- 根目录:
- mm
- zsmalloc.c
/*
* zsmalloc memory allocator
*
* Copyright (C) 2011 Nitin Gupta
* Copyright (C) 2012, 2013 Minchan Kim
*
* This code is released using a dual license strategy: BSD/GPL
* You can choose the license that better fits your requirements.
*
* Released under the terms of 3-clause BSD License
* Released under the terms of GNU General Public License Version 2.0
*/
/*
* Following is how we use various fields and flags of underlying
* struct page(s) to form a zspage.
*
* Usage of struct page fields:
* page->private: points to the first component (0-order) page
* page->index (union with page->freelist): offset of the first object
* starting in this page. For the first page, this is
* always 0, so we use this field (aka freelist) to point
* to the first free object in zspage.
* page->lru: links together all component pages (except the first page)
* of a zspage
*
* For _first_ page only:
*
* page->private: refers to the component page after the first page
* If the page is first_page for huge object, it stores handle.
* Look at size_class->huge.
* page->freelist: points to the first free object in zspage.
* Free objects are linked together using in-place
* metadata.
* page->objects: maximum number of objects we can store in this
* zspage (class->zspage_order * PAGE_SIZE / class->size)
* page->lru: links together first pages of various zspages.
* Basically forming list of zspages in a fullness group.
* page->mapping: class index and fullness group of the zspage
* page->inuse: the number of objects that are used in this zspage
*
* Usage of struct page flags:
* PG_private: identifies the first component page
* PG_private2: identifies the last component page
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/highmem.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>
#include <linux/cpumask.h>
#include <linux/cpu.h>
#include <linux/vmalloc.h>
#include <linux/preempt.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/debugfs.h>
#include <linux/zsmalloc.h>
#include <linux/zpool.h>
/*
* This must be power of 2 and greater than of equal to sizeof(link_free).
* These two conditions ensure that any 'struct link_free' itself doesn't
* span more than 1 page which avoids complex case of mapping 2 pages simply
* to restore link_free pointer values.
*/
#define ZS_ALIGN 8
/*
* A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
* pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
*/
#define ZS_MAX_ZSPAGE_ORDER 2
#define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
#define ZS_HANDLE_SIZE (sizeof(unsigned long))
/*
* Object location (<PFN>, <obj_idx>) is encoded as
* as single (unsigned long) handle value.
*
* Note that object index <obj_idx> is relative to system
* page <PFN> it is stored in, so for each sub-page belonging
* to a zspage, obj_idx starts with 0.
*
* This is made more complicated by various memory models and PAE.
*/
#ifndef MAX_PHYSMEM_BITS
#ifdef CONFIG_HIGHMEM64G
#define MAX_PHYSMEM_BITS 36
#else /* !CONFIG_HIGHMEM64G */
/*
* If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
* be PAGE_SHIFT
*/
#define MAX_PHYSMEM_BITS BITS_PER_LONG
#endif
#endif
#define _PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT)
/*
* Memory for allocating for handle keeps object position by
* encoding <page, obj_idx> and the encoded value has a room
* in least bit(ie, look at obj_to_location).
* We use the bit to synchronize between object access by
* user and migration.
*/
#define HANDLE_PIN_BIT 0
/*
* Head in allocated object should have OBJ_ALLOCATED_TAG
* to identify the object was allocated or not.
* It's okay to add the status bit in the least bit because
* header keeps handle which is 4byte-aligned address so we
* have room for two bit at least.
*/
#define OBJ_ALLOCATED_TAG 1
#define OBJ_TAG_BITS 1
#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
#define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
#define MAX(a, b) ((a) >= (b) ? (a) : (b))
/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
#define ZS_MIN_ALLOC_SIZE \
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
/* each chunk includes extra space to keep handle */
#define ZS_MAX_ALLOC_SIZE PAGE_SIZE
/*
* On systems with 4K page size, this gives 255 size classes! There is a
* trader-off here:
* - Large number of size classes is potentially wasteful as free page are
* spread across these classes
* - Small number of size classes causes large internal fragmentation
* - Probably its better to use specific size classes (empirically
* determined). NOTE: all those class sizes must be set as multiple of
* ZS_ALIGN to make sure link_free itself never has to span 2 pages.
*
* ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
* (reason above)
*/
#define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> 8)
/*
* We do not maintain any list for completely empty or full pages
*/
enum fullness_group {
ZS_ALMOST_FULL,
ZS_ALMOST_EMPTY,
_ZS_NR_FULLNESS_GROUPS,
ZS_EMPTY,
ZS_FULL
};
enum zs_stat_type {
OBJ_ALLOCATED,
OBJ_USED,
CLASS_ALMOST_FULL,
CLASS_ALMOST_EMPTY,
};
#ifdef CONFIG_ZSMALLOC_STAT
#define NR_ZS_STAT_TYPE (CLASS_ALMOST_EMPTY + 1)
#else
#define NR_ZS_STAT_TYPE (OBJ_USED + 1)
#endif
struct zs_size_stat {
unsigned long objs[NR_ZS_STAT_TYPE];
};
#ifdef CONFIG_ZSMALLOC_STAT
static struct dentry *zs_stat_root;
#endif
/*
* number of size_classes
*/
static int zs_size_classes;
/*
* We assign a page to ZS_ALMOST_EMPTY fullness group when:
* n <= N / f, where
* n = number of allocated objects
* N = total number of objects zspage can store
* f = fullness_threshold_frac
*
* Similarly, we assign zspage to:
* ZS_ALMOST_FULL when n > N / f
* ZS_EMPTY when n == 0
* ZS_FULL when n == N
*
* (see: fix_fullness_group())
*/
static const int fullness_threshold_frac = 4;
struct size_class {
spinlock_t lock;
struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
/*
* Size of objects stored in this class. Must be multiple
* of ZS_ALIGN.
*/
int size;
unsigned int index;
/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
int pages_per_zspage;
struct zs_size_stat stats;
/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
bool huge;
};
/*
* Placed within free objects to form a singly linked list.
* For every zspage, first_page->freelist gives head of this list.
*
* This must be power of 2 and less than or equal to ZS_ALIGN
*/
struct link_free {
union {
/*
* Position of next free chunk (encodes <PFN, obj_idx>)
* It's valid for non-allocated object
*/
void *next;
/*
* Handle of allocated object.
