1 // SPDX-License-Identifier: GPL-2.0
4 * Anonymous Shared Memory Subsystem, ashmem
6 * Copyright (C) 2008 Google, Inc.
8 * Robert Love <rlove@google.com>
11 #define pr_fmt(fmt) "ashmem: " fmt
13 #include <linux/init.h>
14 #include <linux/export.h>
15 #include <linux/file.h>
17 #include <linux/falloc.h>
18 #include <linux/miscdevice.h>
19 #include <linux/security.h>
21 #include <linux/mman.h>
22 #include <linux/uaccess.h>
23 #include <linux/personality.h>
24 #include <linux/bitops.h>
25 #include <linux/mutex.h>
26 #include <linux/shmem_fs.h>
29 #define ASHMEM_NAME_PREFIX "dev/ashmem/"
30 #define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1)
31 #define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN)
34 * struct ashmem_area - The anonymous shared memory area
35 * @name: The optional name in /proc/pid/maps
36 * @unpinned_list: The list of all ashmem areas
37 * @file: The shmem-based backing file
38 * @size: The size of the mapping, in bytes
39 * @prot_mask: The allowed protection bits, as vm_flags
41 * The lifecycle of this structure is from our parent file's open() until
42 * its release(). It is also protected by 'ashmem_mutex'
44 * Warning: Mappings do NOT pin this structure; It dies on close()
47 char name[ASHMEM_FULL_NAME_LEN];
48 struct list_head unpinned_list;
51 unsigned long prot_mask;
55 * struct ashmem_range - A range of unpinned/evictable pages
56 * @lru: The entry in the LRU list
57 * @unpinned: The entry in its area's unpinned list
58 * @asma: The associated anonymous shared memory area.
59 * @pgstart: The starting page (inclusive)
60 * @pgend: The ending page (inclusive)
61 * @purged: The purge status (ASHMEM_NOT or ASHMEM_WAS_PURGED)
63 * The lifecycle of this structure is from unpin to pin.
64 * It is protected by 'ashmem_mutex'
68 struct list_head unpinned;
69 struct ashmem_area *asma;
75 /* LRU list of unpinned pages, protected by ashmem_mutex */
76 static LIST_HEAD(ashmem_lru_list);
78 static atomic_t ashmem_shrink_inflight = ATOMIC_INIT(0);
79 static DECLARE_WAIT_QUEUE_HEAD(ashmem_shrink_wait);
82 * long lru_count - The count of pages on our LRU list.
84 * This is protected by ashmem_mutex.
86 static unsigned long lru_count;
89 * ashmem_mutex - protects the list of and each individual ashmem_area
91 * Lock Ordering: ashmex_mutex -> i_mutex -> i_alloc_sem
93 static DEFINE_MUTEX(ashmem_mutex);
95 static struct kmem_cache *ashmem_area_cachep __read_mostly;
96 static struct kmem_cache *ashmem_range_cachep __read_mostly;
98 static inline unsigned long range_size(struct ashmem_range *range)
100 return range->pgend - range->pgstart + 1;
103 static inline bool range_on_lru(struct ashmem_range *range)
105 return range->purged == ASHMEM_NOT_PURGED;
108 static inline bool page_range_subsumes_range(struct ashmem_range *range,
109 size_t start, size_t end)
111 return (range->pgstart >= start) && (range->pgend <= end);
114 static inline bool page_range_subsumed_by_range(struct ashmem_range *range,
115 size_t start, size_t end)
117 return (range->pgstart <= start) && (range->pgend >= end);
120 static inline bool page_in_range(struct ashmem_range *range, size_t page)
122 return (range->pgstart <= page) && (range->pgend >= page);
125 static inline bool page_range_in_range(struct ashmem_range *range,
126 size_t start, size_t end)
128 return page_in_range(range, start) || page_in_range(range, end) ||
129 page_range_subsumes_range(range, start, end);
132 static inline bool range_before_page(struct ashmem_range *range,
135 return range->pgend < page;
138 #define PROT_MASK (PROT_EXEC | PROT_READ | PROT_WRITE)
141 * lru_add() - Adds a range of memory to the LRU list
142 * @range: The memory range being added.
