Version:  2.0.40 2.2.26 2.4.37 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8

Linux/mm/mmap.c

  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/shmem_fs.h>
 29 #include <linux/profile.h>
 30 #include <linux/export.h>
 31 #include <linux/mount.h>
 32 #include <linux/mempolicy.h>
 33 #include <linux/rmap.h>
 34 #include <linux/mmu_notifier.h>
 35 #include <linux/mmdebug.h>
 36 #include <linux/perf_event.h>
 37 #include <linux/audit.h>
 38 #include <linux/khugepaged.h>
 39 #include <linux/uprobes.h>
 40 #include <linux/rbtree_augmented.h>
 41 #include <linux/notifier.h>
 42 #include <linux/memory.h>
 43 #include <linux/printk.h>
 44 #include <linux/userfaultfd_k.h>
 45 #include <linux/moduleparam.h>
 46 #include <linux/pkeys.h>
 47 
 48 #include <asm/uaccess.h>
 49 #include <asm/cacheflush.h>
 50 #include <asm/tlb.h>
 51 #include <asm/mmu_context.h>
 52 
 53 #include "internal.h"
 54 
 55 #ifndef arch_mmap_check
 56 #define arch_mmap_check(addr, len, flags)       (0)
 57 #endif
 58 
 59 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
 60 const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
 61 const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
 62 int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
 63 #endif
 64 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
 65 const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
 66 const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
 67 int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
 68 #endif
 69 
 70 static bool ignore_rlimit_data;
 71 core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
 72 
 73 static void unmap_region(struct mm_struct *mm,
 74                 struct vm_area_struct *vma, struct vm_area_struct *prev,
 75                 unsigned long start, unsigned long end);
 76 
 77 /* description of effects of mapping type and prot in current implementation.
 78  * this is due to the limited x86 page protection hardware.  The expected
 79  * behavior is in parens:
 80  *
 81  * map_type     prot
 82  *              PROT_NONE       PROT_READ       PROT_WRITE      PROT_EXEC
 83  * MAP_SHARED   r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
 84  *              w: (no) no      w: (no) no      w: (yes) yes    w: (no) no
 85  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
 86  *
 87  * MAP_PRIVATE  r: (no) no      r: (yes) yes    r: (no) yes     r: (no) yes
 88  *              w: (no) no      w: (no) no      w: (copy) copy  w: (no) no
 89  *              x: (no) no      x: (no) yes     x: (no) yes     x: (yes) yes
 90  *
 91  */
 92 pgprot_t protection_map[16] = {
 93         __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
 94         __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
 95 };
 96 
 97 pgprot_t vm_get_page_prot(unsigned long vm_flags)
 98 {
 99         return __pgprot(pgprot_val(protection_map[vm_flags &
100                                 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
101                         pgprot_val(arch_vm_get_page_prot(vm_flags)));
102 }
103 EXPORT_SYMBOL(vm_get_page_prot);
104 
105 static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
106 {
107         return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));
108 }
109 
110 /* Update vma->vm_page_prot to reflect vma->vm_flags. */
111 void vma_set_page_prot(struct vm_area_struct *vma)
112 {
113         unsigned long vm_flags = vma->vm_flags;
114 
115         vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags);
116         if (vma_wants_writenotify(vma)) {
117                 vm_flags &= ~VM_SHARED;
118                 vma->vm_page_prot = vm_pgprot_modify(vma->vm_page_prot,
119                                                      vm_flags);
120         }
121 }
122 
123 /*
124  * Requires inode->i_mapping->i_mmap_rwsem
125  */
126 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
127                 struct file *file, struct address_space *mapping)
128 {
129         if (vma->vm_flags & VM_DENYWRITE)
130                 atomic_inc(&file_inode(file)->i_writecount);
131         if (vma->vm_flags & VM_SHARED)
132                 mapping_unmap_writable(mapping);
133 
134         flush_dcache_mmap_lock(mapping);
135         vma_interval_tree_remove(vma, &mapping->i_mmap);
136         flush_dcache_mmap_unlock(mapping);
137 }
138 
139 /*
140  * Unlink a file-based vm structure from its interval tree, to hide
141  * vma from rmap and vmtruncate before freeing its page tables.
142  */
143 void unlink_file_vma(struct vm_area_struct *vma)
144 {
145         struct file *file = vma->vm_file;
146 
147         if (file) {
148                 struct address_space *mapping = file->f_mapping;
149                 i_mmap_lock_write(mapping);
150                 __remove_shared_vm_struct(vma, file, mapping);
151                 i_mmap_unlock_write(mapping);
152         }
153 }
154 
155 /*
156  * Close a vm structure and free it, returning the next.
157  */
158 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
159 {
160         struct vm_area_struct *next = vma->vm_next;
161 
162         might_sleep();
163         if (vma->vm_ops && vma->vm_ops->close)
164                 vma->vm_ops->close(vma);
165         if (vma->vm_file)
166                 fput(vma->vm_file);
167         mpol_put(vma_policy(vma));
168         kmem_cache_free(vm_area_cachep, vma);
169         return next;
170 }
171 
172 static int do_brk(unsigned long addr, unsigned long len);
173 
174 SYSCALL_DEFINE1(brk, unsigned long, brk)
175 {
176         unsigned long retval;
177         unsigned long newbrk, oldbrk;
178         struct mm_struct *mm = current->mm;
179         unsigned long min_brk;
180         bool populate;
181 
182         if (down_write_killable(&mm->mmap_sem))
183                 return -EINTR;
184 
185 #ifdef CONFIG_COMPAT_BRK
186         /*
187          * CONFIG_COMPAT_BRK can still be overridden by setting
188          * randomize_va_space to 2, which will still cause mm->start_brk
189          * to be arbitrarily shifted
190          */
191         if (current->brk_randomized)
192                 min_brk = mm->start_brk;
193         else
194                 min_brk = mm->end_data;
195 #else
196         min_brk = mm->start_brk;
197 #endif
198         if (brk < min_brk)
199                 goto out;
200 
201         /*
202          * Check against rlimit here. If this check is done later after the test
203          * of oldbrk with newbrk then it can escape the test and let the data
204          * segment grow beyond its set limit the in case where the limit is
205          * not page aligned -Ram Gupta
206          */
207         if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk,
208                               mm->end_data, mm->start_data))
209                 goto out;
210 
211         newbrk = PAGE_ALIGN(brk);
212         oldbrk = PAGE_ALIGN(mm->brk);
213         if (oldbrk == newbrk)
214                 goto set_brk;
215 
216         /* Always allow shrinking brk. */
217         if (brk <= mm->brk) {
218                 if (!do_munmap(mm, newbrk, oldbrk-newbrk))
219                         goto set_brk;
220                 goto out;
221         }
222 
223         /* Check against existing mmap mappings. */
224         if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
225                 goto out;
226 
227         /* Ok, looks good - let it rip. */
228         if (do_brk(oldbrk, newbrk-oldbrk) < 0)
229                 goto out;
230 
231 set_brk:
232         mm->brk = brk;
233         populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0;
234         up_write(&mm->mmap_sem);
235         if (populate)
236                 mm_populate(oldbrk, newbrk - oldbrk);
237         return brk;
238 
239 out:
240         retval = mm->brk;
241         up_write(&mm->mmap_sem);
242         return retval;
243 }
244 
245 static long vma_compute_subtree_gap(struct vm_area_struct *vma)
246 {
247         unsigned long max, subtree_gap;
248         max = vma->vm_start;
249         if (vma->vm_prev)
250                 max -= vma->vm_prev->vm_end;
251         if (vma->vm_rb.rb_left) {
252                 subtree_gap = rb_entry(vma->vm_rb.rb_left,
253                                 struct vm_area_struct, vm_rb)->rb_subtree_gap;
254                 if (subtree_gap > max)
255                         max = subtree_gap;
256         }
257         if (vma->vm_rb.rb_right) {
258                 subtree_gap = rb_entry(vma->vm_rb.rb_right,
259                                 struct vm_area_struct, vm_rb)->rb_subtree_gap;
260                 if (subtree_gap > max)
261                         max = subtree_gap;
262         }
263         return max;
264 }
265 
266 #ifdef CONFIG_DEBUG_VM_RB
267 static int browse_rb(struct mm_struct *mm)
268 {
269         struct rb_root *root = &mm->mm_rb;
270         int i = 0, j, bug = 0;
271         struct rb_node *nd, *pn = NULL;
272         unsigned long prev = 0, pend = 0;
273 
274         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
275                 struct vm_area_struct *vma;
276                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
277                 if (vma->vm_start < prev) {
278                         pr_emerg("vm_start %lx < prev %lx\n",
279                                   vma->vm_start, prev);
280                         bug = 1;
281                 }
282                 if (vma->vm_start < pend) {
283                         pr_emerg("vm_start %lx < pend %lx\n",
284                                   vma->vm_start, pend);
285                         bug = 1;
286                 }
287                 if (vma->vm_start > vma->vm_end) {
288                         pr_emerg("vm_start %lx > vm_end %lx\n",
289                                   vma->vm_start, vma->vm_end);
290                         bug = 1;
291                 }
292                 spin_lock(&mm->page_table_lock);
293                 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) {
294                         pr_emerg("free gap %lx, correct %lx\n",
295                                vma->rb_subtree_gap,
296                                vma_compute_subtree_gap(vma));
297                         bug = 1;
298                 }
299                 spin_unlock(&mm->page_table_lock);
300                 i++;
301                 pn = nd;
302                 prev = vma->vm_start;
303                 pend = vma->vm_end;
304         }
305         j = 0;
306         for (nd = pn; nd; nd = rb_prev(nd))
307                 j++;
308         if (i != j) {
309                 pr_emerg("backwards %d, forwards %d\n", j, i);
310                 bug = 1;
311         }
312         return bug ? -1 : i;
313 }
314 
315 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore)
316 {
317         struct rb_node *nd;
318 
319         for (nd = rb_first(root); nd; nd = rb_next(nd)) {
320                 struct vm_area_struct *vma;
321                 vma = rb_entry(nd, struct vm_area_struct, vm_rb);
322                 VM_BUG_ON_VMA(vma != ignore &&
323                         vma->rb_subtree_gap != vma_compute_subtree_gap(vma),
324                         vma);
325         }
326 }
327 
328 static void validate_mm(struct mm_struct *mm)
329 {
330         int bug = 0;
331         int i = 0;
332         unsigned long highest_address = 0;
333         struct vm_area_struct *vma = mm->mmap;
334 
335         while (vma) {
336                 struct anon_vma *anon_vma = vma->anon_vma;
337                 struct anon_vma_chain *avc;
338 
339                 if (anon_vma) {
340                         anon_vma_lock_read(anon_vma);
341                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
342                                 anon_vma_interval_tree_verify(avc);
343                         anon_vma_unlock_read(anon_vma);
344                 }
345 
346                 highest_address = vma->vm_end;
347                 vma = vma->vm_next;
348                 i++;
349         }
350         if (i != mm->map_count) {
351                 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i);
352                 bug = 1;
353         }
354         if (highest_address != mm->highest_vm_end) {
355                 pr_emerg("mm->highest_vm_end %lx, found %lx\n",
356                           mm->highest_vm_end, highest_address);
357                 bug = 1;
358         }
359         i = browse_rb(mm);
360         if (i != mm->map_count) {
361                 if (i != -1)
362                         pr_emerg("map_count %d rb %d\n", mm->map_count, i);
363                 bug = 1;
364         }
365         VM_BUG_ON_MM(bug, mm);
366 }
367 #else
368 #define validate_mm_rb(root, ignore) do { } while (0)
369 #define validate_mm(mm) do { } while (0)
370 #endif
371 
372 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb,
373                      unsigned long, rb_subtree_gap, vma_compute_subtree_gap)
374 
375 /*
376  * Update augmented rbtree rb_subtree_gap values after vma->vm_start or
377  * vma->vm_prev->vm_end values changed, without modifying the vma's position
378  * in the rbtree.
379  */
380 static void vma_gap_update(struct vm_area_struct *vma)
381 {
382         /*
383          * As it turns out, RB_DECLARE_CALLBACKS() already created a callback
384          * function that does exacltly what we want.
385          */
386         vma_gap_callbacks_propagate(&vma->vm_rb, NULL);
387 }
388 
389 static inline void vma_rb_insert(struct vm_area_struct *vma,
390                                  struct rb_root *root)
391 {
392         /* All rb_subtree_gap values must be consistent prior to insertion */
393         validate_mm_rb(root, NULL);
394 
395         rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
396 }
397 
398 static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root)
399 {
400         /*
401          * All rb_subtree_gap values must be consistent prior to erase,
402          * with the possible exception of the vma being erased.
403          */
404         validate_mm_rb(root, vma);
405 
406         /*
407          * Note rb_erase_augmented is a fairly large inline function,
408          * so make sure we instantiate it only once with our desired
409          * augmented rbtree callbacks.
410          */
411         rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks);
412 }
413 
414 /*
415  * vma has some anon_vma assigned, and is already inserted on that
416  * anon_vma's interval trees.
417  *
418  * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
419  * vma must be removed from the anon_vma's interval trees using
420  * anon_vma_interval_tree_pre_update_vma().
421  *
422  * After the update, the vma will be reinserted using
423  * anon_vma_interval_tree_post_update_vma().
424  *
425  * The entire update must be protected by exclusive mmap_sem and by
426  * the root anon_vma's mutex.
