1/* mm/ashmem.c
2**
3** Anonymous Shared Memory Subsystem, ashmem
4**
5** Copyright (C) 2008 Google, Inc.
6**
7** Robert Love <rlove@google.com>
8**
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.
12**
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.
17*/
18
19#include <linux/module.h>
20#include <linux/file.h>
21#include <linux/fs.h>
22#include <linux/miscdevice.h>
23#include <linux/security.h>
24#include <linux/mm.h>
25#include <linux/mman.h>
26#include <linux/uaccess.h>
27#include <linux/personality.h>
28#include <linux/bitops.h>
29#include <linux/mutex.h>
30#include <linux/shmem_fs.h>
31#include "ashmem.h"
32
33#define ASHMEM_NAME_PREFIX "dev/ashmem/"
34#define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1)
35#define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN)
36
37/*
38 * ashmem_area - anonymous shared memory area
39 * Lifecycle: From our parent file's open() until its release()
40 * Locking: Protected by `ashmem_mutex'
41 * Big Note: Mappings do NOT pin this structure; it dies on close()
42 */
43struct ashmem_area {
44	char name[ASHMEM_FULL_NAME_LEN]; /* optional name in /proc/pid/maps */
45	struct list_head unpinned_list;	 /* list of all ashmem areas */
46	struct file *file;		 /* the shmem-based backing file */
47	size_t size;			 /* size of the mapping, in bytes */
48	unsigned long prot_mask;	 /* allowed prot bits, as vm_flags */
49};
50
51/*
52 * ashmem_range - represents an interval of unpinned (evictable) pages
53 * Lifecycle: From unpin to pin
54 * Locking: Protected by `ashmem_mutex'
55 */
56struct ashmem_range {
57	struct list_head lru;		/* entry in LRU list */
58	struct list_head unpinned;	/* entry in its area's unpinned list */
59	struct ashmem_area *asma;	/* associated area */
60	size_t pgstart;			/* starting page, inclusive */
61	size_t pgend;			/* ending page, inclusive */
62	unsigned int purged;		/* ASHMEM_NOT or ASHMEM_WAS_PURGED */
63};
64
65/* LRU list of unpinned pages, protected by ashmem_mutex */
66static LIST_HEAD(ashmem_lru_list);
67
68/* Count of pages on our LRU list, protected by ashmem_mutex */
69static unsigned long lru_count;
70
71/*
72 * ashmem_mutex - protects the list of and each individual ashmem_area
73 *
74 * Lock Ordering: ashmex_mutex -> i_mutex -> i_alloc_sem
75 */
76static DEFINE_MUTEX(ashmem_mutex);
77
78static struct kmem_cache *ashmem_area_cachep __read_mostly;
79static struct kmem_cache *ashmem_range_cachep __read_mostly;
80
81#define range_size(range) \
82	((range)->pgend - (range)->pgstart + 1)
83
84#define range_on_lru(range) \
85	((range)->purged == ASHMEM_NOT_PURGED)
86
87#define page_range_subsumes_range(range, start, end) \
88	(((range)->pgstart >= (start)) && ((range)->pgend <= (end)))
89
90#define page_range_subsumed_by_range(range, start, end) \
91	(((range)->pgstart <= (start)) && ((range)->pgend >= (end)))
92
93#define page_in_range(range, page) \
94	(((range)->pgstart <= (page)) && ((range)->pgend >= (page)))
95
96#define page_range_in_range(range, start, end) \
97	(page_in_range(range, start) || page_in_range(range, end) || \
98		page_range_subsumes_range(range, start, end))
99
100#define range_before_page(range, page) \
101	((range)->pgend < (page))
102
103#define PROT_MASK		(PROT_EXEC | PROT_READ | PROT_WRITE)
104
105static inline void lru_add(struct ashmem_range *range)
106{
107	list_add_tail(&range->lru, &ashmem_lru_list);
108	lru_count += range_size(range);
109}
110
111static inline void lru_del(struct ashmem_range *range)
112{
113	list_del(&range->lru);
114	lru_count -= range_size(range);
115}
116
117/*
118 * range_alloc - allocate and initialize a new ashmem_range structure
119 *
120 * 'asma' - associated ashmem_area
121 * 'prev_range' - the previous ashmem_range in the sorted asma->unpinned list
122 * 'purged' - initial purge value (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED)
123 * 'start' - starting page, inclusive
124 * 'end' - ending page, inclusive
125 *
126 * Caller must hold ashmem_mutex.