144 * The range is first added to the end (tail) of the LRU list.
145 * After this, the size of the range is added to @lru_count
147 static inline void lru_add(struct ashmem_range *range)
149 list_add_tail(&range->lru, &ashmem_lru_list);
150 lru_count += range_size(range);
154 * lru_del() - Removes a range of memory from the LRU list
155 * @range: The memory range being removed
157 * The range is first deleted from the LRU list.
158 * After this, the size of the range is removed from @lru_count
160 static inline void lru_del(struct ashmem_range *range)
162 list_del(&range->lru);
163 lru_count -= range_size(range);
167 * range_alloc() - Allocates and initializes a new ashmem_range structure
168 * @asma: The associated ashmem_area
169 * @prev_range: The previous ashmem_range in the sorted asma->unpinned list
170 * @purged: Initial purge status (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED)
171 * @start: The starting page (inclusive)
172 * @end: The ending page (inclusive)
174 * This function is protected by ashmem_mutex.
176 static void range_alloc(struct ashmem_area *asma,
177 struct ashmem_range *prev_range, unsigned int purged,
178 size_t start, size_t end,
179 struct ashmem_range **new_range)
181 struct ashmem_range *range = *new_range;
185 range->pgstart = start;
187 range->purged = purged;
189 list_add_tail(&range->unpinned, &prev_range->unpinned);
191 if (range_on_lru(range))
196 * range_del() - Deletes and deallocates an ashmem_range structure
197 * @range: The associated ashmem_range that has previously been allocated
199 static void range_del(struct ashmem_range *range)
201 list_del(&range->unpinned);
202 if (range_on_lru(range))
204 kmem_cache_free(ashmem_range_cachep, range);
208 * range_shrink() - Shrinks an ashmem_range
209 * @range: The associated ashmem_range being shrunk
210 * @start: The starting byte of the new range
211 * @end: The ending byte of the new range
213 * This does not modify the data inside the existing range in any way - It
214 * simply shrinks the boundaries of the range.
216 * Theoretically, with a little tweaking, this could eventually be changed
217 * to range_resize, and expand the lru_count if the new range is larger.
219 static inline void range_shrink(struct ashmem_range *range,
220 size_t start, size_t end)
222 size_t pre = range_size(range);
224 range->pgstart = start;
227 if (range_on_lru(range))
228 lru_count -= pre - range_size(range);
232 * ashmem_open() - Opens an Anonymous Shared Memory structure
233 * @inode: The backing file's index node(?)
234 * @file: The backing file
236 * Please note that the ashmem_area is not returned by this function - It is
237 * instead written to "file->private_data".
239 * Return: 0 if successful, or another code if unsuccessful.
241 static int ashmem_open(struct inode *inode, struct file *file)
243 struct ashmem_area *asma;
246 ret = generic_file_open(inode, file);
250 asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL);
254 INIT_LIST_HEAD(&asma->unpinned_list);
255 memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN);
256 asma->prot_mask = PROT_MASK;
257 file->private_data = asma;
263 * ashmem_release() - Releases an Anonymous Shared Memory structure
264 * @ignored: The backing file's Index Node(?) - It is ignored here.
265 * @file: The backing file
267 * Return: 0 if successful. If it is anything else, go have a coffee and
270 static int ashmem_release(struct inode *ignored, struct file *file)
272 struct ashmem_area *asma = file->private_data;
273 struct ashmem_range *range, *next;
275 mutex_lock(&ashmem_mutex);
276 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned)
278 mutex_unlock(&ashmem_mutex);
282 kmem_cache_free(ashmem_area_cachep, asma);
287 static ssize_t ashmem_read_iter(struct kiocb *iocb, struct iov_iter *iter)
289 struct ashmem_area *asma = iocb->ki_filp->private_data;
292 mutex_lock(&ashmem_mutex);
294 /* If size is not set, or set to 0, always return EOF. */
304 * asma and asma->file are used outside the lock here. We assume
305 * once asma->file is set it will never be changed, and will not
306 * be destroyed until all references to the file are dropped and
307 * ashmem_release is called.
