Root/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#include <linux/slab.h>
10#include <linux/backing-dev.h>
11#include <linux/mm.h>
12#include <linux/shm.h>
13#include <linux/mman.h>
14#include <linux/pagemap.h>
15#include <linux/swap.h>
16#include <linux/syscalls.h>
17#include <linux/capability.h>
18#include <linux/init.h>
19#include <linux/file.h>
20#include <linux/fs.h>
21#include <linux/personality.h>
22#include <linux/security.h>
23#include <linux/hugetlb.h>
24#include <linux/profile.h>
25#include <linux/export.h>
26#include <linux/mount.h>
27#include <linux/mempolicy.h>
28#include <linux/rmap.h>
29#include <linux/mmu_notifier.h>
30#include <linux/perf_event.h>
31#include <linux/audit.h>
32#include <linux/khugepaged.h>
33
34#include <asm/uaccess.h>
35#include <asm/cacheflush.h>
36#include <asm/tlb.h>
37#include <asm/mmu_context.h>
38
39#include "internal.h"
40
41#ifndef arch_mmap_check
42#define arch_mmap_check(addr, len, flags) (0)
43#endif
44
45#ifndef arch_rebalance_pgtables
46#define arch_rebalance_pgtables(addr, len) (addr)
47#endif
48
49static void unmap_region(struct mm_struct *mm,
50        struct vm_area_struct *vma, struct vm_area_struct *prev,
51        unsigned long start, unsigned long end);
52
53/*
54 * WARNING: the debugging will use recursive algorithms so never enable this
55 * unless you know what you are doing.
56 */
57#undef DEBUG_MM_RB
58
59/* description of effects of mapping type and prot in current implementation.
60 * this is due to the limited x86 page protection hardware. The expected
61 * behavior is in parens:
62 *
63 * map_type prot
64 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC
65 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes
66 * w: (no) no w: (no) no w: (yes) yes w: (no) no
67 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
68 *
69 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes
70 * w: (no) no w: (no) no w: (copy) copy w: (no) no
71 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes
72 *
73 */
74pgprot_t protection_map[16] = {
75    __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111,
76    __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111
77};
78
79pgprot_t vm_get_page_prot(unsigned long vm_flags)
80{
81    return __pgprot(pgprot_val(protection_map[vm_flags &
82                (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
83            pgprot_val(arch_vm_get_page_prot(vm_flags)));
84}
85EXPORT_SYMBOL(vm_get_page_prot);
86
87int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */
88int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */
89int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
90/*
91 * Make sure vm_committed_as in one cacheline and not cacheline shared with
92 * other variables. It can be updated by several CPUs frequently.
93 */
94struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp;
95
96/*
97 * Check that a process has enough memory to allocate a new virtual
98 * mapping. 0 means there is enough memory for the allocation to
99 * succeed and -ENOMEM implies there is not.
100 *
101 * We currently support three overcommit policies, which are set via the
102 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
103 *
104 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
105 * Additional code 2002 Jul 20 by Robert Love.
106 *
107 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
108 *
109 * Note this is a helper function intended to be used by LSMs which
110 * wish to use this logic.
111 */
112int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
113{
114    unsigned long free, allowed;
115
116    vm_acct_memory(pages);
117
118    /*
119     * Sometimes we want to use more memory than we have
120     */
121    if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
122        return 0;
123
124    if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
125        free = global_page_state(NR_FREE_PAGES);
126        free += global_page_state(NR_FILE_PAGES);
127
128        /*
129         * shmem pages shouldn't be counted as free in this
130         * case, they can't be purged, only swapped out, and
131         * that won't affect the overall amount of available
132         * memory in the system.
133         */
134        free -= global_page_state(NR_SHMEM);
135
136        free += nr_swap_pages;
137
138        /*
139         * Any slabs which are created with the
140         * SLAB_RECLAIM_ACCOUNT flag claim to have contents
141         * which are reclaimable, under pressure. The dentry
142         * cache and most inode caches should fall into this
143         */
144        free += global_page_state(NR_SLAB_RECLAIMABLE);
145
146        /*
147         * Leave reserved pages. The pages are not for anonymous pages.
148         */
149        if (free <= totalreserve_pages)
150            goto error;
151        else
152            free -= totalreserve_pages;
153
154        /*
155         * Leave the last 3% for root
156         */
157        if (!cap_sys_admin)
158            free -= free / 32;
159
160        if (free > pages)
161            return 0;
162
163        goto error;
164    }
165
166    allowed = (totalram_pages - hugetlb_total_pages())
167               * sysctl_overcommit_ratio / 100;
168    /*
169     * Leave the last 3% for root
170     */
171    if (!cap_sys_admin)
172        allowed -= allowed / 32;
173    allowed += total_swap_pages;
174
175    /* Don't let a single process grow too big:
176       leave 3% of the size of this process for other processes */
177    if (mm)
178        allowed -= mm->total_vm / 32;
179
180    if (percpu_counter_read_positive(&vm_committed_as) < allowed)
181        return 0;
182error:
183    vm_unacct_memory(pages);
184
185    return -ENOMEM;
186}
187
188/*
189 * Requires inode->i_mapping->i_mmap_mutex
190 */
191static void __remove_shared_vm_struct(struct vm_area_struct *vma,
192        struct file *file, struct address_space *mapping)
193{
194    if (vma->vm_flags & VM_DENYWRITE)
195        atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
196    if (vma->vm_flags & VM_SHARED)
197        mapping->i_mmap_writable--;
198
199    flush_dcache_mmap_lock(mapping);
200    if (unlikely(vma->vm_flags & VM_NONLINEAR))
201        list_del_init(&vma->shared.vm_set.list);
202    else
203        vma_prio_tree_remove(vma, &mapping->i_mmap);
204    flush_dcache_mmap_unlock(mapping);
205}
206
207/*
208 * Unlink a file-based vm structure from its prio_tree, to hide
209 * vma from rmap and vmtruncate before freeing its page tables.
210 */
211void unlink_file_vma(struct vm_area_struct *vma)
212{
213    struct file *file = vma->vm_file;
214
215    if (file) {
216        struct address_space *mapping = file->f_mapping;
217        mutex_lock(&mapping->i_mmap_mutex);
218        __remove_shared_vm_struct(vma, file, mapping);
219        mutex_unlock(&mapping->i_mmap_mutex);
220    }
221}
222
223/*
224 * Close a vm structure and free it, returning the next.
225 */
226static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
227{
228    struct vm_area_struct *next = vma->vm_next;
229
230    might_sleep();
231    if (vma->vm_ops && vma->vm_ops->close)
232        vma->vm_ops->close(vma);
233    if (vma->vm_file) {
234        fput(vma->vm_file);
235        if (vma->vm_flags & VM_EXECUTABLE)
236            removed_exe_file_vma(vma->vm_mm);
237    }
238    mpol_put(vma_policy(vma));
239    kmem_cache_free(vm_area_cachep, vma);
240    return next;
241}
242
243static unsigned long do_brk(unsigned long addr, unsigned long len);
244
245SYSCALL_DEFINE1(brk, unsigned long, brk)
246{
247    unsigned long rlim, retval;
248    unsigned long newbrk, oldbrk;
249    struct mm_struct *mm = current->mm;
250    unsigned long min_brk;
251
252    down_write(&mm->mmap_sem);
253
254#ifdef CONFIG_COMPAT_BRK
255    /*
256     * CONFIG_COMPAT_BRK can still be overridden by setting
257     * randomize_va_space to 2, which will still cause mm->start_brk
258     * to be arbitrarily shifted
259     */
260    if (current->brk_randomized)
261        min_brk = mm->start_brk;
262    else
263        min_brk = mm->end_data;
264#else
265    min_brk = mm->start_brk;
266#endif
267    if (brk < min_brk)
268        goto out;
269
270    /*
271     * Check against rlimit here. If this check is done later after the test
272     * of oldbrk with newbrk then it can escape the test and let the data
273     * segment grow beyond its set limit the in case where the limit is
274     * not page aligned -Ram Gupta
275     */
276    rlim = rlimit(RLIMIT_DATA);
277    if (rlim < RLIM_INFINITY && (brk - mm->start_brk) +
278            (mm->end_data - mm->start_data) > rlim)
279        goto out;
280
281    newbrk = PAGE_ALIGN(brk);
282    oldbrk = PAGE_ALIGN(mm->brk);
283    if (oldbrk == newbrk)
284        goto set_brk;
285
286    /* Always allow shrinking brk. */
287    if (brk <= mm->brk) {
288        if (!do_munmap(mm, newbrk, oldbrk-newbrk))
289            goto set_brk;
290        goto out;
291    }
292
293    /* Check against existing mmap mappings. */
294    if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE))
295        goto out;
296
297    /* Ok, looks good - let it rip. */
298    if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk)
299        goto out;
300set_brk:
301    mm->brk = brk;
302out:
303    retval = mm->brk;
304    up_write(&mm->mmap_sem);
305    return retval;
306}
307
308#ifdef DEBUG_MM_RB
309static int browse_rb(struct rb_root *root)
310{
311    int i = 0, j;
312    struct rb_node *nd, *pn = NULL;
313    unsigned long prev = 0, pend = 0;
314
315    for (nd = rb_first(root); nd; nd = rb_next(nd)) {
316        struct vm_area_struct *vma;
317        vma = rb_entry(nd, struct vm_area_struct, vm_rb);
318        if (vma->vm_start < prev)
319            printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1;
320        if (vma->vm_start < pend)
321            printk("vm_start %lx pend %lx\n", vma->vm_start, pend);
322        if (vma->vm_start > vma->vm_end)
323            printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start);
324        i++;
325        pn = nd;
326        prev = vma->vm_start;
327        pend = vma->vm_end;
328    }
329    j = 0;
330    for (nd = pn; nd; nd = rb_prev(nd)) {
331        j++;
332    }
333    if (i != j)
334        printk("backwards %d, forwards %d\n", j, i), i = 0;
335    return i;
336}
337
338void validate_mm(struct mm_struct *mm)
339{
340    int bug = 0;
341    int i = 0;
342    struct vm_area_struct *tmp = mm->mmap;
343    while (tmp) {
344        tmp = tmp->vm_next;
345        i++;
346    }
347    if (i != mm->map_count)
348        printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1;
349    i = browse_rb(&mm->mm_rb);
350    if (i != mm->map_count)
351        printk("map_count %d rb %d\n", mm->map_count, i), bug = 1;
352    BUG_ON(bug);
353}
354#else
355#define validate_mm(mm) do { } while (0)
356#endif
357
358static struct vm_area_struct *
359find_vma_prepare(struct mm_struct *mm, unsigned long addr,
360        struct vm_area_struct **pprev, struct rb_node ***rb_link,
361        struct rb_node ** rb_parent)
362{
363    struct vm_area_struct * vma;
364    struct rb_node ** __rb_link, * __rb_parent, * rb_prev;
365
366    __rb_link = &mm->mm_rb.rb_node;
367    rb_prev = __rb_parent = NULL;
368    vma = NULL;
369
370    while (*__rb_link) {
371        struct vm_area_struct *vma_tmp;
372
373        __rb_parent = *__rb_link;
374        vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb);
375
376        if (vma_tmp->vm_end > addr) {
377            vma = vma_tmp;
378            if (vma_tmp->vm_start <= addr)
379                break;
380            __rb_link = &__rb_parent->rb_left;
381        } else {
382            rb_prev = __rb_parent;
383            __rb_link = &__rb_parent->rb_right;
384        }
385    }
386
387    *pprev = NULL;
388    if (rb_prev)
389        *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
390    *rb_link = __rb_link;
391    *rb_parent = __rb_parent;
392    return vma;
393}
394
395void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
396        struct rb_node **rb_link, struct rb_node *rb_parent)
397{
398    rb_link_node(&vma->vm_rb, rb_parent, rb_link);
399    rb_insert_color(&vma->vm_rb, &mm->mm_rb);
400}
401
402static void __vma_link_file(struct vm_area_struct *vma)
403{
404    struct file *file;
405
406    file = vma->vm_file;
407    if (file) {
408        struct address_space *mapping = file->f_mapping;
409
410        if (vma->vm_flags & VM_DENYWRITE)
411            atomic_dec(&file->f_path.dentry->d_inode->i_writecount);
412        if (vma->vm_flags & VM_SHARED)
413            mapping->i_mmap_writable++;
414
415        flush_dcache_mmap_lock(mapping);
416        if (unlikely(vma->vm_flags & VM_NONLINEAR))
417            vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
418        else
419            vma_prio_tree_insert(vma, &mapping->i_mmap);
420        flush_dcache_mmap_unlock(mapping);
421    }
422}
423
424static void
425__vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
426    struct vm_area_struct *prev, struct rb_node **rb_link,
427    struct rb_node *rb_parent)
428{
429    __vma_link_list(mm, vma, prev, rb_parent);
430    __vma_link_rb(mm, vma, rb_link, rb_parent);
431}
432
433static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma,
434            struct vm_area_struct *prev, struct rb_node **rb_link,
435            struct rb_node *rb_parent)
436{
437    struct address_space *mapping = NULL;
438
439    if (vma->vm_file)
440        mapping = vma->vm_file->f_mapping;
441
442    if (mapping)
443        mutex_lock(&mapping->i_mmap_mutex);
444
445    __vma_link(mm, vma, prev, rb_link, rb_parent);
446    __vma_link_file(vma);
447
448    if (mapping)
449        mutex_unlock(&mapping->i_mmap_mutex);
450
451    mm->map_count++;
452    validate_mm(mm);
453}
454
455/*
456 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the
457 * mm's list and rbtree. It has already been inserted into the prio_tree.
