1 files changed, 748 insertions, 0 deletions

diff --git a/mm/ashmem.c b/mm/ashmem.c
new file mode 100644
index 00000000000..66e3f23ee33
--- /dev/null
+++ b/mm/ashmem.c
@@ -0,0 +1,748 @@
+/* mm/ashmem.c
+**
+** Anonymous Shared Memory Subsystem, ashmem
+**
+** Copyright (C) 2008 Google, Inc.
+**
+** Robert Love <rlove@google.com>
+**
+** This software is licensed under the terms of the GNU General Public
+** License version 2, as published by the Free Software Foundation, and
+** may be copied, distributed, and modified under those terms.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+*/
+
+#include <linux/module.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/security.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/uaccess.h>
+#include <linux/personality.h>
+#include <linux/bitops.h>
+#include <linux/mutex.h>
+#include <linux/shmem_fs.h>
+#include <linux/ashmem.h>
+
+#define ASHMEM_NAME_PREFIX "dev/ashmem/"
+#define ASHMEM_NAME_PREFIX_LEN (sizeof(ASHMEM_NAME_PREFIX) - 1)
+#define ASHMEM_FULL_NAME_LEN (ASHMEM_NAME_LEN + ASHMEM_NAME_PREFIX_LEN)
+
+/*
+ * ashmem_area - anonymous shared memory area
+ * Lifecycle: From our parent file's open() until its release()
+ * Locking: Protected by `ashmem_mutex'
+ * Big Note: Mappings do NOT pin this structure; it dies on close()
+ */
+struct ashmem_area {
+        char name[ASHMEM_FULL_NAME_LEN];/* optional name for /proc/pid/maps */
+        struct list_head unpinned_list; /* list of all ashmem areas */
+        struct file *file;              /* the shmem-based backing file */
+        size_t size;                    /* size of the mapping, in bytes */
+        unsigned long prot_mask;        /* allowed prot bits, as vm_flags */
+};
+
+/*
+ * ashmem_range - represents an interval of unpinned (evictable) pages
+ * Lifecycle: From unpin to pin
+ * Locking: Protected by `ashmem_mutex'
+ */
+struct ashmem_range {
+        struct list_head lru;           /* entry in LRU list */
+        struct list_head unpinned;      /* entry in its area's unpinned list */
+        struct ashmem_area *asma;       /* associated area */
+        size_t pgstart;                 /* starting page, inclusive */
+        size_t pgend;                   /* ending page, inclusive */
+        unsigned int purged;            /* ASHMEM_NOT or ASHMEM_WAS_PURGED */
+};
+
+/* LRU list of unpinned pages, protected by ashmem_mutex */
+static LIST_HEAD(ashmem_lru_list);
+
+/* Count of pages on our LRU list, protected by ashmem_mutex */
+static unsigned long lru_count;
+
+/*
+ * ashmem_mutex - protects the list of and each individual ashmem_area
+ *
+ * Lock Ordering: ashmex_mutex -> i_mutex -> i_alloc_sem
+ */
+static DEFINE_MUTEX(ashmem_mutex);
+
+static struct kmem_cache *ashmem_area_cachep __read_mostly;
+static struct kmem_cache *ashmem_range_cachep __read_mostly;
+
+#define range_size(range) \
+  ((range)->pgend - (range)->pgstart + 1)
+
+#define range_on_lru(range) \
+  ((range)->purged == ASHMEM_NOT_PURGED)
+
+#define page_range_subsumes_range(range, start, end) \
+  (((range)->pgstart >= (start)) && ((range)->pgend <= (end)))
+
+#define page_range_subsumed_by_range(range, start, end) \
+  (((range)->pgstart <= (start)) && ((range)->pgend >= (end)))
+
+#define page_in_range(range, page) \
+ (((range)->pgstart <= (page)) && ((range)->pgend >= (page)))
+
+#define page_range_in_range(range, start, end) \
+  (page_in_range(range, start) || page_in_range(range, end) || \
+   page_range_subsumes_range(range, start, end))
+
+#define range_before_page(range, page) \
+  ((range)->pgend < (page))
+
+#define PROT_MASK               (PROT_EXEC | PROT_READ | PROT_WRITE)
+
+static inline void lru_add(struct ashmem_range *range)
+{
+        list_add_tail(&range->lru, &ashmem_lru_list);
+        lru_count += range_size(range);
+}
+
+static inline void lru_del(struct ashmem_range *range)
+{
+        list_del(&range->lru);
+        lru_count -= range_size(range);
+}
+
+/*
+ * range_alloc - allocate and initialize a new ashmem_range structure
+ *
+ * 'asma' - associated ashmem_area
+ * 'prev_range' - the previous ashmem_range in the sorted asma->unpinned list
+ * 'purged' - initial purge value (ASMEM_NOT_PURGED or ASHMEM_WAS_PURGED)
+ * 'start' - starting page, inclusive
+ * 'end' - ending page, inclusive
+ *
+ * Caller must hold ashmem_mutex.