427  */
428 static inline void
429 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
430 {
431         struct anon_vma_chain *avc;
432 
433         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
434                 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root);
435 }
436 
437 static inline void
438 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
439 {
440         struct anon_vma_chain *avc;
441 
442         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
443                 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root);
444 }
445 
446 static int find_vma_links(struct mm_struct *mm, unsigned long addr,
447                 unsigned long end, struct vm_area_struct **pprev,
448                 struct rb_node ***rb_link, struct rb_node **rb_parent)
449 {
450         struct rb_node **__rb_link, *__rb_parent, *rb_prev;
451 
452         __rb_link = &mm->mm_rb.rb_node;
453         rb_prev = __rb_parent = NULL;
454 
455         while (*__rb_link) {
456                 struct vm_area_struct *vma_tmp;
457 
458                 __rb_parent = *__rb_link;
459                 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
460 
461                 if (vma_tmp->vm_end > addr) {
462                         /* Fail if an existing vma overlaps the area */
463                         if (vma_tmp->vm_start < end)
464                                 return -ENOMEM;
465                         __rb_link = &__rb_parent->rb_left;
466                 } else {
467                         rb_prev = __rb_parent;
468                         __rb_link = &__rb_parent->rb_right;
469                 }
470         }
471 
472         *pprev = NULL;
473         if (rb_prev)
474                 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
475         *rb_link = __rb_link;
476         *rb_parent = __rb_parent;
477         return 0;
478 }
479 
480 static unsigned long count_vma_pages_range(struct mm_struct *mm,
481                 unsigned long addr, unsigned long end)
482 {
483         unsigned long nr_pages = 0;
484         struct vm_area_struct *vma;
485 
486         /* Find first overlaping mapping */
487         vma = find_vma_intersection(mm, addr, end);
488         if (!vma)
489                 return 0;
490 
491         nr_pages = (min(end, vma->vm_end) -
492                 max(addr, vma->vm_start)) >> PAGE_SHIFT;
493 
494         /* Iterate over the rest of the overlaps */
495         for (vma = vma->vm_next; vma; vma = vma->vm_next) {
496                 unsigned long overlap_len;
497 
498                 if (vma->vm_start > end)
499                         break;
500 
501                 overlap_len = min(end, vma->vm_end) - vma->vm_start;
502                 nr_pages += overlap_len >> PAGE_SHIFT;
503         }
504 
505         return nr_pages;
506 }
507 
508 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
509                 struct rb_node **rb_link, struct rb_node *rb_parent)
510 {
511         /* Update tracking information for the gap following the new vma. */
512         if (vma->vm_next)
513                 vma_gap_update(vma->vm_next);
514         else
515                 mm->highest_vm_end = vma->vm_end;
516 
517         /*
518          * vma->vm_prev wasn't known when we followed the rbtree to find the
519          * correct insertion point for that vma. As a result, we could not
520          * update the vma vm_rb parents rb_subtree_gap values on the way down.
521          * So, we first insert the vma with a zero rb_subtree_gap value
522          * (to be consistent with what we did on the way down), and then
523          * immediately update the gap to the correct value. Finally we
524          * rebalance the rbtree after all augmented values have been set.
525          */
526         rb_link_node(&vma->vm_rb, rb_parent, rb_link);
527         vma->rb_subtree_gap = 0;
528         vma_gap_update(vma);
529         vma_rb_insert(vma, &mm->mm_rb);
530 }
531 
532 static void __vma_link_file(struct vm_area_struct *vma)
533 {
534         struct file *file;
535 
536         file = vma->vm_file;
537         if (file) {
538                 struct address_space *mapping = file->f_mapping;
539 
540                 if (vma->vm_flags & VM_DENYWRITE)
541                         atomic_dec(&file_inode(file)->i_writecount);
542                 if (vma->vm_flags & VM_SHARED)
543                         atomic_inc(&mapping->i_mmap_writable);
544 
545                 flush_dcache_mmap_lock(mapping);
546                 vma_interval_tree_insert(vma, &mapping->i_mmap);
547                 flush_dcache_mmap_unlock(mapping);
548         }
549 }
550 
551 static void
552 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
553         struct vm_area_struct *prev, struct rb_node **rb_link,
554         struct rb_node *rb_parent)
555 {
556         __vma_link_list(mm, vma, prev, rb_parent);
557         __vma_link_rb(mm, vma, rb_link, rb_parent);
558 }
559 
560 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
561                         struct vm_area_struct *prev, struct rb_node **rb_link,
562                         struct rb_node *rb_parent)
563 {
564         struct address_space *mapping = NULL;
565 
566         if (vma->vm_file) {
567                 mapping = vma->vm_file->f_mapping;
568                 i_mmap_lock_write(mapping);
569         }
570 
571         __vma_link(mm, vma, prev, rb_link, rb_parent);
572         __vma_link_file(vma);
573 
574         if (mapping)
575                 i_mmap_unlock_write(mapping);
576 
577         mm->map_count++;
578         validate_mm(mm);
579 }
580 
581 /*
582  * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
583  * mm's list and rbtree.  It has already been inserted into the interval tree.
584  */
585 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
586 {
587         struct vm_area_struct *prev;
588         struct rb_node **rb_link, *rb_parent;
589 
590         if (find_vma_links(mm, vma->vm_start, vma->vm_end,
591                            &prev, &rb_link, &rb_parent))
592                 BUG();
593         __vma_link(mm, vma, prev, rb_link, rb_parent);
594         mm->map_count++;
595 }
596 
597 static inline void
598 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
599                 struct vm_area_struct *prev)
600 {
601         struct vm_area_struct *next;
602 
603         vma_rb_erase(vma, &mm->mm_rb);
604         prev->vm_next = next = vma->vm_next;
605         if (next)
606                 next->vm_prev = prev;
607 
608         /* Kill the cache */
609         vmacache_invalidate(mm);
610 }
611 
612 /*
613  * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
614  * is already present in an i_mmap tree without adjusting the tree.
615  * The following helper function should be used when such adjustments
616  * are necessary.  The "insert" vma (if any) is to be inserted
617  * before we drop the necessary locks.
618  */
619 int vma_adjust(struct vm_area_struct *vma, unsigned long start,
620         unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
621 {
622         struct mm_struct *mm = vma->vm_mm;
623         struct vm_area_struct *next = vma->vm_next;
624         struct address_space *mapping = NULL;
625         struct rb_root *root = NULL;
626         struct anon_vma *anon_vma = NULL;
627         struct file *file = vma->vm_file;
628         bool start_changed = false, end_changed = false;
629         long adjust_next = 0;
630         int remove_next = 0;
631 
632         if (next && !insert) {
633                 struct vm_area_struct *exporter = NULL, *importer = NULL;
634 
635                 if (end >= next->vm_end) {
636                         /*
637                          * vma expands, overlapping all the next, and
638                          * perhaps the one after too (mprotect case 6).
639                          */
640                         remove_next = 1 + (end > next->vm_end);
641                         end = next->vm_end;
642                         exporter = next;
643                         importer = vma;
644 
645                         /*
646                          * If next doesn't have anon_vma, import from vma after
647                          * next, if the vma overlaps with it.
648                          */
649                         if (remove_next == 2 && next && !next->anon_vma)
650                                 exporter = next->vm_next;
651 
652                 } else if (end > next->vm_start) {
653                         /*
654                          * vma expands, overlapping part of the next:
655                          * mprotect case 5 shifting the boundary up.
656                          */
657                         adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
658                         exporter = next;
659                         importer = vma;
660                 } else if (end < vma->vm_end) {
661                         /*
662                          * vma shrinks, and !insert tells it's not
663                          * split_vma inserting another: so it must be
664                          * mprotect case 4 shifting the boundary down.
665                          */
666                         adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT);
667                         exporter = vma;
668                         importer = next;
669                 }
670 
671                 /*
672                  * Easily overlooked: when mprotect shifts the boundary,
673                  * make sure the expanding vma has anon_vma set if the
674                  * shrinking vma had, to cover any anon pages imported.
675                  */
676                 if (exporter && exporter->anon_vma && !importer->anon_vma) {
677                         int error;
678 
679                         importer->anon_vma = exporter->anon_vma;
680                         error = anon_vma_clone(importer, exporter);
681                         if (error)
682                                 return error;
683                 }
684         }
685 again:
686         vma_adjust_trans_huge(vma, start, end, adjust_next);
687 
688         if (file) {
689                 mapping = file->f_mapping;
690                 root = &mapping->i_mmap;
691                 uprobe_munmap(vma, vma->vm_start, vma->vm_end);
692 
693                 if (adjust_next)
694                         uprobe_munmap(next, next->vm_start, next->vm_end);
695 
696                 i_mmap_lock_write(mapping);
697                 if (insert) {
698                         /*
699                          * Put into interval tree now, so instantiated pages
700                          * are visible to arm/parisc __flush_dcache_page
701                          * throughout; but we cannot insert into address
702                          * space until vma start or end is updated.
703                          */
704                         __vma_link_file(insert);
705                 }
706         }
707 
708         anon_vma = vma->anon_vma;
709         if (!anon_vma && adjust_next)
710                 anon_vma = next->anon_vma;
711         if (anon_vma) {
712                 VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
713                           anon_vma != next->anon_vma, next);
714                 anon_vma_lock_write(anon_vma);
715                 anon_vma_interval_tree_pre_update_vma(vma);
716                 if (adjust_next)
717                         anon_vma_interval_tree_pre_update_vma(next);
718         }
719 
720         if (root) {
721                 flush_dcache_mmap_lock(mapping);
722                 vma_interval_tree_remove(vma, root);
723                 if (adjust_next)
724                         vma_interval_tree_remove(next, root);
725         }
726 
727         if (start != vma->vm_start) {
728                 vma->vm_start = start;
729                 start_changed = true;
730         }
731         if (end != vma->vm_end) {
732                 vma->vm_end = end;
733                 end_changed = true;
734         }
735         vma->vm_pgoff = pgoff;
736         if (adjust_next) {
737                 next->vm_start += adjust_next << PAGE_SHIFT;
738                 next->vm_pgoff += adjust_next;
739         }
740 
741         if (root) {
742                 if (adjust_next)
743                         vma_interval_tree_insert(next, root);
744                 vma_interval_tree_insert(vma, root);
745                 flush_dcache_mmap_unlock(mapping);
746         }
747 
748         if (remove_next) {
749                 /*
750                  * vma_merge has merged next into vma, and needs
751                  * us to remove next before dropping the locks.
752                  */
753                 __vma_unlink(mm, next, vma);
754                 if (file)
755                         __remove_shared_vm_struct(next, file, mapping);
756         } else if (insert) {
757                 /*
758                  * split_vma has split insert from vma, and needs
759                  * us to insert it before dropping the locks
760                  * (it may either follow vma or precede it).
761                  */
762                 __insert_vm_struct(mm, insert);
763         } else {
764                 if (start_changed)
765                         vma_gap_update(vma);
766                 if (end_changed) {
767                         if (!next)
768                                 mm->highest_vm_end = end;
769                         else if (!adjust_next)
770                                 vma_gap_update(next);
771                 }
772         }
773 
774         if (anon_vma) {
775                 anon_vma_interval_tree_post_update_vma(vma);
776                 if (adjust_next)
777                         anon_vma_interval_tree_post_update_vma(next);
778                 anon_vma_unlock_write(anon_vma);
779         }
780         if (mapping)
781                 i_mmap_unlock_write(mapping);
782 
783         if (root) {
784                 uprobe_mmap(vma);
785 
786                 if (adjust_next)
787                         uprobe_mmap(next);
788         }
789 
790         if (remove_next) {
791                 if (file) {
792                         uprobe_munmap(next, next->vm_start, next->vm_end);
793                         fput(file);
794                 }
795                 if (next->anon_vma)
796                         anon_vma_merge(vma, next);
797                 mm->map_count--;
798                 mpol_put(vma_policy(next));
799                 kmem_cache_free(vm_area_cachep, next);
800                 /*
801                  * In mprotect's case 6 (see comments on vma_merge),
802                  * we must remove another next too. It would clutter
803                  * up the code too much to do both in one go.
804                  */
805                 next = vma->vm_next;
806                 if (remove_next == 2) {
807                         remove_next = 1;
808                         end = next->vm_end;
809                         goto again;
810                 }
811                 else if (next)
812                         vma_gap_update(next);
813                 else
814                         mm->highest_vm_end = end;
815         }
816         if (insert && file)
817                 uprobe_mmap(insert);
818 
819         validate_mm(mm);
820 
821         return 0;
822 }
823 
824 /*
825  * If the vma has a ->close operation then the driver probably needs to release
826  * per-vma resources, so we don't attempt to merge those.
827  */
828 static inline int is_mergeable_vma(struct vm_area_struct *vma,
829                                 struct file *file, unsigned long vm_flags,
830                                 struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
831 {
832         /*
833          * VM_SOFTDIRTY should not prevent from VMA merging, if we
834          * match the flags but dirty bit -- the caller should mark
835          * merged VMA as dirty. If dirty bit won't be excluded from
836          * comparison, we increase pressue on the memory system forcing
837          * the kernel to generate new VMAs when old one could be
838          * extended instead.
839          */
840         if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
841                 return 0;
842         if (vma->vm_file != file)
843                 return 0;
844         if (vma->vm_ops && vma->vm_ops->close)
845                 return 0;
846         if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx))
847                 return 0;
848         return 1;
849 }
850 
851 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
852                                         struct anon_vma *anon_vma2,
853                                         struct vm_area_struct *vma)
854 {
855         /*
856          * The list_is_singular() test is to avoid merging VMA cloned from
857          * parents. This can improve scalability caused by anon_vma lock.
858          */
859         if ((!anon_vma1 || !anon_vma2) && (!vma ||
860                 list_is_singular(&vma->anon_vma_chain)))
861                 return 1;
862         return anon_vma1 == anon_vma2;
863 }
864 
865 /*
866  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
867  * in front of (at a lower virtual address and file offset than) the vma.
868  *
869  * We cannot merge two vmas if they have differently assigned (non-NULL)
870  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
871  *
872  * We don't check here for the merged mmap wrapping around the end of pagecache
873  * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
874  * wrap, nor mmaps which cover the final page at index -1UL.
875  */
876 static int
877 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
878                      struct anon_vma *anon_vma, struct file *file,
879                      pgoff_t vm_pgoff,
880                      struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
881 {
882         if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
883             is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
884                 if (vma->vm_pgoff == vm_pgoff)
885                         return 1;
886         }
887         return 0;
888 }
889 
890 /*
891  * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
892  * beyond (at a higher virtual address and file offset than) the vma.
893  *
894  * We cannot merge two vmas if they have differently assigned (non-NULL)
895  * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
896  */
897 static int
898 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
899                     struct anon_vma *anon_vma, struct file *file,
900                     pgoff_t vm_pgoff,
901                     struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
902 {
903         if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) &&
904             is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
905                 pgoff_t vm_pglen;
906                 vm_pglen = vma_pages(vma);
907                 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
908                         return 1;
909         }
910         return 0;
911 }
912 
913 /*
914  * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
915  * whether that can be merged with its predecessor or its successor.