458 */
459static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
460{
461    struct vm_area_struct *__vma, *prev;
462    struct rb_node **rb_link, *rb_parent;
463
464    __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent);
465    BUG_ON(__vma && __vma->vm_start < vma->vm_end);
466    __vma_link(mm, vma, prev, rb_link, rb_parent);
467    mm->map_count++;
468}
469
470static inline void
471__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma,
472        struct vm_area_struct *prev)
473{
474    struct vm_area_struct *next = vma->vm_next;
475
476    prev->vm_next = next;
477    if (next)
478        next->vm_prev = prev;
479    rb_erase(&vma->vm_rb, &mm->mm_rb);
480    if (mm->mmap_cache == vma)
481        mm->mmap_cache = prev;
482}
483
484/*
485 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that
486 * is already present in an i_mmap tree without adjusting the tree.
487 * The following helper function should be used when such adjustments
488 * are necessary. The "insert" vma (if any) is to be inserted
489 * before we drop the necessary locks.
490 */
491int vma_adjust(struct vm_area_struct *vma, unsigned long start,
492    unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
493{
494    struct mm_struct *mm = vma->vm_mm;
495    struct vm_area_struct *next = vma->vm_next;
496    struct vm_area_struct *importer = NULL;
497    struct address_space *mapping = NULL;
498    struct prio_tree_root *root = NULL;
499    struct anon_vma *anon_vma = NULL;
500    struct file *file = vma->vm_file;
501    long adjust_next = 0;
502    int remove_next = 0;
503
504    if (next && !insert) {
505        struct vm_area_struct *exporter = NULL;
506
507        if (end >= next->vm_end) {
508            /*
509             * vma expands, overlapping all the next, and
510             * perhaps the one after too (mprotect case 6).
511             */
512again: remove_next = 1 + (end > next->vm_end);
513            end = next->vm_end;
514            exporter = next;
515            importer = vma;
516        } else if (end > next->vm_start) {
517            /*
518             * vma expands, overlapping part of the next:
519             * mprotect case 5 shifting the boundary up.
520             */
521            adjust_next = (end - next->vm_start) >> PAGE_SHIFT;
522            exporter = next;
523            importer = vma;
524        } else if (end < vma->vm_end) {
525            /*
526             * vma shrinks, and !insert tells it's not
527             * split_vma inserting another: so it must be
528             * mprotect case 4 shifting the boundary down.
529             */
530            adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT);
531            exporter = vma;
532            importer = next;
533        }
534
535        /*
536         * Easily overlooked: when mprotect shifts the boundary,
537         * make sure the expanding vma has anon_vma set if the
538         * shrinking vma had, to cover any anon pages imported.
539         */
540        if (exporter && exporter->anon_vma && !importer->anon_vma) {
541            if (anon_vma_clone(importer, exporter))
542                return -ENOMEM;
543            importer->anon_vma = exporter->anon_vma;
544        }
545    }
546
547    if (file) {
548        mapping = file->f_mapping;
549        if (!(vma->vm_flags & VM_NONLINEAR))
550            root = &mapping->i_mmap;
551        mutex_lock(&mapping->i_mmap_mutex);
552        if (insert) {
553            /*
554             * Put into prio_tree now, so instantiated pages
555             * are visible to arm/parisc __flush_dcache_page
556             * throughout; but we cannot insert into address
557             * space until vma start or end is updated.
558             */
559            __vma_link_file(insert);
560        }
561    }
562
563    vma_adjust_trans_huge(vma, start, end, adjust_next);
564
565    /*
566     * When changing only vma->vm_end, we don't really need anon_vma
567     * lock. This is a fairly rare case by itself, but the anon_vma
568     * lock may be shared between many sibling processes. Skipping
569     * the lock for brk adjustments makes a difference sometimes.
570     */
571    if (vma->anon_vma && (importer || start != vma->vm_start)) {
572        anon_vma = vma->anon_vma;
573        anon_vma_lock(anon_vma);
574    }
575
576    if (root) {
577        flush_dcache_mmap_lock(mapping);
578        vma_prio_tree_remove(vma, root);
579        if (adjust_next)
580            vma_prio_tree_remove(next, root);
581    }
582
583    vma->vm_start = start;
584    vma->vm_end = end;
585    vma->vm_pgoff = pgoff;
586    if (adjust_next) {
587        next->vm_start += adjust_next << PAGE_SHIFT;
588        next->vm_pgoff += adjust_next;
589    }
590
591    if (root) {
592        if (adjust_next)
593            vma_prio_tree_insert(next, root);
594        vma_prio_tree_insert(vma, root);
595        flush_dcache_mmap_unlock(mapping);
596    }
597
598    if (remove_next) {
599        /*
600         * vma_merge has merged next into vma, and needs
601         * us to remove next before dropping the locks.
602         */
603        __vma_unlink(mm, next, vma);
604        if (file)
605            __remove_shared_vm_struct(next, file, mapping);
606    } else if (insert) {
607        /*
608         * split_vma has split insert from vma, and needs
609         * us to insert it before dropping the locks
610         * (it may either follow vma or precede it).
611         */
612        __insert_vm_struct(mm, insert);
613    }
614
615    if (anon_vma)
616        anon_vma_unlock(anon_vma);
617    if (mapping)
618        mutex_unlock(&mapping->i_mmap_mutex);
619
620    if (remove_next) {
621        if (file) {
622            fput(file);
623            if (next->vm_flags & VM_EXECUTABLE)
624                removed_exe_file_vma(mm);
625        }
626        if (next->anon_vma)
627            anon_vma_merge(vma, next);
628        mm->map_count--;
629        mpol_put(vma_policy(next));
630        kmem_cache_free(vm_area_cachep, next);
631        /*
632         * In mprotect's case 6 (see comments on vma_merge),
633         * we must remove another next too. It would clutter
634         * up the code too much to do both in one go.
635         */
636        if (remove_next == 2) {
637            next = vma->vm_next;
638            goto again;
639        }
640    }
641
642    validate_mm(mm);
643
644    return 0;
645}
646
647/*
648 * If the vma has a ->close operation then the driver probably needs to release
649 * per-vma resources, so we don't attempt to merge those.
650 */
651static inline int is_mergeable_vma(struct vm_area_struct *vma,
652            struct file *file, unsigned long vm_flags)
653{
654    /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
655    if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
656        return 0;
657    if (vma->vm_file != file)
658        return 0;
659    if (vma->vm_ops && vma->vm_ops->close)
660        return 0;
661    return 1;
662}
663
664static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
665                    struct anon_vma *anon_vma2,
666                    struct vm_area_struct *vma)
667{
668    /*
669     * The list_is_singular() test is to avoid merging VMA cloned from
670     * parents. This can improve scalability caused by anon_vma lock.
671     */
672    if ((!anon_vma1 || !anon_vma2) && (!vma ||
673        list_is_singular(&vma->anon_vma_chain)))
674        return 1;
675    return anon_vma1 == anon_vma2;
676}
677
678/*
679 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
680 * in front of (at a lower virtual address and file offset than) the vma.
681 *
682 * We cannot merge two vmas if they have differently assigned (non-NULL)
683 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
684 *
685 * We don't check here for the merged mmap wrapping around the end of pagecache
686 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
687 * wrap, nor mmaps which cover the final page at index -1UL.
688 */
689static int
690can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
691    struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
692{
693    if (is_mergeable_vma(vma, file, vm_flags) &&
694        is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
695        if (vma->vm_pgoff == vm_pgoff)
696            return 1;
697    }
698    return 0;
699}
700
701/*
702 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
703 * beyond (at a higher virtual address and file offset than) the vma.
704 *
705 * We cannot merge two vmas if they have differently assigned (non-NULL)
706 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
707 */
708static int
709can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
710    struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
711{
712    if (is_mergeable_vma(vma, file, vm_flags) &&
713        is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
714        pgoff_t vm_pglen;
715        vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
716        if (vma->vm_pgoff + vm_pglen == vm_pgoff)
717            return 1;
718    }
719    return 0;
720}
721
722/*
723 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
724 * whether that can be merged with its predecessor or its successor.
