (mm->map_count >= sysctl_max_map_count)
2513 return -ENOMEM;
2514
2515 return __split_vma(mm, vma, addr, new_below);
2516 }
2517
2518 /* Munmap is split into 2 main parts -- this part which finds
2519 * what needs doing, and the areas themselves, which do the
2520 * work. This now handles partial unmappings.
2521 * Jeremy Fitzhardinge <jeremy@goop.org>
2522 */
2523 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2524 {
2525 unsigned long end;
2526 struct vm_area_struct *vma, *prev, *last;
2527
2528 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2529 return -EINVAL;
2530
2531 len = PAGE_ALIGN(len);
2532 if (len == 0)
2533 return -EINVAL;
2534
2535 /* Find the first overlapping VMA */
2536 vma = find_vma(mm, start);
2537 if (!vma)
2538 return 0;
2539 prev = vma->vm_prev;
2540 /* we have start < vma->vm_end */
2541
2542 /* if it doesn't overlap, we have nothing.. */
2543 end = start + len;
2544 if (vma->vm_start >= end)
2545 return 0;
2546
2547 /*
2548 * If we need to split any vma, do it now to save pain later.
2549 *
2550 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2551 * unmapped vm_area_struct will remain in use: so lower split_vma
2552 * places tmp vma above, and higher split_vma places tmp vma below.
2553 */
2554 if (start > vma->vm_start) {
2555 int error;
2556
2557 /*
2558 * Make sure that map_count on return from munmap() will
2559 * not exceed its limit; but let map_count go just above
2560 * its limit temporarily, to help free resources as expected.
2561 */
2562 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2563 return -ENOMEM;
2564
2565 error = __split_vma(mm, vma, start, 0);
2566 if (error)
2567 return error;
2568 prev = vma;
2569 }
2570
2571 /* Does it split the last one? */
2572 last = find_vma(mm, end);
2573 if (last && end > last->vm_start) {
2574 int error = __split_vma(mm, last, end, 1);
2575 if (error)
2576 return error;
2577 }
2578 vma = prev ? prev->vm_next : mm->mmap;
2579
2580 /*
2581 * unlock any mlock()ed ranges before detaching vmas
2582 */
2583 if (mm->locked_vm) {
2584 struct vm_area_struct *tmp = vma;
2585 while (tmp && tmp->vm_start < end) {
2586 if (tmp->vm_flags & VM_LOCKED) {
2587 mm->locked_vm -= vma_pages(tmp);
2588 munlock_vma_pages_all(tmp);
2589 }
2590 tmp = tmp->vm_next;
2591 }
2592 }
2593
2594 /*
2595 * Remove the vma's, and unmap the actual pages
2596 */
2597 detach_vmas_to_be_unmapped(mm, vma, prev, end);
2598 unmap_region(mm, vma, prev, start, end);
2599
2600 arch_unmap(mm, vma, start, end);
2601
2602 /* Fix up all other VM information */
2603 remove_vma_list(mm, vma);
2604
2605 return 0;
2606 }
2607
2608 int vm_munmap(unsigned long start, size_t len)
2609 {
2610 int ret;
2611 struct mm_struct *mm = current->mm;
2612
2613 down_write(&mm->mmap_sem);
2614 ret = do_munmap(mm, start, len);
2615 up_write(&mm->mmap_sem);
2616 return ret;
2617 }
2618 EXPORT_SYMBOL(vm_munmap);
2619
2620 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2621 {
2622 profile_munmap(addr);
2623 return vm_munmap(addr, len);
2624 }
2625
2626
2627 /*
2628 * Emulation of deprecated remap_file_pages() syscall.