127 */
128static int range_alloc(struct ashmem_area *asma,
129		       struct ashmem_range *prev_range, unsigned int purged,
130		       size_t start, size_t end)
131{
132	struct ashmem_range *range;
133
134	range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL);
135	if (unlikely(!range))
136		return -ENOMEM;
137
138	range->asma = asma;
139	range->pgstart = start;
140	range->pgend = end;
141	range->purged = purged;
142
143	list_add_tail(&range->unpinned, &prev_range->unpinned);
144
145	if (range_on_lru(range))
146		lru_add(range);
147
148	return 0;
149}
150
151static void range_del(struct ashmem_range *range)
152{
153	list_del(&range->unpinned);
154	if (range_on_lru(range))
155		lru_del(range);
156	kmem_cache_free(ashmem_range_cachep, range);
157}
158
159/*
160 * range_shrink - shrinks a range
161 *
162 * Caller must hold ashmem_mutex.
163 */
164static inline void range_shrink(struct ashmem_range *range,
165				size_t start, size_t end)
166{
167	size_t pre = range_size(range);
168
169	range->pgstart = start;
170	range->pgend = end;
171
172	if (range_on_lru(range))
173		lru_count -= pre - range_size(range);
174}
175
176static int ashmem_open(struct inode *inode, struct file *file)
177{
178	struct ashmem_area *asma;
179	int ret;
180
181	ret = generic_file_open(inode, file);
182	if (unlikely(ret))
183		return ret;
184
185	asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL);
186	if (unlikely(!asma))
187		return -ENOMEM;
188
189	INIT_LIST_HEAD(&asma->unpinned_list);
190	memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN);
191	asma->prot_mask = PROT_MASK;
192	file->private_data = asma;
193
194	return 0;
195}
196
197static int ashmem_release(struct inode *ignored, struct file *file)
198{
199	struct ashmem_area *asma = file->private_data;
200	struct ashmem_range *range, *next;
201
202	mutex_lock(&ashmem_mutex);
203	list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned)
204		range_del(range);
205	mutex_unlock(&ashmem_mutex);
206
207	if (asma->file)
208		fput(asma->file);
209	kmem_cache_free(ashmem_area_cachep, asma);
210
211	return 0;
212}
213
214static ssize_t ashmem_read(struct file *file, char __user *buf,
215			   size_t len, loff_t *pos)
216{
217	struct ashmem_area *asma = file->private_data;
218	int ret = 0;
219
220	mutex_lock(&ashmem_mutex);
221
222	/* If size is not set, or set to 0, always return EOF. */
223	if (asma->size == 0)
224		goto out;
225
226	if (!asma->file) {
227		ret = -EBADF;
228		goto out;
229	}
230
231	ret = asma->file->f_op->read(asma->file, buf, len, pos);
232	if (ret < 0)
233		goto out;
234
235	/** Update backing file pos, since f_ops->read() doesn't */
236	asma->file->f_pos = *pos;
237
238out:
239	mutex_unlock(&ashmem_mutex);
240	return ret;
241}
242