916  * Or both (it neatly fills a hole).
917  *
918  * In most cases - when called for mmap, brk or mremap - [addr,end) is
919  * certain not to be mapped by the time vma_merge is called; but when
920  * called for mprotect, it is certain to be already mapped (either at
921  * an offset within prev, or at the start of next), and the flags of
922  * this area are about to be changed to vm_flags - and the no-change
923  * case has already been eliminated.
924  *
925  * The following mprotect cases have to be considered, where AAAA is
926  * the area passed down from mprotect_fixup, never extending beyond one
927  * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
928  *
929  *     AAAA             AAAA                AAAA          AAAA
930  *    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPPPNNNNNN    PPPPNNNNXXXX
931  *    cannot merge    might become    might become    might become
932  *                    PPNNNNNNNNNN    PPPPPPPPPPNN    PPPPPPPPPPPP 6 or
933  *    mmap, brk or    case 4 below    case 5 below    PPPPPPPPXXXX 7 or
934  *    mremap move:                                    PPPPNNNNNNNN 8
935  *        AAAA
936  *    PPPP    NNNN    PPPPPPPPPPPP    PPPPPPPPNNNN    PPPPNNNNNNNN
937  *    might become    case 1 below    case 2 below    case 3 below
938  *
939  * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
940  * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
941  */
942 struct vm_area_struct *vma_merge(struct mm_struct *mm,
943                         struct vm_area_struct *prev, unsigned long addr,
944                         unsigned long end, unsigned long vm_flags,
945                         struct anon_vma *anon_vma, struct file *file,
946                         pgoff_t pgoff, struct mempolicy *policy,
947                         struct vm_userfaultfd_ctx vm_userfaultfd_ctx)
948 {
949         pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
950         struct vm_area_struct *area, *next;
951         int err;
952 
953         /*
954          * We later require that vma->vm_flags == vm_flags,
955          * so this tests vma->vm_flags & VM_SPECIAL, too.
956          */
957         if (vm_flags & VM_SPECIAL)
958                 return NULL;
959 
960         if (prev)
961                 next = prev->vm_next;
962         else
963                 next = mm->mmap;
964         area = next;
965         if (next && next->vm_end == end)                /* cases 6, 7, 8 */
966                 next = next->vm_next;
967 
968         /*
969          * Can it merge with the predecessor?
970          */
971         if (prev && prev->vm_end == addr &&
972                         mpol_equal(vma_policy(prev), policy) &&
973                         can_vma_merge_after(prev, vm_flags,
974                                             anon_vma, file, pgoff,
975                                             vm_userfaultfd_ctx)) {
976                 /*
977                  * OK, it can.  Can we now merge in the successor as well?
978                  */
979                 if (next && end == next->vm_start &&
980                                 mpol_equal(policy, vma_policy(next)) &&
981                                 can_vma_merge_before(next, vm_flags,
982                                                      anon_vma, file,
983                                                      pgoff+pglen,
984                                                      vm_userfaultfd_ctx) &&
985                                 is_mergeable_anon_vma(prev->anon_vma,
986                                                       next->anon_vma, NULL)) {
987                                                         /* cases 1, 6 */
988                         err = vma_adjust(prev, prev->vm_start,
989                                 next->vm_end, prev->vm_pgoff, NULL);
990                 } else                                  /* cases 2, 5, 7 */
991                         err = vma_adjust(prev, prev->vm_start,
992                                 end, prev->vm_pgoff, NULL);
993                 if (err)
994                         return NULL;
995                 khugepaged_enter_vma_merge(prev, vm_flags);
996                 return prev;
997         }
998 
999         /*
1000          * Can this new request be merged in front of next?
1001          */
1002         if (next && end == next->vm_start &&
1003                         mpol_equal(policy, vma_policy(next)) &&
1004                         can_vma_merge_before(next, vm_flags,
1005                                              anon_vma, file, pgoff+pglen,
1006                                              vm_userfaultfd_ctx)) {
1007                 if (prev && addr < prev->vm_end)        /* case 4 */
1008                         err = vma_adjust(prev, prev->vm_start,
1009                                 addr, prev->vm_pgoff, NULL);
1010                 else                                    /* cases 3, 8 */
1011                         err = vma_adjust(area, addr, next->vm_end,
1012                                 next->vm_pgoff - pglen, NULL);
1013                 if (err)
1014                         return NULL;
1015                 khugepaged_enter_vma_merge(area, vm_flags);
1016                 return area;
1017         }
1018 
1019         return NULL;
1020 }
1021 
1022 /*
1023  * Rough compatbility check to quickly see if it's even worth looking
1024  * at sharing an anon_vma.
1025  *
1026  * They need to have the same vm_file, and the flags can only differ
1027  * in things that mprotect may change.
1028  *
1029  * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1030  * we can merge the two vma's. For example, we refuse to merge a vma if
1031  * there is a vm_ops->close() function, because that indicates that the
1032  * driver is doing some kind of reference counting. But that doesn't
1033  * really matter for the anon_vma sharing case.
1034  */
1035 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1036 {
1037         return a->vm_end == b->vm_start &&
1038                 mpol_equal(vma_policy(a), vma_policy(b)) &&
1039                 a->vm_file == b->vm_file &&
1040                 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) &&
1041                 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1042 }
1043 
1044 /*
1045  * Do some basic sanity checking to see if we can re-use the anon_vma
1046  * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1047  * the same as 'old', the other will be the new one that is trying
1048  * to share the anon_vma.
1049  *
1050  * NOTE! This runs with mm_sem held for reading, so it is possible that
1051  * the anon_vma of 'old' is concurrently in the process of being set up
1052  * by another page fault trying to merge _that_. But that's ok: if it
1053  * is being set up, that automatically means that it will be a singleton
1054  * acceptable for merging, so we can do all of this optimistically. But
1055  * we do that READ_ONCE() to make sure that we never re-load the pointer.
1056  *
1057  * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1058  * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1059  * is to return an anon_vma that is "complex" due to having gone through
1060  * a fork).
1061  *
1062  * We also make sure that the two vma's are compatible (adjacent,
1063  * and with the same memory policies). That's all stable, even with just
1064  * a read lock on the mm_sem.
1065  */
1066 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1067 {
1068         if (anon_vma_compatible(a, b)) {
1069                 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1070 
1071                 if (anon_vma && list_is_singular(&old->anon_vma_chain))
1072                         return anon_vma;
1073         }
1074         return NULL;
1075 }
1076 
1077 /*
1078  * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1079  * neighbouring vmas for a suitable anon_vma, before it goes off
1080  * to allocate a new anon_vma.  It checks because a repetitive
1081  * sequence of mprotects and faults may otherwise lead to distinct
1082  * anon_vmas being allocated, preventing vma merge in subsequent
1083  * mprotect.
1084  */
1085 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1086 {
1087         struct anon_vma *anon_vma;
1088         struct vm_area_struct *near;
1089 
1090         near = vma->vm_next;
1091         if (!near)
1092                 goto try_prev;
1093 
1094         anon_vma = reusable_anon_vma(near, vma, near);
1095         if (anon_vma)
1096                 return anon_vma;
1097 try_prev:
1098         near = vma->vm_prev;
1099         if (!near)
1100                 goto none;
1101 
1102         anon_vma = reusable_anon_vma(near, near, vma);
1103         if (anon_vma)
1104                 return anon_vma;
1105 none:
1106         /*
1107          * There's no absolute need to look only at touching neighbours:
1108          * we could search further afield for "compatible" anon_vmas.
1109          * But it would probably just be a waste of time searching,
1110          * or lead to too many vmas hanging off the same anon_vma.
1111          * We're trying to allow mprotect remerging later on,
1112          * not trying to minimize memory used for anon_vmas.
1113          */
1114         return NULL;
1115 }
1116 
1117 /*
1118  * If a hint addr is less than mmap_min_addr change hint to be as
1119  * low as possible but still greater than mmap_min_addr
1120  */
1121 static inline unsigned long round_hint_to_min(unsigned long hint)
1122 {
1123         hint &= PAGE_MASK;
1124         if (((void *)hint != NULL) &&
1125             (hint < mmap_min_addr))
1126                 return PAGE_ALIGN(mmap_min_addr);
1127         return hint;
1128 }
1129 
1130 static inline int mlock_future_check(struct mm_struct *mm,
1131                                      unsigned long flags,
1132                                      unsigned long len)
1133 {
1134         unsigned long locked, lock_limit;
1135 
1136         /*  mlock MCL_FUTURE? */
1137         if (flags & VM_LOCKED) {
1138                 locked = len >> PAGE_SHIFT;
1139                 locked += mm->locked_vm;
1140                 lock_limit = rlimit(RLIMIT_MEMLOCK);
1141                 lock_limit >>= PAGE_SHIFT;
1142                 if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1143                         return -EAGAIN;
1144         }
1145         return 0;
1146 }
1147 
1148 /*
1149  * The caller must hold down_write(&current->mm->mmap_sem).
1150  */
1151 unsigned long do_mmap(struct file *file, unsigned long addr,
1152                         unsigned long len, unsigned long prot,
1153                         unsigned long flags, vm_flags_t vm_flags,
1154                         unsigned long pgoff, unsigned long *populate)
1155 {
1156         struct mm_struct *mm = current->mm;
1157         int pkey = 0;
1158 
1159         *populate = 0;
1160 
1161         if (!len)
1162                 return -EINVAL;
1163 
1164         /*
1165          * Does the application expect PROT_READ to imply PROT_EXEC?
1166          *
1167          * (the exception is when the underlying filesystem is noexec
1168          *  mounted, in which case we dont add PROT_EXEC.)
1169          */
1170         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1171                 if (!(file && path_noexec(&file->f_path)))
1172                         prot |= PROT_EXEC;
1173 
1174         if (!(flags & MAP_FIXED))
1175                 addr = round_hint_to_min(addr);
1176 
1177         /* Careful about overflows.. */
1178         len = PAGE_ALIGN(len);
1179         if (!len)
1180                 return -ENOMEM;
1181 
1182         /* offset overflow? */
1183         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1184                 return -EOVERFLOW;
1185 
1186         /* Too many mappings? */
1187         if (mm->map_count > sysctl_max_map_count)
1188                 return -ENOMEM;
1189 
1190         /* Obtain the address to map to. we verify (or select) it and ensure
1191          * that it represents a valid section of the address space.
1192          */
1193         addr = get_unmapped_area(file, addr, len, pgoff, flags);
1194         if (offset_in_page(addr))
1195                 return addr;
1196 
1197         if (prot == PROT_EXEC) {
1198                 pkey = execute_only_pkey(mm);
1199                 if (pkey < 0)
1200                         pkey = 0;
1201         }
1202 
1203         /* Do simple checking here so the lower-level routines won't have
1204          * to. we assume access permissions have been handled by the open
1205          * of the memory object, so we don't do any here.
1206          */
1207         vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1208                         mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1209 
1210         if (flags & MAP_LOCKED)
1211                 if (!can_do_mlock())
1212                         return -EPERM;
1213 
1214         if (mlock_future_check(mm, vm_flags, len))
1215                 return -EAGAIN;
1216 
1217         if (file) {
1218                 struct inode *inode = file_inode(file);
1219 
1220                 switch (flags & MAP_TYPE) {
1221                 case MAP_SHARED:
1222                         if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1223                                 return -EACCES;
1224 
1225                         /*
1226                          * Make sure we don't allow writing to an append-only
1227                          * file..
1228                          */
1229                         if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1230                                 return -EACCES;
1231 
1232                         /*
1233                          * Make sure there are no mandatory locks on the file.
1234                          */
1235                         if (locks_verify_locked(file))
1236                                 return -EAGAIN;
1237 
1238                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1239                         if (!(file->f_mode & FMODE_WRITE))
1240                                 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1241 
1242                         /* fall through */
1243                 case MAP_PRIVATE:
1244                         if (!(file->f_mode & FMODE_READ))
1245                                 return -EACCES;
1246                         if (path_noexec(&file->f_path)) {
1247                                 if (vm_flags & VM_EXEC)
1248                                         return -EPERM;
1249                                 vm_flags &= ~VM_MAYEXEC;
1250                         }
1251 
1252                         if (!file->f_op->mmap)
1253                                 return -ENODEV;
1254                         if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1255                                 return -EINVAL;
1256                         break;
1257 
1258                 default:
1259                         return -EINVAL;
1260                 }
1261         } else {
1262                 switch (flags & MAP_TYPE) {
1263                 case MAP_SHARED:
1264                         if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1265                                 return -EINVAL;
1266                         /*
1267                          * Ignore pgoff.
1268                          */
1269                         pgoff = 0;
1270                         vm_flags |= VM_SHARED | VM_MAYSHARE;
1271                         break;
1272                 case MAP_PRIVATE:
1273                         /*
1274                          * Set pgoff according to addr for anon_vma.
1275                          */
1276                         pgoff = addr >> PAGE_SHIFT;
1277                         break;
1278                 default:
1279                         return -EINVAL;
1280                 }
1281         }
1282 
1283         /*
1284          * Set 'VM_NORESERVE' if we should not account for the
1285          * memory use of this mapping.