2629 */
2630 SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2631 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2632 {
2633
2634 struct mm_struct *mm = current->mm;
2635 struct vm_area_struct *vma;
2636 unsigned long populate = 0;
2637 unsigned long ret = -EINVAL;
2638 struct file *file;
2639
2640 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. "
2641 "See Documentation/vm/remap_file_pages.txt.\n",
2642 current->comm, current->pid);
2643
2644 if (prot)
2645 return ret;
2646 start = start & PAGE_MASK;
2647 size = size & PAGE_MASK;
2648
2649 if (start + size <= start)
2650 return ret;
2651
2652 /* Does pgoff wrap? */
2653 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2654 return ret;
2655
2656 down_write(&mm->mmap_sem);
2657 vma = find_vma(mm, start);
2658
2659 if (!vma || !(vma->vm_flags & VM_SHARED))
2660 goto out;
2661
2662 if (start < vma->vm_start || start + size > vma->vm_end)
2663 goto out;
2664
2665 if (pgoff == linear_page_index(vma, start)) {
2666 ret = 0;
2667 goto out;
2668 }
2669
2670 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
2671 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
2672 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
2673
2674 flags &= MAP_NONBLOCK;
2675 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
2676 if (vma->vm_flags & VM_LOCKED) {
2677 flags |= MAP_LOCKED;
2678 /* drop PG_Mlocked flag for over-mapped range */
2679 munlock_vma_pages_range(vma, start, start + size);
2680 }
2681
2682 file = get_file(vma->vm_file);
2683 ret = do_mmap_pgoff(vma->vm_file, start, size,
2684 prot, flags, pgoff, &populate);
2685 fput(file);
2686 out:
2687 up_write(&mm->mmap_sem);
2688 if (populate)
2689 mm_populate(ret, populate);
2690 if (!IS_ERR_VALUE(ret))
2691 ret = 0;
2692 return ret;
2693 }
2694
2695 static inline void verify_mm_writelocked(struct mm_struct *mm)
2696 {
2697 #ifdef CONFIG_DEBUG_VM
2698 if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2699 WARN_ON(1);
2700 up_read(&mm->mmap_sem);
2701 }
2702 #endif
2703 }
2704
2705 /*
2706 * this is really a simplified "do_mmap". it only handles
2707 * anonymous maps. eventually we may be able to do some
2708 * brk-specific accounting here.
2709 */
2710 static unsigned long do_brk(unsigned long addr, unsigned long len)
2711 {
2712 struct mm_struct *mm = current->mm;
2713 struct vm_area_struct *vma, *prev;
2714 unsigned long flags;
2715 struct rb_node **rb_link, *rb_parent;
2716 pgoff_t pgoff = addr >> PAGE_SHIFT;
2717 int error;
2718
2719 len = PAGE_ALIGN(len);
2720 if (!len)
2721 return addr;
2722
2723 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2724
2725 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2726 if (error & ~PAGE_MASK)
2727 return error;
2728
2729 error = mlock_future_check(mm, mm->def_flags, len);
2730 if (error)
2731 return error;
2732
2733 /*
2734 * mm->mmap_sem is required to protect against another thread
2735 * changing the mappings in case we sleep.
2736 */
2737 verify_mm_writelocked(mm);
2738
2739 /*
2740 * Clear old maps. this also does some error checking for us
2741 */
2742 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
2743 &rb_parent)) {
2744 if (do_munmap(mm, addr, len))
2745 return -ENOMEM;
2746 }
2747
2748 /* Check against address space limits *after* clearing old maps... */
2749 if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2750 return -ENOMEM;
2751
2752 if (mm->map_count > sysctl_max_map_count)
2753 return -ENOMEM;
2754
2755 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2756 return -ENOMEM;
2757
2758 /* Can we just expand an old private anonymous mapping? */
2759 vma = vma_merge(mm, prev, addr, addr + len, flags,
2760 NULL, NULL, pgoff, NULL);
2761 if (vma)
2762 goto out;
2763
2764 /*
2765 * create a vma struct for an anonymous mapping
2766 */