+ */
+static int range_alloc(struct ashmem_area *asma,
+                       struct ashmem_range *prev_range, unsigned int purged,
+                       size_t start, size_t end)
+{
+        struct ashmem_range *range;
+
+        range = kmem_cache_zalloc(ashmem_range_cachep, GFP_KERNEL);
+        if (unlikely(!range))
+                return -ENOMEM;
+
+        range->asma = asma;
+        range->pgstart = start;
+        range->pgend = end;
+        range->purged = purged;
+
+        list_add_tail(&range->unpinned, &prev_range->unpinned);
+
+        if (range_on_lru(range))
+                lru_add(range);
+
+        return 0;
+}
+
+static void range_del(struct ashmem_range *range)
+{
+        list_del(&range->unpinned);
+        if (range_on_lru(range))
+                lru_del(range);
+        kmem_cache_free(ashmem_range_cachep, range);
+}
+
+/*
+ * range_shrink - shrinks a range
+ *
+ * Caller must hold ashmem_mutex.
+ */
+static inline void range_shrink(struct ashmem_range *range,
+                                size_t start, size_t end)
+{
+        size_t pre = range_size(range);
+
+        range->pgstart = start;
+        range->pgend = end;
+
+        if (range_on_lru(range))
+                lru_count -= pre - range_size(range);
+}
+
+static int ashmem_open(struct inode *inode, struct file *file)
+{
+        struct ashmem_area *asma;
+        int ret;
+
+        ret = generic_file_open(inode, file);
+        if (unlikely(ret))
+                return ret;
+
+        asma = kmem_cache_zalloc(ashmem_area_cachep, GFP_KERNEL);
+        if (unlikely(!asma))
+                return -ENOMEM;
+
+        INIT_LIST_HEAD(&asma->unpinned_list);
+        memcpy(asma->name, ASHMEM_NAME_PREFIX, ASHMEM_NAME_PREFIX_LEN);
+        asma->prot_mask = PROT_MASK;
+        file->private_data = asma;
+
+        return 0;
+}
+
+static int ashmem_release(struct inode *ignored, struct file *file)
+{
+        struct ashmem_area *asma = file->private_data;
+        struct ashmem_range *range, *next;
+
+        mutex_lock(&ashmem_mutex);
+        list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned)
+                range_del(range);
+        mutex_unlock(&ashmem_mutex);
+
+        if (asma->file)
+                fput(asma->file);
+        kmem_cache_free(ashmem_area_cachep, asma);
+
+        return 0;
+}
+
+static ssize_t ashmem_read(struct file *file, char __user *buf,
+                           size_t len, loff_t *pos)
+{
+        struct ashmem_area *asma = file->private_data;
+        int ret = 0;
+
+        mutex_lock(&ashmem_mutex);
+
+        /* If size is not set, or set to 0, always return EOF. */
+        if (asma->size == 0) {
+                goto out;
+        }
+
+        if (!asma->file) {
+                ret = -EBADF;
+                goto out;
+        }
+
+        ret = asma->file->f_op->read(asma->file, buf, len, pos);
+        if (ret < 0) {
+                goto out;
+        }
+
+        /** Update backing file pos, since f_ops->read() doesn't */
+        asma->file->f_pos = *pos;
+
+out:
+        mutex_unlock(&ashmem_mutex);
+        return ret;
+}
+
+static loff_t ashmem_llseek(struct file *file, loff_t offset, int origin)
