3 * Anonymous Shared Memory Subsystem, ashmem
5 * Copyright (C) 2008 Google, Inc.
7 * Robert Love <rlove@google.com>
9 * This software is licensed under the terms of the GNU General Public
10 * License version 2, as published by the Free Software Foundation, and
11 * may be copied, distributed, and modified under those terms.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
19 #define pr_fmt(fmt) "ashmem: " fmt
21 #include <linux/init.h>
22 #include <linux/export.h>
23 #include <linux/file.h>
25 #include <linux/falloc.h>
26 #include <linux/miscdevice.h>
27 #include <linux/security.h>
29 #include <linux/mman.h>
30 #include <linux/uaccess.h>
31 #include <linux/personality.h>
32 #include <linux/bitops.h>
33 #include <linux/mutex.h>
34 #include <linux/shmem_fs.h>
37 #define ASHMEM_NAME_PREFIX "dev/ashmem/"
38 #define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1)
39 #define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN)
42 * struct ashmem_area - The anonymous shared memory area
43 * @name: The optional name in /proc/pid/maps
44 * @unpinned_list: The list of all ashmem areas
45 * @file: The shmem-based backing file
46 * @size: The size of the mapping, in bytes
47 * @prot_mask: The allowed protection bits, as vm_flags
49 * The lifecycle of this structure is from our parent file's open() until
50 * its release(). It is also protected by 'ashmem_mutex'
52 * Warning: Mappings do NOT pin this structure; It dies on close()
55 char name[ASHMEM_FULL_NAME_LEN];
56 struct list_head unpinned_list;
59 unsigned long prot_mask;
63 * struct ashmem_range - A range of unpinned/evictable pages
64 * @lru: The entry in the LRU list
65 * @unpinned: The entry in its area's unpinned list
66 * @asma: The associated anonymous shared memory area.
67 * @pgstart: The starting page (inclusive)
68 * @pgend: The ending page (inclusive)
69 * @purged: The purge status (ASHMEM_NOT or ASHMEM_WAS_PURGED)
71 * The lifecycle of this structure is from unpin to pin.
72 * It is protected by 'ashmem_mutex'
76 struct list_head unpinned;
77 struct ashmem_area *asma;
83 /* LRU list of unpinned pages, protected by ashmem_mutex */
84 static LIST_HEAD(ashmem_lru_list);
87 * long lru_count - The count of pages on our LRU list.
89 * This is protected by ashmem_mutex.
91 static unsigned long lru_count;
94 * ashmem_mutex - protects the list of and each individual ashmem_area
96 * Lock Ordering: ashmex_mutex -> i_mutex -> i_alloc_sem
98 static DEFINE_MUTEX(ashmem_mutex);
100 static struct kmem_cache *ashmem_area_cachep __read_mostly;
101 static struct kmem_cache *ashmem_range_cachep __read_mostly;
104 * A separate lockdep class for the backing shmem inodes to resolve the lockdep
105 * warning about the race between kswapd taking fs_reclaim before inode_lock
106 * and write syscall taking inode_lock and then fs_reclaim.
107 * Note that such race is impossible because ashmem does not support write
108 * syscalls operating on the backing shmem.
110 static struct lock_class_key backing_shmem_inode_class;
112 static inline unsigned long range_size(struct ashmem_range *range)
114 return range->pgend - range->pgstart + 1;
117 static inline bool range_on_lru(struct ashmem_range *range)
119 return range->purged == ASHMEM_NOT_PURGED;
122 static inline bool page_range_subsumes_range(struct ashmem_range *range,
123 size_t start, size_t end)
125 return (range->pgstart >= start) && (range->pgend <= end);
128 static inline bool page_range_subsumed_by_range(struct ashmem_range *range,
129 size_t start, size_t end)
131 return (range->pgstart <= start) && (range->pgend >= end);
134 static inline bool page_in_range(struct ashmem_range *range, size_t page)
136 return (range->pgstart <= page) && (range->pgend >= page);
139 static inline bool page_range_in_range(struct ashmem_range *range,
140 size_t start, size_t end)
142 return page_in_range(range, start) || page_in_range(range, end) ||
143 page_range_subsumes_range(range, start, end);
146 static inline bool range_before_page(struct ashmem_range *range, size_t page)
148 return range->pgend < page;
151 #define PROT_MASK (PROT_EXEC | PROT_READ | PROT_WRITE)
154 * lru_add() - Adds a range of memory to the LRU list
155 * @range: The memory range being added.
157 * The range is first added to the end (tail) of the LRU list.