243static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin)
244{
245	struct ashmem_area *asma = file->private_data;
246	int ret;
247
248	mutex_lock(&ashmem_mutex);
249
250	if (asma->size == 0) {
251		ret = -EINVAL;
252		goto out;
253	}
254
255	if (!asma->file) {
256		ret = -EBADF;
257		goto out;
258	}
259
260	ret = asma->file->f_op->llseek(asma->file, offset, origin);
261	if (ret < 0)
262		goto out;
263
264	/** Copy f_pos from backing file, since f_ops->llseek() sets it */
265	file->f_pos = asma->file->f_pos;
266
267out:
268	mutex_unlock(&ashmem_mutex);
269	return ret;
270}
271
272static inline unsigned long calc_vm_may_flags(unsigned long prot)
273{
274	return _calc_vm_trans(prot, PROT_READ,  VM_MAYREAD) |
275	       _calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) |
276	       _calc_vm_trans(prot, PROT_EXEC,  VM_MAYEXEC);
277}
278
279static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
280{
281	struct ashmem_area *asma = file->private_data;
282	int ret = 0;
283
284	mutex_lock(&ashmem_mutex);
285
286	/* user needs to SET_SIZE before mapping */
287	if (unlikely(!asma->size)) {
288		ret = -EINVAL;
289		goto out;
290	}
291
292	/* requested protection bits must match our allowed protection mask */
293	if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask)) &
294		     calc_vm_prot_bits(PROT_MASK))) {
295		ret = -EPERM;
296		goto out;
297	}
298	vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
299
300	if (!asma->file) {
301		char *name = ASHMEM_NAME_DEF;
302		struct file *vmfile;
303
304		if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
305			name = asma->name;
306
307		/* ... and allocate the backing shmem file */
308		vmfile = shmem_file_setup(name, asma->size, vma->vm_flags);
309		if (unlikely(IS_ERR(vmfile))) {
310			ret = PTR_ERR(vmfile);
311			goto out;
312		}
313		asma->file = vmfile;
314	}
315	get_file(asma->file);
316
317	if (vma->vm_flags & VM_SHARED)
318		shmem_set_file(vma, asma->file);
319	else {
320		if (vma->vm_file)
321			fput(vma->vm_file);
322		vma->vm_file = asma->file;
323	}
324	vma->vm_flags |= VM_CAN_NONLINEAR;
325
326out:
327	mutex_unlock(&ashmem_mutex);
328	return ret;
329}
330
331/*
332 * ashmem_shrink - our cache shrinker, called from mm/vmscan.c :: shrink_slab
333 *
334 * 'nr_to_scan' is the number of objects (pages) to prune, or 0 to query how
335 * many objects (pages) we have in total.
336 *
337 * 'gfp_mask' is the mask of the allocation that got us into this mess.
338 *
339 * Return value is the number of objects (pages) remaining, or -1 if we cannot
340 * proceed without risk of deadlock (due to gfp_mask).
341 *
342 * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial
343 * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan'
344 * pages freed.