725 * Or both (it neatly fills a hole).
726 *
727 * In most cases - when called for mmap, brk or mremap - [addr,end) is
728 * certain not to be mapped by the time vma_merge is called; but when
729 * called for mprotect, it is certain to be already mapped (either at
730 * an offset within prev, or at the start of next), and the flags of
731 * this area are about to be changed to vm_flags - and the no-change
732 * case has already been eliminated.
733 *
734 * The following mprotect cases have to be considered, where AAAA is
735 * the area passed down from mprotect_fixup, never extending beyond one
736 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after:
737 *
738 * AAAA AAAA AAAA AAAA
739 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX
740 * cannot merge might become might become might become
741 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or
742 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or
743 * mremap move: PPPPNNNNNNNN 8
744 * AAAA
745 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN
746 * might become case 1 below case 2 below case 3 below
747 *
748 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX:
749 * mprotect_fixup updates vm_flags & vm_page_prot on successful return.
750 */
751struct vm_area_struct *vma_merge(struct mm_struct *mm,
752            struct vm_area_struct *prev, unsigned long addr,
753            unsigned long end, unsigned long vm_flags,
754                 struct anon_vma *anon_vma, struct file *file,
755            pgoff_t pgoff, struct mempolicy *policy)
756{
757    pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
758    struct vm_area_struct *area, *next;
759    int err;
760
761    /*
762     * We later require that vma->vm_flags == vm_flags,
763     * so this tests vma->vm_flags & VM_SPECIAL, too.
764     */
765    if (vm_flags & VM_SPECIAL)
766        return NULL;
767
768    if (prev)
769        next = prev->vm_next;
770    else
771        next = mm->mmap;
772    area = next;
773    if (next && next->vm_end == end) /* cases 6, 7, 8 */
774        next = next->vm_next;
775
776    /*
777     * Can it merge with the predecessor?
778     */
779    if (prev && prev->vm_end == addr &&
780              mpol_equal(vma_policy(prev), policy) &&
781            can_vma_merge_after(prev, vm_flags,
782                        anon_vma, file, pgoff)) {
783        /*
784         * OK, it can. Can we now merge in the successor as well?
785         */
786        if (next && end == next->vm_start &&
787                mpol_equal(policy, vma_policy(next)) &&
788                can_vma_merge_before(next, vm_flags,
789                    anon_vma, file, pgoff+pglen) &&
790                is_mergeable_anon_vma(prev->anon_vma,
791                              next->anon_vma, NULL)) {
792                            /* cases 1, 6 */
793            err = vma_adjust(prev, prev->vm_start,
794                next->vm_end, prev->vm_pgoff, NULL);
795        } else /* cases 2, 5, 7 */
796            err = vma_adjust(prev, prev->vm_start,
797                end, prev->vm_pgoff, NULL);
798        if (err)
799            return NULL;
800        khugepaged_enter_vma_merge(prev);
801        return prev;
802    }
803
804    /*
805     * Can this new request be merged in front of next?
806     */
807    if (next && end == next->vm_start &&
808             mpol_equal(policy, vma_policy(next)) &&
809            can_vma_merge_before(next, vm_flags,
810                    anon_vma, file, pgoff+pglen)) {
811        if (prev && addr < prev->vm_end) /* case 4 */
812            err = vma_adjust(prev, prev->vm_start,
813                addr, prev->vm_pgoff, NULL);
814        else /* cases 3, 8 */
815            err = vma_adjust(area, addr, next->vm_end,
816                next->vm_pgoff - pglen, NULL);
817        if (err)
818            return NULL;
819        khugepaged_enter_vma_merge(area);
820        return area;
821    }
822
823    return NULL;
824}
825
826/*
827 * Rough compatbility check to quickly see if it's even worth looking
828 * at sharing an anon_vma.
829 *
830 * They need to have the same vm_file, and the flags can only differ
831 * in things that mprotect may change.
832 *
833 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
834 * we can merge the two vma's. For example, we refuse to merge a vma if
835 * there is a vm_ops->close() function, because that indicates that the
836 * driver is doing some kind of reference counting. But that doesn't
837 * really matter for the anon_vma sharing case.
838 */
839static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
840{
841    return a->vm_end == b->vm_start &&
842        mpol_equal(vma_policy(a), vma_policy(b)) &&
843        a->vm_file == b->vm_file &&
844        !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) &&
845        b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
846}
847
848/*
849 * Do some basic sanity checking to see if we can re-use the anon_vma
850 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
851 * the same as 'old', the other will be the new one that is trying
852 * to share the anon_vma.
853 *
854 * NOTE! This runs with mm_sem held for reading, so it is possible that
855 * the anon_vma of 'old' is concurrently in the process of being set up
856 * by another page fault trying to merge _that_. But that's ok: if it
857 * is being set up, that automatically means that it will be a singleton
858 * acceptable for merging, so we can do all of this optimistically. But
859 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer.
860 *
861 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
862 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
863 * is to return an anon_vma that is "complex" due to having gone through
864 * a fork).
865 *
866 * We also make sure that the two vma's are compatible (adjacent,
867 * and with the same memory policies). That's all stable, even with just
868 * a read lock on the mm_sem.
869 */
870static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
871{
872    if (anon_vma_compatible(a, b)) {
873        struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma);
874
875        if (anon_vma && list_is_singular(&old->anon_vma_chain))
876            return anon_vma;
877    }
878    return NULL;
879}
880
881/*
882 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
883 * neighbouring vmas for a suitable anon_vma, before it goes off
884 * to allocate a new anon_vma. It checks because a repetitive
885 * sequence of mprotects and faults may otherwise lead to distinct
886 * anon_vmas being allocated, preventing vma merge in subsequent
887 * mprotect.
888 */
889struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
890{
891    struct anon_vma *anon_vma;
892    struct vm_area_struct *near;
893
894    near = vma->vm_next;
895    if (!near)
896        goto try_prev;
897
898    anon_vma = reusable_anon_vma(near, vma, near);
899    if (anon_vma)
900        return anon_vma;
901try_prev:
902    near = vma->vm_prev;
903    if (!near)
904        goto none;
905
906    anon_vma = reusable_anon_vma(near, near, vma);
907    if (anon_vma)
908        return anon_vma;
909none:
910    /*
911     * There's no absolute need to look only at touching neighbours:
912     * we could search further afield for "compatible" anon_vmas.
913     * But it would probably just be a waste of time searching,
914     * or lead to too many vmas hanging off the same anon_vma.
915     * We're trying to allow mprotect remerging later on,
916     * not trying to minimize memory used for anon_vmas.
917     */
918    return NULL;
919}
920
921#ifdef CONFIG_PROC_FS
922void vm_stat_account(struct mm_struct *mm, unsigned long flags,
923                        struct file *file, long pages)
924{
925    const unsigned long stack_flags
926        = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
927
928    if (file) {
929        mm->shared_vm += pages;
930        if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
931            mm->exec_vm += pages;
932    } else if (flags & stack_flags)
933        mm->stack_vm += pages;
934    if (flags & (VM_RESERVED|VM_IO))
935        mm->reserved_vm += pages;
936}
937#endif /* CONFIG_PROC_FS */
938
939/*
940 * If a hint addr is less than mmap_min_addr change hint to be as
941 * low as possible but still greater than mmap_min_addr
942 */
943static inline unsigned long round_hint_to_min(unsigned long hint)
944{
945    hint &= PAGE_MASK;
946    if (((void *)hint != NULL) &&
947        (hint < mmap_min_addr))
948        return PAGE_ALIGN(mmap_min_addr);
949    return hint;
950}
951
952/*
953 * The caller must hold down_write(&current->mm->mmap_sem).
954 */
955
956static unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
957            unsigned long len, unsigned long prot,
958            unsigned long flags, unsigned long pgoff)
959{
960    struct mm_struct * mm = current->mm;
961    struct inode *inode;
962    vm_flags_t vm_flags;
963    int error;
964    unsigned long reqprot = prot;
965
966    /*
967     * Does the application expect PROT_READ to imply PROT_EXEC?
968     *
969     * (the exception is when the underlying filesystem is noexec
970     * mounted, in which case we dont add PROT_EXEC.)
971     */
972    if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
973        if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
974            prot |= PROT_EXEC;
975
976    if (!len)
977        return -EINVAL;
978
979    if (!(flags & MAP_FIXED))
980        addr = round_hint_to_min(addr);
981
982    /* Careful about overflows.. */
983    len = PAGE_ALIGN(len);
984    if (!len)
985        return -ENOMEM;
986
987    /* offset overflow? */
988    if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
989               return -EOVERFLOW;
990
991    /* Too many mappings? */
992    if (mm->map_count > sysctl_max_map_count)
993        return -ENOMEM;
994
995    /* Obtain the address to map to. we verify (or select) it and ensure
996     * that it represents a valid section of the address space.
997     */
998    addr = get_unmapped_area(file, addr, len, pgoff, flags);
999    if (addr & ~PAGE_MASK)
1000        return addr;
1001
1002    /* Do simple checking here so the lower-level routines won't have
1003     * to. we assume access permissions have been handled by the open
1004     * of the memory object, so we don't do any here.
1005     */
1006    vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
1007            mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1008
1009    if (flags & MAP_LOCKED)
1010        if (!can_do_mlock())
1011            return -EPERM;
1012
1013    /* mlock MCL_FUTURE? */
1014    if (vm_flags & VM_LOCKED) {
1015        unsigned long locked, lock_limit;
1016        locked = len >> PAGE_SHIFT;
1017        locked += mm->locked_vm;
1018        lock_limit = rlimit(RLIMIT_MEMLOCK);
1019        lock_limit >>= PAGE_SHIFT;
1020        if (locked > lock_limit && !capable(CAP_IPC_LOCK))
1021            return -EAGAIN;
1022    }
1023
1024    inode = file ? file->f_path.dentry->d_inode : NULL;
1025
1026    if (file) {
1027        switch (flags & MAP_TYPE) {
1028        case MAP_SHARED:
1029            if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
1030                return -EACCES;
1031
1032            /*
1033             * Make sure we don't allow writing to an append-only
1034             * file..
1035             */
1036            if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1037                return -EACCES;
1038
1039            /*
1040             * Make sure there are no mandatory locks on the file.
1041             */
1042            if (locks_verify_locked(inode))
1043                return -EAGAIN;
1044
1045            vm_flags |= VM_SHARED | VM_MAYSHARE;
1046            if (!(file->f_mode & FMODE_WRITE))
1047                vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1048
1049            /* fall through */
1050        case MAP_PRIVATE:
1051            if (!(file->f_mode & FMODE_READ))
1052                return -EACCES;
1053            if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1054                if (vm_flags & VM_EXEC)
1055                    return -EPERM;
1056                vm_flags &= ~VM_MAYEXEC;
1057            }
1058
1059            if (!file->f_op || !file->f_op->mmap)
1060                return -ENODEV;
1061            break;
1062
1063        default:
1064            return -EINVAL;
1065        }
1066    } else {
1067        switch (flags & MAP_TYPE) {
1068        case MAP_SHARED:
1069            /*
1070             * Ignore pgoff.