158 * After this, the size of the range is added to @lru_count
160 static inline void lru_add(struct ashmem_range *range)
162 list_add_tail(&range->lru, &ashmem_lru_list);
163 lru_count += range_size(range);
167 * lru_del() - Removes a range of memory from the LRU list
168 * @range: The memory range being removed
170 * The range is first deleted from the LRU list.
171 * After this, the size of the range is removed from @lru_count
173 static inline void lru_del(struct ashmem_range *range)
175 list_del(&range->lru);
176 lru_count -= range_size(range);
180 * range_alloc() - Allocates and initializes a new ashmem_range structure
181 * @asma: The associated ashmem_area
182 * @prev_range: The previous ashmem_range in the sorted asma->unpinned list
183 * @purged: Initial purge status (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED)
184 * @start: The starting page (inclusive)
185 * @end: The ending page (inclusive)
187 * This function is protected by ashmem_mutex.
189 * Return: 0 if successful, or -ENOMEM if there is an error
191 static int range_alloc(struct ashmem_area *asma,
192 struct ashmem_range *prev_range, unsigned int purged,
193 size_t start, size_t end)
195 struct ashmem_range *range;
197 range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL);
198 if (unlikely(!range))
202 range->pgstart = start;
204 range->purged = purged;
206 list_add_tail(&range->unpinned, &prev_range->unpinned);
208 if (range_on_lru(range))
215 * range_del() - Deletes and dealloctes an ashmem_range structure
216 * @range: The associated ashmem_range that has previously been allocated
218 static void range_del(struct ashmem_range *range)
220 list_del(&range->unpinned);
221 if (range_on_lru(range))
223 kmem_cache_free(ashmem_range_cachep, range);
227 * range_shrink() - Shrinks an ashmem_range
228 * @range: The associated ashmem_range being shrunk
229 * @start: The starting byte of the new range
230 * @end: The ending byte of the new range
232 * This does not modify the data inside the existing range in any way - It
233 * simply shrinks the boundaries of the range.
235 * Theoretically, with a little tweaking, this could eventually be changed
236 * to range_resize, and expand the lru_count if the new range is larger.
238 static inline void range_shrink(struct ashmem_range *range,
239 size_t start, size_t end)
241 size_t pre = range_size(range);
243 range->pgstart = start;
246 if (range_on_lru(range))
247 lru_count -= pre - range_size(range);
251 * ashmem_open() - Opens an Anonymous Shared Memory structure
252 * @inode: The backing file's index node(?)
253 * @file: The backing file
255 * Please note that the ashmem_area is not returned by this function - It is
256 * instead written to "file->private_data".
258 * Return: 0 if successful, or another code if unsuccessful.
260 static int ashmem_open(struct inode *inode, struct file *file)
262 struct ashmem_area *asma;
265 ret = generic_file_open(inode, file);
269 asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL);
273 INIT_LIST_HEAD(&asma->unpinned_list);
274 memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN);
275 asma->prot_mask = PROT_MASK;
276 file->private_data = asma;
282 * ashmem_release() - Releases an Anonymous Shared Memory structure
283 * @ignored: The backing file's Index Node(?) - It is ignored here.
284 * @file: The backing file
286 * Return: 0 if successful. If it is anything else, go have a coffee and
289 static int ashmem_release(struct inode *ignored, struct file *file)
291 struct ashmem_area *asma = file->private_data;
292 struct ashmem_range *range, *next;
294 mutex_lock(&ashmem_mutex);
295 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned)
297 mutex_unlock(&ashmem_mutex);
301 kmem_cache_free(ashmem_area_cachep, asma);
306 static ssize_t ashmem_read_iter(struct kiocb *iocb, struct iov_iter *iter)
308 struct ashmem_area *asma = iocb->ki_filp->private_data;
311 mutex_lock(&ashmem_mutex);
313 /* If size is not set, or set to 0, always return EOF. */
323 * asma and asma->file are used outside the lock here. We assume
324 * once asma->file is set it will never be changed, and will not
325 * be destroyed until all references to the file are dropped and
326 * ashmem_release is called.