309 mutex_unlock(&ashmem_mutex);
310 ret = vfs_iter_read(asma->file, iter, &iocb->ki_pos, 0);
311 mutex_lock(&ashmem_mutex);
313 asma->file->f_pos = iocb->ki_pos;
315 mutex_unlock(&ashmem_mutex);
319 static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin)
321 struct ashmem_area *asma = file->private_data;
324 mutex_lock(&ashmem_mutex);
326 if (asma->size == 0) {
327 mutex_unlock(&ashmem_mutex);
332 mutex_unlock(&ashmem_mutex);
336 mutex_unlock(&ashmem_mutex);
338 ret = vfs_llseek(asma->file, offset, origin);
342 /** Copy f_pos from backing file, since f_ops->llseek() sets it */
343 file->f_pos = asma->file->f_pos;
347 static inline vm_flags_t calc_vm_may_flags(unsigned long prot)
349 return _calc_vm_trans(prot, PROT_READ, VM_MAYREAD) |
350 _calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) |
351 _calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC);
354 static int ashmem_vmfile_mmap(struct file *file, struct vm_area_struct *vma)
356 /* do not allow to mmap ashmem backing shmem file directly */
361 ashmem_vmfile_get_unmapped_area(struct file *file, unsigned long addr,
362 unsigned long len, unsigned long pgoff,
365 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
368 static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
370 static struct file_operations vmfile_fops;
371 struct ashmem_area *asma = file->private_data;
374 mutex_lock(&ashmem_mutex);
376 /* user needs to SET_SIZE before mapping */
382 /* requested mapping size larger than object size */
383 if (vma->vm_end - vma->vm_start > PAGE_ALIGN(asma->size)) {
388 /* requested protection bits must match our allowed protection mask */
389 if ((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) &
390 calc_vm_prot_bits(PROT_MASK, 0)) {
394 vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
397 char *name = ASHMEM_NAME_DEF;
400 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
403 /* ... and allocate the backing shmem file */
404 vmfile = shmem_file_setup(name, asma->size, vma->vm_flags);
405 if (IS_ERR(vmfile)) {
406 ret = PTR_ERR(vmfile);
409 vmfile->f_mode |= FMODE_LSEEK;
412 * override mmap operation of the vmfile so that it can't be
413 * remapped which would lead to creation of a new vma with no
414 * asma permission checks. Have to override get_unmapped_area
415 * as well to prevent VM_BUG_ON check for f_ops modification.
417 if (!vmfile_fops.mmap) {
418 vmfile_fops = *vmfile->f_op;
419 vmfile_fops.mmap = ashmem_vmfile_mmap;
420 vmfile_fops.get_unmapped_area =
421 ashmem_vmfile_get_unmapped_area;
423 vmfile->f_op = &vmfile_fops;
425 get_file(asma->file);
428 * XXX - Reworked to use shmem_zero_setup() instead of
429 * shmem_set_file while we're in staging. -jstultz
431 if (vma->vm_flags & VM_SHARED) {
432 ret = shmem_zero_setup(vma);
438 vma_set_anonymous(vma);
443 vma->vm_file = asma->file;
446 mutex_unlock(&ashmem_mutex);
451 * ashmem_shrink - our cache shrinker, called from mm/vmscan.c
453 * 'nr_to_scan' is the number of objects to scan for freeing.
455 * 'gfp_mask' is the mask of the allocation that got us into this mess.
457 * Return value is the number of objects freed or -1 if we cannot
458 * proceed without risk of deadlock (due to gfp_mask).