1286          */
1287         if (flags & MAP_NORESERVE) {
1288                 /* We honor MAP_NORESERVE if allowed to overcommit */
1289                 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1290                         vm_flags |= VM_NORESERVE;
1291 
1292                 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1293                 if (file && is_file_hugepages(file))
1294                         vm_flags |= VM_NORESERVE;
1295         }
1296 
1297         addr = mmap_region(file, addr, len, vm_flags, pgoff);
1298         if (!IS_ERR_VALUE(addr) &&
1299             ((vm_flags & VM_LOCKED) ||
1300              (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1301                 *populate = len;
1302         return addr;
1303 }
1304 
1305 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1306                 unsigned long, prot, unsigned long, flags,
1307                 unsigned long, fd, unsigned long, pgoff)
1308 {
1309         struct file *file = NULL;
1310         unsigned long retval;
1311 
1312         if (!(flags & MAP_ANONYMOUS)) {
1313                 audit_mmap_fd(fd, flags);
1314                 file = fget(fd);
1315                 if (!file)
1316                         return -EBADF;
1317                 if (is_file_hugepages(file))
1318                         len = ALIGN(len, huge_page_size(hstate_file(file)));
1319                 retval = -EINVAL;
1320                 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file)))
1321                         goto out_fput;
1322         } else if (flags & MAP_HUGETLB) {
1323                 struct user_struct *user = NULL;
1324                 struct hstate *hs;
1325 
1326                 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & SHM_HUGE_MASK);
1327                 if (!hs)
1328                         return -EINVAL;
1329 
1330                 len = ALIGN(len, huge_page_size(hs));
1331                 /*
1332                  * VM_NORESERVE is used because the reservations will be
1333                  * taken when vm_ops->mmap() is called
1334                  * A dummy user value is used because we are not locking
1335                  * memory so no accounting is necessary
1336                  */
1337                 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len,
1338                                 VM_NORESERVE,
1339                                 &user, HUGETLB_ANONHUGE_INODE,
1340                                 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1341                 if (IS_ERR(file))
1342                         return PTR_ERR(file);
1343         }
1344 
1345         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1346 
1347         retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1348 out_fput:
1349         if (file)
1350                 fput(file);
1351         return retval;
1352 }
1353 
1354 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1355 struct mmap_arg_struct {
1356         unsigned long addr;
1357         unsigned long len;
1358         unsigned long prot;
1359         unsigned long flags;
1360         unsigned long fd;
1361         unsigned long offset;
1362 };
1363 
1364 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1365 {
1366         struct mmap_arg_struct a;
1367 
1368         if (copy_from_user(&a, arg, sizeof(a)))
1369                 return -EFAULT;
1370         if (offset_in_page(a.offset))
1371                 return -EINVAL;
1372 
1373         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1374                               a.offset >> PAGE_SHIFT);
1375 }
1376 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1377 
1378 /*
1379  * Some shared mappigns will want the pages marked read-only
1380  * to track write events. If so, we'll downgrade vm_page_prot
1381  * to the private version (using protection_map[] without the
1382  * VM_SHARED bit).
1383  */
1384 int vma_wants_writenotify(struct vm_area_struct *vma)
1385 {
1386         vm_flags_t vm_flags = vma->vm_flags;
1387         const struct vm_operations_struct *vm_ops = vma->vm_ops;
1388 
1389         /* If it was private or non-writable, the write bit is already clear */
1390         if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1391                 return 0;
1392 
1393         /* The backer wishes to know when pages are first written to? */
1394         if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
1395                 return 1;
1396 
1397         /* The open routine did something to the protections that pgprot_modify
1398          * won't preserve? */
1399         if (pgprot_val(vma->vm_page_prot) !=
1400             pgprot_val(vm_pgprot_modify(vma->vm_page_prot, vm_flags)))
1401                 return 0;
1402 
1403         /* Do we need to track softdirty? */
1404         if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY))
1405                 return 1;
1406 
1407         /* Specialty mapping? */
1408         if (vm_flags & VM_PFNMAP)
1409                 return 0;
1410 
1411         /* Can the mapping track the dirty pages? */
1412         return vma->vm_file && vma->vm_file->f_mapping &&
1413                 mapping_cap_account_dirty(vma->vm_file->f_mapping);
1414 }
1415 
1416 /*
1417  * We account for memory if it's a private writeable mapping,
1418  * not hugepages and VM_NORESERVE wasn't set.
1419  */
1420 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1421 {
1422         /*
1423          * hugetlb has its own accounting separate from the core VM
1424          * VM_HUGETLB may not be set yet so we cannot check for that flag.
1425          */
1426         if (file && is_file_hugepages(file))
1427                 return 0;
1428 
1429         return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1430 }
1431 
1432 unsigned long mmap_region(struct file *file, unsigned long addr,
1433                 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff)
1434 {
1435         struct mm_struct *mm = current->mm;
1436         struct vm_area_struct *vma, *prev;
1437         int error;
1438         struct rb_node **rb_link, *rb_parent;
1439         unsigned long charged = 0;
1440 
1441         /* Check against address space limit. */
1442         if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
1443                 unsigned long nr_pages;
1444 
1445                 /*
1446                  * MAP_FIXED may remove pages of mappings that intersects with
1447                  * requested mapping. Account for the pages it would unmap.
1448                  */
1449                 nr_pages = count_vma_pages_range(mm, addr, addr + len);
1450 
1451                 if (!may_expand_vm(mm, vm_flags,
1452                                         (len >> PAGE_SHIFT) - nr_pages))
1453                         return -ENOMEM;
1454         }
1455 
1456         /* Clear old maps */
1457         while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
1458                               &rb_parent)) {
1459                 if (do_munmap(mm, addr, len))
1460                         return -ENOMEM;
1461         }
1462 
1463         /*
1464          * Private writable mapping: check memory availability
1465          */
1466         if (accountable_mapping(file, vm_flags)) {
1467                 charged = len >> PAGE_SHIFT;
1468                 if (security_vm_enough_memory_mm(mm, charged))
1469                         return -ENOMEM;
1470                 vm_flags |= VM_ACCOUNT;
1471         }
1472 
1473         /*
1474          * Can we just expand an old mapping?
1475          */
1476         vma = vma_merge(mm, prev, addr, addr + len, vm_flags,
1477                         NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX);
1478         if (vma)
1479                 goto out;
1480 
1481         /*
1482          * Determine the object being mapped and call the appropriate
1483          * specific mapper. the address has already been validated, but
1484          * not unmapped, but the maps are removed from the list.
1485          */
1486         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1487         if (!vma) {
1488                 error = -ENOMEM;
1489                 goto unacct_error;
1490         }
1491 
1492         vma->vm_mm = mm;
1493         vma->vm_start = addr;
1494         vma->vm_end = addr + len;
1495         vma->vm_flags = vm_flags;
1496         vma->vm_page_prot = vm_get_page_prot(vm_flags);
1497         vma->vm_pgoff = pgoff;
1498         INIT_LIST_HEAD(&vma->anon_vma_chain);
1499 
1500         if (file) {
1501                 if (vm_flags & VM_DENYWRITE) {
1502                         error = deny_write_access(file);
1503                         if (error)
1504                                 goto free_vma;
1505                 }
1506                 if (vm_flags & VM_SHARED) {
1507                         error = mapping_map_writable(file->f_mapping);
1508                         if (error)
1509                                 goto allow_write_and_free_vma;
1510                 }
1511 
1512                 /* ->mmap() can change vma->vm_file, but must guarantee that
1513                  * vma_link() below can deny write-access if VM_DENYWRITE is set
1514                  * and map writably if VM_SHARED is set. This usually means the
1515                  * new file must not have been exposed to user-space, yet.
1516                  */
1517                 vma->vm_file = get_file(file);
1518                 error = file->f_op->mmap(file, vma);
1519                 if (error)
1520                         goto unmap_and_free_vma;
1521 
1522                 /* Can addr have changed??
1523                  *
1524                  * Answer: Yes, several device drivers can do it in their
1525                  *         f_op->mmap method. -DaveM
1526                  * Bug: If addr is changed, prev, rb_link, rb_parent should
1527                  *      be updated for vma_link()
1528                  */
1529                 WARN_ON_ONCE(addr != vma->vm_start);
1530 
1531                 addr = vma->vm_start;
1532                 vm_flags = vma->vm_flags;
1533         } else if (vm_flags & VM_SHARED) {
1534                 error = shmem_zero_setup(vma);
1535                 if (error)
1536                         goto free_vma;
1537         }
1538 
1539         vma_link(mm, vma, prev, rb_link, rb_parent);
1540         /* Once vma denies write, undo our temporary denial count */
1541         if (file) {
1542                 if (vm_flags & VM_SHARED)
1543                         mapping_unmap_writable(file->f_mapping);
1544                 if (vm_flags & VM_DENYWRITE)
1545                         allow_write_access(file);
1546         }
1547         file = vma->vm_file;
1548 out:
1549         perf_event_mmap(vma);
1550 
1551         vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
1552         if (vm_flags & VM_LOCKED) {
1553                 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
1554                                         vma == get_gate_vma(current->mm)))
1555                         mm->locked_vm += (len >> PAGE_SHIFT);
1556                 else
1557                         vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
1558         }
1559 
1560         if (file)
1561                 uprobe_mmap(vma);
1562 
1563         /*
1564          * New (or expanded) vma always get soft dirty status.
1565          * Otherwise user-space soft-dirty page tracker won't
1566          * be able to distinguish situation when vma area unmapped,
1567          * then new mapped in-place (which must be aimed as
1568          * a completely new data area).
1569          */
1570         vma->vm_flags |= VM_SOFTDIRTY;
1571 
1572         vma_set_page_prot(vma);
1573 
1574         return addr;
1575 
1576 unmap_and_free_vma:
1577         vma->vm_file = NULL;
1578         fput(file);
1579 
1580         /* Undo any partial mapping done by a device driver. */
1581         unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1582         charged = 0;
1583         if (vm_flags & VM_SHARED)
1584                 mapping_unmap_writable(file->f_mapping);
1585 allow_write_and_free_vma:
1586         if (vm_flags & VM_DENYWRITE)
1587                 allow_write_access(file);
1588 free_vma:
1589         kmem_cache_free(vm_area_cachep, vma);
1590 unacct_error:
1591         if (charged)
1592                 vm_unacct_memory(charged);
1593         return error;
1594 }
1595 
1596 unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1597 {
1598         /*
1599          * We implement the search by looking for an rbtree node that
1600          * immediately follows a suitable gap. That is,
1601          * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length;
1602          * - gap_end   = vma->vm_start        >= info->low_limit  + length;
1603          * - gap_end - gap_start >= length
1604          */
1605 
1606         struct mm_struct *mm = current->mm;
1607         struct vm_area_struct *vma;
1608         unsigned long length, low_limit, high_limit, gap_start, gap_end;
1609 
1610         /* Adjust search length to account for worst case alignment overhead */
1611         length = info->length + info->align_mask;
1612         if (length < info->length)
1613                 return -ENOMEM;
1614 
1615         /* Adjust search limits by the desired length */
1616         if (info->high_limit < length)
1617                 return -ENOMEM;
1618         high_limit = info->high_limit - length;
1619 
1620         if (info->low_limit > high_limit)
1621                 return -ENOMEM;
1622         low_limit = info->low_limit + length;
1623 
1624         /* Check if rbtree root looks promising */
1625         if (RB_EMPTY_ROOT(&mm->mm_rb))
1626                 goto check_highest;
1627         vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1628         if (vma->rb_subtree_gap < length)
1629                 goto check_highest;
1630 
1631         while (true) {
1632                 /* Visit left subtree if it looks promising */
1633                 gap_end = vma->vm_start;
1634                 if (gap_end >= low_limit && vma->vm_rb.rb_left) {
1635                         struct vm_area_struct *left =
1636                                 rb_entry(vma->vm_rb.rb_left,
1637                                          struct vm_area_struct, vm_rb);
1638                         if (left->rb_subtree_gap >= length) {
1639                                 vma = left;
1640                                 continue;
1641                         }
1642                 }
1643 
1644                 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1645 check_current:
1646                 /* Check if current node has a suitable gap */
1647                 if (gap_start > high_limit)
1648                         return -ENOMEM;
1649                 if (gap_end >= low_limit && gap_end - gap_start >= length)
1650                         goto found;
1651 
1652                 /* Visit right subtree if it looks promising */
1653                 if (vma->vm_rb.rb_right) {
1654                         struct vm_area_struct *right =
1655                                 rb_entry(vma->vm_rb.rb_right,
1656                                          struct vm_area_struct, vm_rb);
1657                         if (right->rb_subtree_gap >= length) {
1658                                 vma = right;
1659                                 continue;
1660                         }
1661                 }
1662 
1663                 /* Go back up the rbtree to find next candidate node */
1664                 while (true) {
1665                         struct rb_node *prev = &vma->vm_rb;
1666                         if (!rb_parent(prev))
1667                                 goto check_highest;
1668                         vma = rb_entry(rb_parent(prev),
1669                                        struct vm_area_struct, vm_rb);
1670                         if (prev == vma->vm_rb.rb_left) {
1671                                 gap_start = vma->vm_prev->vm_end;
1672                                 gap_end = vma->vm_start;
1673                                 goto check_current;
1674                         }
1675                 }
1676         }
1677 
1678 check_highest:
1679         /* Check highest gap, which does not precede any rbtree node */
1680         gap_start = mm->highest_vm_end;
1681         gap_end = ULONG_MAX;  /* Only for VM_BUG_ON below */
1682         if (gap_start > high_limit)
1683                 return -ENOMEM;
1684 
1685 found:
1686         /* We found a suitable gap. Clip it with the original low_limit. */
1687         if (gap_start < info->low_limit)
1688                 gap_start = info->low_limit;
1689 
1690         /* Adjust gap address to the desired alignment */
1691         gap_start += (info->align_offset - gap_start) & info->align_mask;
1692 
1693         VM_BUG_ON(gap_start + info->length > info->high_limit);
1694         VM_BUG_ON(gap_start + info->length > gap_end);
1695         return gap_start;
1696 }
1697 
1698 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1699 {
1700         struct mm_struct *mm = current->mm;
1701         struct vm_area_struct *vma;
1702         unsigned long length, low_limit, high_limit, gap_start, gap_end;
1703 
1704         /* Adjust search length to account for worst case alignment overhead */
1705         length = info->length + info->align_mask;
1706         if (length < info->length)
1707                 return -ENOMEM;
1708 
1709         /*
1710          * Adjust search limits by the desired length.
1711          * See implementation comment at top of unmapped_area().