328 mutex_unlock(&ashmem_mutex);
329 ret = vfs_iter_read(asma->file, iter, &iocb->ki_pos, 0);
330 mutex_lock(&ashmem_mutex);
332 asma->file->f_pos = iocb->ki_pos;
334 mutex_unlock(&ashmem_mutex);
338 static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin)
340 struct ashmem_area *asma = file->private_data;
343 mutex_lock(&ashmem_mutex);
345 if (asma->size == 0) {
346 mutex_unlock(&ashmem_mutex);
351 mutex_unlock(&ashmem_mutex);
355 mutex_unlock(&ashmem_mutex);
357 ret = vfs_llseek(asma->file, offset, origin);
361 /** Copy f_pos from backing file, since f_ops->llseek() sets it */
362 file->f_pos = asma->file->f_pos;
366 static inline vm_flags_t calc_vm_may_flags(unsigned long prot)
368 return _calc_vm_trans(prot, PROT_READ, VM_MAYREAD) |
369 _calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) |
370 _calc_vm_trans(prot, PROT_EXEC, VM_MAYEXEC);
373 static int ashmem_vmfile_mmap(struct file *file, struct vm_area_struct *vma)
375 /* do not allow to mmap ashmem backing shmem file directly */
380 ashmem_vmfile_get_unmapped_area(struct file *file, unsigned long addr,
381 unsigned long len, unsigned long pgoff,
384 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
387 static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
389 static struct file_operations vmfile_fops;
390 struct ashmem_area *asma = file->private_data;
393 mutex_lock(&ashmem_mutex);
395 /* user needs to SET_SIZE before mapping */
396 if (unlikely(!asma->size)) {
401 /* requested mapping size larger than object size */
402 if (vma->vm_end - vma->vm_start > PAGE_ALIGN(asma->size)) {
407 /* requested protection bits must match our allowed protection mask */
408 if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) &
409 calc_vm_prot_bits(PROT_MASK, 0))) {
413 vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
416 char *name = ASHMEM_NAME_DEF;
420 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
423 /* ... and allocate the backing shmem file */
424 vmfile = shmem_file_setup(name, asma->size, vma->vm_flags);
425 if (IS_ERR(vmfile)) {
426 ret = PTR_ERR(vmfile);
429 vmfile->f_mode |= FMODE_LSEEK;
430 inode = file_inode(vmfile);
431 lockdep_set_class(&inode->i_rwsem, &backing_shmem_inode_class);
434 * override mmap operation of the vmfile so that it can't be
435 * remapped which would lead to creation of a new vma with no
436 * asma permission checks. Have to override get_unmapped_area
437 * as well to prevent VM_BUG_ON check for f_ops modification.
439 if (!vmfile_fops.mmap) {
440 vmfile_fops = *vmfile->f_op;
441 vmfile_fops.mmap = ashmem_vmfile_mmap;
442 vmfile_fops.get_unmapped_area =
443 ashmem_vmfile_get_unmapped_area;
445 vmfile->f_op = &vmfile_fops;
447 get_file(asma->file);
450 * XXX - Reworked to use shmem_zero_setup() instead of
451 * shmem_set_file while we're in staging. -jstultz
453 if (vma->vm_flags & VM_SHARED) {
454 ret = shmem_zero_setup(vma);
463 vma->vm_file = asma->file;
466 mutex_unlock(&ashmem_mutex);
471 * ashmem_shrink - our cache shrinker, called from mm/vmscan.c
473 * 'nr_to_scan' is the number of objects to scan for freeing.
475 * 'gfp_mask' is the mask of the allocation that got us into this mess.
477 * Return value is the number of objects freed or -1 if we cannot
478 * proceed without risk of deadlock (due to gfp_mask).
480 * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial
481 * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan'
485 ashmem_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
487 struct ashmem_range *range, *next;
488 unsigned long freed = 0;
490 /* We might recurse into filesystem code, so bail out if necessary */
491 if (!(sc->gfp_mask & __GFP_FS))
494 if (!mutex_trylock(&ashmem_mutex))
497 list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) {
498 loff_t start = range->pgstart * PAGE_SIZE;
499 loff_t end = (range->pgend + 1) * PAGE_SIZE;
501 vfs_fallocate(range->asma->file,
502 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
504 range->purged = ASHMEM_WAS_PURGED;
507 freed += range_size(range);
508 if (--sc->nr_to_scan <= 0)
511 mutex_unlock(&ashmem_mutex);
516 ashmem_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
519 * note that lru_count is count of pages on the lru, not a count of
520 * objects on the list. This means the scan function needs to return the
521 * number of pages freed, not the number of objects scanned.