345 */
346static int ashmem_shrink(struct shrinker *s, struct shrink_control *sc)
347{
348	struct ashmem_range *range, *next;
349
350	/* We might recurse into filesystem code, so bail out if necessary */
351	if (sc->nr_to_scan && !(sc->gfp_mask & __GFP_FS))
352		return -1;
353	if (!sc->nr_to_scan)
354		return lru_count;
355
356	mutex_lock(&ashmem_mutex);
357	list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) {
358		struct inode *inode = range->asma->file->f_dentry->d_inode;
359		loff_t start = range->pgstart * PAGE_SIZE;
360		loff_t end = (range->pgend + 1) * PAGE_SIZE - 1;
361
362		vmtruncate_range(inode, start, end);
363		range->purged = ASHMEM_WAS_PURGED;
364		lru_del(range);
365
366		sc->nr_to_scan -= range_size(range);
367		if (sc->nr_to_scan <= 0)
368			break;
369	}
370	mutex_unlock(&ashmem_mutex);
371
372	return lru_count;
373}
374
375static struct shrinker ashmem_shrinker = {
376	.shrink = ashmem_shrink,
377	.seeks = DEFAULT_SEEKS * 4,
378};
379
380static int set_prot_mask(struct ashmem_area *asma, unsigned long prot)
381{
382	int ret = 0;
383
384	mutex_lock(&ashmem_mutex);
385
386	/* the user can only remove, not add, protection bits */
387	if (unlikely((asma->prot_mask & prot) != prot)) {
388		ret = -EINVAL;
389		goto out;
390	}
391
392	/* does the application expect PROT_READ to imply PROT_EXEC? */
393	if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
394		prot |= PROT_EXEC;
395
396	asma->prot_mask = prot;
397
398out:
399	mutex_unlock(&ashmem_mutex);
400	return ret;
401}
402
403static int set_name(struct ashmem_area *asma, void __user *name)
404{
405	int ret = 0;
406
407	mutex_lock(&ashmem_mutex);
408
409	/* cannot change an existing mapping's name */
410	if (unlikely(asma->file)) {
411		ret = -EINVAL;
412		goto out;
413	}
414
415	if (unlikely(copy_from_user(asma->name + ASHMEM_NAME_PREFIX_LEN,
416				    name, ASHMEM_NAME_LEN)))
417		ret = -EFAULT;
418	asma->name[ASHMEM_FULL_NAME_LEN-1] = '\0';
419
420out:
421	mutex_unlock(&ashmem_mutex);
422
423	return ret;
424}
425
426static int get_name(struct ashmem_area *asma, void __user *name)
427{
428	int ret = 0;
429
430	mutex_lock(&ashmem_mutex);
431	if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') {
432		size_t len;
433
434		/*
435		 * Copying only `len', instead of ASHMEM_NAME_LEN, bytes
436		 * prevents us from revealing one user's stack to another.
437		 */
438		len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1;
439		if (unlikely(copy_to_user(name,
440				asma->name + ASHMEM_NAME_PREFIX_LEN, len)))
441			ret = -EFAULT;
442	} else {
443		if (unlikely(copy_to_user(name, ASHMEM_NAME_DEF,
444					  sizeof(ASHMEM_NAME_DEF))))
445			ret = -EFAULT;
446	}
447	mutex_unlock(&ashmem_mutex);
448
449	return ret;
450}
451
452/*
453 * ashmem_pin - pin the given ashmem region, returning whether it was
454 * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED).
455 *
456 * Caller must hold ashmem_mutex.
457 */
458static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
459{
460	struct ashmem_range *range, *next;
461	int ret = ASHMEM_NOT_PURGED;
462
463	list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
464		/* moved past last applicable page; we can short circuit */
465		if (range_before_page(range, pgstart))
466			break;
467
468		/*
469		 * The user can ask us to pin pages that span multiple ranges,
470		 * or to pin pages that aren't even unpinned, so this is messy.
471		 *
472		 * Four cases:
473		 * 1. The requested range subsumes an existing range, so we
474		 *    just remove the entire matching range.
475		 * 2. The requested range overlaps the start of an existing
476		 *    range, so we just update that range.
477		 * 3. The requested range overlaps the end of an existing
478		 *    range, so we just update that range.
479		 * 4. The requested range punches a hole in an existing range,
480		 *    so we have to update one side of the range and then
481		 *    create a new range for the other side.
482		 */
483		if (page_range_in_range(range, pgstart, pgend)) {
484			ret |= range->purged;
485
486			/* Case #1: Easy. Just nuke the whole thing. */
487			if (page_range_subsumes_range(range, pgstart, pgend)) {
488				range_del(range);
489				continue;
490			}
491
492			/* Case #2: We overlap from the start, so adjust it */
493			if (range->pgstart >= pgstart) {
494				range_shrink(range, pgend + 1, range->pgend);
495				continue;
496			}
497
498			/* Case #3: We overlap from the rear, so adjust it */
499			if (range->pgend <= pgend) {
500				range_shrink(range, range->pgstart, pgstart-1);
501				continue;
502			}
503
504			/*
505			 * Case #4: We eat a chunk out of the middle. A bit
506			 * more complicated, we allocate a new range for the
507			 * second half and adjust the first chunk's endpoint.