1712          */
1713         gap_end = info->high_limit;
1714         if (gap_end < length)
1715                 return -ENOMEM;
1716         high_limit = gap_end - length;
1717 
1718         if (info->low_limit > high_limit)
1719                 return -ENOMEM;
1720         low_limit = info->low_limit + length;
1721 
1722         /* Check highest gap, which does not precede any rbtree node */
1723         gap_start = mm->highest_vm_end;
1724         if (gap_start <= high_limit)
1725                 goto found_highest;
1726 
1727         /* Check if rbtree root looks promising */
1728         if (RB_EMPTY_ROOT(&mm->mm_rb))
1729                 return -ENOMEM;
1730         vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb);
1731         if (vma->rb_subtree_gap < length)
1732                 return -ENOMEM;
1733 
1734         while (true) {
1735                 /* Visit right subtree if it looks promising */
1736                 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0;
1737                 if (gap_start <= high_limit && vma->vm_rb.rb_right) {
1738                         struct vm_area_struct *right =
1739                                 rb_entry(vma->vm_rb.rb_right,
1740                                          struct vm_area_struct, vm_rb);
1741                         if (right->rb_subtree_gap >= length) {
1742                                 vma = right;
1743                                 continue;
1744                         }
1745                 }
1746 
1747 check_current:
1748                 /* Check if current node has a suitable gap */
1749                 gap_end = vma->vm_start;
1750                 if (gap_end < low_limit)
1751                         return -ENOMEM;
1752                 if (gap_start <= high_limit && gap_end - gap_start >= length)
1753                         goto found;
1754 
1755                 /* Visit left subtree if it looks promising */
1756                 if (vma->vm_rb.rb_left) {
1757                         struct vm_area_struct *left =
1758                                 rb_entry(vma->vm_rb.rb_left,
1759                                          struct vm_area_struct, vm_rb);
1760                         if (left->rb_subtree_gap >= length) {
1761                                 vma = left;
1762                                 continue;
1763                         }
1764                 }
1765 
1766                 /* Go back up the rbtree to find next candidate node */
1767                 while (true) {
1768                         struct rb_node *prev = &vma->vm_rb;
1769                         if (!rb_parent(prev))
1770                                 return -ENOMEM;
1771                         vma = rb_entry(rb_parent(prev),
1772                                        struct vm_area_struct, vm_rb);
1773                         if (prev == vma->vm_rb.rb_right) {
1774                                 gap_start = vma->vm_prev ?
1775                                         vma->vm_prev->vm_end : 0;
1776                                 goto check_current;
1777                         }
1778                 }
1779         }
1780 
1781 found:
1782         /* We found a suitable gap. Clip it with the original high_limit. */
1783         if (gap_end > info->high_limit)
1784                 gap_end = info->high_limit;
1785 
1786 found_highest:
1787         /* Compute highest gap address at the desired alignment */
1788         gap_end -= info->length;
1789         gap_end -= (gap_end - info->align_offset) & info->align_mask;
1790 
1791         VM_BUG_ON(gap_end < info->low_limit);
1792         VM_BUG_ON(gap_end < gap_start);
1793         return gap_end;
1794 }
1795 
1796 /* Get an address range which is currently unmapped.
1797  * For shmat() with addr=0.
1798  *
1799  * Ugly calling convention alert:
1800  * Return value with the low bits set means error value,
1801  * ie
1802  *      if (ret & ~PAGE_MASK)
1803  *              error = ret;
1804  *
1805  * This function "knows" that -ENOMEM has the bits set.
1806  */
1807 #ifndef HAVE_ARCH_UNMAPPED_AREA
1808 unsigned long
1809 arch_get_unmapped_area(struct file *filp, unsigned long addr,
1810                 unsigned long len, unsigned long pgoff, unsigned long flags)
1811 {
1812         struct mm_struct *mm = current->mm;
1813         struct vm_area_struct *vma;
1814         struct vm_unmapped_area_info info;
1815 
1816         if (len > TASK_SIZE - mmap_min_addr)
1817                 return -ENOMEM;
1818 
1819         if (flags & MAP_FIXED)
1820                 return addr;
1821 
1822         if (addr) {
1823                 addr = PAGE_ALIGN(addr);
1824                 vma = find_vma(mm, addr);
1825                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1826                     (!vma || addr + len <= vma->vm_start))
1827                         return addr;
1828         }
1829 
1830         info.flags = 0;
1831         info.length = len;
1832         info.low_limit = mm->mmap_base;
1833         info.high_limit = TASK_SIZE;
1834         info.align_mask = 0;
1835         return vm_unmapped_area(&info);
1836 }
1837 #endif
1838 
1839 /*
1840  * This mmap-allocator allocates new areas top-down from below the
1841  * stack's low limit (the base):
1842  */
1843 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1844 unsigned long
1845 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1846                           const unsigned long len, const unsigned long pgoff,
1847                           const unsigned long flags)
1848 {
1849         struct vm_area_struct *vma;
1850         struct mm_struct *mm = current->mm;
1851         unsigned long addr = addr0;
1852         struct vm_unmapped_area_info info;
1853 
1854         /* requested length too big for entire address space */
1855         if (len > TASK_SIZE - mmap_min_addr)
1856                 return -ENOMEM;
1857 
1858         if (flags & MAP_FIXED)
1859                 return addr;
1860 
1861         /* requesting a specific address */
1862         if (addr) {
1863                 addr = PAGE_ALIGN(addr);
1864                 vma = find_vma(mm, addr);
1865                 if (TASK_SIZE - len >= addr && addr >= mmap_min_addr &&
1866                                 (!vma || addr + len <= vma->vm_start))
1867                         return addr;
1868         }
1869 
1870         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1871         info.length = len;
1872         info.low_limit = max(PAGE_SIZE, mmap_min_addr);
1873         info.high_limit = mm->mmap_base;
1874         info.align_mask = 0;
1875         addr = vm_unmapped_area(&info);
1876 
1877         /*
1878          * A failed mmap() very likely causes application failure,
1879          * so fall back to the bottom-up function here. This scenario
1880          * can happen with large stack limits and large mmap()
1881          * allocations.
1882          */
1883         if (offset_in_page(addr)) {
1884                 VM_BUG_ON(addr != -ENOMEM);
1885                 info.flags = 0;
1886                 info.low_limit = TASK_UNMAPPED_BASE;
1887                 info.high_limit = TASK_SIZE;
1888                 addr = vm_unmapped_area(&info);
1889         }
1890 
1891         return addr;
1892 }
1893 #endif
1894 
1895 unsigned long
1896 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1897                 unsigned long pgoff, unsigned long flags)
1898 {
1899         unsigned long (*get_area)(struct file *, unsigned long,
1900                                   unsigned long, unsigned long, unsigned long);
1901 
1902         unsigned long error = arch_mmap_check(addr, len, flags);
1903         if (error)
1904                 return error;
1905 
1906         /* Careful about overflows.. */
1907         if (len > TASK_SIZE)
1908                 return -ENOMEM;
1909 
1910         get_area = current->mm->get_unmapped_area;
1911         if (file) {
1912                 if (file->f_op->get_unmapped_area)
1913                         get_area = file->f_op->get_unmapped_area;
1914         } else if (flags & MAP_SHARED) {
1915                 /*
1916                  * mmap_region() will call shmem_zero_setup() to create a file,
1917                  * so use shmem's get_unmapped_area in case it can be huge.
1918                  * do_mmap_pgoff() will clear pgoff, so match alignment.
1919                  */
1920                 pgoff = 0;
1921                 get_area = shmem_get_unmapped_area;
1922         }
1923 
1924         addr = get_area(file, addr, len, pgoff, flags);
1925         if (IS_ERR_VALUE(addr))
1926                 return addr;
1927 
1928         if (addr > TASK_SIZE - len)
1929                 return -ENOMEM;
1930         if (offset_in_page(addr))
1931                 return -EINVAL;
1932 
1933         error = security_mmap_addr(addr);
1934         return error ? error : addr;
1935 }
1936 
1937 EXPORT_SYMBOL(get_unmapped_area);
1938 
1939 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
1940 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1941 {
1942         struct rb_node *rb_node;
1943         struct vm_area_struct *vma;
1944 
1945         /* Check the cache first. */
1946         vma = vmacache_find(mm, addr);
1947         if (likely(vma))
1948                 return vma;
1949 
1950         rb_node = mm->mm_rb.rb_node;
1951 
1952         while (rb_node) {
1953                 struct vm_area_struct *tmp;
1954 
1955                 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1956 
1957                 if (tmp->vm_end > addr) {
1958                         vma = tmp;
1959                         if (tmp->vm_start <= addr)
1960                                 break;
1961                         rb_node = rb_node->rb_left;
1962                 } else
1963                         rb_node = rb_node->rb_right;
1964         }
1965 
1966         if (vma)
1967                 vmacache_update(addr, vma);
1968         return vma;
1969 }
1970 
1971 EXPORT_SYMBOL(find_vma);
1972 
1973 /*
1974  * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
1975  */
1976 struct vm_area_struct *
1977 find_vma_prev(struct mm_struct *mm, unsigned long addr,
1978                         struct vm_area_struct **pprev)
1979 {
1980         struct vm_area_struct *vma;
1981 
1982         vma = find_vma(mm, addr);
1983         if (vma) {
1984                 *pprev = vma->vm_prev;
1985         } else {
1986                 struct rb_node *rb_node = mm->mm_rb.rb_node;
1987                 *pprev = NULL;
1988                 while (rb_node) {
1989                         *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1990                         rb_node = rb_node->rb_right;
1991                 }
1992         }
1993         return vma;
1994 }
1995 
1996 /*
1997  * Verify that the stack growth is acceptable and
1998  * update accounting. This is shared with both the
1999  * grow-up and grow-down cases.
2000  */
2001 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
2002 {
2003         struct mm_struct *mm = vma->vm_mm;
2004         struct rlimit *rlim = current->signal->rlim;
2005         unsigned long new_start, actual_size;
2006 
2007         /* address space limit tests */
2008         if (!may_expand_vm(mm, vma->vm_flags, grow))
2009                 return -ENOMEM;
2010 
2011         /* Stack limit test */
2012         actual_size = size;
2013         if (size && (vma->vm_flags & (VM_GROWSUP | VM_GROWSDOWN)))
2014                 actual_size -= PAGE_SIZE;
2015         if (actual_size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur))
2016                 return -ENOMEM;
2017 
2018         /* mlock limit tests */
2019         if (vma->vm_flags & VM_LOCKED) {
2020                 unsigned long locked;
2021                 unsigned long limit;
2022                 locked = mm->locked_vm + grow;
2023                 limit = READ_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
2024                 limit >>= PAGE_SHIFT;
2025                 if (locked > limit && !capable(CAP_IPC_LOCK))
2026                         return -ENOMEM;
2027         }
2028 
2029         /* Check to ensure the stack will not grow into a hugetlb-only region */
2030         new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
2031                         vma->vm_end - size;
2032         if (is_hugepage_only_range(vma->vm_mm, new_start, size))
2033                 return -EFAULT;
2034 
2035         /*
2036          * Overcommit..  This must be the final test, as it will
2037          * update security statistics.
2038          */
2039         if (security_vm_enough_memory_mm(mm, grow))
2040                 return -ENOMEM;
2041 
2042         return 0;
2043 }
2044 
2045 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
2046 /*
2047  * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
2048  * vma is the last one with address > vma->vm_end.  Have to extend vma.
2049  */
2050 int expand_upwards(struct vm_area_struct *vma, unsigned long address)
2051 {
2052         struct mm_struct *mm = vma->vm_mm;
2053         int error = 0;
2054 
2055         if (!(vma->vm_flags & VM_GROWSUP))
2056                 return -EFAULT;
2057 
2058         /* Guard against wrapping around to address 0. */
2059         if (address < PAGE_ALIGN(address+4))
2060                 address = PAGE_ALIGN(address+4);
2061         else
2062                 return -ENOMEM;
2063 
2064         /* We must make sure the anon_vma is allocated. */
2065         if (unlikely(anon_vma_prepare(vma)))
2066                 return -ENOMEM;
2067 
2068         /*
2069          * vma->vm_start/vm_end cannot change under us because the caller
2070          * is required to hold the mmap_sem in read mode.  We need the
2071          * anon_vma lock to serialize against concurrent expand_stacks.
2072          */
2073         anon_vma_lock_write(vma->anon_vma);
2074 
2075         /* Somebody else might have raced and expanded it already */
2076         if (address > vma->vm_end) {
2077                 unsigned long size, grow;
2078 
2079                 size = address - vma->vm_start;
2080                 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2081 
2082                 error = -ENOMEM;
2083                 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2084                         error = acct_stack_growth(vma, size, grow);
2085                         if (!error) {
2086                                 /*
2087                                  * vma_gap_update() doesn't support concurrent
2088                                  * updates, but we only hold a shared mmap_sem
2089                                  * lock here, so we need to protect against
2090                                  * concurrent vma expansions.
2091                                  * anon_vma_lock_write() doesn't help here, as
2092                                  * we don't guarantee that all growable vmas
2093                                  * in a mm share the same root anon vma.
2094                                  * So, we reuse mm->page_table_lock to guard
2095                                  * against concurrent vma expansions.
2096                                  */
2097                                 spin_lock(&mm->page_table_lock);
2098                                 if (vma->vm_flags & VM_LOCKED)
2099                                         mm->locked_vm += grow;
2100                                 vm_stat_account(mm, vma->vm_flags, grow);
2101                                 anon_vma_interval_tree_pre_update_vma(vma);
2102                                 vma->vm_end = address;
2103                                 anon_vma_interval_tree_post_update_vma(vma);
2104                                 if (vma->vm_next)
2105                                         vma_gap_update(vma->vm_next);
2106                                 else
2107                                         mm->highest_vm_end = address;
2108                                 spin_unlock(&mm->page_table_lock);
2109 
2110                                 perf_event_mmap(vma);
2111                         }
2112                 }
2113         }
2114         anon_vma_unlock_write(vma->anon_vma);
2115         khugepaged_enter_vma_merge(vma, vma->vm_flags);
2116         validate_mm(mm);
2117         return error;
2118 }
2119 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
2120 
2121 /*
2122  * vma is the first one with address < vma->vm_start.  Have to extend vma.