*/
unsigned long handle;
};
};
struct zs_pool {
const char *name;
struct size_class **size_class;
struct kmem_cache *handle_cachep;
gfp_t flags; /* allocation flags used when growing pool */
atomic_long_t pages_allocated;
struct zs_pool_stats stats;
/* Compact classes */
struct shrinker shrinker;
/*
* To signify that register_shrinker() was successful
* and unregister_shrinker() will not Oops.
*/
bool shrinker_enabled;
#ifdef CONFIG_ZSMALLOC_STAT
struct dentry *stat_dentry;
#endif
};
/*
* A zspage's class index and fullness group
* are encoded in its (first)page->mapping
*/
#define CLASS_IDX_BITS 28
#define FULLNESS_BITS 4
#define CLASS_IDX_MASK ((1 << CLASS_IDX_BITS) - 1)
#define FULLNESS_MASK ((1 << FULLNESS_BITS) - 1)
struct mapping_area {
#ifdef CONFIG_PGTABLE_MAPPING
struct vm_struct *vm; /* vm area for mapping object that span pages */
#else
char *vm_buf; /* copy buffer for objects that span pages */
#endif
char *vm_addr; /* address of kmap_atomic()'ed pages */
enum zs_mapmode vm_mm; /* mapping mode */
bool huge;
};
static int create_handle_cache(struct zs_pool *pool)
{
pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
0, 0, NULL);
return pool->handle_cachep ? 0 : 1;
}
static void destroy_handle_cache(struct zs_pool *pool)
{
kmem_cache_destroy(pool->handle_cachep);
}
static unsigned long alloc_handle(struct zs_pool *pool)
{
return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
pool->flags & ~__GFP_HIGHMEM);
}
static void free_handle(struct zs_pool *pool, unsigned long handle)
{
kmem_cache_free(pool->handle_cachep, (void *)handle);
}
static void record_obj(unsigned long handle, unsigned long obj)
{
*(unsigned long *)handle = obj;
}
/* zpool driver */
#ifdef CONFIG_ZPOOL
static void *zs_zpool_create(const char *name, gfp_t gfp,
const struct zpool_ops *zpool_ops,
struct zpool *zpool)
{
return zs_create_pool(name, gfp);
}
static void zs_zpool_destroy(void *pool)
{
zs_destroy_pool(pool);
}
static int zs_zpool_malloc(void *pool, size_t size, gfp_t gfp,
unsigned long *handle)
{
*handle = zs_malloc(pool, size);
return *handle ? 0 : -1;
}
static void zs_zpool_free(void *pool, unsigned long handle)
{
zs_free(pool, handle);
}
static int zs_zpool_shrink(void *pool, unsigned int pages,
unsigned int *reclaimed)
{
return -EINVAL;
}
static void *zs_zpool_map(void *pool, unsigned long handle,
enum zpool_mapmode mm)
{
enum zs_mapmode zs_mm;
switch (mm) {
case ZPOOL_MM_RO:
zs_mm = ZS_MM_RO;
break;
case ZPOOL_MM_WO:
zs_mm = ZS_MM_WO;
break;
case ZPOOL_MM_RW: /* fallthru */
default:
zs_mm = ZS_MM_RW;
break;
}
return zs_map_object(pool, handle, zs_mm);
}
static void zs_zpool_unmap(void *pool, unsigned long handle)
{
zs_unmap_object(pool, handle);
}
static u64 zs_zpool_total_size(void *pool)
{
return zs_get_total_pages(pool) << PAGE_SHIFT;
}
static struct zpool_driver zs_zpool_driver = {
.type = "zsmalloc",
.owner = THIS_MODULE,
.create = zs_zpool_create,
.destroy = zs_zpool_destroy,
.malloc = zs_zpool_malloc,
.free = zs_zpool_free,
.shrink = zs_zpool_shrink,
.map = zs_zpool_map,
.unmap = zs_zpool_unmap,
.total_size = zs_zpool_total_size,
};
MODULE_ALIAS("zpool-zsmalloc");
#endif /* CONFIG_ZPOOL */
static unsigned int get_maxobj_per_zspage(int size, int pages_per_zspage)
{
return pages_per_zspage * PAGE_SIZE / size;
}
/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
static int is_first_page(struct page *page)
{
return PagePrivate(page);
}
static int is_last_page(struct page *page)
{
return PagePrivate2(page);
}
static void get_zspage_mapping(struct page *page, unsigned int *class_idx,
enum fullness_group *fullness)
{
unsigned long m;
BUG_ON(!is_first_page(page));
m = (unsigned long)page->mapping;
*fullness = m & FULLNESS_MASK;
*class_idx = (m >> FULLNESS_BITS) & CLASS_IDX_MASK;
}
static void set_zspage_mapping(struct page *page, unsigned int class_idx,
enum fullness_group fullness)
{
unsigned long m;
BUG_ON(!is_first_page(page));
m = ((class_idx & CLASS_IDX_MASK) << FULLNESS_BITS) |
(fullness & FULLNESS_MASK);
page->mapping = (struct address_space *)m;
}
/*
* zsmalloc divides the pool into various size classes where each
* class maintains a list of zspages where each zspage is divided
* into equal sized chunks. Each allocation falls into one of these
* classes depending on its size. This function returns index of the
* size class which has chunk size big enough to hold the give size.