2767 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2768 if (!vma) {
2769 vm_unacct_memory(len >> PAGE_SHIFT);
2770 return -ENOMEM;
2771 }
2772
2773 INIT_LIST_HEAD(&vma->anon_vma_chain);
2774 vma->vm_mm = mm;
2775 vma->vm_start = addr;
2776 vma->vm_end = addr + len;
2777 vma->vm_pgoff = pgoff;
2778 vma->vm_flags = flags;
2779 vma->vm_page_prot = vm_get_page_prot(flags);
2780 vma_link(mm, vma, prev, rb_link, rb_parent);
2781 out:
2782 perf_event_mmap(vma);
2783 mm->total_vm += len >> PAGE_SHIFT;
2784 if (flags & VM_LOCKED)
2785 mm->locked_vm += (len >> PAGE_SHIFT);
2786 vma->vm_flags |= VM_SOFTDIRTY;
2787 return addr;
2788 }
2789
2790 unsigned long vm_brk(unsigned long addr, unsigned long len)
2791 {
2792 struct mm_struct *mm = current->mm;
2793 unsigned long ret;
2794 bool populate;
2795
2796 down_write(&mm->mmap_sem);
2797 ret = do_brk(addr, len);
2798 populate = ((mm->def_flags & VM_LOCKED) != 0);
2799 up_write(&mm->mmap_sem);
2800 if (populate)
2801 mm_populate(addr, len);
2802 return ret;
2803 }
2804 EXPORT_SYMBOL(vm_brk);
2805
2806 /* Release all mmaps. */
2807 void exit_mmap(struct mm_struct *mm)
2808 {
2809 struct mmu_gather tlb;
2810 struct vm_area_struct *vma;
2811 unsigned long nr_accounted = 0;
2812
2813 /* mm's last user has gone, and its about to be pulled down */
2814 mmu_notifier_release(mm);
2815
2816 if (mm->locked_vm) {
2817 vma = mm->mmap;
2818 while (vma) {
2819 if (vma->vm_flags & VM_LOCKED)
2820 munlock_vma_pages_all(vma);
2821 vma = vma->vm_next;
2822 }
2823 }
2824
2825 arch_exit_mmap(mm);
2826
2827 vma = mm->mmap;
2828 if (!vma) /* Can happen if dup_mmap() received an OOM */
2829 return;
2830
2831 lru_add_drain();
2832 flush_cache_mm(mm);
2833 tlb_gather_mmu(&tlb, mm, 0, -1);
2834 /* update_hiwater_rss(mm) here? but nobody should be looking */
2835 /* Use -1 here to ensure all VMAs in the mm are unmapped */
2836 unmap_vmas(&tlb, vma, 0, -1);
2837
2838 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2839 tlb_finish_mmu(&tlb, 0, -1);
2840
2841 /*
2842 * Walk the list again, actually closing and freeing it,
2843 * with preemption enabled, without holding any MM locks.
2844 */
2845 while (vma) {
2846 if (vma->vm_flags & VM_ACCOUNT)
2847 nr_accounted += vma_pages(vma);
2848 vma = remove_vma(vma);
2849 }
2850 vm_unacct_memory(nr_accounted);
2851 }
2852
2853 /* Insert vm structure into process list sorted by address
2854 * and into the inode's i_mmap tree. If vm_file is non-NULL
2855 * then i_mmap_rwsem is taken here.
2856 */
2857 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2858 {
2859 struct vm_area_struct *prev;
2860 struct rb_node **rb_link, *rb_parent;
2861
2862 /*
2863 * The vm_pgoff of a purely anonymous vma should be irrelevant
2864 * until its first write fault, when page's anon_vma and index
2865 * are set. But now set the vm_pgoff it will almost certainly
2866 * end up with (unless mremap moves it elsewhere before that
2867 * first wfault), so /proc/pid/maps tells a consistent story.
2868 *
2869 * By setting it to reflect the virtual start address of the
2870 * vma, merges and splits can happen in a seamless way, just
2871 * using the existing file pgoff checks and manipulations.
2872 * Similarly in do_mmap_pgoff and in do_brk.
2873 */
2874 if (!vma->vm_file) {
2875 BUG_ON(vma->anon_vma);
2876 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2877 }
2878 if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2879 &prev, &rb_link, &rb_parent))
2880 return -ENOMEM;
2881 if ((vma->vm_flags & VM_ACCOUNT) &&
2882 security_vm_enough_memory_mm(mm, vma_pages(vma)))
2883 return -ENOMEM;
2884
2885 vma_link(mm, vma, prev, rb_link, rb_parent);
2886 return 0;
2887 }
2888
2889 /*
2890 * Copy the vma structure to a new location in the same mm,
2891 * prior to moving page table entries, to effect an mremap move.