1071             */
1072            pgoff = 0;
1073            vm_flags |= VM_SHARED | VM_MAYSHARE;
1074            break;
1075        case MAP_PRIVATE:
1076            /*
1077             * Set pgoff according to addr for anon_vma.
1078             */
1079            pgoff = addr >> PAGE_SHIFT;
1080            break;
1081        default:
1082            return -EINVAL;
1083        }
1084    }
1085
1086    error = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1087    if (error)
1088        return error;
1089
1090    return mmap_region(file, addr, len, flags, vm_flags, pgoff);
1091}
1092
1093unsigned long do_mmap(struct file *file, unsigned long addr,
1094    unsigned long len, unsigned long prot,
1095    unsigned long flag, unsigned long offset)
1096{
1097    if (unlikely(offset + PAGE_ALIGN(len) < offset))
1098        return -EINVAL;
1099    if (unlikely(offset & ~PAGE_MASK))
1100        return -EINVAL;
1101    return do_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
1102}
1103EXPORT_SYMBOL(do_mmap);
1104
1105unsigned long vm_mmap(struct file *file, unsigned long addr,
1106    unsigned long len, unsigned long prot,
1107    unsigned long flag, unsigned long offset)
1108{
1109    unsigned long ret;
1110    struct mm_struct *mm = current->mm;
1111
1112    down_write(&mm->mmap_sem);
1113    ret = do_mmap(file, addr, len, prot, flag, offset);
1114    up_write(&mm->mmap_sem);
1115    return ret;
1116}
1117EXPORT_SYMBOL(vm_mmap);
1118
1119SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1120        unsigned long, prot, unsigned long, flags,
1121        unsigned long, fd, unsigned long, pgoff)
1122{
1123    struct file *file = NULL;
1124    unsigned long retval = -EBADF;
1125
1126    if (!(flags & MAP_ANONYMOUS)) {
1127        audit_mmap_fd(fd, flags);
1128        if (unlikely(flags & MAP_HUGETLB))
1129            return -EINVAL;
1130        file = fget(fd);
1131        if (!file)
1132            goto out;
1133    } else if (flags & MAP_HUGETLB) {
1134        struct user_struct *user = NULL;
1135        /*
1136         * VM_NORESERVE is used because the reservations will be
1137         * taken when vm_ops->mmap() is called
1138         * A dummy user value is used because we are not locking
1139         * memory so no accounting is necessary
1140         */
1141        file = hugetlb_file_setup(HUGETLB_ANON_FILE, addr, len,
1142                        VM_NORESERVE, &user,
1143                        HUGETLB_ANONHUGE_INODE);
1144        if (IS_ERR(file))
1145            return PTR_ERR(file);
1146    }
1147
1148    flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1149
1150    down_write(&current->mm->mmap_sem);
1151    retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1152    up_write(&current->mm->mmap_sem);
1153
1154    if (file)
1155        fput(file);
1156out:
1157    return retval;
1158}
1159
1160#ifdef __ARCH_WANT_SYS_OLD_MMAP
1161struct mmap_arg_struct {
1162    unsigned long addr;
1163    unsigned long len;
1164    unsigned long prot;
1165    unsigned long flags;
1166    unsigned long fd;
1167    unsigned long offset;
1168};
1169
1170SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1171{
1172    struct mmap_arg_struct a;
1173
1174    if (copy_from_user(&a, arg, sizeof(a)))
1175        return -EFAULT;
1176    if (a.offset & ~PAGE_MASK)
1177        return -EINVAL;
1178
1179    return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1180                  a.offset >> PAGE_SHIFT);
1181}
1182#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1183
1184/*
1185 * Some shared mappigns will want the pages marked read-only
1186 * to track write events. If so, we'll downgrade vm_page_prot
1187 * to the private version (using protection_map[] without the
1188 * VM_SHARED bit).
1189 */
1190int vma_wants_writenotify(struct vm_area_struct *vma)
1191{
1192    vm_flags_t vm_flags = vma->vm_flags;
1193
1194    /* If it was private or non-writable, the write bit is already clear */
1195    if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
1196        return 0;
1197
1198    /* The backer wishes to know when pages are first written to? */
1199    if (vma->vm_ops && vma->vm_ops->page_mkwrite)
1200        return 1;
1201
1202    /* The open routine did something to the protections already? */
1203    if (pgprot_val(vma->vm_page_prot) !=
1204        pgprot_val(vm_get_page_prot(vm_flags)))
1205        return 0;
1206
1207    /* Specialty mapping? */
1208    if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE))
1209        return 0;
1210
1211    /* Can the mapping track the dirty pages? */
1212    return vma->vm_file && vma->vm_file->f_mapping &&
1213        mapping_cap_account_dirty(vma->vm_file->f_mapping);
1214}
1215
1216/*
1217 * We account for memory if it's a private writeable mapping,
1218 * not hugepages and VM_NORESERVE wasn't set.
1219 */
1220static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1221{
1222    /*
1223     * hugetlb has its own accounting separate from the core VM
1224     * VM_HUGETLB may not be set yet so we cannot check for that flag.
1225     */
1226    if (file && is_file_hugepages(file))
1227        return 0;
1228
1229    return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1230}
1231
1232unsigned long mmap_region(struct file *file, unsigned long addr,
1233              unsigned long len, unsigned long flags,
1234              vm_flags_t vm_flags, unsigned long pgoff)
1235{
1236    struct mm_struct *mm = current->mm;
1237    struct vm_area_struct *vma, *prev;
1238    int correct_wcount = 0;
1239    int error;
1240    struct rb_node **rb_link, *rb_parent;
1241    unsigned long charged = 0;
1242    struct inode *inode = file ? file->f_path.dentry->d_inode : NULL;
1243
1244    /* Clear old maps */
1245    error = -ENOMEM;
1246munmap_back:
1247    vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
1248    if (vma && vma->vm_start < addr + len) {
1249        if (do_munmap(mm, addr, len))
1250            return -ENOMEM;
1251        goto munmap_back;
1252    }
1253
1254    /* Check against address space limit. */
1255    if (!may_expand_vm(mm, len >> PAGE_SHIFT))
1256        return -ENOMEM;
1257
1258    /*
1259     * Set 'VM_NORESERVE' if we should not account for the
1260     * memory use of this mapping.
1261     */
1262    if ((flags & MAP_NORESERVE)) {
1263        /* We honor MAP_NORESERVE if allowed to overcommit */
1264        if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1265            vm_flags |= VM_NORESERVE;
1266
1267        /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1268        if (file && is_file_hugepages(file))
1269            vm_flags |= VM_NORESERVE;
1270    }
1271
1272    /*
1273     * Private writable mapping: check memory availability
1274     */
1275    if (accountable_mapping(file, vm_flags)) {
1276        charged = len >> PAGE_SHIFT;
1277        if (security_vm_enough_memory_mm(mm, charged))
1278            return -ENOMEM;
1279        vm_flags |= VM_ACCOUNT;
1280    }
1281
1282    /*
1283     * Can we just expand an old mapping?
1284     */
1285    vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
1286    if (vma)
1287        goto out;
1288
1289    /*
1290     * Determine the object being mapped and call the appropriate
1291     * specific mapper. the address has already been validated, but
1292     * not unmapped, but the maps are removed from the list.
1293     */
1294    vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1295    if (!vma) {
1296        error = -ENOMEM;
1297        goto unacct_error;
1298    }
1299
1300    vma->vm_mm = mm;
1301    vma->vm_start = addr;
1302    vma->vm_end = addr + len;
1303    vma->vm_flags = vm_flags;
1304    vma->vm_page_prot = vm_get_page_prot(vm_flags);
1305    vma->vm_pgoff = pgoff;
1306    INIT_LIST_HEAD(&vma->anon_vma_chain);
1307
1308    error = -EINVAL; /* when rejecting VM_GROWSDOWN|VM_GROWSUP */
1309
1310    if (file) {
1311        if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1312            goto free_vma;
1313        if (vm_flags & VM_DENYWRITE) {
1314            error = deny_write_access(file);
1315            if (error)
1316                goto free_vma;
1317            correct_wcount = 1;
1318        }
1319        vma->vm_file = file;
1320        get_file(file);
1321        error = file->f_op->mmap(file, vma);
1322        if (error)
1323            goto unmap_and_free_vma;
1324        if (vm_flags & VM_EXECUTABLE)
1325            added_exe_file_vma(mm);
1326
1327        /* Can addr have changed??
1328         *
1329         * Answer: Yes, several device drivers can do it in their
1330         * f_op->mmap method. -DaveM
1331         */
1332        addr = vma->vm_start;
1333        pgoff = vma->vm_pgoff;
1334        vm_flags = vma->vm_flags;
1335    } else if (vm_flags & VM_SHARED) {
1336        if (unlikely(vm_flags & (VM_GROWSDOWN|VM_GROWSUP)))
1337            goto free_vma;
1338        error = shmem_zero_setup(vma);
1339        if (error)
1340            goto free_vma;
1341    }
1342
1343    if (vma_wants_writenotify(vma)) {
1344        pgprot_t pprot = vma->vm_page_prot;
1345
1346        /* Can vma->vm_page_prot have changed??
1347         *
1348         * Answer: Yes, drivers may have changed it in their
1349         * f_op->mmap method.
1350         *
1351         * Ensures that vmas marked as uncached stay that way.
1352         */
1353        vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED);
1354        if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot)))
1355            vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
1356    }
1357
1358    vma_link(mm, vma, prev, rb_link, rb_parent);
1359    file = vma->vm_file;
1360
1361    /* Once vma denies write, undo our temporary denial count */
1362    if (correct_wcount)
1363        atomic_inc(&inode->i_writecount);
1364out:
1365    perf_event_mmap(vma);
1366
1367    mm->total_vm += len >> PAGE_SHIFT;
1368    vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
1369    if (vm_flags & VM_LOCKED) {
1370        if (!mlock_vma_pages_range(vma, addr, addr + len))
1371            mm->locked_vm += (len >> PAGE_SHIFT);
1372    } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
1373        make_pages_present(addr, addr + len);
1374    return addr;
1375
1376unmap_and_free_vma:
1377    if (correct_wcount)
1378        atomic_inc(&inode->i_writecount);
1379    vma->vm_file = NULL;
1380    fput(file);
1381
1382    /* Undo any partial mapping done by a device driver. */
1383    unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end);
1384    charged = 0;
1385free_vma:
1386    kmem_cache_free(vm_area_cachep, vma);
1387unacct_error:
1388    if (charged)
1389        vm_unacct_memory(charged);
1390    return error;
1391}
1392
1393/* Get an address range which is currently unmapped.