+{
+        struct ashmem_area *asma = file->private_data;
+        int ret;
+
+        mutex_lock(&ashmem_mutex);
+
+        if (asma->size == 0) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        if (!asma->file) {
+                ret = -EBADF;
+                goto out;
+        }
+
+        ret = asma->file->f_op->llseek(asma->file, offset, origin);
+        if (ret < 0) {
+                goto out;
+        }
+
+        /** Copy f_pos from backing file, since f_ops->llseek() sets it */
+        file->f_pos = asma->file->f_pos;
+
+out:
+        mutex_unlock(&ashmem_mutex);
+        return ret;
+}
+
+static inline unsigned long
+calc_vm_may_flags(unsigned long prot)
+{
+        return _calc_vm_trans(prot, PROT_READ,  VM_MAYREAD ) |
+               _calc_vm_trans(prot, PROT_WRITE, VM_MAYWRITE) |
+               _calc_vm_trans(prot, PROT_EXEC,  VM_MAYEXEC);
+}
+
+static int ashmem_mmap(struct file *file, struct vm_area_struct *vma)
+{
+        struct ashmem_area *asma = file->private_data;
+        int ret = 0;
+
+        mutex_lock(&ashmem_mutex);
+
+        /* user needs to SET_SIZE before mapping */
+        if (unlikely(!asma->size)) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        /* requested protection bits must match our allowed protection mask */
+        if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask)) &
+                                                calc_vm_prot_bits(PROT_MASK))) {
+                ret = -EPERM;
+                goto out;
+        }
+        vma->vm_flags &= ~calc_vm_may_flags(~asma->prot_mask);
+
+        if (!asma->file) {
+                char *name = ASHMEM_NAME_DEF;
+                struct file *vmfile;
+
+                if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0')
+                        name = asma->name;
+
+                /* ... and allocate the backing shmem file */
+                vmfile = shmem_file_setup(name, asma->size, vma->vm_flags);
+                if (unlikely(IS_ERR(vmfile))) {
+                        ret = PTR_ERR(vmfile);
+                        goto out;
+                }
+                asma->file = vmfile;
+        }
+        get_file(asma->file);
+
+        if (vma->vm_flags & VM_SHARED)
+                shmem_set_file(vma, asma->file);
+        else {
+                if (vma->vm_file)
+                        fput(vma->vm_file);
+                vma->vm_file = asma->file;
+        }
+        vma->vm_flags |= VM_CAN_NONLINEAR;
+
+out:
+        mutex_unlock(&ashmem_mutex);
+        return ret;
+}
+
+/*
+ * ashmem_shrink - our cache shrinker, called from mm/vmscan.c :: shrink_slab
+ *
+ * 'nr_to_scan' is the number of objects (pages) to prune, or 0 to query how
+ * many objects (pages) we have in total.
+ *
+ * 'gfp_mask' is the mask of the allocation that got us into this mess.
+ *
+ * Return value is the number of objects (pages) remaining, or -1 if we cannot
+ * proceed without risk of deadlock (due to gfp_mask).
+ *
+ * We approximate LRU via least-recently-unpinned, jettisoning unpinned partial
+ * chunks of ashmem regions LRU-wise one-at-a-time until we hit 'nr_to_scan'
+ * pages freed.