2892 */
2893 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2894 unsigned long addr, unsigned long len, pgoff_t pgoff,
2895 bool *need_rmap_locks)
2896 {
2897 struct vm_area_struct *vma = *vmap;
2898 unsigned long vma_start = vma->vm_start;
2899 struct mm_struct *mm = vma->vm_mm;
2900 struct vm_area_struct *new_vma, *prev;
2901 struct rb_node **rb_link, *rb_parent;
2902 bool faulted_in_anon_vma = true;
2903
2904 /*
2905 * If anonymous vma has not yet been faulted, update new pgoff
2906 * to match new location, to increase its chance of merging.
2907 */
2908 if (unlikely(!vma->vm_file && !vma->anon_vma)) {
2909 pgoff = addr >> PAGE_SHIFT;
2910 faulted_in_anon_vma = false;
2911 }
2912
2913 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
2914 return NULL; /* should never get here */
2915 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2916 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2917 if (new_vma) {
2918 /*
2919 * Source vma may have been merged into new_vma
2920 */
2921 if (unlikely(vma_start >= new_vma->vm_start &&
2922 vma_start < new_vma->vm_end)) {
2923 /*
2924 * The only way we can get a vma_merge with
2925 * self during an mremap is if the vma hasn't
2926 * been faulted in yet and we were allowed to
2927 * reset the dst vma->vm_pgoff to the
2928 * destination address of the mremap to allow
2929 * the merge to happen. mremap must change the
2930 * vm_pgoff linearity between src and dst vmas
2931 * (in turn preventing a vma_merge) to be
2932 * safe. It is only safe to keep the vm_pgoff
2933 * linear if there are no pages mapped yet.
2934 */
2935 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
2936 *vmap = vma = new_vma;
2937 }
2938 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
2939 } else {
2940 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2941 if (new_vma) {
2942 *new_vma = *vma;
2943 new_vma->vm_start = addr;
2944 new_vma->vm_end = addr + len;
2945 new_vma->vm_pgoff = pgoff;
2946 if (vma_dup_policy(vma, new_vma))
2947 goto out_free_vma;
2948 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2949 if (anon_vma_clone(new_vma, vma))
2950 goto out_free_mempol;
2951 if (new_vma->vm_file)
2952 get_file(new_vma->vm_file);
2953 if (new_vma->vm_ops && new_vma->vm_ops->open)
2954 new_vma->vm_ops->open(new_vma);
2955 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2956 *need_rmap_locks = false;
2957 }
2958 }
2959 return new_vma;
2960
2961 out_free_mempol:
2962 mpol_put(vma_policy(new_vma));
2963 out_free_vma:
2964 kmem_cache_free(vm_area_cachep, new_vma);
2965 return NULL;
2966 }
2967
2968 /*
2969 * Return true if the calling process may expand its vm space by the passed
2970 * number of pages
2971 */
2972 int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2973 {
2974 unsigned long cur = mm->total_vm; /* pages */
2975 unsigned long lim;
2976
2977 lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2978
2979 if (cur + npages > lim)
2980 return 0;
2981 return 1;
2982 }
2983
2984 static int special_mapping_fault(struct vm_area_struct *vma,
2985 struct vm_fault *vmf);
2986
2987 /*
2988 * Having a close hook prevents vma merging regardless of flags.
2989 */
2990 static void special_mapping_close(struct vm_area_struct *vma)
2991 {
2992 }
2993
2994 static const char *special_mapping_name(struct vm_area_struct *vma)
2995 {
2996 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
2997 }
2998
2999 static const struct vm_operations_struct special_mapping_vmops = {
3000 .close = special_mapping_close,
3001 .fault = special_mapping_fault,
3002 .name = special_mapping_name,
3003 };
3004
3005 static const struct vm_operations_struct legacy_special_mapping_vmops = {
3006 .close = special_mapping_close,
3007 .fault = special_mapping_fault,
3008 };
3009
3010 static int special_mapping_fault(struct vm_area_struct *vma,
3011 struct vm_fault *vmf)
3012 {
3013 pgoff_t pgoff;
3014 struct page **pages;
3015
3016 /*
3017 * special mappings have no vm_file, and in that case, the mm
3018 * uses vm_pgoff internally. So we have to subtract it from here.