1394 * For shmat() with addr=0.
1395 *
1396 * Ugly calling convention alert:
1397 * Return value with the low bits set means error value,
1398 * ie
1399 * if (ret & ~PAGE_MASK)
1400 * error = ret;
1401 *
1402 * This function "knows" that -ENOMEM has the bits set.
1403 */
1404#ifndef HAVE_ARCH_UNMAPPED_AREA
1405unsigned long
1406arch_get_unmapped_area(struct file *filp, unsigned long addr,
1407        unsigned long len, unsigned long pgoff, unsigned long flags)
1408{
1409    struct mm_struct *mm = current->mm;
1410    struct vm_area_struct *vma;
1411    unsigned long start_addr;
1412
1413    if (len > TASK_SIZE)
1414        return -ENOMEM;
1415
1416    if (flags & MAP_FIXED)
1417        return addr;
1418
1419    if (addr) {
1420        addr = PAGE_ALIGN(addr);
1421        vma = find_vma(mm, addr);
1422        if (TASK_SIZE - len >= addr &&
1423            (!vma || addr + len <= vma->vm_start))
1424            return addr;
1425    }
1426    if (len > mm->cached_hole_size) {
1427            start_addr = addr = mm->free_area_cache;
1428    } else {
1429            start_addr = addr = TASK_UNMAPPED_BASE;
1430            mm->cached_hole_size = 0;
1431    }
1432
1433full_search:
1434    for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
1435        /* At this point: (!vma || addr < vma->vm_end). */
1436        if (TASK_SIZE - len < addr) {
1437            /*
1438             * Start a new search - just in case we missed
1439             * some holes.
1440             */
1441            if (start_addr != TASK_UNMAPPED_BASE) {
1442                addr = TASK_UNMAPPED_BASE;
1443                    start_addr = addr;
1444                mm->cached_hole_size = 0;
1445                goto full_search;
1446            }
1447            return -ENOMEM;
1448        }
1449        if (!vma || addr + len <= vma->vm_start) {
1450            /*
1451             * Remember the place where we stopped the search:
1452             */
1453            mm->free_area_cache = addr + len;
1454            return addr;
1455        }
1456        if (addr + mm->cached_hole_size < vma->vm_start)
1457                mm->cached_hole_size = vma->vm_start - addr;
1458        addr = vma->vm_end;
1459    }
1460}
1461#endif
1462
1463void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1464{
1465    /*
1466     * Is this a new hole at the lowest possible address?
1467     */
1468    if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache)
1469        mm->free_area_cache = addr;
1470}
1471
1472/*
1473 * This mmap-allocator allocates new areas top-down from below the
1474 * stack's low limit (the base):
1475 */
1476#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1477unsigned long
1478arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
1479              const unsigned long len, const unsigned long pgoff,
1480              const unsigned long flags)
1481{
1482    struct vm_area_struct *vma;
1483    struct mm_struct *mm = current->mm;
1484    unsigned long addr = addr0, start_addr;
1485
1486    /* requested length too big for entire address space */
1487    if (len > TASK_SIZE)
1488        return -ENOMEM;
1489
1490    if (flags & MAP_FIXED)
1491        return addr;
1492
1493    /* requesting a specific address */
1494    if (addr) {
1495        addr = PAGE_ALIGN(addr);
1496        vma = find_vma(mm, addr);
1497        if (TASK_SIZE - len >= addr &&
1498                (!vma || addr + len <= vma->vm_start))
1499            return addr;
1500    }
1501
1502    /* check if free_area_cache is useful for us */
1503    if (len <= mm->cached_hole_size) {
1504             mm->cached_hole_size = 0;
1505         mm->free_area_cache = mm->mmap_base;
1506     }
1507
1508try_again:
1509    /* either no address requested or can't fit in requested address hole */
1510    start_addr = addr = mm->free_area_cache;
1511
1512    if (addr < len)
1513        goto fail;
1514
1515    addr -= len;
1516    do {
1517        /*
1518         * Lookup failure means no vma is above this address,
1519         * else if new region fits below vma->vm_start,
1520         * return with success:
1521         */
1522        vma = find_vma(mm, addr);
1523        if (!vma || addr+len <= vma->vm_start)
1524            /* remember the address as a hint for next time */
1525            return (mm->free_area_cache = addr);
1526
1527         /* remember the largest hole we saw so far */
1528         if (addr + mm->cached_hole_size < vma->vm_start)
1529                 mm->cached_hole_size = vma->vm_start - addr;
1530
1531        /* try just below the current vma->vm_start */
1532        addr = vma->vm_start-len;
1533    } while (len < vma->vm_start);
1534
1535fail:
1536    /*
1537     * if hint left us with no space for the requested
1538     * mapping then try again:
1539     *
1540     * Note: this is different with the case of bottomup
1541     * which does the fully line-search, but we use find_vma
1542     * here that causes some holes skipped.
1543     */
1544    if (start_addr != mm->mmap_base) {
1545        mm->free_area_cache = mm->mmap_base;
1546        mm->cached_hole_size = 0;
1547        goto try_again;
1548    }
1549
1550    /*
1551     * A failed mmap() very likely causes application failure,
1552     * so fall back to the bottom-up function here. This scenario
1553     * can happen with large stack limits and large mmap()
1554     * allocations.
1555     */
1556    mm->cached_hole_size = ~0UL;
1557      mm->free_area_cache = TASK_UNMAPPED_BASE;
1558    addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
1559    /*
1560     * Restore the topdown base:
1561     */
1562    mm->free_area_cache = mm->mmap_base;
1563    mm->cached_hole_size = ~0UL;
1564
1565    return addr;
1566}
1567#endif
1568
1569void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
1570{
1571    /*
1572     * Is this a new hole at the highest possible address?
1573     */
1574    if (addr > mm->free_area_cache)
1575        mm->free_area_cache = addr;
1576
1577    /* dont allow allocations above current base */
1578    if (mm->free_area_cache > mm->mmap_base)
1579        mm->free_area_cache = mm->mmap_base;
1580}
1581
1582unsigned long
1583get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1584        unsigned long pgoff, unsigned long flags)
1585{
1586    unsigned long (*get_area)(struct file *, unsigned long,
1587                  unsigned long, unsigned long, unsigned long);
1588
1589    unsigned long error = arch_mmap_check(addr, len, flags);
1590    if (error)
1591        return error;
1592
1593    /* Careful about overflows.. */
1594    if (len > TASK_SIZE)
1595        return -ENOMEM;
1596
1597    get_area = current->mm->get_unmapped_area;
1598    if (file && file->f_op && file->f_op->get_unmapped_area)
1599        get_area = file->f_op->get_unmapped_area;
1600    addr = get_area(file, addr, len, pgoff, flags);
1601    if (IS_ERR_VALUE(addr))
1602        return addr;
1603
1604    if (addr > TASK_SIZE - len)
1605        return -ENOMEM;
1606    if (addr & ~PAGE_MASK)
1607        return -EINVAL;
1608
1609    return arch_rebalance_pgtables(addr, len);
1610}
1611
1612EXPORT_SYMBOL(get_unmapped_area);
1613
1614/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */
1615struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1616{
1617    struct vm_area_struct *vma = NULL;
1618
1619    if (mm) {
1620        /* Check the cache first. */
1621        /* (Cache hit rate is typically around 35%.) */
1622        vma = mm->mmap_cache;
1623        if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) {
1624            struct rb_node * rb_node;
1625
1626            rb_node = mm->mm_rb.rb_node;
1627            vma = NULL;
1628
1629            while (rb_node) {
1630                struct vm_area_struct * vma_tmp;
1631
1632                vma_tmp = rb_entry(rb_node,
1633                        struct vm_area_struct, vm_rb);
1634
1635                if (vma_tmp->vm_end > addr) {
1636                    vma = vma_tmp;
1637                    if (vma_tmp->vm_start <= addr)
1638                        break;
1639                    rb_node = rb_node->rb_left;
1640                } else
1641                    rb_node = rb_node->rb_right;
1642            }
1643            if (vma)
1644                mm->mmap_cache = vma;
1645        }
1646    }
1647    return vma;
1648}
1649
1650EXPORT_SYMBOL(find_vma);
1651
1652/*
1653 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.
1654 */
1655struct vm_area_struct *
1656find_vma_prev(struct mm_struct *mm, unsigned long addr,
1657            struct vm_area_struct **pprev)
1658{
1659    struct vm_area_struct *vma;
1660
1661    vma = find_vma(mm, addr);
1662    if (vma) {
1663        *pprev = vma->vm_prev;
1664    } else {
1665        struct rb_node *rb_node = mm->mm_rb.rb_node;
1666        *pprev = NULL;
1667        while (rb_node) {
1668            *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb);
1669            rb_node = rb_node->rb_right;
1670        }
1671    }
1672    return vma;
1673}
1674
1675/*
1676 * Verify that the stack growth is acceptable and
1677 * update accounting. This is shared with both the
1678 * grow-up and grow-down cases.
1679 */
1680static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow)
1681{
1682    struct mm_struct *mm = vma->vm_mm;
1683    struct rlimit *rlim = current->signal->rlim;
1684    unsigned long new_start;
1685
1686    /* address space limit tests */
1687    if (!may_expand_vm(mm, grow))
1688        return -ENOMEM;
1689
1690    /* Stack limit test */
1691    if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur))
1692        return -ENOMEM;
1693
1694    /* mlock limit tests */
1695    if (vma->vm_flags & VM_LOCKED) {
1696        unsigned long locked;
1697        unsigned long limit;
1698        locked = mm->locked_vm + grow;
1699        limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur);
1700        limit >>= PAGE_SHIFT;
1701        if (locked > limit && !capable(CAP_IPC_LOCK))
1702            return -ENOMEM;
1703    }
1704
1705    /* Check to ensure the stack will not grow into a hugetlb-only region */
1706    new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1707            vma->vm_end - size;
1708    if (is_hugepage_only_range(vma->vm_mm, new_start, size))
1709        return -EFAULT;
1710
1711    /*
1712     * Overcommit.. This must be the final test, as it will
1713     * update security statistics.
1714     */
1715    if (security_vm_enough_memory_mm(mm, grow))
1716        return -ENOMEM;
1717
1718    /* Ok, everything looks good - let it rip */
1719    mm->total_vm += grow;
1720    if (vma->vm_flags & VM_LOCKED)
1721        mm->locked_vm += grow;
1722    vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow);
1723    return 0;
1724}
1725
1726#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
1727/*
1728 * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
1729 * vma is the last one with address > vma->vm_end. Have to extend vma.
1730 */
1731int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1732{
1733    int error;
1734
1735    if (!(vma->vm_flags & VM_GROWSUP))
1736        return -EFAULT;
1737
1738    /*
1739     * We must make sure the anon_vma is allocated
1740     * so that the anon_vma locking is not a noop.