526 static struct shrinker ashmem_shrinker = {
527 .count_objects = ashmem_shrink_count,
528 .scan_objects = ashmem_shrink_scan,
530 * XXX (dchinner): I wish people would comment on why they need on
531 * significant changes to the default value here
533 .seeks = DEFAULT_SEEKS * 4,
536 static int set_prot_mask(struct ashmem_area *asma, unsigned long prot)
540 mutex_lock(&ashmem_mutex);
542 /* the user can only remove, not add, protection bits */
543 if (unlikely((asma->prot_mask & prot) != prot)) {
548 /* does the application expect PROT_READ to imply PROT_EXEC? */
549 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
552 asma->prot_mask = prot;
555 mutex_unlock(&ashmem_mutex);
559 static int set_name(struct ashmem_area *asma, void __user *name)
563 char local_name[ASHMEM_NAME_LEN];
566 * Holding the ashmem_mutex while doing a copy_from_user might cause
567 * an data abort which would try to access mmap_sem. If another
568 * thread has invoked ashmem_mmap then it will be holding the
569 * semaphore and will be waiting for ashmem_mutex, there by leading to
570 * deadlock. We'll release the mutex and take the name to a local
571 * variable that does not need protection and later copy the local
572 * variable to the structure member with lock held.
574 len = strncpy_from_user(local_name, name, ASHMEM_NAME_LEN);
577 if (len == ASHMEM_NAME_LEN)
578 local_name[ASHMEM_NAME_LEN - 1] = '\0';
579 mutex_lock(&ashmem_mutex);
580 /* cannot change an existing mapping's name */
581 if (unlikely(asma->file))
584 strcpy(asma->name + ASHMEM_NAME_PREFIX_LEN, local_name);
586 mutex_unlock(&ashmem_mutex);
590 static int get_name(struct ashmem_area *asma, void __user *name)
595 * Have a local variable to which we'll copy the content
596 * from asma with the lock held. Later we can copy this to the user
597 * space safely without holding any locks. So even if we proceed to
598 * wait for mmap_sem, it won't lead to deadlock.
600 char local_name[ASHMEM_NAME_LEN];
602 mutex_lock(&ashmem_mutex);
603 if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') {
605 * Copying only `len', instead of ASHMEM_NAME_LEN, bytes
606 * prevents us from revealing one user's stack to another.
608 len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1;
609 memcpy(local_name, asma->name + ASHMEM_NAME_PREFIX_LEN, len);
611 len = sizeof(ASHMEM_NAME_DEF);
612 memcpy(local_name, ASHMEM_NAME_DEF, len);
614 mutex_unlock(&ashmem_mutex);
617 * Now we are just copying from the stack variable to userland
620 if (unlikely(copy_to_user(name, local_name, len)))
626 * ashmem_pin - pin the given ashmem region, returning whether it was
627 * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED).
629 * Caller must hold ashmem_mutex.
631 static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
633 struct ashmem_range *range, *next;
634 int ret = ASHMEM_NOT_PURGED;
636 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
637 /* moved past last applicable page; we can short circuit */
638 if (range_before_page(range, pgstart))
642 * The user can ask us to pin pages that span multiple ranges,
643 * or to pin pages that aren't even unpinned, so this is messy.
646 * 1. The requested range subsumes an existing range, so we
647 * just remove the entire matching range.
648 * 2. The requested range overlaps the start of an existing
649 * range, so we just update that range.
650 * 3. The requested range overlaps the end of an existing
651 * range, so we just update that range.
652 * 4. The requested range punches a hole in an existing range,
653 * so we have to update one side of the range and then
654 * create a new range for the other side.
656 if (page_range_in_range(range, pgstart, pgend)) {
657 ret |= range->purged;
659 /* Case #1: Easy. Just nuke the whole thing. */
660 if (page_range_subsumes_range(range, pgstart, pgend)) {
665 /* Case #2: We overlap from the start, so adjust it */
666 if (range->pgstart >= pgstart) {
667 range_shrink(range, pgend + 1, range->pgend);
671 /* Case #3: We overlap from the rear, so adjust it */
672 if (range->pgend <= pgend) {
673 range_shrink(range, range->pgstart,
679 * Case #4: We eat a chunk out of the middle. A bit
680 * more complicated, we allocate a new range for the
681 * second half and adjust the first chunk's endpoint.
683 range_alloc(asma, range, range->purged,
684 pgend + 1, range->pgend);
685 range_shrink(range, range->pgstart, pgstart - 1);
694 * ashmem_unpin - unpin the given range of pages. Returns zero on success.
696 * Caller must hold ashmem_mutex.
698 static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
700 struct ashmem_range *range, *next;
701 unsigned int purged = ASHMEM_NOT_PURGED;
704 list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
705 /* short circuit: this is our insertion point */
706 if (range_before_page(range, pgstart))
710 * The user can ask us to unpin pages that are already entirely
711 * or partially pinned. We handle those two cases here.
713 if (page_range_subsumed_by_range(range, pgstart, pgend))
715 if (page_range_in_range(range, pgstart, pgend)) {
716 pgstart = min(range->pgstart, pgstart);
717 pgend = max(range->pgend, pgend);
718 purged |= range->purged;
724 return range_alloc(asma, range, purged, pgstart, pgend);
728 * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the
729 * given interval are unpinned and ASHMEM_IS_PINNED otherwise.