3019 * We are allowed to do this because we are the mm; do not copy
3020 * this code into drivers!
3021 */
3022 pgoff = vmf->pgoff - vma->vm_pgoff;
3023
3024 if (vma->vm_ops == &legacy_special_mapping_vmops)
3025 pages = vma->vm_private_data;
3026 else
3027 pages = ((struct vm_special_mapping *)vma->vm_private_data)->
3028 pages;
3029
3030 for (; pgoff && *pages; ++pages)
3031 pgoff--;
3032
3033 if (*pages) {
3034 struct page *page = *pages;
3035 get_page(page);
3036 vmf->page = page;
3037 return 0;
3038 }
3039
3040 return VM_FAULT_SIGBUS;
3041 }
3042
3043 static struct vm_area_struct *__install_special_mapping(
3044 struct mm_struct *mm,
3045 unsigned long addr, unsigned long len,
3046 unsigned long vm_flags, const struct vm_operations_struct *ops,
3047 void *priv)
3048 {
3049 int ret;
3050 struct vm_area_struct *vma;
3051
3052 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
3053 if (unlikely(vma == NULL))
3054 return ERR_PTR(-ENOMEM);
3055
3056 INIT_LIST_HEAD(&vma->anon_vma_chain);
3057 vma->vm_mm = mm;
3058 vma->vm_start = addr;
3059 vma->vm_end = addr + len;
3060
3061 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3062 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3063
3064 vma->vm_ops = ops;
3065 vma->vm_private_data = priv;
3066
3067 ret = insert_vm_struct(mm, vma);
3068 if (ret)
3069 goto out;
3070
3071 mm->total_vm += len >> PAGE_SHIFT;
3072
3073 perf_event_mmap(vma);
3074
3075 return vma;
3076
3077 out:
3078 kmem_cache_free(vm_area_cachep, vma);
3079 return ERR_PTR(ret);
3080 }
3081
3082 /*
3083 * Called with mm->mmap_sem held for writing.
3084 * Insert a new vma covering the given region, with the given flags.
3085 * Its pages are supplied by the given array of struct page *.
3086 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3087 * The region past the last page supplied will always produce SIGBUS.
3088 * The array pointer and the pages it points to are assumed to stay alive
3089 * for as long as this mapping might exist.
3090 */
3091 struct vm_area_struct *_install_special_mapping(
3092 struct mm_struct *mm,
3093 unsigned long addr, unsigned long len,
3094 unsigned long vm_flags, const struct vm_special_mapping *spec)
3095 {
3096 return __install_special_mapping(mm, addr, len, vm_flags,
3097 &special_mapping_vmops, (void *)spec);
3098 }
3099
3100 int install_special_mapping(struct mm_struct *mm,
3101 unsigned long addr, unsigned long len,
3102 unsigned long vm_flags, struct page **pages)
3103 {
3104 struct vm_area_struct *vma = __install_special_mapping(
3105 mm, addr, len, vm_flags, &legacy_special_mapping_vmops,
3106 (void *)pages);
3107
3108 return PTR_ERR_OR_ZERO(vma);
3109 }
3110
3111 static DEFINE_MUTEX(mm_all_locks_mutex);
3112
3113 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3114 {
3115 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3116 /*
3117 * The LSB of head.next can't change from under us
3118 * because we hold the mm_all_locks_mutex.
3119 */
3120 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3121 /*
3122 * We can safely modify head.next after taking the
3123 * anon_vma->root->rwsem. If some other vma in this mm shares
3124 * the same anon_vma we won't take it again.
3125 *
3126 * No need of atomic instructions here, head.next
3127 * can't change from under us thanks to the
3128 * anon_vma->root->rwsem.
3129 */
3130 if (__test_and_set_bit(0, (unsigned long *)
3131 &anon_vma->root->rb_root.rb_node))
3132 BUG();
3133 }
3134 }
3135
3136 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3137 {
3138 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3139 /*
3140 * AS_MM_ALL_LOCKS can't change from under us because
3141 * we hold the mm_all_locks_mutex.