2123  */
2124 int expand_downwards(struct vm_area_struct *vma,
2125                                    unsigned long address)
2126 {
2127         struct mm_struct *mm = vma->vm_mm;
2128         int error;
2129 
2130         address &= PAGE_MASK;
2131         error = security_mmap_addr(address);
2132         if (error)
2133                 return error;
2134 
2135         /* We must make sure the anon_vma is allocated. */
2136         if (unlikely(anon_vma_prepare(vma)))
2137                 return -ENOMEM;
2138 
2139         /*
2140          * vma->vm_start/vm_end cannot change under us because the caller
2141          * is required to hold the mmap_sem in read mode.  We need the
2142          * anon_vma lock to serialize against concurrent expand_stacks.
2143          */
2144         anon_vma_lock_write(vma->anon_vma);
2145 
2146         /* Somebody else might have raced and expanded it already */
2147         if (address < vma->vm_start) {
2148                 unsigned long size, grow;
2149 
2150                 size = vma->vm_end - address;
2151                 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2152 
2153                 error = -ENOMEM;
2154                 if (grow <= vma->vm_pgoff) {
2155                         error = acct_stack_growth(vma, size, grow);
2156                         if (!error) {
2157                                 /*
2158                                  * vma_gap_update() doesn't support concurrent
2159                                  * updates, but we only hold a shared mmap_sem
2160                                  * lock here, so we need to protect against
2161                                  * concurrent vma expansions.
2162                                  * anon_vma_lock_write() doesn't help here, as
2163                                  * we don't guarantee that all growable vmas
2164                                  * in a mm share the same root anon vma.
2165                                  * So, we reuse mm->page_table_lock to guard
2166                                  * against concurrent vma expansions.
2167                                  */
2168                                 spin_lock(&mm->page_table_lock);
2169                                 if (vma->vm_flags & VM_LOCKED)
2170                                         mm->locked_vm += grow;
2171                                 vm_stat_account(mm, vma->vm_flags, grow);
2172                                 anon_vma_interval_tree_pre_update_vma(vma);
2173                                 vma->vm_start = address;
2174                                 vma->vm_pgoff -= grow;
2175                                 anon_vma_interval_tree_post_update_vma(vma);
2176                                 vma_gap_update(vma);
2177                                 spin_unlock(&mm->page_table_lock);
2178 
2179                                 perf_event_mmap(vma);
2180                         }
2181                 }
2182         }
2183         anon_vma_unlock_write(vma->anon_vma);
2184         khugepaged_enter_vma_merge(vma, vma->vm_flags);
2185         validate_mm(mm);
2186         return error;
2187 }
2188 
2189 /*
2190  * Note how expand_stack() refuses to expand the stack all the way to
2191  * abut the next virtual mapping, *unless* that mapping itself is also
2192  * a stack mapping. We want to leave room for a guard page, after all
2193  * (the guard page itself is not added here, that is done by the
2194  * actual page faulting logic)
2195  *
2196  * This matches the behavior of the guard page logic (see mm/memory.c:
2197  * check_stack_guard_page()), which only allows the guard page to be
2198  * removed under these circumstances.
2199  */
2200 #ifdef CONFIG_STACK_GROWSUP
2201 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2202 {
2203         struct vm_area_struct *next;
2204 
2205         address &= PAGE_MASK;
2206         next = vma->vm_next;
2207         if (next && next->vm_start == address + PAGE_SIZE) {
2208                 if (!(next->vm_flags & VM_GROWSUP))
2209                         return -ENOMEM;
2210         }
2211         return expand_upwards(vma, address);
2212 }
2213 
2214 struct vm_area_struct *
2215 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2216 {
2217         struct vm_area_struct *vma, *prev;
2218 
2219         addr &= PAGE_MASK;
2220         vma = find_vma_prev(mm, addr, &prev);
2221         if (vma && (vma->vm_start <= addr))
2222                 return vma;
2223         if (!prev || expand_stack(prev, addr))
2224                 return NULL;
2225         if (prev->vm_flags & VM_LOCKED)
2226                 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2227         return prev;
2228 }
2229 #else
2230 int expand_stack(struct vm_area_struct *vma, unsigned long address)
2231 {
2232         struct vm_area_struct *prev;
2233 
2234         address &= PAGE_MASK;
2235         prev = vma->vm_prev;
2236         if (prev && prev->vm_end == address) {
2237                 if (!(prev->vm_flags & VM_GROWSDOWN))
2238                         return -ENOMEM;
2239         }
2240         return expand_downwards(vma, address);
2241 }
2242 
2243 struct vm_area_struct *
2244 find_extend_vma(struct mm_struct *mm, unsigned long addr)
2245 {
2246         struct vm_area_struct *vma;
2247         unsigned long start;
2248 
2249         addr &= PAGE_MASK;
2250         vma = find_vma(mm, addr);
2251         if (!vma)
2252                 return NULL;
2253         if (vma->vm_start <= addr)
2254                 return vma;
2255         if (!(vma->vm_flags & VM_GROWSDOWN))
2256                 return NULL;
2257         start = vma->vm_start;
2258         if (expand_stack(vma, addr))
2259                 return NULL;
2260         if (vma->vm_flags & VM_LOCKED)
2261                 populate_vma_page_range(vma, addr, start, NULL);
2262         return vma;
2263 }
2264 #endif
2265 
2266 EXPORT_SYMBOL_GPL(find_extend_vma);
2267 
2268 /*
2269  * Ok - we have the memory areas we should free on the vma list,
2270  * so release them, and do the vma updates.
2271  *
2272  * Called with the mm semaphore held.
2273  */
2274 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
2275 {
2276         unsigned long nr_accounted = 0;
2277 
2278         /* Update high watermark before we lower total_vm */
2279         update_hiwater_vm(mm);
2280         do {
2281                 long nrpages = vma_pages(vma);
2282 
2283                 if (vma->vm_flags & VM_ACCOUNT)
2284                         nr_accounted += nrpages;
2285                 vm_stat_account(mm, vma->vm_flags, -nrpages);
2286                 vma = remove_vma(vma);
2287         } while (vma);
2288         vm_unacct_memory(nr_accounted);
2289         validate_mm(mm);
2290 }
2291 
2292 /*
2293  * Get rid of page table information in the indicated region.
2294  *
2295  * Called with the mm semaphore held.
2296  */
2297 static void unmap_region(struct mm_struct *mm,
2298                 struct vm_area_struct *vma, struct vm_area_struct *prev,
2299                 unsigned long start, unsigned long end)
2300 {
2301         struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap;
2302         struct mmu_gather tlb;
2303 
2304         lru_add_drain();
2305         tlb_gather_mmu(&tlb, mm, start, end);
2306         update_hiwater_rss(mm);
2307         unmap_vmas(&tlb, vma, start, end);
2308         free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
2309                                  next ? next->vm_start : USER_PGTABLES_CEILING);
2310         tlb_finish_mmu(&tlb, start, end);
2311 }
2312 
2313 /*
2314  * Create a list of vma's touched by the unmap, removing them from the mm's
2315  * vma list as we go..
2316  */
2317 static void
2318 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
2319         struct vm_area_struct *prev, unsigned long end)
2320 {
2321         struct vm_area_struct **insertion_point;
2322         struct vm_area_struct *tail_vma = NULL;
2323 
2324         insertion_point = (prev ? &prev->vm_next : &mm->mmap);
2325         vma->vm_prev = NULL;
2326         do {
2327                 vma_rb_erase(vma, &mm->mm_rb);
2328                 mm->map_count--;
2329                 tail_vma = vma;
2330                 vma = vma->vm_next;
2331         } while (vma && vma->vm_start < end);
2332         *insertion_point = vma;
2333         if (vma) {
2334                 vma->vm_prev = prev;
2335                 vma_gap_update(vma);
2336         } else
2337                 mm->highest_vm_end = prev ? prev->vm_end : 0;
2338         tail_vma->vm_next = NULL;
2339 
2340         /* Kill the cache */
2341         vmacache_invalidate(mm);
2342 }
2343 
2344 /*
2345  * __split_vma() bypasses sysctl_max_map_count checking.  We use this on the
2346  * munmap path where it doesn't make sense to fail.
2347  */
2348 static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2349               unsigned long addr, int new_below)
2350 {
2351         struct vm_area_struct *new;
2352         int err;
2353 
2354         if (is_vm_hugetlb_page(vma) && (addr &
2355                                         ~(huge_page_mask(hstate_vma(vma)))))
2356                 return -EINVAL;
2357 
2358         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2359         if (!new)
2360                 return -ENOMEM;
2361 
2362         /* most fields are the same, copy all, and then fixup */
2363         *new = *vma;
2364 
2365         INIT_LIST_HEAD(&new->anon_vma_chain);
2366 
2367         if (new_below)
2368                 new->vm_end = addr;
2369         else {
2370                 new->vm_start = addr;
2371                 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2372         }
2373 
2374         err = vma_dup_policy(vma, new);
2375         if (err)
2376                 goto out_free_vma;
2377 
2378         err = anon_vma_clone(new, vma);
2379         if (err)
2380                 goto out_free_mpol;
2381 
2382         if (new->vm_file)
2383                 get_file(new->vm_file);
2384 
2385         if (new->vm_ops && new->vm_ops->open)
2386                 new->vm_ops->open(new);
2387 
2388         if (new_below)
2389                 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2390                         ((addr - new->vm_start) >> PAGE_SHIFT), new);
2391         else
2392                 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2393 
2394         /* Success. */
2395         if (!err)
2396                 return 0;
2397 
2398         /* Clean everything up if vma_adjust failed. */
2399         if (new->vm_ops && new->vm_ops->close)
2400                 new->vm_ops->close(new);
2401         if (new->vm_file)
2402                 fput(new->vm_file);
2403         unlink_anon_vmas(new);
2404  out_free_mpol:
2405         mpol_put(vma_policy(new));
2406  out_free_vma:
2407         kmem_cache_free(vm_area_cachep, new);
2408         return err;
2409 }
2410 
2411 /*
2412  * Split a vma into two pieces at address 'addr', a new vma is allocated
2413  * either for the first part or the tail.
2414  */
2415 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2416               unsigned long addr, int new_below)
2417 {
2418         if (mm->map_count >= sysctl_max_map_count)
2419                 return -ENOMEM;
2420 
2421         return __split_vma(mm, vma, addr, new_below);
2422 }
2423 
2424 /* Munmap is split into 2 main parts -- this part which finds
2425  * what needs doing, and the areas themselves, which do the
2426  * work.  This now handles partial unmappings.
2427  * Jeremy Fitzhardinge <jeremy@goop.org>
2428  */
2429 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2430 {
2431         unsigned long end;
2432         struct vm_area_struct *vma, *prev, *last;
2433 
2434         if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2435                 return -EINVAL;
2436 
2437         len = PAGE_ALIGN(len);
2438         if (len == 0)
2439                 return -EINVAL;
2440 
2441         /* Find the first overlapping VMA */
2442         vma = find_vma(mm, start);
2443         if (!vma)
2444                 return 0;
2445         prev = vma->vm_prev;
2446         /* we have  start < vma->vm_end  */
2447 
2448         /* if it doesn't overlap, we have nothing.. */
2449         end = start + len;
2450         if (vma->vm_start >= end)
2451                 return 0;
2452 
2453         /*
2454          * If we need to split any vma, do it now to save pain later.
2455          *
2456          * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2457          * unmapped vm_area_struct will remain in use: so lower split_vma
2458          * places tmp vma above, and higher split_vma places tmp vma below.
2459          */
2460         if (start > vma->vm_start) {
2461                 int error;
2462 
2463                 /*
2464                  * Make sure that map_count on return from munmap() will
2465                  * not exceed its limit; but let map_count go just above
2466                  * its limit temporarily, to help free resources as expected.
2467                  */
2468                 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2469                         return -ENOMEM;
2470 
2471                 error = __split_vma(mm, vma, start, 0);
2472                 if (error)
2473                         return error;
2474                 prev = vma;
2475         }
2476 
2477         /* Does it split the last one? */
2478         last = find_vma(mm, end);
2479         if (last && end > last->vm_start) {
2480                 int error = __split_vma(mm, last, end, 1);
2481                 if (error)
2482                         return error;
2483         }
2484         vma = prev ? prev->vm_next : mm->mmap;
2485 
2486         /*
2487          * unlock any mlock()ed ranges before detaching vmas
2488          */
2489         if (mm->locked_vm) {
2490                 struct vm_area_struct *tmp = vma;
2491                 while (tmp && tmp->vm_start < end) {
2492                         if (tmp->vm_flags & VM_LOCKED) {
2493                                 mm->locked_vm -= vma_pages(tmp);
2494                                 munlock_vma_pages_all(tmp);
2495                         }
2496                         tmp = tmp->vm_next;
2497                 }
2498         }
2499 
2500         /*
2501          * Remove the vma's, and unmap the actual pages
2502          */
2503         detach_vmas_to_be_unmapped(mm, vma, prev, end);
2504         unmap_region(mm, vma, prev, start, end);
2505 
2506         arch_unmap(mm, vma, start, end);
2507 
2508         /* Fix up all other VM information */
2509         remove_vma_list(mm, vma);
2510 
2511         return 0;
2512 }
2513 
2514 int vm_munmap(unsigned long start, size_t len)
2515 {
2516         int ret;
2517         struct mm_struct *mm = current->mm;
2518 
2519         if (down_write_killable(&mm->mmap_sem))
2520                 return -EINTR;
2521 
2522         ret = do_munmap(mm, start, len);
2523         up_write(&mm->mmap_sem);
2524         return ret;
2525 }
2526 EXPORT_SYMBOL(vm_munmap);
2527 
2528 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2529 {
2530         int ret;
2531         struct mm_struct *mm = current->mm;
2532 
2533         profile_munmap(addr);
2534         if (down_write_killable(&mm->mmap_sem))
2535                 return -EINTR;
2536         ret = do_munmap(mm, addr, len);
2537         up_write(&mm->mmap_sem);
2538         return ret;
2539 }
2540 
2541 
2542 /*
2543  * Emulation of deprecated remap_file_pages() syscall.