+ */
+static int ashmem_shrink(struct shrinker *s, struct shrink_control *sc)
+{
+        struct ashmem_range *range, *next;
+
+        /* We might recurse into filesystem code, so bail out if necessary */
+        if (sc->nr_to_scan && !(sc->gfp_mask & __GFP_FS))
+                return -1;
+        if (!sc->nr_to_scan)
+                return lru_count;
+
+        mutex_lock(&ashmem_mutex);
+        list_for_each_entry_safe(range, next, &ashmem_lru_list, lru) {
+                struct inode *inode = range->asma->file->f_dentry->d_inode;
+                loff_t start = range->pgstart * PAGE_SIZE;
+                loff_t end = (range->pgend + 1) * PAGE_SIZE - 1;
+
+                vmtruncate_range(inode, start, end);
+                range->purged = ASHMEM_WAS_PURGED;
+                lru_del(range);
+
+                sc->nr_to_scan -= range_size(range);
+                if (sc->nr_to_scan <= 0)
+                        break;
+        }
+        mutex_unlock(&ashmem_mutex);
+
+        return lru_count;
+}
+
+static struct shrinker ashmem_shrinker = {
+        .shrink = ashmem_shrink,
+        .seeks = DEFAULT_SEEKS * 4,
+};
+
+static int set_prot_mask(struct ashmem_area *asma, unsigned long prot)
+{
+        int ret = 0;
+
+        mutex_lock(&ashmem_mutex);
+
+        /* the user can only remove, not add, protection bits */
+        if (unlikely((asma->prot_mask & prot) != prot)) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        /* does the application expect PROT_READ to imply PROT_EXEC? */
+        if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
+                prot |= PROT_EXEC;
+
+        asma->prot_mask = prot;
+
+out:
+        mutex_unlock(&ashmem_mutex);
+        return ret;
+}
+
+static int set_name(struct ashmem_area *asma, void __user *name)
+{
+        int ret = 0;
+
+        mutex_lock(&ashmem_mutex);
+
+        /* cannot change an existing mapping's name */
+        if (unlikely(asma->file)) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        if (unlikely(copy_from_user(asma->name + ASHMEM_NAME_PREFIX_LEN,
+                                    name, ASHMEM_NAME_LEN)))
+                ret = -EFAULT;
+        asma->name[ASHMEM_FULL_NAME_LEN-1] = '\0';
+
+out:
+        mutex_unlock(&ashmem_mutex);
+
+        return ret;
+}
+
+static int get_name(struct ashmem_area *asma, void __user *name)
+{
+        int ret = 0;
+
+        mutex_lock(&ashmem_mutex);
+        if (asma->name[ASHMEM_NAME_PREFIX_LEN] != '\0') {
+                size_t len;
+
+                /*
+                 * Copying only `len', instead of ASHMEM_NAME_LEN, bytes
+                 * prevents us from revealing one user's stack to another.
+                 */
+                len = strlen(asma->name + ASHMEM_NAME_PREFIX_LEN) + 1;
+                if (unlikely(copy_to_user(name,
+                                asma->name + ASHMEM_NAME_PREFIX_LEN, len)))
+                        ret = -EFAULT;
+        } else {
+                if (unlikely(copy_to_user(name, ASHMEM_NAME_DEF,
+                                          sizeof(ASHMEM_NAME_DEF))))
+                        ret = -EFAULT;
+        }
+        mutex_unlock(&ashmem_mutex);
+
+        return ret;
+}
+
+/*
+ * ashmem_pin - pin the given ashmem region, returning whether it was
+ * previously purged (ASHMEM_WAS_PURGED) or not (ASHMEM_NOT_PURGED).
+ *
+ * Caller must hold ashmem_mutex.
+ */
+static int ashmem_pin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
+{
+        struct ashmem_range *range, *next;
+        int ret = ASHMEM_NOT_PURGED;
+
+        list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
+                /* moved past last applicable page; we can short circuit */
+                if (range_before_page(range, pgstart))
+                        break;
+
+                /*
+                 * The user can ask us to pin pages that span multiple ranges,
+                 * or to pin pages that aren't even unpinned, so this is messy.
+                 *
+                 * Four cases:
+                 * 1. The requested range subsumes an existing range, so we
+                 *    just remove the entire matching range.
+                 * 2. The requested range overlaps the start of an existing
+                 *    range, so we just update that range.
+                 * 3. The requested range overlaps the end of an existing
+                 *    range, so we just update that range.
+                 * 4. The requested range punches a hole in an existing range,
+                 *    so we have to update one side of the range and then
+                 *    create a new range for the other side.
+                 */
+                if (page_range_in_range(range, pgstart, pgend)) {
+                        ret |= range->purged;
+
+                        /* Case #1: Easy. Just nuke the whole thing. */
+                        if (page_range_subsumes_range(range, pgstart, pgend)) {
+                                range_del(range);
+                                continue;
+                        }
+
+                        /* Case #2: We overlap from the start, so adjust it */
+                        if (range->pgstart >= pgstart) {
+                                range_shrink(range, pgend + 1, range->pgend);
+                                continue;
+                        }
+
+                        /* Case #3: We overlap from the rear, so adjust it */
+                        if (range->pgend <= pgend) {
+                                range_shrink(range, range->pgstart, pgstart-1);
+                                continue;
+                        }
+
+                        /*
+                         * Case #4: We eat a chunk out of the middle. A bit
+                         * more complicated, we allocate a new range for the
+                         * second half and adjust the first chunk's endpoint.