1741     */
1742    if (unlikely(anon_vma_prepare(vma)))
1743        return -ENOMEM;
1744    vma_lock_anon_vma(vma);
1745
1746    /*
1747     * vma->vm_start/vm_end cannot change under us because the caller
1748     * is required to hold the mmap_sem in read mode. We need the
1749     * anon_vma lock to serialize against concurrent expand_stacks.
1750     * Also guard against wrapping around to address 0.
1751     */
1752    if (address < PAGE_ALIGN(address+4))
1753        address = PAGE_ALIGN(address+4);
1754    else {
1755        vma_unlock_anon_vma(vma);
1756        return -ENOMEM;
1757    }
1758    error = 0;
1759
1760    /* Somebody else might have raced and expanded it already */
1761    if (address > vma->vm_end) {
1762        unsigned long size, grow;
1763
1764        size = address - vma->vm_start;
1765        grow = (address - vma->vm_end) >> PAGE_SHIFT;
1766
1767        error = -ENOMEM;
1768        if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
1769            error = acct_stack_growth(vma, size, grow);
1770            if (!error) {
1771                vma->vm_end = address;
1772                perf_event_mmap(vma);
1773            }
1774        }
1775    }
1776    vma_unlock_anon_vma(vma);
1777    khugepaged_enter_vma_merge(vma);
1778    return error;
1779}
1780#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
1781
1782/*
1783 * vma is the first one with address < vma->vm_start. Have to extend vma.
1784 */
1785int expand_downwards(struct vm_area_struct *vma,
1786                   unsigned long address)
1787{
1788    int error;
1789
1790    /*
1791     * We must make sure the anon_vma is allocated
1792     * so that the anon_vma locking is not a noop.
1793     */
1794    if (unlikely(anon_vma_prepare(vma)))
1795        return -ENOMEM;
1796
1797    address &= PAGE_MASK;
1798    error = security_file_mmap(NULL, 0, 0, 0, address, 1);
1799    if (error)
1800        return error;
1801
1802    vma_lock_anon_vma(vma);
1803
1804    /*
1805     * vma->vm_start/vm_end cannot change under us because the caller
1806     * is required to hold the mmap_sem in read mode. We need the
1807     * anon_vma lock to serialize against concurrent expand_stacks.
1808     */
1809
1810    /* Somebody else might have raced and expanded it already */
1811    if (address < vma->vm_start) {
1812        unsigned long size, grow;
1813
1814        size = vma->vm_end - address;
1815        grow = (vma->vm_start - address) >> PAGE_SHIFT;
1816
1817        error = -ENOMEM;
1818        if (grow <= vma->vm_pgoff) {
1819            error = acct_stack_growth(vma, size, grow);
1820            if (!error) {
1821                vma->vm_start = address;
1822                vma->vm_pgoff -= grow;
1823                perf_event_mmap(vma);
1824            }
1825        }
1826    }
1827    vma_unlock_anon_vma(vma);
1828    khugepaged_enter_vma_merge(vma);
1829    return error;
1830}
1831
1832#ifdef CONFIG_STACK_GROWSUP
1833int expand_stack(struct vm_area_struct *vma, unsigned long address)
1834{
1835    return expand_upwards(vma, address);
1836}
1837
1838struct vm_area_struct *
1839find_extend_vma(struct mm_struct *mm, unsigned long addr)
1840{
1841    struct vm_area_struct *vma, *prev;
1842
1843    addr &= PAGE_MASK;
1844    vma = find_vma_prev(mm, addr, &prev);
1845    if (vma && (vma->vm_start <= addr))
1846        return vma;
1847    if (!prev || expand_stack(prev, addr))
1848        return NULL;
1849    if (prev->vm_flags & VM_LOCKED) {
1850        mlock_vma_pages_range(prev, addr, prev->vm_end);
1851    }
1852    return prev;
1853}
1854#else
1855int expand_stack(struct vm_area_struct *vma, unsigned long address)
1856{
1857    return expand_downwards(vma, address);
1858}
1859
1860struct vm_area_struct *
1861find_extend_vma(struct mm_struct * mm, unsigned long addr)
1862{
1863    struct vm_area_struct * vma;
1864    unsigned long start;
1865
1866    addr &= PAGE_MASK;
1867    vma = find_vma(mm,addr);
1868    if (!vma)
1869        return NULL;
1870    if (vma->vm_start <= addr)
1871        return vma;
1872    if (!(vma->vm_flags & VM_GROWSDOWN))
1873        return NULL;
1874    start = vma->vm_start;
1875    if (expand_stack(vma, addr))
1876        return NULL;
1877    if (vma->vm_flags & VM_LOCKED) {
1878        mlock_vma_pages_range(vma, addr, start);
1879    }
1880    return vma;
1881}
1882#endif
1883
1884/*
1885 * Ok - we have the memory areas we should free on the vma list,
1886 * so release them, and do the vma updates.
1887 *
1888 * Called with the mm semaphore held.
1889 */
1890static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
1891{
1892    /* Update high watermark before we lower total_vm */
1893    update_hiwater_vm(mm);
1894    do {
1895        long nrpages = vma_pages(vma);
1896
1897        mm->total_vm -= nrpages;
1898        vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
1899        vma = remove_vma(vma);
1900    } while (vma);
1901    validate_mm(mm);
1902}
1903
1904/*
1905 * Get rid of page table information in the indicated region.
1906 *
1907 * Called with the mm semaphore held.
1908 */
1909static void unmap_region(struct mm_struct *mm,
1910        struct vm_area_struct *vma, struct vm_area_struct *prev,
1911        unsigned long start, unsigned long end)
1912{
1913    struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
1914    struct mmu_gather tlb;
1915    unsigned long nr_accounted = 0;
1916
1917    lru_add_drain();
1918    tlb_gather_mmu(&tlb, mm, 0);
1919    update_hiwater_rss(mm);
1920    unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
1921    vm_unacct_memory(nr_accounted);
1922    free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
1923                 next ? next->vm_start : 0);
1924    tlb_finish_mmu(&tlb, start, end);
1925}
1926
1927/*
1928 * Create a list of vma's touched by the unmap, removing them from the mm's
1929 * vma list as we go..
1930 */
1931static void
1932detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma,
1933    struct vm_area_struct *prev, unsigned long end)
1934{
1935    struct vm_area_struct **insertion_point;
1936    struct vm_area_struct *tail_vma = NULL;
1937    unsigned long addr;
1938
1939    insertion_point = (prev ? &prev->vm_next : &mm->mmap);
1940    vma->vm_prev = NULL;
1941    do {
1942        rb_erase(&vma->vm_rb, &mm->mm_rb);
1943        mm->map_count--;
1944        tail_vma = vma;
1945        vma = vma->vm_next;
1946    } while (vma && vma->vm_start < end);
1947    *insertion_point = vma;
1948    if (vma)
1949        vma->vm_prev = prev;
1950    tail_vma->vm_next = NULL;
1951    if (mm->unmap_area == arch_unmap_area)
1952        addr = prev ? prev->vm_end : mm->mmap_base;
1953    else
1954        addr = vma ? vma->vm_start : mm->mmap_base;
1955    mm->unmap_area(mm, addr);
1956    mm->mmap_cache = NULL; /* Kill the cache. */
1957}
1958
1959/*
1960 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the
1961 * munmap path where it doesn't make sense to fail.
1962 */
1963static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma,
1964          unsigned long addr, int new_below)
1965{
1966    struct mempolicy *pol;
1967    struct vm_area_struct *new;
1968    int err = -ENOMEM;
1969
1970    if (is_vm_hugetlb_page(vma) && (addr &
1971                    ~(huge_page_mask(hstate_vma(vma)))))
1972        return -EINVAL;
1973
1974    new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1975    if (!new)
1976        goto out_err;
1977
1978    /* most fields are the same, copy all, and then fixup */
1979    *new = *vma;
1980
1981    INIT_LIST_HEAD(&new->anon_vma_chain);
1982
1983    if (new_below)
1984        new->vm_end = addr;
1985    else {
1986        new->vm_start = addr;
1987        new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
1988    }
1989
1990    pol = mpol_dup(vma_policy(vma));
1991    if (IS_ERR(pol)) {
1992        err = PTR_ERR(pol);
1993        goto out_free_vma;
1994    }
1995    vma_set_policy(new, pol);
1996
1997    if (anon_vma_clone(new, vma))
1998        goto out_free_mpol;
1999
2000    if (new->vm_file) {
2001        get_file(new->vm_file);
2002        if (vma->vm_flags & VM_EXECUTABLE)
2003            added_exe_file_vma(mm);
2004    }
2005
2006    if (new->vm_ops && new->vm_ops->open)
2007        new->vm_ops->open(new);
2008
2009    if (new_below)
2010        err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff +
2011            ((addr - new->vm_start) >> PAGE_SHIFT), new);
2012    else
2013        err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
2014
2015    /* Success. */
2016    if (!err)
2017        return 0;
2018
2019    /* Clean everything up if vma_adjust failed. */
2020    if (new->vm_ops && new->vm_ops->close)
2021        new->vm_ops->close(new);
2022    if (new->vm_file) {
2023        if (vma->vm_flags & VM_EXECUTABLE)
2024            removed_exe_file_vma(mm);
2025        fput(new->vm_file);
2026    }
2027    unlink_anon_vmas(new);
2028 out_free_mpol:
2029    mpol_put(pol);
2030 out_free_vma:
2031    kmem_cache_free(vm_area_cachep, new);
2032 out_err:
2033    return err;
2034}
2035
2036/*
2037 * Split a vma into two pieces at address 'addr', a new vma is allocated
2038 * either for the first part or the tail.
2039 */
2040int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
2041          unsigned long addr, int new_below)
2042{
2043    if (mm->map_count >= sysctl_max_map_count)
2044        return -ENOMEM;
2045
2046    return __split_vma(mm, vma, addr, new_below);
2047}
2048
2049/* Munmap is split into 2 main parts -- this part which finds
2050 * what needs doing, and the areas themselves, which do the
2051 * work. This now handles partial unmappings.
2052 * Jeremy Fitzhardinge <jeremy@goop.org>
2053 */
2054int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
2055{
2056    unsigned long end;
2057    struct vm_area_struct *vma, *prev, *last;
2058
2059    if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start)
2060        return -EINVAL;
2061
2062    if ((len = PAGE_ALIGN(len)) == 0)
2063        return -EINVAL;
2064
2065    /* Find the first overlapping VMA */
2066    vma = find_vma(mm, start);
2067    if (!vma)
2068        return 0;
2069    prev = vma->vm_prev;
2070    /* we have start < vma->vm_end */
2071
2072    /* if it doesn't overlap, we have nothing.. */
2073    end = start + len;
2074    if (vma->vm_start >= end)
2075        return 0;
2076
2077    /*
2078     * If we need to split any vma, do it now to save pain later.