*/
static int get_size_class_index(int size)
{
int idx = 0;
if (likely(size > ZS_MIN_ALLOC_SIZE))
idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
ZS_SIZE_CLASS_DELTA);
return min(zs_size_classes - 1, idx);
}
static inline void zs_stat_inc(struct size_class *class,
enum zs_stat_type type, unsigned long cnt)
{
if (type < NR_ZS_STAT_TYPE)
class->stats.objs[type] += cnt;
}
static inline void zs_stat_dec(struct size_class *class,
enum zs_stat_type type, unsigned long cnt)
{
if (type < NR_ZS_STAT_TYPE)
class->stats.objs[type] -= cnt;
}
static inline unsigned long zs_stat_get(struct size_class *class,
enum zs_stat_type type)
{
if (type < NR_ZS_STAT_TYPE)
return class->stats.objs[type];
return 0;
}
#ifdef CONFIG_ZSMALLOC_STAT
static int __init zs_stat_init(void)
{
if (!debugfs_initialized())
return -ENODEV;
zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
if (!zs_stat_root)
return -ENOMEM;
return 0;
}
static void __exit zs_stat_exit(void)
{
debugfs_remove_recursive(zs_stat_root);
}
static int zs_stats_size_show(struct seq_file *s, void *v)
{
int i;
struct zs_pool *pool = s->private;
struct size_class *class;
int objs_per_zspage;
unsigned long class_almost_full, class_almost_empty;
unsigned long obj_allocated, obj_used, pages_used;
unsigned long total_class_almost_full = 0, total_class_almost_empty = 0;
unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
seq_printf(s, " %5s %5s %11s %12s %13s %10s %10s %16s\n",
"class", "size", "almost_full", "almost_empty",
"obj_allocated", "obj_used", "pages_used",
"pages_per_zspage");
for (i = 0; i < zs_size_classes; i++) {
class = pool->size_class[i];
if (class->index != i)
continue;
spin_lock(&class->lock);
class_almost_full = zs_stat_get(class, CLASS_ALMOST_FULL);
class_almost_empty = zs_stat_get(class, CLASS_ALMOST_EMPTY);
obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
obj_used = zs_stat_get(class, OBJ_USED);
spin_unlock(&class->lock);
objs_per_zspage = get_maxobj_per_zspage(class->size,
class->pages_per_zspage);
pages_used = obj_allocated / objs_per_zspage *
class->pages_per_zspage;
seq_printf(s, " %5u %5u %11lu %12lu %13lu %10lu %10lu %16d\n",
i, class->size, class_almost_full, class_almost_empty,
obj_allocated, obj_used, pages_used,
class->pages_per_zspage);
total_class_almost_full += class_almost_full;
total_class_almost_empty += class_almost_empty;
total_objs += obj_allocated;
total_used_objs += obj_used;
total_pages += pages_used;
}
seq_puts(s, "\n");
seq_printf(s, " %5s %5s %11lu %12lu %13lu %10lu %10lu\n",
"Total", "", total_class_almost_full,
total_class_almost_empty, total_objs,
total_used_objs, total_pages);
return 0;
}
static int zs_stats_size_open(struct inode *inode, struct file *file)
{
return single_open(file, zs_stats_size_show, inode->i_private);
}
static const struct file_operations zs_stat_size_ops = {
.open = zs_stats_size_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int zs_pool_stat_create(const char *name, struct zs_pool *pool)
{
struct dentry *entry;
if (!zs_stat_root)
return -ENODEV;
entry = debugfs_create_dir(name, zs_stat_root);
if (!entry) {
pr_warn("debugfs dir <%s> creation failed\n", name);
return -ENOMEM;
}
pool->stat_dentry = entry;
entry = debugfs_create_file("classes", S_IFREG | S_IRUGO,
pool->stat_dentry, pool, &zs_stat_size_ops);
if (!entry) {
pr_warn("%s: debugfs file entry <%s> creation failed\n",
name, "classes");
return -ENOMEM;
}
return 0;
}
static void zs_pool_stat_destroy(struct zs_pool *pool)
{
debugfs_remove_recursive(pool->stat_dentry);
}
#else /* CONFIG_ZSMALLOC_STAT */
static int __init zs_stat_init(void)
{
return 0;
}
static void __exit zs_stat_exit(void)
{
}
static inline int zs_pool_stat_create(const char *name, struct zs_pool *pool)
{
return 0;
}
static inline void zs_pool_stat_destroy(struct zs_pool *pool)
{
}
#endif
/*
* For each size class, zspages are divided into different groups
* depending on how "full" they are. This was done so that we could
* easily find empty or nearly empty zspages when we try to shrink
* the pool (not yet implemented). This function returns fullness
* status of the given page.
*/
static enum fullness_group get_fullness_group(struct page *page)
{
int inuse, max_objects;
enum fullness_group fg;
BUG_ON(!is_first_page(page));
inuse = page->inuse;
max_objects = page->objects;
if (inuse == 0)
fg = ZS_EMPTY;
else if (inuse == max_objects)
fg = ZS_FULL;
else if (inuse <= 3 * max_objects / fullness_threshold_frac)
fg = ZS_ALMOST_EMPTY;
else
fg = ZS_ALMOST_FULL;
return fg;
}
/*
* Each size class maintains various freelists and zspages are assigned
* to one of these freelists based on the number of live objects they
* have. This functions inserts the given zspage into the freelist
* identified by <class, fullness_group>.
*/
static void insert_zspage(struct page *page, struct size_class *class,
enum fullness_group fullness)
{
struct page **head;
BUG_ON(!is_first_page(page));
if (fullness >= _ZS_NR_FULLNESS_GROUPS)
return;
zs_stat_inc(class, fullness == ZS_ALMOST_EMPTY ?
CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
head = &class->fullness_list[fullness];
if (!*head) {
*head = page;
return;
}
/*
* We want to see more ZS_FULL pages and less almost
* empty/full. Put pages with higher ->inuse first.
*/
list_add_tail(&page->lru, &(*head)->lru);
if (page->inuse >= (*head)->inuse)
*head = page;
}
/*
* This function removes the given zspage from the freelist identified
* by <class, fullness_group>.
*/
static void remove_zspage(struct page *page, struct size_class *class,
enum fullness_group fullness)
{
struct page **head;
BUG_ON(!is_first_page(page));
if (fullness >= _ZS_NR_FULLNESS_GROUPS)
return;
head = &class->fullness_list[fullness];
BUG_ON(!*head);
if (list_empty(&(*head)->lru))
*head = NULL;
else if (*head == page)
*head = (struct page *)list_entry((*head)->lru.next,
struct page, lru);
list_del_init(&page->lru);
zs_stat_dec(class, fullness == ZS_ALMOST_EMPTY ?
CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
}
/*
* Each size class maintains zspages in different fullness groups depending
* on the number of live objects they contain. When allocating or freeing
* objects, the fullness status of the page can change, say, from ALMOST_FULL
* to ALMOST_EMPTY when freeing an object. This function checks if such
* a status change has occurred for the given page and accordingly moves the
* page from the freelist of the old fullness group to that of the new
* fullness group.
*/
static enum fullness_group fix_fullness_group(struct size_class *class,
struct page *page)
{
int class_idx;
enum fullness_group currfg, newfg;
BUG_ON(!is_first_page(page));
get_zspage_mapping(page, &class_idx, &currfg);
newfg = get_fullness_group(page);
if (newfg == currfg)
goto out;
remove_zspage(page, class, currfg);
insert_zspage(page, class, newfg);
set_zspage_mapping(page, class_idx, newfg);
out:
return newfg;
}
/*
* We have to decide on how many pages to link together
* to form a zspage for each size class. This is important
* to reduce wastage due to unusable space left at end of
* each zspage which is given as:
* wastage = Zp % class_size
* usage = Zp - wastage
* where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
*
* For example, for size class of 3/8 * PAGE_SIZE, we should
* link together 3 PAGE_SIZE sized pages to form a zspage
* since then we can perfectly fit in 8 such objects.