+                         */
+                        range_alloc(asma, range, range->purged,
+                                    pgend + 1, range->pgend);
+                        range_shrink(range, range->pgstart, pgstart - 1);
+                        break;
+                }
+        }
+
+        return ret;
+}
+
+/*
+ * ashmem_unpin - unpin the given range of pages. Returns zero on success.
+ *
+ * Caller must hold ashmem_mutex.
+ */
+static int ashmem_unpin(struct ashmem_area *asma, size_t pgstart, size_t pgend)
+{
+        struct ashmem_range *range, *next;
+        unsigned int purged = ASHMEM_NOT_PURGED;
+
+restart:
+        list_for_each_entry_safe(range, next, &asma->unpinned_list, unpinned) {
+                /* short circuit: this is our insertion point */
+                if (range_before_page(range, pgstart))
+                        break;
+
+                /*
+                 * The user can ask us to unpin pages that are already entirely
+                 * or partially pinned. We handle those two cases here.
+                 */
+                if (page_range_subsumed_by_range(range, pgstart, pgend))
+                        return 0;
+                if (page_range_in_range(range, pgstart, pgend)) {
+                        pgstart = min_t(size_t, range->pgstart, pgstart),
+                        pgend = max_t(size_t, range->pgend, pgend);
+                        purged |= range->purged;
+                        range_del(range);
+                        goto restart;
+                }
+        }
+
+        return range_alloc(asma, range, purged, pgstart, pgend);
+}
+
+/*
+ * ashmem_get_pin_status - Returns ASHMEM_IS_UNPINNED if _any_ pages in the
+ * given interval are unpinned and ASHMEM_IS_PINNED otherwise.
+ *
+ * Caller must hold ashmem_mutex.
+ */
+static int ashmem_get_pin_status(struct ashmem_area *asma, size_t pgstart,
+                                 size_t pgend)
+{
+        struct ashmem_range *range;
+        int ret = ASHMEM_IS_PINNED;
+
+        list_for_each_entry(range, &asma->unpinned_list, unpinned) {
+                if (range_before_page(range, pgstart))
+                        break;
+                if (page_range_in_range(range, pgstart, pgend)) {
+                        ret = ASHMEM_IS_UNPINNED;
+                        break;
+                }
+        }
+
+        return ret;
+}
+
+static int ashmem_pin_unpin(struct ashmem_area *asma, unsigned long cmd,
+                            void __user *p)
+{
+        struct ashmem_pin pin;
+        size_t pgstart, pgend;
+        int ret = -EINVAL;
+
+        if (unlikely(!asma->file))
+                return -EINVAL;
+
+        if (unlikely(copy_from_user(&pin, p, sizeof(pin))))
+                return -EFAULT;
+
+        /* per custom, you can pass zero for len to mean "everything onward" */
+        if (!pin.len)
+                pin.len = PAGE_ALIGN(asma->size) - pin.offset;
+
+        if (unlikely((pin.offset | pin.len) & ~PAGE_MASK))
+                return -EINVAL;
+
+        if (unlikely(((__u32) -1) - pin.offset < pin.len))
+                return -EINVAL;
+
+        if (unlikely(PAGE_ALIGN(asma->size) < pin.offset + pin.len))
+                return -EINVAL;
+
+        pgstart = pin.offset / PAGE_SIZE;
+        pgend = pgstart + (pin.len / PAGE_SIZE) - 1;
+
+        mutex_lock(&ashmem_mutex);
+
+        switch (cmd) {
+        case ASHMEM_PIN:
+                ret = ashmem_pin(asma, pgstart, pgend);
+                break;
+        case ASHMEM_UNPIN:
+                ret = ashmem_unpin(asma, pgstart, pgend);
+                break;
+        case ASHMEM_GET_PIN_STATUS:
+                ret = ashmem_get_pin_status(asma, pgstart, pgend);
+                break;
+        }
+
+        mutex_unlock(&ashmem_mutex);
+