2079     *
2080     * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2081     * unmapped vm_area_struct will remain in use: so lower split_vma
2082     * places tmp vma above, and higher split_vma places tmp vma below.
2083     */
2084    if (start > vma->vm_start) {
2085        int error;
2086
2087        /*
2088         * Make sure that map_count on return from munmap() will
2089         * not exceed its limit; but let map_count go just above
2090         * its limit temporarily, to help free resources as expected.
2091         */
2092        if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2093            return -ENOMEM;
2094
2095        error = __split_vma(mm, vma, start, 0);
2096        if (error)
2097            return error;
2098        prev = vma;
2099    }
2100
2101    /* Does it split the last one? */
2102    last = find_vma(mm, end);
2103    if (last && end > last->vm_start) {
2104        int error = __split_vma(mm, last, end, 1);
2105        if (error)
2106            return error;
2107    }
2108    vma = prev? prev->vm_next: mm->mmap;
2109
2110    /*
2111     * unlock any mlock()ed ranges before detaching vmas
2112     */
2113    if (mm->locked_vm) {
2114        struct vm_area_struct *tmp = vma;
2115        while (tmp && tmp->vm_start < end) {
2116            if (tmp->vm_flags & VM_LOCKED) {
2117                mm->locked_vm -= vma_pages(tmp);
2118                munlock_vma_pages_all(tmp);
2119            }
2120            tmp = tmp->vm_next;
2121        }
2122    }
2123
2124    /*
2125     * Remove the vma's, and unmap the actual pages
2126     */
2127    detach_vmas_to_be_unmapped(mm, vma, prev, end);
2128    unmap_region(mm, vma, prev, start, end);
2129
2130    /* Fix up all other VM information */
2131    remove_vma_list(mm, vma);
2132
2133    return 0;
2134}
2135EXPORT_SYMBOL(do_munmap);
2136
2137int vm_munmap(unsigned long start, size_t len)
2138{
2139    int ret;
2140    struct mm_struct *mm = current->mm;
2141
2142    down_write(&mm->mmap_sem);
2143    ret = do_munmap(mm, start, len);
2144    up_write(&mm->mmap_sem);
2145    return ret;
2146}
2147EXPORT_SYMBOL(vm_munmap);
2148
2149SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
2150{
2151    profile_munmap(addr);
2152    return vm_munmap(addr, len);
2153}
2154
2155static inline void verify_mm_writelocked(struct mm_struct *mm)
2156{
2157#ifdef CONFIG_DEBUG_VM
2158    if (unlikely(down_read_trylock(&mm->mmap_sem))) {
2159        WARN_ON(1);
2160        up_read(&mm->mmap_sem);
2161    }
2162#endif
2163}
2164
2165/*
2166 * this is really a simplified "do_mmap". it only handles
2167 * anonymous maps. eventually we may be able to do some
2168 * brk-specific accounting here.
2169 */
2170static unsigned long do_brk(unsigned long addr, unsigned long len)
2171{
2172    struct mm_struct * mm = current->mm;
2173    struct vm_area_struct * vma, * prev;
2174    unsigned long flags;
2175    struct rb_node ** rb_link, * rb_parent;
2176    pgoff_t pgoff = addr >> PAGE_SHIFT;
2177    int error;
2178
2179    len = PAGE_ALIGN(len);
2180    if (!len)
2181        return addr;
2182
2183    error = security_file_mmap(NULL, 0, 0, 0, addr, 1);
2184    if (error)
2185        return error;
2186
2187    flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
2188
2189    error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
2190    if (error & ~PAGE_MASK)
2191        return error;
2192
2193    /*
2194     * mlock MCL_FUTURE?
2195     */
2196    if (mm->def_flags & VM_LOCKED) {
2197        unsigned long locked, lock_limit;
2198        locked = len >> PAGE_SHIFT;
2199        locked += mm->locked_vm;
2200        lock_limit = rlimit(RLIMIT_MEMLOCK);
2201        lock_limit >>= PAGE_SHIFT;
2202        if (locked > lock_limit && !capable(CAP_IPC_LOCK))
2203            return -EAGAIN;
2204    }
2205
2206    /*
2207     * mm->mmap_sem is required to protect against another thread
2208     * changing the mappings in case we sleep.
2209     */
2210    verify_mm_writelocked(mm);
2211
2212    /*
2213     * Clear old maps. this also does some error checking for us
2214     */
2215 munmap_back:
2216    vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2217    if (vma && vma->vm_start < addr + len) {
2218        if (do_munmap(mm, addr, len))
2219            return -ENOMEM;
2220        goto munmap_back;
2221    }
2222
2223    /* Check against address space limits *after* clearing old maps... */
2224    if (!may_expand_vm(mm, len >> PAGE_SHIFT))
2225        return -ENOMEM;
2226
2227    if (mm->map_count > sysctl_max_map_count)
2228        return -ENOMEM;
2229
2230    if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
2231        return -ENOMEM;
2232
2233    /* Can we just expand an old private anonymous mapping? */
2234    vma = vma_merge(mm, prev, addr, addr + len, flags,
2235                    NULL, NULL, pgoff, NULL);
2236    if (vma)
2237        goto out;
2238
2239    /*
2240     * create a vma struct for an anonymous mapping
2241     */
2242    vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2243    if (!vma) {
2244        vm_unacct_memory(len >> PAGE_SHIFT);
2245        return -ENOMEM;
2246    }
2247
2248    INIT_LIST_HEAD(&vma->anon_vma_chain);
2249    vma->vm_mm = mm;
2250    vma->vm_start = addr;
2251    vma->vm_end = addr + len;
2252    vma->vm_pgoff = pgoff;
2253    vma->vm_flags = flags;
2254    vma->vm_page_prot = vm_get_page_prot(flags);
2255    vma_link(mm, vma, prev, rb_link, rb_parent);
2256out:
2257    perf_event_mmap(vma);
2258    mm->total_vm += len >> PAGE_SHIFT;
2259    if (flags & VM_LOCKED) {
2260        if (!mlock_vma_pages_range(vma, addr, addr + len))
2261            mm->locked_vm += (len >> PAGE_SHIFT);
2262    }
2263    return addr;
2264}
2265
2266unsigned long vm_brk(unsigned long addr, unsigned long len)
2267{
2268    struct mm_struct *mm = current->mm;
2269    unsigned long ret;
2270
2271    down_write(&mm->mmap_sem);
2272    ret = do_brk(addr, len);
2273    up_write(&mm->mmap_sem);
2274    return ret;
2275}
2276EXPORT_SYMBOL(vm_brk);
2277
2278/* Release all mmaps. */
2279void exit_mmap(struct mm_struct *mm)
2280{
2281    struct mmu_gather tlb;
2282    struct vm_area_struct *vma;
2283    unsigned long nr_accounted = 0;
2284
2285    /* mm's last user has gone, and its about to be pulled down */
2286    mmu_notifier_release(mm);
2287
2288    if (mm->locked_vm) {
2289        vma = mm->mmap;
2290        while (vma) {
2291            if (vma->vm_flags & VM_LOCKED)
2292                munlock_vma_pages_all(vma);
2293            vma = vma->vm_next;
2294        }
2295    }
2296
2297    arch_exit_mmap(mm);
2298
2299    vma = mm->mmap;
2300    if (!vma) /* Can happen if dup_mmap() received an OOM */
2301        return;
2302
2303    lru_add_drain();
2304    flush_cache_mm(mm);
2305    tlb_gather_mmu(&tlb, mm, 1);
2306    /* update_hiwater_rss(mm) here? but nobody should be looking */
2307    /* Use -1 here to ensure all VMAs in the mm are unmapped */
2308    unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
2309    vm_unacct_memory(nr_accounted);
2310
2311    free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
2312    tlb_finish_mmu(&tlb, 0, -1);
2313
2314    /*
2315     * Walk the list again, actually closing and freeing it,
2316     * with preemption enabled, without holding any MM locks.
2317     */
2318    while (vma)
2319        vma = remove_vma(vma);
2320
2321    BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT);
2322}
2323
2324/* Insert vm structure into process list sorted by address
2325 * and into the inode's i_mmap tree. If vm_file is non-NULL
2326 * then i_mmap_mutex is taken here.
2327 */
2328int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
2329{
2330    struct vm_area_struct * __vma, * prev;
2331    struct rb_node ** rb_link, * rb_parent;
2332
2333    /*
2334     * The vm_pgoff of a purely anonymous vma should be irrelevant
2335     * until its first write fault, when page's anon_vma and index
2336     * are set. But now set the vm_pgoff it will almost certainly
2337     * end up with (unless mremap moves it elsewhere before that
2338     * first wfault), so /proc/pid/maps tells a consistent story.
2339     *
2340     * By setting it to reflect the virtual start address of the
2341     * vma, merges and splits can happen in a seamless way, just
2342     * using the existing file pgoff checks and manipulations.
2343     * Similarly in do_mmap_pgoff and in do_brk.
2344     */
2345    if (!vma->vm_file) {
2346        BUG_ON(vma->anon_vma);
2347        vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
2348    }
2349    __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent);
2350    if (__vma && __vma->vm_start < vma->vm_end)
2351        return -ENOMEM;
2352    if ((vma->vm_flags & VM_ACCOUNT) &&
2353         security_vm_enough_memory_mm(mm, vma_pages(vma)))
2354        return -ENOMEM;
2355    vma_link(mm, vma, prev, rb_link, rb_parent);
2356    return 0;
2357}
2358
2359/*
2360 * Copy the vma structure to a new location in the same mm,
2361 * prior to moving page table entries, to effect an mremap move.
2362 */
2363struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
2364    unsigned long addr, unsigned long len, pgoff_t pgoff)
2365{
2366    struct vm_area_struct *vma = *vmap;
2367    unsigned long vma_start = vma->vm_start;
2368    struct mm_struct *mm = vma->vm_mm;
2369    struct vm_area_struct *new_vma, *prev;
2370    struct rb_node **rb_link, *rb_parent;
2371    struct mempolicy *pol;
2372    bool faulted_in_anon_vma = true;
2373
2374    /*
2375     * If anonymous vma has not yet been faulted, update new pgoff
2376     * to match new location, to increase its chance of merging.
2377     */
2378    if (unlikely(!vma->vm_file && !vma->anon_vma)) {
2379        pgoff = addr >> PAGE_SHIFT;
2380        faulted_in_anon_vma = false;
2381    }
2382
2383    find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
2384    new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
2385            vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
2386    if (new_vma) {
2387        /*
2388         * Source vma may have been merged into new_vma
2389         */
2390        if (unlikely(vma_start >= new_vma->vm_start &&
2391                 vma_start < new_vma->vm_end)) {
2392            /*
2393             * The only way we can get a vma_merge with
2394             * self during an mremap is if the vma hasn't
2395             * been faulted in yet and we were allowed to
2396             * reset the dst vma->vm_pgoff to the
2397             * destination address of the mremap to allow
2398             * the merge to happen. mremap must change the
2399             * vm_pgoff linearity between src and dst vmas
2400             * (in turn preventing a vma_merge) to be
2401             * safe. It is only safe to keep the vm_pgoff
2402             * linear if there are no pages mapped yet.