*/
static int get_pages_per_zspage(int class_size)
{
int i, max_usedpc = 0;
/* zspage order which gives maximum used size per KB */
int max_usedpc_order = 1;
for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) {
int zspage_size;
int waste, usedpc;
zspage_size = i * PAGE_SIZE;
waste = zspage_size % class_size;
usedpc = (zspage_size - waste) * 100 / zspage_size;
if (usedpc > max_usedpc) {
max_usedpc = usedpc;
max_usedpc_order = i;
}
}
return max_usedpc_order;
}
/*
* A single 'zspage' is composed of many system pages which are
* linked together using fields in struct page. This function finds
* the first/head page, given any component page of a zspage.
*/
static struct page *get_first_page(struct page *page)
{
if (is_first_page(page))
return page;
else
return (struct page *)page_private(page);
}
static struct page *get_next_page(struct page *page)
{
struct page *next;
if (is_last_page(page))
next = NULL;
else if (is_first_page(page))
next = (struct page *)page_private(page);
else
next = list_entry(page->lru.next, struct page, lru);
return next;
}
/*
* Encode <page, obj_idx> as a single handle value.
* We use the least bit of handle for tagging.
*/
static void *location_to_obj(struct page *page, unsigned long obj_idx)
{
unsigned long obj;
if (!page) {
BUG_ON(obj_idx);
return NULL;
}
obj = page_to_pfn(page) << OBJ_INDEX_BITS;
obj |= ((obj_idx) & OBJ_INDEX_MASK);
obj <<= OBJ_TAG_BITS;
return (void *)obj;
}
/*
* Decode <page, obj_idx> pair from the given object handle. We adjust the
* decoded obj_idx back to its original value since it was adjusted in
* location_to_obj().
*/
static void obj_to_location(unsigned long obj, struct page **page,
unsigned long *obj_idx)
{
obj >>= OBJ_TAG_BITS;
*page = pfn_to_page(obj >> OBJ_INDEX_BITS);
*obj_idx = (obj & OBJ_INDEX_MASK);
}
static unsigned long handle_to_obj(unsigned long handle)
{
return *(unsigned long *)handle;
}
static unsigned long obj_to_head(struct size_class *class, struct page *page,
void *obj)
{
if (class->huge) {
VM_BUG_ON(!is_first_page(page));
return page_private(page);
} else
return *(unsigned long *)obj;
}
static unsigned long obj_idx_to_offset(struct page *page,
unsigned long obj_idx, int class_size)
{
unsigned long off = 0;
if (!is_first_page(page))
off = page->index;
return off + obj_idx * class_size;
}
static inline int trypin_tag(unsigned long handle)
{
unsigned long *ptr = (unsigned long *)handle;
return !test_and_set_bit_lock(HANDLE_PIN_BIT, ptr);
}
static void pin_tag(unsigned long handle)
{
while (!trypin_tag(handle));
}
static void unpin_tag(unsigned long handle)
{
unsigned long *ptr = (unsigned long *)handle;
clear_bit_unlock(HANDLE_PIN_BIT, ptr);
}
static void reset_page(struct page *page)
{
clear_bit(PG_private, &page->flags);
clear_bit(PG_private_2, &page->flags);
set_page_private(page, 0);
page->mapping = NULL;
page->freelist = NULL;
page_mapcount_reset(page);
}
static void free_zspage(struct page *first_page)
{
struct page *nextp, *tmp, *head_extra;
BUG_ON(!is_first_page(first_page));
BUG_ON(first_page->inuse);
head_extra = (struct page *)page_private(first_page);
reset_page(first_page);
__free_page(first_page);
/* zspage with only 1 system page */
if (!head_extra)
return;
list_for_each_entry_safe(nextp, tmp, &head_extra->lru, lru) {
list_del(&nextp->lru);
reset_page(nextp);
__free_page(nextp);
}
reset_page(head_extra);
__free_page(head_extra);
}
/* Initialize a newly allocated zspage */
static void init_zspage(struct page *first_page, struct size_class *class)
{
unsigned long off = 0;
struct page *page = first_page;
BUG_ON(!is_first_page(first_page));
while (page) {
struct page *next_page;
struct link_free *link;
unsigned int i = 1;
void *vaddr;
/*
* page->index stores offset of first object starting
* in the page. For the first page, this is always 0,
* so we use first_page->index (aka ->freelist) to store
* head of corresponding zspage's freelist.
*/
if (page != first_page)
page->index = off;
vaddr = kmap_atomic(page);
link = (struct link_free *)vaddr + off / sizeof(*link);
while ((off += class->size) < PAGE_SIZE) {
link->next = location_to_obj(page, i++);
link += class->size / sizeof(*link);
}
/*
* We now come to the last (full or partial) object on this
* page, which must point to the first object on the next
* page (if present)
*/
next_page = get_next_page(page);
link->next = location_to_obj(next_page, 0);
kunmap_atomic(vaddr);
page = next_page;
off %= PAGE_SIZE;
}
}
/*
* Allocate a zspage for the given size class
*/
static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
{
int i, error;
struct page *first_page = NULL, *uninitialized_var(prev_page);
/*
* Allocate individual pages and link them together as:
* 1. first page->private = first sub-page
* 2. all sub-pages are linked together using page->lru
* 3. each sub-page is linked to the first page using page->private
*
* For each size class, First/Head pages are linked together using
* page->lru. Also, we set PG_private to identify the first page
* (i.e. no other sub-page has this flag set) and PG_private_2 to
* identify the last page.