+        return ret;
+}
+
+static long ashmem_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+        struct ashmem_area *asma = file->private_data;
+        long ret = -ENOTTY;
+
+        switch (cmd) {
+        case ASHMEM_SET_NAME:
+                ret = set_name(asma, (void __user *) arg);
+                break;
+        case ASHMEM_GET_NAME:
+                ret = get_name(asma, (void __user *) arg);
+                break;
+        case ASHMEM_SET_SIZE:
+                ret = -EINVAL;
+                if (!asma->file) {
+                        ret = 0;
+                        asma->size = (size_t) arg;
+                }
+                break;
+        case ASHMEM_GET_SIZE:
+                ret = asma->size;
+                break;
+        case ASHMEM_SET_PROT_MASK:
+                ret = set_prot_mask(asma, arg);
+                break;
+        case ASHMEM_GET_PROT_MASK:
+                ret = asma->prot_mask;
+                break;
+        case ASHMEM_PIN:
+        case ASHMEM_UNPIN:
+        case ASHMEM_GET_PIN_STATUS:
+                ret = ashmem_pin_unpin(asma, cmd, (void __user *) arg);
+                break;
+        case ASHMEM_PURGE_ALL_CACHES:
+                ret = -EPERM;
+                if (capable(CAP_SYS_ADMIN)) {
+                        struct shrink_control sc = {
+                                .gfp_mask = GFP_KERNEL,
+                                .nr_to_scan = 0,
+                        };
+                        ret = ashmem_shrink(&ashmem_shrinker, &sc);
+                        sc.nr_to_scan = ret;
+                        ashmem_shrink(&ashmem_shrinker, &sc);
+                }
+                break;
+        }
+
+        return ret;
+}
+
+static struct file_operations ashmem_fops = {
+        .owner = THIS_MODULE,
+        .open = ashmem_open,
+        .release = ashmem_release,
+        .read = ashmem_read,
+        .llseek = ashmem_llseek,
+        .mmap = ashmem_mmap,
+        .unlocked_ioctl = ashmem_ioctl,
+        .compat_ioctl = ashmem_ioctl,
+};
+
+static struct miscdevice ashmem_misc = {
+        .minor = MISC_DYNAMIC_MINOR,
+        .name = "ashmem",
+        .fops = &ashmem_fops,
+};
+
+static int __init ashmem_init(void)
+{
+        int ret;
+
+        ashmem_area_cachep = kmem_cache_create("ashmem_area_cache",
+                                          sizeof(struct ashmem_area),
+                                          0, 0, NULL);
+        if (unlikely(!ashmem_area_cachep)) {
+                printk(KERN_ERR "ashmem: failed to create slab cache\n");
+                return -ENOMEM;
+        }
+
+        ashmem_range_cachep = kmem_cache_create("ashmem_range_cache",
+                                          sizeof(struct ashmem_range),
+                                          0, 0, NULL);
+        if (unlikely(!ashmem_range_cachep)) {
+                printk(KERN_ERR "ashmem: failed to create slab cache\n");
+                return -ENOMEM;
+        }
+
+        ret = misc_register(&ashmem_misc);
+        if (unlikely(ret)) {
+                printk(KERN_ERR "ashmem: failed to register misc device!\n");
+                return ret;
+        }
+
+        register_shrinker(&ashmem_shrinker);
+
+        printk(KERN_INFO "ashmem: initialized\n");
+
+        return 0;
+}
+
+static void __exit ashmem_exit(void)
+{
+        int ret;
+
+        unregister_shrinker(&ashmem_shrinker);
+
+        ret = misc_deregister(&ashmem_misc);
+        if (unlikely(ret))
+                printk(KERN_ERR "ashmem: failed to unregister misc device!\n");
+
+        kmem_cache_destroy(ashmem_range_cachep);
+        kmem_cache_destroy(ashmem_area_cachep);
+
+        printk(KERN_INFO "ashmem: unloaded\n");
+}
+
+module_init(ashmem_init);
+module_exit(ashmem_exit);
+
+MODULE_LICENSE("GPL");