508			 */
509			range_alloc(asma, range, range->purged,
510				    pgend + 1, range->pgend);
511			range_shrink(range, range->pgstart, pgstart - 1);
512			break;
513		}
514	}
515
516	return ret;
517}
518
519/*
520 * ashmem_unpin - unpin the given range of pages. Returns zero on success.
521 *
522 * Caller must hold ashmem_mutex.
523 */
524static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
525{
526	struct ashmem_range *range, *next;
527	unsigned int purged = ASHMEM_NOT_PURGED;
528
529restart:
530	list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
531		/* short circuit: this is our insertion point */
532		if (range_before_page(range, pgstart))
533			break;
534
535		/*
536		 * The user can ask us to unpin pages that are already entirely
537		 * or partially pinned. We handle those two cases here.
538		 */
539		if (page_range_subsumed_by_range(range, pgstart, pgend))
540			return 0;
541		if (page_range_in_range(range, pgstart, pgend)) {
542			pgstart = min_t(size_t, range->pgstart, pgstart),
543			pgend = max_t(size_t, range->pgend, pgend);
544			purged |= range->purged;
545			range_del(range);
546			goto restart;
547		}
548	}
549
550	return range_alloc(asma, range, purged, pgstart, pgend);
551}
552
553/*
554 * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the
555 * given interval are unpinned and ASHMEM_IS_PINNED otherwise.
556 *
557 * Caller must hold ashmem_mutex.
558 */
559static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart,
560				 size_t pgend)
561{
562	struct ashmem_range *range;
563	int ret = ASHMEM_IS_PINNED;
564
565	list_for_each_entry(range, &asma->unpinned_list, unpinned) {
566		if (range_before_page(range, pgstart))
567			break;
568		if (page_range_in_range(range, pgstart, pgend)) {
569			ret = ASHMEM_IS_UNPINNED;
570			break;
571		}
572	}
573
574	return ret;
575}
576
577static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
578			    void __user *p)
579{
580	struct ashmem_pin pin;
581	size_t pgstart, pgend;
582	int ret = -EINVAL;
583
584	if (unlikely(!asma->file))
585		return -EINVAL;
586
587	if (unlikely(copy_from_user(&pin, p, sizeof(pin))))
588		return -EFAULT;
589
590	/* per custom, you can pass zero for len to mean "everything onward" */
591	if (!pin.len)
592		pin.len = PAGE_ALIGN(asma->size) - pin.offset;
593
594	if (unlikely((pin.offset | pin.len) & ~PAGE_MASK))
595		return -EINVAL;
596
597	if (unlikely(((__u32) -1) - pin.offset < pin.len))
598		return -EINVAL;
599
600	if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len))
601		return -EINVAL;
602
603	pgstart = pin.offset / PAGE_SIZE;
604	pgend = pgstart + (pin.len / PAGE_SIZE) - 1;
605
606	mutex_lock(&ashmem_mutex);
607
608	switch (cmd) {
609	case ASHMEM_PIN:
610		ret = ashmem_pin(asma, pgstart, pgend);
611		break;
612	case ASHMEM_UNPIN:
613		ret = ashmem_unpin(asma, pgstart, pgend);
614		break;
615	case ASHMEM_GET_PIN_STATUS:
616		ret = ashmem_get_pin_status(asma, pgstart, pgend);
617		break;
618	}
619
620	mutex_unlock(&ashmem_mutex);