*/
error = -ENOMEM;
for (i = 0; i < class->pages_per_zspage; i++) {
struct page *page;
page = alloc_page(flags);
if (!page)
goto cleanup;
INIT_LIST_HEAD(&page->lru);
if (i == 0) { /* first page */
SetPagePrivate(page);
set_page_private(page, 0);
first_page = page;
first_page->inuse = 0;
}
if (i == 1)
set_page_private(first_page, (unsigned long)page);
if (i >= 1)
set_page_private(page, (unsigned long)first_page);
if (i >= 2)
list_add(&page->lru, &prev_page->lru);
if (i == class->pages_per_zspage - 1) /* last page */
SetPagePrivate2(page);
prev_page = page;
}
init_zspage(first_page, class);
first_page->freelist = location_to_obj(first_page, 0);
/* Maximum number of objects we can store in this zspage */
first_page->objects = class->pages_per_zspage * PAGE_SIZE / class->size;
error = 0; /* Success */
cleanup:
if (unlikely(error) && first_page) {
free_zspage(first_page);
first_page = NULL;
}
return first_page;
}
static struct page *find_get_zspage(struct size_class *class)
{
int i;
struct page *page;
for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
page = class->fullness_list[i];
if (page)
break;
}
return page;
}
#ifdef CONFIG_PGTABLE_MAPPING
static inline int __zs_cpu_up(struct mapping_area *area)
{
/*
* Make sure we don't leak memory if a cpu UP notification
* and zs_init() race and both call zs_cpu_up() on the same cpu
*/
if (area->vm)
return 0;
area->vm = alloc_vm_area(PAGE_SIZE * 2, NULL);
if (!area->vm)
return -ENOMEM;
return 0;
}
static inline void __zs_cpu_down(struct mapping_area *area)
{
if (area->vm)
free_vm_area(area->vm);
area->vm = NULL;
}
static inline void *__zs_map_object(struct mapping_area *area,
struct page *pages[2], int off, int size)
{
BUG_ON(map_vm_area(area->vm, PAGE_KERNEL, pages));
area->vm_addr = area->vm->addr;
return area->vm_addr + off;
}
static inline void __zs_unmap_object(struct mapping_area *area,
struct page *pages[2], int off, int size)
{
unsigned long addr = (unsigned long)area->vm_addr;
unmap_kernel_range(addr, PAGE_SIZE * 2);
}
#else /* CONFIG_PGTABLE_MAPPING */
static inline int __zs_cpu_up(struct mapping_area *area)
{
/*
* Make sure we don't leak memory if a cpu UP notification
* and zs_init() race and both call zs_cpu_up() on the same cpu
*/
if (area->vm_buf)
return 0;
area->vm_buf = kmalloc(ZS_MAX_ALLOC_SIZE, GFP_KERNEL);
if (!area->vm_buf)
return -ENOMEM;
return 0;
}
static inline void __zs_cpu_down(struct mapping_area *area)
{
kfree(area->vm_buf);
area->vm_buf = NULL;
}
static void *__zs_map_object(struct mapping_area *area,
struct page *pages[2], int off, int size)
{
int sizes[2];
void *addr;
char *buf = area->vm_buf;
/* disable page faults to match kmap_atomic() return conditions */
pagefault_disable();
/* no read fastpath */
if (area->vm_mm == ZS_MM_WO)
goto out;
sizes[0] = PAGE_SIZE - off;
sizes[1] = size - sizes[0];
/* copy object to per-cpu buffer */
addr = kmap_atomic(pages[0]);
memcpy(buf, addr + off, sizes[0]);
kunmap_atomic(addr);
addr = kmap_atomic(pages[1]);
memcpy(buf + sizes[0], addr, sizes[1]);
kunmap_atomic(addr);
out:
return area->vm_buf;
}
static void __zs_unmap_object(struct mapping_area *area,
struct page *pages[2], int off, int size)
{
int sizes[2];
void *addr;
char *buf;
/* no write fastpath */
if (area->vm_mm == ZS_MM_RO)
goto out;
buf = area->vm_buf;
if (!area->huge) {
buf = buf + ZS_HANDLE_SIZE;
size -= ZS_HANDLE_SIZE;
off += ZS_HANDLE_SIZE;
}
sizes[0] = PAGE_SIZE - off;
sizes[1] = size - sizes[0];
/* copy per-cpu buffer to object */
addr = kmap_atomic(pages[0]);
memcpy(addr + off, buf, sizes[0]);
kunmap_atomic(addr);
addr = kmap_atomic(pages[1]);
memcpy(addr, buf + sizes[0], sizes[1]);
kunmap_atomic(addr);
out:
/* enable page faults to match kunmap_atomic() return conditions */
pagefault_enable();
}
#endif /* CONFIG_PGTABLE_MAPPING */
static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
void *pcpu)
{
int ret, cpu = (long)pcpu;
struct mapping_area *area;
switch (action) {
case CPU_UP_PREPARE:
area = &per_cpu(zs_map_area, cpu);
ret = __zs_cpu_up(area);
if (ret)
return notifier_from_errno(ret);
break;
case CPU_DEAD:
case CPU_UP_CANCELED:
area = &per_cpu(zs_map_area, cpu);
__zs_cpu_down(area);
break;
}
return NOTIFY_OK;
}
static struct notifier_block zs_cpu_nb = {
.notifier_call = zs_cpu_notifier
};
static int zs_register_cpu_notifier(void)
{
int cpu, uninitialized_var(ret);
cpu_notifier_register_begin();
__register_cpu_notifier(&zs_cpu_nb);
for_each_online_cpu(cpu) {
ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
if (notifier_to_errno(ret))
break;
}
cpu_notifier_register_done();
return notifier_to_errno(ret);
}
static void zs_unregister_cpu_notifier(void)
{
int cpu;
cpu_notifier_register_begin();
for_each_online_cpu(cpu)
zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu);
__unregister_cpu_notifier(&zs_cpu_nb);
cpu_notifier_register_done();
}
static void init_zs_size_classes(void)
{
int nr;
nr = (ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / ZS_SIZE_CLASS_DELTA + 1;
if ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) % ZS_SIZE_CLASS_DELTA)
nr += 1;
zs_size_classes = nr;
}
static bool can_merge(struct size_class *prev, int size, int pages_per_zspage)
{
if (prev->pages_per_zspage != pages_per_zspage)
return false;
if (get_maxobj_per_zspage(prev->size, prev->pages_per_zspage)
!= get_maxobj_per_zspage(size, pages_per_zspage))
return false;
return true;
}
static bool zspage_full(struct page *page)
{
BUG_ON(!is_first_page(page));
return page->inuse == page->objects;
}
unsigned long zs_get_total_pages(struct zs_pool *pool)
{
return atomic_long_read(&pool->pages_allocated);
}
EXPORT_SYMBOL_GPL(zs_get_total_pages);
/**
* zs_map_object - get address of allocated object from handle.
* @pool: pool from which the object was allocated
* @handle: handle returned from zs_malloc
*
* Before using an object allocated from zs_malloc, it must be mapped using
* this function. When done with the object, it must be unmapped using
* zs_unmap_object.
*
* Only one object can be mapped per cpu at a time. There is no protection
* against nested mappings.