3142 *
3143 * Operations on ->flags have to be atomic because
3144 * even if AS_MM_ALL_LOCKS is stable thanks to the
3145 * mm_all_locks_mutex, there may be other cpus
3146 * changing other bitflags in parallel to us.
3147 */
3148 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3149 BUG();
3150 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
3151 }
3152 }
3153
3154 /*
3155 * This operation locks against the VM for all pte/vma/mm related
3156 * operations that could ever happen on a certain mm. This includes
3157 * vmtruncate, try_to_unmap, and all page faults.
3158 *
3159 * The caller must take the mmap_sem in write mode before calling
3160 * mm_take_all_locks(). The caller isn't allowed to release the
3161 * mmap_sem until mm_drop_all_locks() returns.
3162 *
3163 * mmap_sem in write mode is required in order to block all operations
3164 * that could modify pagetables and free pages without need of
3165 * altering the vma layout. It's also needed in write mode to avoid new
3166 * anon_vmas to be associated with existing vmas.
3167 *
3168 * A single task can't take more than one mm_take_all_locks() in a row
3169 * or it would deadlock.
3170 *
3171 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3172 * mapping->flags avoid to take the same lock twice, if more than one
3173 * vma in this mm is backed by the same anon_vma or address_space.
3174 *
3175 * We can take all the locks in random order because the VM code
3176 * taking i_mmap_rwsem or anon_vma->rwsem outside the mmap_sem never
3177 * takes more than one of them in a row. Secondly we're protected
3178 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
3179 *
3180 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3181 * that may have to take thousand of locks.
3182 *
3183 * mm_take_all_locks() can fail if it's interrupted by signals.
3184 */
3185 int mm_take_all_locks(struct mm_struct *mm)
3186 {
3187 struct vm_area_struct *vma;
3188 struct anon_vma_chain *avc;
3189
3190 BUG_ON(down_read_trylock(&mm->mmap_sem));
3191
3192 mutex_lock(&mm_all_locks_mutex);
3193
3194 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3195 if (signal_pending(current))
3196 goto out_unlock;
3197 if (vma->vm_file && vma->vm_file->f_mapping)
3198 vm_lock_mapping(mm, vma->vm_file->f_mapping);
3199 }
3200
3201 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3202 if (signal_pending(current))
3203 goto out_unlock;
3204 if (vma->anon_vma)
3205 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3206 vm_lock_anon_vma(mm, avc->anon_vma);
3207 }
3208
3209 return 0;
3210
3211 out_unlock:
3212 mm_drop_all_locks(mm);
3213 return -EINTR;
3214 }
3215
3216 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3217 {
3218 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3219 /*
3220 * The LSB of head.next can't change to 0 from under
3221 * us because we hold the mm_all_locks_mutex.
3222 *
3223 * We must however clear the bitflag before unlocking
3224 * the vma so the users using the anon_vma->rb_root will
3225 * never see our bitflag.
3226 *
3227 * No need of atomic instructions here, head.next
3228 * can't change from under us until we release the
3229 * anon_vma->root->rwsem.
3230 */
3231 if (!__test_and_clear_bit(0, (unsigned long *)
3232 &anon_vma->root->rb_root.rb_node))
3233 BUG();
3234 anon_vma_unlock_write(anon_vma);
3235 }
3236 }
3237
3238 static void vm_unlock_mapping(struct address_space *mapping)
3239 {
3240 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3241 /*
3242 * AS_MM_ALL_LOCKS can't change to 0 from under us
3243 * because we hold the mm_all_locks_mutex.
3244 */
3245 i_mmap_unlock_write(mapping);
3246 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3247 &mapping->flags))
3248 BUG();
3249 }
3250 }
3251
3252 /*
3253 * The mmap_sem cannot be released by the caller until
3254 * mm_drop_all_locks() returns.