621
622	return ret;
623}
624
625static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
626{
627	struct ashmem_area *asma = file->private_data;
628	long ret = -ENOTTY;
629
630	switch (cmd) {
631	case ASHMEM_SET_NAME:
632		ret = set_name(asma, (void __user *) arg);
633		break;
634	case ASHMEM_GET_NAME:
635		ret = get_name(asma, (void __user *) arg);
636		break;
637	case ASHMEM_SET_SIZE:
638		ret = -EINVAL;
639		if (!asma->file) {
640			ret = 0;
641			asma->size = (size_t) arg;
642		}
643		break;
644	case ASHMEM_GET_SIZE:
645		ret = asma->size;
646		break;
647	case ASHMEM_SET_PROT_MASK:
648		ret = set_prot_mask(asma, arg);
649		break;
650	case ASHMEM_GET_PROT_MASK:
651		ret = asma->prot_mask;
652		break;
653	case ASHMEM_PIN:
654	case ASHMEM_UNPIN:
655	case ASHMEM_GET_PIN_STATUS:
656		ret = ashmem_pin_unpin(asma, cmd, (void __user *) arg);
657		break;
658	case ASHMEM_PURGE_ALL_CACHES:
659		ret = -EPERM;
660		if (capable(CAP_SYS_ADMIN)) {
661			struct shrink_control sc = {
662				.gfp_mask = GFP_KERNEL,
663				.nr_to_scan = 0,
664			};
665			ret = ashmem_shrink(&ashmem_shrinker, &sc);
666			sc.nr_to_scan = ret;
667			ashmem_shrink(&ashmem_shrinker, &sc);
668		}
669		break;
670	}
671
672	return ret;
673}
674
675static const struct file_operations ashmem_fops = {
676	.owner = THIS_MODULE,
677	.open = ashmem_open,
678	.release = ashmem_release,
679	.read = ashmem_read,
680	.llseek = ashmem_llseek,
681	.mmap = ashmem_mmap,
682	.unlocked_ioctl = ashmem_ioctl,
683	.compat_ioctl = ashmem_ioctl,
684};
685
686static struct miscdevice ashmem_misc = {
687	.minor = MISC_DYNAMIC_MINOR,
688	.name = "ashmem",
689	.fops = &ashmem_fops,
690};
691
692static int __init ashmem_init(void)
693{
694	int ret;
695
696	ashmem_area_cachep = kmem_cache_create("ashmem_area_cache",
697					  sizeof(struct ashmem_area),
698					  0, 0, NULL);
699	if (unlikely(!ashmem_area_cachep)) {
700		printk(KERN_ERR "ashmem: failed to create slab cache\n");
701		return -ENOMEM;
702	}
703
704	ashmem_range_cachep = kmem_cache_create("ashmem_range_cache",
705					  sizeof(struct ashmem_range),
706					  0, 0, NULL);
707	if (unlikely(!ashmem_range_cachep)) {
708		printk(KERN_ERR "ashmem: failed to create slab cache\n");
709		return -ENOMEM;
710	}
711
712	ret = misc_register(&ashmem_misc);
713	if (unlikely(ret)) {
714		printk(KERN_ERR "ashmem: failed to register misc device!\n");
715		return ret;
716	}
717
718	register_shrinker(&ashmem_shrinker);
719
720	printk(KERN_INFO "ashmem: initialized\n");
721
722	return 0;
723}
724
725static void __exit ashmem_exit(void)
726{
727	int ret;
728
729	unregister_shrinker(&ashmem_shrinker);
730
731	ret = misc_deregister(&ashmem_misc);
732	if (unlikely(ret))
733		printk(KERN_ERR "ashmem: failed to unregister misc device!\n");
734
735	kmem_cache_destroy(ashmem_range_cachep);
736	kmem_cache_destroy(ashmem_area_cachep);
737
738	printk(KERN_INFO "ashmem: unloaded\n");
739}
740
741module_init(ashmem_init);
742module_exit(ashmem_exit);
743
744MODULE_LICENSE("GPL");
745