*
* This function returns with preemption and page faults disabled.
*/
void *zs_map_object(struct zs_pool *pool, unsigned long handle,
enum zs_mapmode mm)
{
struct page *page;
unsigned long obj, obj_idx, off;
unsigned int class_idx;
enum fullness_group fg;
struct size_class *class;
struct mapping_area *area;
struct page *pages[2];
void *ret;
BUG_ON(!handle);
/*
* Because we use per-cpu mapping areas shared among the
* pools/users, we can't allow mapping in interrupt context
* because it can corrupt another users mappings.
*/
BUG_ON(in_interrupt());
/* From now on, migration cannot move the object */
pin_tag(handle);
obj = handle_to_obj(handle);
obj_to_location(obj, &page, &obj_idx);
get_zspage_mapping(get_first_page(page), &class_idx, &fg);
class = pool->size_class[class_idx];
off = obj_idx_to_offset(page, obj_idx, class->size);
area = &get_cpu_var(zs_map_area);
area->vm_mm = mm;
if (off + class->size <= PAGE_SIZE) {
/* this object is contained entirely within a page */
area->vm_addr = kmap_atomic(page);
ret = area->vm_addr + off;
goto out;
}
/* this object spans two pages */
pages[0] = page;
pages[1] = get_next_page(page);
BUG_ON(!pages[1]);
ret = __zs_map_object(area, pages, off, class->size);
out:
if (!class->huge)
ret += ZS_HANDLE_SIZE;
return ret;
}
EXPORT_SYMBOL_GPL(zs_map_object);
void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
{
struct page *page;
unsigned long obj, obj_idx, off;
unsigned int class_idx;
enum fullness_group fg;
struct size_class *class;
struct mapping_area *area;
BUG_ON(!handle);
obj = handle_to_obj(handle);
obj_to_location(obj, &page, &obj_idx);
get_zspage_mapping(get_first_page(page), &class_idx, &fg);
class = pool->size_class[class_idx];
off = obj_idx_to_offset(page, obj_idx, class->size);
area = this_cpu_ptr(&zs_map_area);
if (off + class->size <= PAGE_SIZE)
kunmap_atomic(area->vm_addr);
else {
struct page *pages[2];
pages[0] = page;
pages[1] = get_next_page(page);
BUG_ON(!pages[1]);
__zs_unmap_object(area, pages, off, class->size);
}
put_cpu_var(zs_map_area);
unpin_tag(handle);
}
EXPORT_SYMBOL_GPL(zs_unmap_object);
static unsigned long obj_malloc(struct page *first_page,
struct size_class *class, unsigned long handle)
{
unsigned long obj;
struct link_free *link;
struct page *m_page;
unsigned long m_objidx, m_offset;
void *vaddr;
handle |= OBJ_ALLOCATED_TAG;
obj = (unsigned long)first_page->freelist;
obj_to_location(obj, &m_page, &m_objidx);
m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
vaddr = kmap_atomic(m_page);
link = (struct link_free *)vaddr + m_offset / sizeof(*link);
first_page->freelist = link->next;
if (!class->huge)
/* record handle in the header of allocated chunk */
link->handle = handle;
else
/* record handle in first_page->private */
set_page_private(first_page, handle);
kunmap_atomic(vaddr);
first_page->inuse++;
zs_stat_inc(class, OBJ_USED, 1);
return obj;
}
/**
* zs_malloc - Allocate block of given size from pool.
* @pool: pool to allocate from
* @size: size of block to allocate
*
* On success, handle to the allocated object is returned,
* otherwise 0.
* Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
*/
unsigned long zs_malloc(struct zs_pool *pool, size_t size)
{
unsigned long handle, obj;
struct size_class *class;
struct page *first_page;
if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
return 0;
handle = alloc_handle(pool);
if (!handle)
return 0;
/* extra space in chunk to keep the handle */
size += ZS_HANDLE_SIZE;
class = pool->size_class[get_size_class_index(size)];
spin_lock(&class->lock);
first_page = find_get_zspage(class);
if (!first_page) {
spin_unlock(&class->lock);
first_page = alloc_zspage(class, pool->flags);
if (unlikely(!first_page)) {
free_handle(pool, handle);
return 0;
}
set_zspage_mapping(first_page, class->index, ZS_EMPTY);
atomic_long_add(class->pages_per_zspage,
&pool->pages_allocated);
spin_lock(&class->lock);
zs_stat_inc(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
class->size, class->pages_per_zspage));
}
obj = obj_malloc(first_page, class, handle);
/* Now move the zspage to another fullness group, if required */
fix_fullness_group(class, first_page);
record_obj(handle, obj);
spin_unlock(&class->lock);
return handle;
}
EXPORT_SYMBOL_GPL(zs_malloc);
static void obj_free(struct zs_pool *pool, struct size_class *class,
unsigned long obj)
{
struct link_free *link;
struct page *first_page, *f_page;
unsigned long f_objidx, f_offset;
void *vaddr;
BUG_ON(!obj);
obj &= ~OBJ_ALLOCATED_TAG;
obj_to_location(obj, &f_page, &f_objidx);
first_page = get_first_page(f_page);
f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);
vaddr = kmap_atomic(f_page);
/* Insert this object in containing zspage's freelist */
link = (struct link_free *)(vaddr + f_offset);
link->next = first_page->freelist;
if (class->huge)
set_page_private(first_page, 0);
kunmap_atomic(vaddr);
first_page->freelist = (void *)obj;
first_page->inuse--;
zs_stat_dec(class, OBJ_USED, 1);
}
void zs_free(struct zs_pool *pool, unsigned long handle)
{
struct page *first_page, *f_page;
unsigned long obj, f_objidx;
int class_idx;
struct size_class *class;
enum fullness_group fullness;
if (unlikely(!handle))
return;
pin_tag(handle);
obj = handle_to_obj(handle);
obj_to_location(obj, &f_page, &f_objidx);
first_page = get_first_page(f_page);
get_zspage_mapping(first_page, &class_idx, &fullness);
class = pool->size_class[class_idx];
spin_lock(&class->lock);
obj_free(pool, class, obj);
fullness = fix_fullness_group(class, first_page);
if (fullness == ZS_EMPTY) {
zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
class->size, class->pages_per_zspage));
atomic_long_sub(class->pages_per_zspage,
&pool->pages_allocated);
free_zspage(first_page);
}
spin_unlock(&class->lock);
unpin_tag(handle);
free_handle(pool, handle);
}
EXPORT_SYMBOL_GPL(zs_free);
static void zs_object_copy(unsigned long dst, unsigned long src,
struct size_class *class)
{
struct page *s_page, *d_page;
unsigned long s_objidx, d_objidx;
unsigned long s_off, d_off;
void *s_addr, *d_addr;
int s_size, d_size, size;
int written = 0;
s_size = d_size = class->size;
obj_to_location(src, &s_page, &s_objidx);
obj_to_location(dst, &d_page, &d_objidx);
s_off = obj_idx_to_offset(s_page, s_objidx, class->size);
d_off = obj_idx_to_offset(d_page, d_objidx, class->size);
if (s_off + class->size > PAGE_SIZE)
s_size = PAGE_SIZE - s_off;
if (d_off + class->size > PAGE_SIZE)
d_size = PAGE_SIZE - d_off;
s_addr = kmap_atomic(s_page);
d_addr = kmap_atomic(d_page);
while (1) {
size = min(s_size, d_size);
memcpy(d_addr + d_off, s_addr + s_off, size);
written += size;
if (written == class->size)
break;
s_off += size;
s_size -= size;
d_off += size;
d_size -= size;
if (s_off >= PAGE_SIZE) {
kunmap_atomic(d_addr);
kunmap_atomic(s_addr);
s_page = get_next_page(s_page);
BUG_ON(!s_page);
s_addr = kmap_atomic(s_page);
d_addr = kmap_atomic(d_page);
s_size = class->size - written;
s_off = 0;
}
if (d_off >= PAGE_SIZE) {
kunmap_atomic(d_addr);
d_page = get_next_page(d_page);
BUG_ON(!d_page);
d_addr = kmap_atomic(d_page);
d_size = class->size - written;
d_off = 0;
}
}
kunmap_atomic(d_addr);
kunmap_atomic(s_addr);
}
/*
* Find alloced object in zspage from index object and
* return handle.