460 * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial
461 * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan'
465 ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
467 unsigned long freed = 0;
469 /* We might recurse into filesystem code, so bail out if necessary */
470 if (!(sc->gfp_mask & __GFP_FS))
473 if (!mutex_trylock(&ashmem_mutex))
476 while (!list_empty(&ashmem_lru_list)) {
477 struct ashmem_range *range =
478 list_first_entry(&ashmem_lru_list, typeof(*range), lru);
479 loff_t start = range->pgstart * PAGE_SIZE;
480 loff_t end = (range->pgend + 1) * PAGE_SIZE;
481 struct file *f = range->asma->file;
484 atomic_inc(&ashmem_shrink_inflight);
485 range->purged = ASHMEM_WAS_PURGED;
488 freed += range_size(range);
489 mutex_unlock(&ashmem_mutex);
490 f->f_op->fallocate(f,
491 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
494 if (atomic_dec_and_test(&ashmem_shrink_inflight))
495 wake_up_all(&ashmem_shrink_wait);
496 if (!mutex_trylock(&ashmem_mutex))
498 if (--sc->nr_to_scan <= 0)
501 mutex_unlock(&ashmem_mutex);
507 ashmem_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
510 * note that lru_count is count of pages on the lru, not a count of
511 * objects on the list. This means the scan function needs to return the
512 * number of pages freed, not the number of objects scanned.
517 static struct shrinker ashmem_shrinker = {
518 .count_objects = ashmem_shrink_count,
519 .scan_objects = ashmem_shrink_scan,
521 * XXX (dchinner): I wish people would comment on why they need on
522 * significant changes to the default value here
524 .seeks = DEFAULT_SEEKS * 4,
527 static int set_prot_mask(struct ashmem_area *asma, unsigned long prot)
531 mutex_lock(&ashmem_mutex);
533 /* the user can only remove, not add, protection bits */
534 if ((asma->prot_mask & prot) != prot) {
539 /* does the application expect PROT_READ to imply PROT_EXEC? */
540 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
543 asma->prot_mask = prot;
546 mutex_unlock(&ashmem_mutex);
550 static int set_name(struct ashmem_area *asma, void __user *name)
554 char local_name[ASHMEM_NAME_LEN];
557 * Holding the ashmem_mutex while doing a copy_from_user might cause
558 * an data abort which would try to access mmap_sem. If another
559 * thread has invoked ashmem_mmap then it will be holding the
560 * semaphore and will be waiting for ashmem_mutex, there by leading to
561 * deadlock. We'll release the mutex and take the name to a local
562 * variable that does not need protection and later copy the local
563 * variable to the structure member with lock held.
565 len = strncpy_from_user(local_name, name, ASHMEM_NAME_LEN);
569 mutex_lock(&ashmem_mutex);
570 /* cannot change an existing mapping's name */
574 strscpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name,
577 mutex_unlock(&ashmem_mutex);
581 static int get_name(struct ashmem_area *asma, void __user *name)
586 * Have a local variable to which we'll copy the content
587 * from asma with the lock held. Later we can copy this to the user
588 * space safely without holding any locks. So even if we proceed to
589 * wait for mmap_sem, it won't lead to deadlock.
591 char local_name[ASHMEM_NAME_LEN];
593 mutex_lock(&ashmem_mutex);
594 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') {
596 * Copying only `len', instead of ASHMEM_NAME_LEN, bytes
597 * prevents us from revealing one user's stack to another.
599 len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1;
600 memcpy(local_name, asma->name + ASHMEM_NAME_PREFIX_LEN, len);
602 len = sizeof(ASHMEM_NAME_DEF);
603 memcpy(local_name, ASHMEM_NAME_DEF, len);
605 mutex_unlock(&ashmem_mutex);
608 * Now we are just copying from the stack variable to userland
611 if (copy_to_user(name, local_name, len))
617 * ashmem_pin - pin the given ashmem region, returning whether it was
618 * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED).
620 * Caller must hold ashmem_mutex.