2544  */
2545 SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
2546                 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
2547 {
2548 
2549         struct mm_struct *mm = current->mm;
2550         struct vm_area_struct *vma;
2551         unsigned long populate = 0;
2552         unsigned long ret = -EINVAL;
2553         struct file *file;
2554 
2555         pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.txt.\n",
2556                      current->comm, current->pid);
2557 
2558         if (prot)
2559                 return ret;
2560         start = start & PAGE_MASK;
2561         size = size & PAGE_MASK;
2562 
2563         if (start + size <= start)
2564                 return ret;
2565 
2566         /* Does pgoff wrap? */
2567         if (pgoff + (size >> PAGE_SHIFT) < pgoff)
2568                 return ret;
2569 
2570         if (down_write_killable(&mm->mmap_sem))
2571                 return -EINTR;
2572 
2573         vma = find_vma(mm, start);
2574 
2575         if (!vma || !(vma->vm_flags & VM_SHARED))
2576                 goto out;
2577 
2578         if (start < vma->vm_start)
2579                 goto out;
2580 
2581         if (start + size > vma->vm_end) {
2582                 struct vm_area_struct *next;
2583 
2584                 for (next = vma->vm_next; next; next = next->vm_next) {
2585                         /* hole between vmas ? */
2586                         if (next->vm_start != next->vm_prev->vm_end)
2587                                 goto out;
2588 
2589                         if (next->vm_file != vma->vm_file)
2590                                 goto out;
2591 
2592                         if (next->vm_flags != vma->vm_flags)
2593                                 goto out;
2594 
2595                         if (start + size <= next->vm_end)
2596                                 break;
2597                 }
2598 
2599                 if (!next)
2600                         goto out;
2601         }
2602 
2603         prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
2604         prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
2605         prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
2606 
2607         flags &= MAP_NONBLOCK;
2608         flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
2609         if (vma->vm_flags & VM_LOCKED) {
2610                 struct vm_area_struct *tmp;
2611                 flags |= MAP_LOCKED;
2612 
2613                 /* drop PG_Mlocked flag for over-mapped range */
2614                 for (tmp = vma; tmp->vm_start >= start + size;
2615                                 tmp = tmp->vm_next) {
2616                         /*
2617                          * Split pmd and munlock page on the border
2618                          * of the range.
2619                          */
2620                         vma_adjust_trans_huge(tmp, start, start + size, 0);
2621 
2622                         munlock_vma_pages_range(tmp,
2623                                         max(tmp->vm_start, start),
2624                                         min(tmp->vm_end, start + size));
2625                 }
2626         }
2627 
2628         file = get_file(vma->vm_file);
2629         ret = do_mmap_pgoff(vma->vm_file, start, size,
2630                         prot, flags, pgoff, &populate);
2631         fput(file);
2632 out:
2633         up_write(&mm->mmap_sem);
2634         if (populate)
2635                 mm_populate(ret, populate);
2636         if (!IS_ERR_VALUE(ret))
2637                 ret = 0;
2638         return ret;
2639 }
2640 
2641 static inline void verify_mm_writelocked(struct mm_struct *mm)
2642 {
2643 #ifdef CONFIG_DEBUG_VM
2644         if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2645                 WARN_ON(1);
2646                 up_read(&mm->mmap_sem);
2647         }
2648 #endif
2649 }
2650 
2651 /*
2652  *  this is really a simplified "do_mmap".  it only handles
2653  *  anonymous maps.  eventually we may be able to do some
2654  *  brk-specific accounting here.
2655  */
2656 static int do_brk(unsigned long addr, unsigned long request)
2657 {
2658         struct mm_struct *mm = current->mm;
2659         struct vm_area_struct *vma, *prev;
2660         unsigned long flags, len;
2661         struct rb_node **rb_link, *rb_parent;
2662         pgoff_t pgoff = addr >> PAGE_SHIFT;
2663         int error;
2664 
2665         len = PAGE_ALIGN(request);
2666         if (len < request)
2667                 return -ENOMEM;
2668         if (!len)
2669                 return 0;
2670 
2671         flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2672 
2673         error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2674         if (offset_in_page(error))
2675                 return error;
2676 
2677         error = mlock_future_check(mm, mm->def_flags, len);
2678         if (error)
2679                 return error;
2680 
2681         /*
2682          * mm->mmap_sem is required to protect against another thread
2683          * changing the mappings in case we sleep.
2684          */
2685         verify_mm_writelocked(mm);
2686 
2687         /*
2688          * Clear old maps.  this also does some error checking for us
2689          */
2690         while (find_vma_links(mm, addr, addr + len, &prev, &rb_link,
2691                               &rb_parent)) {
2692                 if (do_munmap(mm, addr, len))
2693                         return -ENOMEM;
2694         }
2695 
2696         /* Check against address space limits *after* clearing old maps... */
2697         if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
2698                 return -ENOMEM;
2699 
2700         if (mm->map_count > sysctl_max_map_count)
2701                 return -ENOMEM;
2702 
2703         if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2704                 return -ENOMEM;
2705 
2706         /* Can we just expand an old private anonymous mapping? */
2707         vma = vma_merge(mm, prev, addr, addr + len, flags,
2708                         NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX);
2709         if (vma)
2710                 goto out;
2711 
2712         /*
2713          * create a vma struct for an anonymous mapping
2714          */
2715         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2716         if (!vma) {
2717                 vm_unacct_memory(len >> PAGE_SHIFT);
2718                 return -ENOMEM;
2719         }
2720 
2721         INIT_LIST_HEAD(&vma->anon_vma_chain);
2722         vma->vm_mm = mm;
2723         vma->vm_start = addr;
2724         vma->vm_end = addr + len;
2725         vma->vm_pgoff = pgoff;
2726         vma->vm_flags = flags;
2727         vma->vm_page_prot = vm_get_page_prot(flags);
2728         vma_link(mm, vma, prev, rb_link, rb_parent);
2729 out:
2730         perf_event_mmap(vma);
2731         mm->total_vm += len >> PAGE_SHIFT;
2732         mm->data_vm += len >> PAGE_SHIFT;
2733         if (flags & VM_LOCKED)
2734                 mm->locked_vm += (len >> PAGE_SHIFT);
2735         vma->vm_flags |= VM_SOFTDIRTY;
2736         return 0;
2737 }
2738 
2739 int vm_brk(unsigned long addr, unsigned long len)
2740 {
2741         struct mm_struct *mm = current->mm;
2742         int ret;
2743         bool populate;
2744 
2745         if (down_write_killable(&mm->mmap_sem))
2746                 return -EINTR;
2747 
2748         ret = do_brk(addr, len);
2749         populate = ((mm->def_flags & VM_LOCKED) != 0);
2750         up_write(&mm->mmap_sem);
2751         if (populate && !ret)
2752                 mm_populate(addr, len);
2753         return ret;
2754 }
2755 EXPORT_SYMBOL(vm_brk);
2756 
2757 /* Release all mmaps. */
2758 void exit_mmap(struct mm_struct *mm)
2759 {
2760         struct mmu_gather tlb;
2761         struct vm_area_struct *vma;
2762         unsigned long nr_accounted = 0;
2763 
2764         /* mm's last user has gone, and its about to be pulled down */
2765         mmu_notifier_release(mm);
2766 
2767         if (mm->locked_vm) {
2768                 vma = mm->mmap;
2769                 while (vma) {
2770                         if (vma->vm_flags & VM_LOCKED)
2771                                 munlock_vma_pages_all(vma);
2772                         vma = vma->vm_next;
2773                 }
2774         }
2775 
2776         arch_exit_mmap(mm);
2777 
2778         vma = mm->mmap;
2779         if (!vma)       /* Can happen if dup_mmap() received an OOM */
2780                 return;
2781 
2782         lru_add_drain();
2783         flush_cache_mm(mm);
2784         tlb_gather_mmu(&tlb, mm, 0, -1);
2785         /* update_hiwater_rss(mm) here? but nobody should be looking */
2786         /* Use -1 here to ensure all VMAs in the mm are unmapped */
2787         unmap_vmas(&tlb, vma, 0, -1);
2788 
2789         free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING);
2790         tlb_finish_mmu(&tlb, 0, -1);
2791 
2792         /*
2793          * Walk the list again, actually closing and freeing it,
2794          * with preemption enabled, without holding any MM locks.
2795          */
2796         while (vma) {
2797                 if (vma->vm_flags & VM_ACCOUNT)
2798                         nr_accounted += vma_pages(vma);
2799                 vma = remove_vma(vma);
2800         }
2801         vm_unacct_memory(nr_accounted);
2802 }
2803 
2804 /* Insert vm structure into process list sorted by address
2805  * and into the inode's i_mmap tree.  If vm_file is non-NULL
2806  * then i_mmap_rwsem is taken here.
2807  */
2808 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
2809 {
2810         struct vm_area_struct *prev;
2811         struct rb_node **rb_link, *rb_parent;
2812 
2813         if (find_vma_links(mm, vma->vm_start, vma->vm_end,
2814                            &prev, &rb_link, &rb_parent))
2815                 return -ENOMEM;
2816         if ((vma->vm_flags & VM_ACCOUNT) &&
2817              security_vm_enough_memory_mm(mm, vma_pages(vma)))
2818                 return -ENOMEM;
2819 
2820         /*
2821          * The vm_pgoff of a purely anonymous vma should be irrelevant
2822          * until its first write fault, when page's anon_vma and index
2823          * are set.  But now set the vm_pgoff it will almost certainly
2824          * end up with (unless mremap moves it elsewhere before that
2825          * first wfault), so /proc/pid/maps tells a consistent story.
2826          *
2827          * By setting it to reflect the virtual start address of the
2828          * vma, merges and splits can happen in a seamless way, just
2829          * using the existing file pgoff checks and manipulations.
2830          * Similarly in do_mmap_pgoff and in do_brk.
2831          */
2832         if (vma_is_anonymous(vma)) {
2833                 BUG_ON(vma->anon_vma);
2834                 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2835         }
2836 
2837         vma_link(mm, vma, prev, rb_link, rb_parent);
2838         return 0;
2839 }
2840 
2841 /*
2842  * Copy the vma structure to a new location in the same mm,
2843  * prior to moving page table entries, to effect an mremap move.
2844  */
2845 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2846         unsigned long addr, unsigned long len, pgoff_t pgoff,
2847         bool *need_rmap_locks)
2848 {
2849         struct vm_area_struct *vma = *vmap;
2850         unsigned long vma_start = vma->vm_start;
2851         struct mm_struct *mm = vma->vm_mm;
2852         struct vm_area_struct *new_vma, *prev;
2853         struct rb_node **rb_link, *rb_parent;
2854         bool faulted_in_anon_vma = true;
2855 
2856         /*
2857          * If anonymous vma has not yet been faulted, update new pgoff
2858          * to match new location, to increase its chance of merging.
2859          */
2860         if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
2861                 pgoff = addr >> PAGE_SHIFT;
2862                 faulted_in_anon_vma = false;
2863         }
2864 
2865         if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent))
2866                 return NULL;    /* should never get here */
2867         new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2868                             vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
2869                             vma->vm_userfaultfd_ctx);
2870         if (new_vma) {
2871                 /*
2872                  * Source vma may have been merged into new_vma
2873                  */
2874                 if (unlikely(vma_start >= new_vma->vm_start &&
2875                              vma_start < new_vma->vm_end)) {
2876                         /*
2877                          * The only way we can get a vma_merge with
2878                          * self during an mremap is if the vma hasn't
2879                          * been faulted in yet and we were allowed to
2880                          * reset the dst vma->vm_pgoff to the
2881                          * destination address of the mremap to allow
2882                          * the merge to happen. mremap must change the
2883                          * vm_pgoff linearity between src and dst vmas
2884                          * (in turn preventing a vma_merge) to be
2885                          * safe. It is only safe to keep the vm_pgoff
2886                          * linear if there are no pages mapped yet.
2887                          */
2888                         VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
2889                         *vmap = vma = new_vma;
2890                 }
2891                 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
2892         } else {
2893                 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2894                 if (!new_vma)
2895                         goto out;
2896                 *new_vma = *vma;
2897                 new_vma->vm_start = addr;
2898                 new_vma->vm_end = addr + len;
2899                 new_vma->vm_pgoff = pgoff;
2900                 if (vma_dup_policy(vma, new_vma))
2901                         goto out_free_vma;
2902                 INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2903                 if (anon_vma_clone(new_vma, vma))
2904                         goto out_free_mempol;
2905                 if (new_vma->vm_file)
2906                         get_file(new_vma->vm_file);
2907                 if (new_vma->vm_ops && new_vma->vm_ops->open)
2908                         new_vma->vm_ops->open(new_vma);
2909                 vma_link(mm, new_vma, prev, rb_link, rb_parent);
2910                 *need_rmap_locks = false;
2911         }
2912         return new_vma;
2913 
2914 out_free_mempol:
2915         mpol_put(vma_policy(new_vma));
2916 out_free_vma:
2917         kmem_cache_free(vm_area_cachep, new_vma);
2918 out:
2919         return NULL;
2920 }
2921 
2922 /*
2923  * Return true if the calling process may expand its vm space by the passed
2924  * number of pages
2925  */
2926 bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
2927 {
2928         if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
2929                 return false;
2930 
2931         if (is_data_mapping(flags) &&
2932             mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
2933                 /* Workaround for Valgrind */
2934                 if (rlimit(RLIMIT_DATA) == 0 &&
2935                     mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
2936                         return true;
2937                 if (!ignore_rlimit_data) {
2938                         pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits or use boot option ignore_rlimit_data.\n",
2939                                      current->comm, current->pid,
2940                                      (mm->data_vm + npages) << PAGE_SHIFT,
2941                                      rlimit(RLIMIT_DATA));
2942                         return false;
2943                 }
2944         }
2945 
2946         return true;
2947 }
2948 
2949 void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
2950 {
2951         mm->total_vm += npages;
2952 
2953         if (is_exec_mapping(flags))
2954                 mm->exec_vm += npages;
2955         else if (is_stack_mapping(flags))
2956                 mm->stack_vm += npages;
2957         else if (is_data_mapping(flags))
2958                 mm->data_vm += npages;
2959 }
2960 
2961 static int special_mapping_fault(struct vm_area_struct *vma,
2962                                  struct vm_fault *vmf);
2963 
2964 /*
2965  * Having a close hook prevents vma merging regardless of flags.