3255 */
3256 void mm_drop_all_locks(struct mm_struct *mm)
3257 {
3258 struct vm_area_struct *vma;
3259 struct anon_vma_chain *avc;
3260
3261 BUG_ON(down_read_trylock(&mm->mmap_sem));
3262 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3263
3264 for (vma = mm->mmap; vma; vma = vma->vm_next) {
3265 if (vma->anon_vma)
3266 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3267 vm_unlock_anon_vma(avc->anon_vma);
3268 if (vma->vm_file && vma->vm_file->f_mapping)
3269 vm_unlock_mapping(vma->vm_file->f_mapping);
3270 }
3271
3272 mutex_unlock(&mm_all_locks_mutex);
3273 }
3274
3275 /*
3276 * initialise the VMA slab
3277 */
3278 void __init mmap_init(void)
3279 {
3280 int ret;
3281
3282 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3283 VM_BUG_ON(ret);
3284 }
3285
3286 /*
3287 * Initialise sysctl_user_reserve_kbytes.
3288 *
3289 * This is intended to prevent a user from starting a single memory hogging
3290 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3291 * mode.
3292 *
3293 * The default value is min(3% of free memory, 128MB)
3294 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3295 */
3296 static int init_user_reserve(void)
3297 {
3298 unsigned long free_kbytes;
3299
3300 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3301
3302 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3303 return 0;
3304 }
3305 subsys_initcall(init_user_reserve);
3306
3307 /*
3308 * Initialise sysctl_admin_reserve_kbytes.
3309 *
3310 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3311 * to log in and kill a memory hogging process.
3312 *
3313 * Systems with more than 256MB will reserve 8MB, enough to recover
3314 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3315 * only reserve 3% of free pages by default.
3316 */
3317 static int init_admin_reserve(void)
3318 {
3319 unsigned long free_kbytes;
3320
3321 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3322
3323 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3324 return 0;
3325 }
3326 subsys_initcall(init_admin_reserve);
3327
3328 /*
3329 * Reinititalise user and admin reserves if memory is added or removed.
3330 *
3331 * The default user reserve max is 128MB, and the default max for the
3332 * admin reserve is 8MB. These are usually, but not always, enough to
3333 * enable recovery from a memory hogging process using login/sshd, a shell,
3334 * and tools like top. It may make sense to increase or even disable the
3335 * reserve depending on the existence of swap or variations in the recovery
3336 * tools. So, the admin may have changed them.
3337 *
3338 * If memory is added and the reserves have been eliminated or increased above
3339 * the default max, then we'll trust the admin.
3340 *
3341 * If memory is removed and there isn't enough free memory, then we
3342 * need to reset the reserves.
3343 *
3344 * Otherwise keep the reserve set by the admin.
3345 */
3346 static int reserve_mem_notifier(struct notifier_block *nb,
3347 unsigned long action, void *data)
3348 {
3349 unsigned long tmp, free_kbytes;
3350
3351 switch (action) {
3352 case MEM_ONLINE:
3353 /* Default max is 128MB. Leave alone if modified by operator. */
3354 tmp = sysctl_user_reserve_kbytes;
3355 if (0 < tmp && tmp < (1UL << 17))
3356 init_user_reserve();
3357
3358 /* Default max is 8MB. Leave alone if modified by operator. */
3359 tmp = sysctl_admin_reserve_kbytes;
3360 if (0 < tmp && tmp < (1UL << 13))
3361 init_admin_reserve();
3362
3363 break;
3364 case MEM_OFFLINE:
3365 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3366
3367 if (sysctl_user_reserve_kbytes > free_kbytes) {
3368 init_user_reserve();
3369 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3370 sysctl_user_reserve_kbytes);
3371 }
3372
3373 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3374 init_admin_reserve();
3375 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3376 sysctl_admin_reserve_kbytes);
3377 }
3378 break;
3379 default:
3380 break;
3381 }
3382 return NOTIFY_OK;
3383 }
3384
3385 static struct notifier_block reserve_mem_nb = {
3386 .notifier_call = reserve_mem_notifier,
3387 };
3388
3389 static int __meminit init_reserve_notifier(void)
3390 {
3391 if (register_hotmemory_notifier(&reserve_mem_nb))
3392 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3393
3394 return 0;
3395 }
3396 subsys_initcall(init_reserve_notifier);