622 static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend,
623 struct ashmem_range **new_range)
625 struct ashmem_range *range, *next;
626 int ret = ASHMEM_NOT_PURGED;
628 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
629 /* moved past last applicable page; we can short circuit */
630 if (range_before_page(range, pgstart))
634 * The user can ask us to pin pages that span multiple ranges,
635 * or to pin pages that aren't even unpinned, so this is messy.
638 * 1. The requested range subsumes an existing range, so we
639 * just remove the entire matching range.
640 * 2. The requested range overlaps the start of an existing
641 * range, so we just update that range.
642 * 3. The requested range overlaps the end of an existing
643 * range, so we just update that range.
644 * 4. The requested range punches a hole in an existing range,
645 * so we have to update one side of the range and then
646 * create a new range for the other side.
648 if (page_range_in_range(range, pgstart, pgend)) {
649 ret |= range->purged;
651 /* Case #1: Easy. Just nuke the whole thing. */
652 if (page_range_subsumes_range(range, pgstart, pgend)) {
657 /* Case #2: We overlap from the start, so adjust it */
658 if (range->pgstart >= pgstart) {
659 range_shrink(range, pgend + 1, range->pgend);
663 /* Case #3: We overlap from the rear, so adjust it */
664 if (range->pgend <= pgend) {
665 range_shrink(range, range->pgstart,
671 * Case #4: We eat a chunk out of the middle. A bit
672 * more complicated, we allocate a new range for the
673 * second half and adjust the first chunk's endpoint.
675 range_alloc(asma, range, range->purged,
676 pgend + 1, range->pgend, new_range);
677 range_shrink(range, range->pgstart, pgstart - 1);
686 * ashmem_unpin - unpin the given range of pages. Returns zero on success.
688 * Caller must hold ashmem_mutex.
690 static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend,
691 struct ashmem_range **new_range)
693 struct ashmem_range *range, *next;
694 unsigned int purged = ASHMEM_NOT_PURGED;
697 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
698 /* short circuit: this is our insertion point */
699 if (range_before_page(range, pgstart))
703 * The user can ask us to unpin pages that are already entirely
704 * or partially pinned. We handle those two cases here.
706 if (page_range_subsumed_by_range(range, pgstart, pgend))
708 if (page_range_in_range(range, pgstart, pgend)) {
709 pgstart = min(range->pgstart, pgstart);
710 pgend = max(range->pgend, pgend);
711 purged |= range->purged;
717 range_alloc(asma, range, purged, pgstart, pgend, new_range);
722 * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the
723 * given interval are unpinned and ASHMEM_IS_PINNED otherwise.
725 * Caller must hold ashmem_mutex.
727 static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart,
730 struct ashmem_range *range;
731 int ret = ASHMEM_IS_PINNED;
733 list_for_each_entry(range, &asma->unpinned_list, unpinned) {
734 if (range_before_page(range, pgstart))
736 if (page_range_in_range(range, pgstart, pgend)) {
737 ret = ASHMEM_IS_UNPINNED;
745 static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
748 struct ashmem_pin pin;
749 size_t pgstart, pgend;
751 struct ashmem_range *range = NULL;
753 if (copy_from_user(&pin, p, sizeof(pin)))
756 if (cmd == ASHMEM_PIN || cmd == ASHMEM_UNPIN) {
757 range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL);
762 mutex_lock(&ashmem_mutex);