731 * Caller must hold ashmem_mutex.
733 static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart,
736 struct ashmem_range *range;
737 int ret = ASHMEM_IS_PINNED;
739 list_for_each_entry(range, &asma->unpinned_list, unpinned) {
740 if (range_before_page(range, pgstart))
742 if (page_range_in_range(range, pgstart, pgend)) {
743 ret = ASHMEM_IS_UNPINNED;
751 static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
754 struct ashmem_pin pin;
755 size_t pgstart, pgend;
758 if (unlikely(copy_from_user(&pin, p, sizeof(pin))))
761 mutex_lock(&ashmem_mutex);
763 if (unlikely(!asma->file))
766 /* per custom, you can pass zero for len to mean "everything onward" */
768 pin.len = PAGE_ALIGN(asma->size) - pin.offset;
770 if (unlikely((pin.offset | pin.len) & ~PAGE_MASK))
773 if (unlikely(((__u32)-1) - pin.offset < pin.len))
776 if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len))
779 pgstart = pin.offset / PAGE_SIZE;
780 pgend = pgstart + (pin.len / PAGE_SIZE) - 1;
784 ret = ashmem_pin(asma, pgstart, pgend);
787 ret = ashmem_unpin(asma, pgstart, pgend);
789 case ASHMEM_GET_PIN_STATUS:
790 ret = ashmem_get_pin_status(asma, pgstart, pgend);
795 mutex_unlock(&ashmem_mutex);
800 static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
802 struct ashmem_area *asma = file->private_data;
806 case ASHMEM_SET_NAME:
807 ret = set_name(asma, (void __user *)arg);
809 case ASHMEM_GET_NAME:
810 ret = get_name(asma, (void __user *)arg);
812 case ASHMEM_SET_SIZE:
814 mutex_lock(&ashmem_mutex);
817 asma->size = (size_t)arg;
819 mutex_unlock(&ashmem_mutex);
821 case ASHMEM_GET_SIZE:
824 case ASHMEM_SET_PROT_MASK:
825 ret = set_prot_mask(asma, arg);
827 case ASHMEM_GET_PROT_MASK:
828 ret = asma->prot_mask;
832 case ASHMEM_GET_PIN_STATUS:
833 ret = ashmem_pin_unpin(asma, cmd, (void __user *)arg);
835 case ASHMEM_PURGE_ALL_CACHES:
837 if (capable(CAP_SYS_ADMIN)) {
838 struct shrink_control sc = {
839 .gfp_mask = GFP_KERNEL,
840 .nr_to_scan = LONG_MAX,
842 ret = ashmem_shrink_count(&ashmem_shrinker, &sc);
843 ashmem_shrink_scan(&ashmem_shrinker, &sc);
851 /* support of 32bit userspace on 64bit platforms */
853 static long compat_ashmem_ioctl(struct file *file, unsigned int cmd,
857 case COMPAT_ASHMEM_SET_SIZE:
858 cmd = ASHMEM_SET_SIZE;
860 case COMPAT_ASHMEM_SET_PROT_MASK:
861 cmd = ASHMEM_SET_PROT_MASK;
864 return ashmem_ioctl(file, cmd, arg);
868 static const struct file_operations ashmem_fops = {
869 .owner = THIS_MODULE,
871 .release = ashmem_release,
872 .read_iter = ashmem_read_iter,
873 .llseek = ashmem_llseek,
875 .unlocked_ioctl = ashmem_ioctl,
877 .compat_ioctl = compat_ashmem_ioctl,
881 static struct miscdevice ashmem_misc = {
882 .minor = MISC_DYNAMIC_MINOR,
884 .fops = &ashmem_fops,
887 static int __init ashmem_init(void)
891 ashmem_area_cachep = kmem_cache_create("ashmem_area_cache",
892 sizeof(struct ashmem_area),
894 if (unlikely(!ashmem_area_cachep)) {
895 pr_err("failed to create slab cache\n");
899 ashmem_range_cachep = kmem_cache_create("ashmem_range_cache",
900 sizeof(struct ashmem_range),
902 if (unlikely(!ashmem_range_cachep)) {
903 pr_err("failed to create slab cache\n");
907 ret = misc_register(&ashmem_misc);
909 pr_err("failed to register misc device!\n");
913 register_shrinker(&ashmem_shrinker);
915 pr_info("initialized\n");
920 kmem_cache_destroy(ashmem_range_cachep);
922 kmem_cache_destroy(ashmem_area_cachep);
926 device_initcall(ashmem_init);