*/
static unsigned long find_alloced_obj(struct page *page, int index,
struct size_class *class)
{
unsigned long head;
int offset = 0;
unsigned long handle = 0;
void *addr = kmap_atomic(page);
if (!is_first_page(page))
offset = page->index;
offset += class->size * index;
while (offset < PAGE_SIZE) {
head = obj_to_head(class, page, addr + offset);
if (head & OBJ_ALLOCATED_TAG) {
handle = head & ~OBJ_ALLOCATED_TAG;
if (trypin_tag(handle))
break;
handle = 0;
}
offset += class->size;
index++;
}
kunmap_atomic(addr);
return handle;
}
struct zs_compact_control {
/* Source page for migration which could be a subpage of zspage. */
struct page *s_page;
/* Destination page for migration which should be a first page
* of zspage. */
struct page *d_page;
/* Starting object index within @s_page which used for live object
* in the subpage. */
int index;
};
static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
struct zs_compact_control *cc)
{
unsigned long used_obj, free_obj;
unsigned long handle;
struct page *s_page = cc->s_page;
struct page *d_page = cc->d_page;
unsigned long index = cc->index;
int ret = 0;
while (1) {
handle = find_alloced_obj(s_page, index, class);
if (!handle) {
s_page = get_next_page(s_page);
if (!s_page)
break;
index = 0;
continue;
}
/* Stop if there is no more space */
if (zspage_full(d_page)) {
unpin_tag(handle);
ret = -ENOMEM;
break;
}
used_obj = handle_to_obj(handle);
free_obj = obj_malloc(d_page, class, handle);
zs_object_copy(free_obj, used_obj, class);
index++;
record_obj(handle, free_obj);
unpin_tag(handle);
obj_free(pool, class, used_obj);
}
/* Remember last position in this iteration */
cc->s_page = s_page;
cc->index = index;
return ret;
}
static struct page *isolate_target_page(struct size_class *class)
{
int i;
struct page *page;
for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
page = class->fullness_list[i];
if (page) {
remove_zspage(page, class, i);
break;
}
}
return page;
}
/*
* putback_zspage - add @first_page into right class's fullness list
* @pool: target pool
* @class: destination class
* @first_page: target page
*
* Return @fist_page's fullness_group
*/
static enum fullness_group putback_zspage(struct zs_pool *pool,
struct size_class *class,
struct page *first_page)
{
enum fullness_group fullness;
BUG_ON(!is_first_page(first_page));
fullness = get_fullness_group(first_page);
insert_zspage(first_page, class, fullness);
set_zspage_mapping(first_page, class->index, fullness);
if (fullness == ZS_EMPTY) {
zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
class->size, class->pages_per_zspage));
atomic_long_sub(class->pages_per_zspage,
&pool->pages_allocated);
free_zspage(first_page);
}
return fullness;
}
static struct page *isolate_source_page(struct size_class *class)
{
int i;
struct page *page = NULL;
for (i = ZS_ALMOST_EMPTY; i >= ZS_ALMOST_FULL; i--) {
page = class->fullness_list[i];
if (!page)
continue;
remove_zspage(page, class, i);
break;
}
return page;
}
/*
*
* Based on the number of unused allocated objects calculate
* and return the number of pages that we can free.
*/
static unsigned long zs_can_compact(struct size_class *class)
{
unsigned long obj_wasted;
obj_wasted = zs_stat_get(class, OBJ_ALLOCATED) -
zs_stat_get(class, OBJ_USED);
obj_wasted /= get_maxobj_per_zspage(class->size,
class->pages_per_zspage);
return obj_wasted * class->pages_per_zspage;
}
static void __zs_compact(struct zs_pool *pool, struct size_class *class)
{
struct zs_compact_control cc;
struct page *src_page;
struct page *dst_page = NULL;
spin_lock(&class->lock);
while ((src_page = isolate_source_page(class))) {
BUG_ON(!is_first_page(src_page));
if (!zs_can_compact(class))
break;
cc.index = 0;
cc.s_page = src_page;
while ((dst_page = isolate_target_page(class))) {
cc.d_page = dst_page;
/*
* If there is no more space in dst_page, resched
* and see if anyone had allocated another zspage.