2966  */
2967 static void special_mapping_close(struct vm_area_struct *vma)
2968 {
2969 }
2970 
2971 static const char *special_mapping_name(struct vm_area_struct *vma)
2972 {
2973         return ((struct vm_special_mapping *)vma->vm_private_data)->name;
2974 }
2975 
2976 static int special_mapping_mremap(struct vm_area_struct *new_vma)
2977 {
2978         struct vm_special_mapping *sm = new_vma->vm_private_data;
2979 
2980         if (sm->mremap)
2981                 return sm->mremap(sm, new_vma);
2982         return 0;
2983 }
2984 
2985 static const struct vm_operations_struct special_mapping_vmops = {
2986         .close = special_mapping_close,
2987         .fault = special_mapping_fault,
2988         .mremap = special_mapping_mremap,
2989         .name = special_mapping_name,
2990 };
2991 
2992 static const struct vm_operations_struct legacy_special_mapping_vmops = {
2993         .close = special_mapping_close,
2994         .fault = special_mapping_fault,
2995 };
2996 
2997 static int special_mapping_fault(struct vm_area_struct *vma,
2998                                 struct vm_fault *vmf)
2999 {
3000         pgoff_t pgoff;
3001         struct page **pages;
3002 
3003         if (vma->vm_ops == &legacy_special_mapping_vmops) {
3004                 pages = vma->vm_private_data;
3005         } else {
3006                 struct vm_special_mapping *sm = vma->vm_private_data;
3007 
3008                 if (sm->fault)
3009                         return sm->fault(sm, vma, vmf);
3010 
3011                 pages = sm->pages;
3012         }
3013 
3014         for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3015                 pgoff--;
3016 
3017         if (*pages) {
3018                 struct page *page = *pages;
3019                 get_page(page);
3020                 vmf->page = page;
3021                 return 0;
3022         }
3023 
3024         return VM_FAULT_SIGBUS;
3025 }
3026 
3027 static struct vm_area_struct *__install_special_mapping(
3028         struct mm_struct *mm,
3029         unsigned long addr, unsigned long len,
3030         unsigned long vm_flags, void *priv,
3031         const struct vm_operations_struct *ops)
3032 {
3033         int ret;
3034         struct vm_area_struct *vma;
3035 
3036         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
3037         if (unlikely(vma == NULL))
3038                 return ERR_PTR(-ENOMEM);
3039 
3040         INIT_LIST_HEAD(&vma->anon_vma_chain);
3041         vma->vm_mm = mm;
3042         vma->vm_start = addr;
3043         vma->vm_end = addr + len;
3044 
3045         vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY;
3046         vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
3047 
3048         vma->vm_ops = ops;
3049         vma->vm_private_data = priv;
3050 
3051         ret = insert_vm_struct(mm, vma);
3052         if (ret)
3053                 goto out;
3054 
3055         vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
3056 
3057         perf_event_mmap(vma);
3058 
3059         return vma;
3060 
3061 out:
3062         kmem_cache_free(vm_area_cachep, vma);
3063         return ERR_PTR(ret);
3064 }
3065 
3066 /*
3067  * Called with mm->mmap_sem held for writing.
3068  * Insert a new vma covering the given region, with the given flags.
3069  * Its pages are supplied by the given array of struct page *.
3070  * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3071  * The region past the last page supplied will always produce SIGBUS.
3072  * The array pointer and the pages it points to are assumed to stay alive
3073  * for as long as this mapping might exist.
3074  */
3075 struct vm_area_struct *_install_special_mapping(
3076         struct mm_struct *mm,
3077         unsigned long addr, unsigned long len,
3078         unsigned long vm_flags, const struct vm_special_mapping *spec)
3079 {
3080         return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec,
3081                                         &special_mapping_vmops);
3082 }
3083 
3084 int install_special_mapping(struct mm_struct *mm,
3085                             unsigned long addr, unsigned long len,
3086                             unsigned long vm_flags, struct page **pages)
3087 {
3088         struct vm_area_struct *vma = __install_special_mapping(
3089                 mm, addr, len, vm_flags, (void *)pages,
3090                 &legacy_special_mapping_vmops);
3091 
3092         return PTR_ERR_OR_ZERO(vma);
3093 }
3094 
3095 static DEFINE_MUTEX(mm_all_locks_mutex);
3096 
3097 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3098 {
3099         if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3100                 /*
3101                  * The LSB of head.next can't change from under us
3102                  * because we hold the mm_all_locks_mutex.
3103                  */
3104                 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem);
3105                 /*
3106                  * We can safely modify head.next after taking the
3107                  * anon_vma->root->rwsem. If some other vma in this mm shares
3108                  * the same anon_vma we won't take it again.
3109                  *
3110                  * No need of atomic instructions here, head.next
3111                  * can't change from under us thanks to the
3112                  * anon_vma->root->rwsem.
3113                  */
3114                 if (__test_and_set_bit(0, (unsigned long *)
3115                                        &anon_vma->root->rb_root.rb_node))
3116                         BUG();
3117         }
3118 }
3119 
3120 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3121 {
3122         if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3123                 /*
3124                  * AS_MM_ALL_LOCKS can't change from under us because
3125                  * we hold the mm_all_locks_mutex.
3126                  *
3127                  * Operations on ->flags have to be atomic because
3128                  * even if AS_MM_ALL_LOCKS is stable thanks to the
3129                  * mm_all_locks_mutex, there may be other cpus
3130                  * changing other bitflags in parallel to us.
3131                  */
3132                 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
3133                         BUG();
3134                 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem);
3135         }
3136 }
3137 
3138 /*
3139  * This operation locks against the VM for all pte/vma/mm related
3140  * operations that could ever happen on a certain mm. This includes
3141  * vmtruncate, try_to_unmap, and all page faults.
3142  *
3143  * The caller must take the mmap_sem in write mode before calling
3144  * mm_take_all_locks(). The caller isn't allowed to release the
3145  * mmap_sem until mm_drop_all_locks() returns.
3146  *
3147  * mmap_sem in write mode is required in order to block all operations
3148  * that could modify pagetables and free pages without need of
3149  * altering the vma layout. It's also needed in write mode to avoid new
3150  * anon_vmas to be associated with existing vmas.
3151  *
3152  * A single task can't take more than one mm_take_all_locks() in a row
3153  * or it would deadlock.
3154  *
3155  * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3156  * mapping->flags avoid to take the same lock twice, if more than one
3157  * vma in this mm is backed by the same anon_vma or address_space.
3158  *
3159  * We take locks in following order, accordingly to comment at beginning
3160  * of mm/rmap.c:
3161  *   - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3162  *     hugetlb mapping);
3163  *   - all i_mmap_rwsem locks;
3164  *   - all anon_vma->rwseml
3165  *
3166  * We can take all locks within these types randomly because the VM code
3167  * doesn't nest them and we protected from parallel mm_take_all_locks() by
3168  * mm_all_locks_mutex.
3169  *
3170  * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3171  * that may have to take thousand of locks.
3172  *
3173  * mm_take_all_locks() can fail if it's interrupted by signals.
3174  */
3175 int mm_take_all_locks(struct mm_struct *mm)
3176 {
3177         struct vm_area_struct *vma;
3178         struct anon_vma_chain *avc;
3179 
3180         BUG_ON(down_read_trylock(&mm->mmap_sem));
3181 
3182         mutex_lock(&mm_all_locks_mutex);
3183 
3184         for (vma = mm->mmap; vma; vma = vma->vm_next) {
3185                 if (signal_pending(current))
3186                         goto out_unlock;
3187                 if (vma->vm_file && vma->vm_file->f_mapping &&
3188                                 is_vm_hugetlb_page(vma))
3189                         vm_lock_mapping(mm, vma->vm_file->f_mapping);
3190         }
3191 
3192         for (vma = mm->mmap; vma; vma = vma->vm_next) {
3193                 if (signal_pending(current))
3194                         goto out_unlock;
3195                 if (vma->vm_file && vma->vm_file->f_mapping &&
3196                                 !is_vm_hugetlb_page(vma))
3197                         vm_lock_mapping(mm, vma->vm_file->f_mapping);
3198         }
3199 
3200         for (vma = mm->mmap; vma; vma = vma->vm_next) {
3201                 if (signal_pending(current))
3202                         goto out_unlock;
3203                 if (vma->anon_vma)
3204                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3205                                 vm_lock_anon_vma(mm, avc->anon_vma);
3206         }
3207 
3208         return 0;
3209 
3210 out_unlock:
3211         mm_drop_all_locks(mm);
3212         return -EINTR;
3213 }
3214 
3215 static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3216 {
3217         if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) {
3218                 /*
3219                  * The LSB of head.next can't change to 0 from under
3220                  * us because we hold the mm_all_locks_mutex.
3221                  *
3222                  * We must however clear the bitflag before unlocking
3223                  * the vma so the users using the anon_vma->rb_root will
3224                  * never see our bitflag.
3225                  *
3226                  * No need of atomic instructions here, head.next
3227                  * can't change from under us until we release the
3228                  * anon_vma->root->rwsem.
3229                  */
3230                 if (!__test_and_clear_bit(0, (unsigned long *)
3231                                           &anon_vma->root->rb_root.rb_node))
3232                         BUG();
3233                 anon_vma_unlock_write(anon_vma);
3234         }
3235 }
3236 
3237 static void vm_unlock_mapping(struct address_space *mapping)
3238 {
3239         if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3240                 /*
3241                  * AS_MM_ALL_LOCKS can't change to 0 from under us
3242                  * because we hold the mm_all_locks_mutex.
3243                  */
3244                 i_mmap_unlock_write(mapping);
3245                 if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
3246                                         &mapping->flags))
3247                         BUG();
3248         }
3249 }
3250 
3251 /*
3252  * The mmap_sem cannot be released by the caller until
3253  * mm_drop_all_locks() returns.
3254  */
3255 void mm_drop_all_locks(struct mm_struct *mm)
3256 {
3257         struct vm_area_struct *vma;
3258         struct anon_vma_chain *avc;
3259 
3260         BUG_ON(down_read_trylock(&mm->mmap_sem));
3261         BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3262 
3263         for (vma = mm->mmap; vma; vma = vma->vm_next) {
3264                 if (vma->anon_vma)
3265                         list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3266                                 vm_unlock_anon_vma(avc->anon_vma);
3267                 if (vma->vm_file && vma->vm_file->f_mapping)
3268                         vm_unlock_mapping(vma->vm_file->f_mapping);
3269         }
3270 
3271         mutex_unlock(&mm_all_locks_mutex);
3272 }
3273 
3274 /*
3275  * initialise the VMA slab
3276  */
3277 void __init mmap_init(void)
3278 {
3279         int ret;
3280 
3281         ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3282         VM_BUG_ON(ret);
3283 }
3284 
3285 /*
3286  * Initialise sysctl_user_reserve_kbytes.
3287  *
3288  * This is intended to prevent a user from starting a single memory hogging
3289  * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3290  * mode.
3291  *
3292  * The default value is min(3% of free memory, 128MB)
3293  * 128MB is enough to recover with sshd/login, bash, and top/kill.
3294  */
3295 static int init_user_reserve(void)
3296 {
3297         unsigned long free_kbytes;
3298 
3299         free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3300 
3301         sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3302         return 0;
3303 }
3304 subsys_initcall(init_user_reserve);
3305 
3306 /*
3307  * Initialise sysctl_admin_reserve_kbytes.
3308  *
3309  * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3310  * to log in and kill a memory hogging process.
3311  *
3312  * Systems with more than 256MB will reserve 8MB, enough to recover
3313  * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3314  * only reserve 3% of free pages by default.
3315  */
3316 static int init_admin_reserve(void)
3317 {
3318         unsigned long free_kbytes;
3319 
3320         free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3321 
3322         sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3323         return 0;
3324 }
3325 subsys_initcall(init_admin_reserve);
3326 
3327 /*
3328  * Reinititalise user and admin reserves if memory is added or removed.
3329  *
3330  * The default user reserve max is 128MB, and the default max for the
3331  * admin reserve is 8MB. These are usually, but not always, enough to
3332  * enable recovery from a memory hogging process using login/sshd, a shell,
3333  * and tools like top. It may make sense to increase or even disable the
3334  * reserve depending on the existence of swap or variations in the recovery
3335  * tools. So, the admin may have changed them.
3336  *
3337  * If memory is added and the reserves have been eliminated or increased above
3338  * the default max, then we'll trust the admin.
3339  *
3340  * If memory is removed and there isn't enough free memory, then we
3341  * need to reset the reserves.
3342  *
3343  * Otherwise keep the reserve set by the admin.
3344  */
3345 static int reserve_mem_notifier(struct notifier_block *nb,
3346                              unsigned long action, void *data)
3347 {
3348         unsigned long tmp, free_kbytes;
3349 
3350         switch (action) {
3351         case MEM_ONLINE:
3352                 /* Default max is 128MB. Leave alone if modified by operator. */
3353                 tmp = sysctl_user_reserve_kbytes;
3354                 if (0 < tmp && tmp < (1UL << 17))
3355                         init_user_reserve();
3356 
3357                 /* Default max is 8MB.  Leave alone if modified by operator. */
3358                 tmp = sysctl_admin_reserve_kbytes;
3359                 if (0 < tmp && tmp < (1UL << 13))
3360                         init_admin_reserve();
3361 
3362                 break;
3363         case MEM_OFFLINE:
3364                 free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
3365 
3366                 if (sysctl_user_reserve_kbytes > free_kbytes) {
3367                         init_user_reserve();
3368                         pr_info("vm.user_reserve_kbytes reset to %lu\n",
3369                                 sysctl_user_reserve_kbytes);
3370                 }
3371 
3372                 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3373                         init_admin_reserve();
3374                         pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3375                                 sysctl_admin_reserve_kbytes);
3376                 }
3377                 break;
3378         default:
3379                 break;
3380         }
3381         return NOTIFY_OK;
3382 }
3383 
3384 static struct notifier_block reserve_mem_nb = {
3385         .notifier_call = reserve_mem_notifier,
3386 };
3387 
3388 static int __meminit init_reserve_notifier(void)
3389 {
3390         if (register_hotmemory_notifier(&reserve_mem_nb))
3391                 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3392 
3393         return 0;
3394 }
3395 subsys_initcall(init_reserve_notifier);
3396 

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