2403             */
2404            VM_BUG_ON(faulted_in_anon_vma);
2405            *vmap = new_vma;
2406        } else
2407            anon_vma_moveto_tail(new_vma);
2408    } else {
2409        new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
2410        if (new_vma) {
2411            *new_vma = *vma;
2412            pol = mpol_dup(vma_policy(vma));
2413            if (IS_ERR(pol))
2414                goto out_free_vma;
2415            INIT_LIST_HEAD(&new_vma->anon_vma_chain);
2416            if (anon_vma_clone(new_vma, vma))
2417                goto out_free_mempol;
2418            vma_set_policy(new_vma, pol);
2419            new_vma->vm_start = addr;
2420            new_vma->vm_end = addr + len;
2421            new_vma->vm_pgoff = pgoff;
2422            if (new_vma->vm_file) {
2423                get_file(new_vma->vm_file);
2424                if (vma->vm_flags & VM_EXECUTABLE)
2425                    added_exe_file_vma(mm);
2426            }
2427            if (new_vma->vm_ops && new_vma->vm_ops->open)
2428                new_vma->vm_ops->open(new_vma);
2429            vma_link(mm, new_vma, prev, rb_link, rb_parent);
2430        }
2431    }
2432    return new_vma;
2433
2434 out_free_mempol:
2435    mpol_put(pol);
2436 out_free_vma:
2437    kmem_cache_free(vm_area_cachep, new_vma);
2438    return NULL;
2439}
2440
2441/*
2442 * Return true if the calling process may expand its vm space by the passed
2443 * number of pages
2444 */
2445int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2446{
2447    unsigned long cur = mm->total_vm; /* pages */
2448    unsigned long lim;
2449
2450    lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT;
2451
2452    if (cur + npages > lim)
2453        return 0;
2454    return 1;
2455}
2456
2457
2458static int special_mapping_fault(struct vm_area_struct *vma,
2459                struct vm_fault *vmf)
2460{
2461    pgoff_t pgoff;
2462    struct page **pages;
2463
2464    /*
2465     * special mappings have no vm_file, and in that case, the mm
2466     * uses vm_pgoff internally. So we have to subtract it from here.
2467     * We are allowed to do this because we are the mm; do not copy
2468     * this code into drivers!
2469     */
2470    pgoff = vmf->pgoff - vma->vm_pgoff;
2471
2472    for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2473        pgoff--;
2474
2475    if (*pages) {
2476        struct page *page = *pages;
2477        get_page(page);
2478        vmf->page = page;
2479        return 0;
2480    }
2481
2482    return VM_FAULT_SIGBUS;
2483}
2484
2485/*
2486 * Having a close hook prevents vma merging regardless of flags.
2487 */
2488static void special_mapping_close(struct vm_area_struct *vma)
2489{
2490}
2491
2492static const struct vm_operations_struct special_mapping_vmops = {
2493    .close = special_mapping_close,
2494    .fault = special_mapping_fault,
2495};
2496
2497/*
2498 * Called with mm->mmap_sem held for writing.
2499 * Insert a new vma covering the given region, with the given flags.
2500 * Its pages are supplied by the given array of struct page *.
2501 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
2502 * The region past the last page supplied will always produce SIGBUS.
2503 * The array pointer and the pages it points to are assumed to stay alive
2504 * for as long as this mapping might exist.
2505 */
2506int install_special_mapping(struct mm_struct *mm,
2507                unsigned long addr, unsigned long len,
2508                unsigned long vm_flags, struct page **pages)
2509{
2510    int ret;
2511    struct vm_area_struct *vma;
2512
2513    vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
2514    if (unlikely(vma == NULL))
2515        return -ENOMEM;
2516
2517    INIT_LIST_HEAD(&vma->anon_vma_chain);
2518    vma->vm_mm = mm;
2519    vma->vm_start = addr;
2520    vma->vm_end = addr + len;
2521
2522    vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
2523    vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
2524
2525    vma->vm_ops = &special_mapping_vmops;
2526    vma->vm_private_data = pages;
2527
2528    ret = security_file_mmap(NULL, 0, 0, 0, vma->vm_start, 1);
2529    if (ret)
2530        goto out;
2531
2532    ret = insert_vm_struct(mm, vma);
2533    if (ret)
2534        goto out;
2535
2536    mm->total_vm += len >> PAGE_SHIFT;
2537
2538    perf_event_mmap(vma);
2539
2540    return 0;
2541
2542out:
2543    kmem_cache_free(vm_area_cachep, vma);
2544    return ret;
2545}
2546
2547static DEFINE_MUTEX(mm_all_locks_mutex);
2548
2549static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
2550{
2551    if (!test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2552        /*
2553         * The LSB of head.next can't change from under us
2554         * because we hold the mm_all_locks_mutex.
2555         */
2556        mutex_lock_nest_lock(&anon_vma->root->mutex, &mm->mmap_sem);
2557        /*
2558         * We can safely modify head.next after taking the
2559         * anon_vma->root->mutex. If some other vma in this mm shares
2560         * the same anon_vma we won't take it again.
2561         *
2562         * No need of atomic instructions here, head.next
2563         * can't change from under us thanks to the
2564         * anon_vma->root->mutex.
2565         */
2566        if (__test_and_set_bit(0, (unsigned long *)
2567                       &anon_vma->root->head.next))
2568            BUG();
2569    }
2570}
2571
2572static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
2573{
2574    if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2575        /*
2576         * AS_MM_ALL_LOCKS can't change from under us because
2577         * we hold the mm_all_locks_mutex.
2578         *
2579         * Operations on ->flags have to be atomic because
2580         * even if AS_MM_ALL_LOCKS is stable thanks to the
2581         * mm_all_locks_mutex, there may be other cpus
2582         * changing other bitflags in parallel to us.
2583         */
2584        if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
2585            BUG();
2586        mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
2587    }
2588}
2589
2590/*
2591 * This operation locks against the VM for all pte/vma/mm related
2592 * operations that could ever happen on a certain mm. This includes
2593 * vmtruncate, try_to_unmap, and all page faults.
2594 *
2595 * The caller must take the mmap_sem in write mode before calling
2596 * mm_take_all_locks(). The caller isn't allowed to release the
2597 * mmap_sem until mm_drop_all_locks() returns.
2598 *
2599 * mmap_sem in write mode is required in order to block all operations
2600 * that could modify pagetables and free pages without need of
2601 * altering the vma layout (for example populate_range() with
2602 * nonlinear vmas). It's also needed in write mode to avoid new
2603 * anon_vmas to be associated with existing vmas.
2604 *
2605 * A single task can't take more than one mm_take_all_locks() in a row
2606 * or it would deadlock.
2607 *
2608 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in
2609 * mapping->flags avoid to take the same lock twice, if more than one
2610 * vma in this mm is backed by the same anon_vma or address_space.
2611 *
2612 * We can take all the locks in random order because the VM code
2613 * taking i_mmap_mutex or anon_vma->mutex outside the mmap_sem never
2614 * takes more than one of them in a row. Secondly we're protected
2615 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
2616 *
2617 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
2618 * that may have to take thousand of locks.
2619 *
2620 * mm_take_all_locks() can fail if it's interrupted by signals.
2621 */
2622int mm_take_all_locks(struct mm_struct *mm)
2623{
2624    struct vm_area_struct *vma;
2625    struct anon_vma_chain *avc;
2626
2627    BUG_ON(down_read_trylock(&mm->mmap_sem));
2628
2629    mutex_lock(&mm_all_locks_mutex);
2630
2631    for (vma = mm->mmap; vma; vma = vma->vm_next) {
2632        if (signal_pending(current))
2633            goto out_unlock;
2634        if (vma->vm_file && vma->vm_file->f_mapping)
2635            vm_lock_mapping(mm, vma->vm_file->f_mapping);
2636    }
2637
2638    for (vma = mm->mmap; vma; vma = vma->vm_next) {
2639        if (signal_pending(current))
2640            goto out_unlock;
2641        if (vma->anon_vma)
2642            list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2643                vm_lock_anon_vma(mm, avc->anon_vma);
2644    }
2645
2646    return 0;
2647
2648out_unlock:
2649    mm_drop_all_locks(mm);
2650    return -EINTR;
2651}
2652
2653static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
2654{
2655    if (test_bit(0, (unsigned long *) &anon_vma->root->head.next)) {
2656        /*
2657         * The LSB of head.next can't change to 0 from under
2658         * us because we hold the mm_all_locks_mutex.
2659         *
2660         * We must however clear the bitflag before unlocking
2661         * the vma so the users using the anon_vma->head will
2662         * never see our bitflag.
2663         *
2664         * No need of atomic instructions here, head.next
2665         * can't change from under us until we release the
2666         * anon_vma->root->mutex.
2667         */
2668        if (!__test_and_clear_bit(0, (unsigned long *)
2669                      &anon_vma->root->head.next))
2670            BUG();
2671        anon_vma_unlock(anon_vma);
2672    }
2673}
2674
2675static void vm_unlock_mapping(struct address_space *mapping)
2676{
2677    if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
2678        /*
2679         * AS_MM_ALL_LOCKS can't change to 0 from under us
2680         * because we hold the mm_all_locks_mutex.
2681         */
2682        mutex_unlock(&mapping->i_mmap_mutex);
2683        if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
2684                    &mapping->flags))
2685            BUG();
2686    }
2687}
2688
2689/*
2690 * The mmap_sem cannot be released by the caller until
2691 * mm_drop_all_locks() returns.
2692 */
2693void mm_drop_all_locks(struct mm_struct *mm)
2694{
2695    struct vm_area_struct *vma;
2696    struct anon_vma_chain *avc;
2697
2698    BUG_ON(down_read_trylock(&mm->mmap_sem));
2699    BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
2700
2701    for (vma = mm->mmap; vma; vma = vma->vm_next) {
2702        if (vma->anon_vma)
2703            list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
2704                vm_unlock_anon_vma(avc->anon_vma);
2705        if (vma->vm_file && vma->vm_file->f_mapping)
2706            vm_unlock_mapping(vma->vm_file->f_mapping);
2707    }
2708
2709    mutex_unlock(&mm_all_locks_mutex);
2710}
2711
2712/*
2713 * initialise the VMA slab
2714 */
2715void __init mmap_init(void)
2716{
2717    int ret;
2718
2719    ret = percpu_counter_init(&vm_committed_as, 0);
2720    VM_BUG_ON(ret);
2721}
2722

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