*/
if (!migrate_zspage(pool, class, &cc))
break;
putback_zspage(pool, class, dst_page);
}
/* Stop if we couldn't find slot */
if (dst_page == NULL)
break;
putback_zspage(pool, class, dst_page);
if (putback_zspage(pool, class, src_page) == ZS_EMPTY)
pool->stats.pages_compacted += class->pages_per_zspage;
spin_unlock(&class->lock);
cond_resched();
spin_lock(&class->lock);
}
if (src_page)
putback_zspage(pool, class, src_page);
spin_unlock(&class->lock);
}
unsigned long zs_compact(struct zs_pool *pool)
{
int i;
struct size_class *class;
for (i = zs_size_classes - 1; i >= 0; i--) {
class = pool->size_class[i];
if (!class)
continue;
if (class->index != i)
continue;
__zs_compact(pool, class);
}
return pool->stats.pages_compacted;
}
EXPORT_SYMBOL_GPL(zs_compact);
void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats)
{
memcpy(stats, &pool->stats, sizeof(struct zs_pool_stats));
}
EXPORT_SYMBOL_GPL(zs_pool_stats);
static unsigned long zs_shrinker_scan(struct shrinker *shrinker,
struct shrink_control *sc)
{
unsigned long pages_freed;
struct zs_pool *pool = container_of(shrinker, struct zs_pool,
shrinker);
pages_freed = pool->stats.pages_compacted;
/*
* Compact classes and calculate compaction delta.
* Can run concurrently with a manually triggered
* (by user) compaction.
*/
pages_freed = zs_compact(pool) - pages_freed;
return pages_freed ? pages_freed : SHRINK_STOP;
}
static unsigned long zs_shrinker_count(struct shrinker *shrinker,
struct shrink_control *sc)
{
int i;
struct size_class *class;
unsigned long pages_to_free = 0;
struct zs_pool *pool = container_of(shrinker, struct zs_pool,
shrinker);
for (i = zs_size_classes - 1; i >= 0; i--) {
class = pool->size_class[i];
if (!class)
continue;
if (class->index != i)
continue;
pages_to_free += zs_can_compact(class);
}
return pages_to_free;
}
static void zs_unregister_shrinker(struct zs_pool *pool)
{
if (pool->shrinker_enabled) {
unregister_shrinker(&pool->shrinker);
pool->shrinker_enabled = false;
}
}
static int zs_register_shrinker(struct zs_pool *pool)
{
pool->shrinker.scan_objects = zs_shrinker_scan;
pool->shrinker.count_objects = zs_shrinker_count;
pool->shrinker.batch = 0;
pool->shrinker.seeks = DEFAULT_SEEKS;
return register_shrinker(&pool->shrinker);
}
/**
* zs_create_pool - Creates an allocation pool to work from.
* @flags: allocation flags used to allocate pool metadata
*
* This function must be called before anything when using
* the zsmalloc allocator.
*
* On success, a pointer to the newly created pool is returned,
* otherwise NULL.
*/
struct zs_pool *zs_create_pool(const char *name, gfp_t flags)
{
int i;
struct zs_pool *pool;
struct size_class *prev_class = NULL;
pool = kzalloc(sizeof(*pool), GFP_KERNEL);
if (!pool)
return NULL;
pool->size_class = kcalloc(zs_size_classes, sizeof(struct size_class *),
GFP_KERNEL);
if (!pool->size_class) {
kfree(pool);
return NULL;
}
pool->name = kstrdup(name, GFP_KERNEL);
if (!pool->name)
goto err;
if (create_handle_cache(pool))
goto err;
/*
* Iterate reversly, because, size of size_class that we want to use
* for merging should be larger or equal to current size.
*/
for (i = zs_size_classes - 1; i >= 0; i--) {
int size;
int pages_per_zspage;
struct size_class *class;
size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
if (size > ZS_MAX_ALLOC_SIZE)
size = ZS_MAX_ALLOC_SIZE;
pages_per_zspage = get_pages_per_zspage(size);
/*
* size_class is used for normal zsmalloc operation such
* as alloc/free for that size. Although it is natural that we
* have one size_class for each size, there is a chance that we
* can get more memory utilization if we use one size_class for
* many different sizes whose size_class have same
* characteristics. So, we makes size_class point to
* previous size_class if possible.
*/
if (prev_class) {
if (can_merge(prev_class, size, pages_per_zspage)) {
pool->size_class[i] = prev_class;
continue;
}
}
class = kzalloc(sizeof(struct size_class), GFP_KERNEL);
if (!class)
goto err;
class->size = size;
class->index = i;
class->pages_per_zspage = pages_per_zspage;
if (pages_per_zspage == 1 &&
get_maxobj_per_zspage(size, pages_per_zspage) == 1)
class->huge = true;
spin_lock_init(&class->lock);
pool->size_class[i] = class;
prev_class = class;
}
pool->flags = flags;
if (zs_pool_stat_create(name, pool))
goto err;
/*
* Not critical, we still can use the pool
* and user can trigger compaction manually.
*/
if (zs_register_shrinker(pool) == 0)
pool->shrinker_enabled = true;
return pool;
err:
zs_destroy_pool(pool);
return NULL;
}
EXPORT_SYMBOL_GPL(zs_create_pool);
void zs_destroy_pool(struct zs_pool *pool)
{
int i;
zs_unregister_shrinker(pool);
zs_pool_stat_destroy(pool);
for (i = 0; i < zs_size_classes; i++) {
int fg;
struct size_class *class = pool->size_class[i];
if (!class)
continue;
if (class->index != i)
continue;
for (fg = 0; fg < _ZS_NR_FULLNESS_GROUPS; fg++) {
if (class->fullness_list[fg]) {
pr_info("Freeing non-empty class with size %db, fullness group %d\n",
class->size, fg);
}
}
kfree(class);
}
destroy_handle_cache(pool);
kfree(pool->size_class);
kfree(pool->name);
kfree(pool);
}
EXPORT_SYMBOL_GPL(zs_destroy_pool);
static int __init zs_init(void)
{
int ret = zs_register_cpu_notifier();
if (ret)
goto notifier_fail;
init_zs_size_classes();
#ifdef CONFIG_ZPOOL
zpool_register_driver(&zs_zpool_driver);
#endif
ret = zs_stat_init();
if (ret) {
pr_err("zs stat initialization failed\n");
goto stat_fail;
}
return 0;
stat_fail:
#ifdef CONFIG_ZPOOL
zpool_unregister_driver(&zs_zpool_driver);
#endif
notifier_fail:
zs_unregister_cpu_notifier();
return ret;
}
static void __exit zs_exit(void)
{
#ifdef CONFIG_ZPOOL
zpool_unregister_driver(&zs_zpool_driver);
#endif
zs_unregister_cpu_notifier();
zs_stat_exit();
}
module_init(zs_init);
module_exit(zs_exit);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");