763 wait_event(ashmem_shrink_wait, !atomic_read(&ashmem_shrink_inflight));
768 /* per custom, you can pass zero for len to mean "everything onward" */
770 pin.len = PAGE_ALIGN(asma->size) - pin.offset;
772 if ((pin.offset | pin.len) & ~PAGE_MASK)
775 if (((__u32)-1) - pin.offset < pin.len)
778 if (PAGE_ALIGN(asma->size) < pin.offset + pin.len)
781 pgstart = pin.offset / PAGE_SIZE;
782 pgend = pgstart + (pin.len / PAGE_SIZE) - 1;
786 ret = ashmem_pin(asma, pgstart, pgend, &range);
789 ret = ashmem_unpin(asma, pgstart, pgend, &range);
791 case ASHMEM_GET_PIN_STATUS:
792 ret = ashmem_get_pin_status(asma, pgstart, pgend);
797 mutex_unlock(&ashmem_mutex);
799 kmem_cache_free(ashmem_range_cachep, range);
804 static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
806 struct ashmem_area *asma = file->private_data;
810 case ASHMEM_SET_NAME:
811 ret = set_name(asma, (void __user *)arg);
813 case ASHMEM_GET_NAME:
814 ret = get_name(asma, (void __user *)arg);
816 case ASHMEM_SET_SIZE:
818 mutex_lock(&ashmem_mutex);
821 asma->size = (size_t)arg;
823 mutex_unlock(&ashmem_mutex);
825 case ASHMEM_GET_SIZE:
828 case ASHMEM_SET_PROT_MASK:
829 ret = set_prot_mask(asma, arg);
831 case ASHMEM_GET_PROT_MASK:
832 ret = asma->prot_mask;
836 case ASHMEM_GET_PIN_STATUS:
837 ret = ashmem_pin_unpin(asma, cmd, (void __user *)arg);
839 case ASHMEM_PURGE_ALL_CACHES:
841 if (capable(CAP_SYS_ADMIN)) {
842 struct shrink_control sc = {
843 .gfp_mask = GFP_KERNEL,
844 .nr_to_scan = LONG_MAX,
846 ret = ashmem_shrink_count(&ashmem_shrinker, &sc);
847 ashmem_shrink_scan(&ashmem_shrinker, &sc);
855 /* support of 32bit userspace on 64bit platforms */
857 static long compat_ashmem_ioctl(struct file *file, unsigned int cmd,
861 case COMPAT_ASHMEM_SET_SIZE:
862 cmd = ASHMEM_SET_SIZE;
864 case COMPAT_ASHMEM_SET_PROT_MASK:
865 cmd = ASHMEM_SET_PROT_MASK;
868 return ashmem_ioctl(file, cmd, arg);
871 #ifdef CONFIG_PROC_FS
872 static void ashmem_show_fdinfo(struct seq_file *m, struct file *file)
874 struct ashmem_area *asma = file->private_data;
876 mutex_lock(&ashmem_mutex);
879 seq_printf(m, "inode:\t%ld\n", file_inode(asma->file)->i_ino);
881 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
882 seq_printf(m, "name:\t%s\n",
883 asma->name + ASHMEM_NAME_PREFIX_LEN);
885 mutex_unlock(&ashmem_mutex);
888 static const struct file_operations ashmem_fops = {
889 .owner = THIS_MODULE,
891 .release = ashmem_release,
892 .read_iter = ashmem_read_iter,
893 .llseek = ashmem_llseek,
895 .unlocked_ioctl = ashmem_ioctl,
897 .compat_ioctl = compat_ashmem_ioctl,
899 #ifdef CONFIG_PROC_FS
900 .show_fdinfo = ashmem_show_fdinfo,
904 static struct miscdevice ashmem_misc = {
905 .minor = MISC_DYNAMIC_MINOR,
907 .fops = &ashmem_fops,
910 static int __init ashmem_init(void)
914 ashmem_area_cachep = kmem_cache_create("ashmem_area_cache",
915 sizeof(struct ashmem_area),
917 if (!ashmem_area_cachep) {
918 pr_err("failed to create slab cache\n");
922 ashmem_range_cachep = kmem_cache_create("ashmem_range_cache",
923 sizeof(struct ashmem_range),
925 if (!ashmem_range_cachep) {
926 pr_err("failed to create slab cache\n");
930 ret = misc_register(&ashmem_misc);
932 pr_err("failed to register misc device!\n");
936 ret = register_shrinker(&ashmem_shrinker);
938 pr_err("failed to register shrinker!\n");
942 pr_info("initialized\n");
947 misc_deregister(&ashmem_misc);
949 kmem_cache_destroy(ashmem_range_cachep);
951 kmem_cache_destroy(ashmem_area_cachep);
955 device_initcall(ashmem_init);