linux_dsm_epyc7002/mm/zsmalloc.c
Heesub Shin 81da9b13f7 zsmalloc: fix fatal corruption due to wrong size class selection
There is no point in overriding the size class below.  It causes fatal
corruption on the next chunk on the 3264-bytes size class, which is the
last size class that is not huge.

For example, if the requested size was exactly 3264 bytes, current
zsmalloc allocates and returns a chunk from the size class of 3264 bytes,
not 4096.  User access to this chunk may overwrite head of the next
adjacent chunk.

Here is the panic log captured when freelist was corrupted due to this:

    Kernel BUG at ffffffc00030659c [verbose debug info unavailable]
    Internal error: Oops - BUG: 96000006 [#1] PREEMPT SMP
    Modules linked in:
    exynos-snapshot: core register saved(CPU:5)
    CPUMERRSR: 0000000000000000, L2MERRSR: 0000000000000000
    exynos-snapshot: context saved(CPU:5)
    exynos-snapshot: item - log_kevents is disabled
    CPU: 5 PID: 898 Comm: kswapd0 Not tainted 3.10.61-4497415-eng #1
    task: ffffffc0b8783d80 ti: ffffffc0b71e8000 task.ti: ffffffc0b71e8000
    PC is at obj_idx_to_offset+0x0/0x1c
    LR is at obj_malloc+0x44/0xe8
    pc : [<ffffffc00030659c>] lr : [<ffffffc000306604>] pstate: a0000045
    sp : ffffffc0b71eb790
    x29: ffffffc0b71eb790 x28: ffffffc00204c000
    x27: 000000000001d96f x26: 0000000000000000
    x25: ffffffc098cc3500 x24: ffffffc0a13f2810
    x23: ffffffc098cc3501 x22: ffffffc0a13f2800
    x21: 000011e1a02006e3 x20: ffffffc0a13f2800
    x19: ffffffbc02a7e000 x18: 0000000000000000
    x17: 0000000000000000 x16: 0000000000000feb
    x15: 0000000000000000 x14: 00000000a01003e3
    x13: 0000000000000020 x12: fffffffffffffff0
    x11: ffffffc08b264000 x10: 00000000e3a01004
    x9 : ffffffc08b263fea x8 : ffffffc0b1e611c0
    x7 : ffffffc000307d24 x6 : 0000000000000000
    x5 : 0000000000000038 x4 : 000000000000011e
    x3 : ffffffbc00003e90 x2 : 0000000000000cc0
    x1 : 00000000d0100371 x0 : ffffffbc00003e90

Reported-by: Sooyong Suk <s.suk@samsung.com>
Signed-off-by: Heesub Shin <heesub.shin@samsung.com>
Tested-by: Sooyong Suk <s.suk@samsung.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-04-15 16:35:22 -07:00

1949 lines
46 KiB
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->first_page: 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 (union with page->first_page): 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
*
* Usage of struct page flags:
* PG_private: identifies the first component page
* PG_private2: identifies the last component page
*
*/
#ifdef CONFIG_ZSMALLOC_DEBUG
#define DEBUG
#endif
#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/hardirq.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,
NR_ZS_STAT_TYPE,
};
#ifdef CONFIG_ZSMALLOC_STAT
static struct dentry *zs_stat_root;
struct zs_size_stat {
unsigned long objs[NR_ZS_STAT_TYPE];
};
#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 {
/*
* 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;
/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
bool huge;
#ifdef CONFIG_ZSMALLOC_STAT
struct zs_size_stat stats;
#endif
spinlock_t lock;
struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
};
/*
* 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 {
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;
#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(char *name, gfp_t gfp, struct zpool_ops *zpool_ops)
{
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);
}
#ifdef CONFIG_ZSMALLOC_STAT
static inline void zs_stat_inc(struct size_class *class,
enum zs_stat_type type, unsigned long cnt)
{
class->stats.objs[type] += cnt;
}
static inline void zs_stat_dec(struct size_class *class,
enum zs_stat_type type, unsigned long cnt)
{
class->stats.objs[type] -= cnt;
}
static inline unsigned long zs_stat_get(struct size_class *class,
enum zs_stat_type type)
{
return class->stats.objs[type];
}
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(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 inline void zs_stat_inc(struct size_class *class,
enum zs_stat_type type, unsigned long cnt)
{
}
static inline void zs_stat_dec(struct size_class *class,
enum zs_stat_type type, unsigned long cnt)
{
}
static inline unsigned long zs_stat_get(struct size_class *class,
enum zs_stat_type type)
{
return 0;
}
static int __init zs_stat_init(void)
{
return 0;
}
static void __exit zs_stat_exit(void)
{
}
static inline int zs_pool_stat_create(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;
head = &class->fullness_list[fullness];
if (*head)
list_add_tail(&page->lru, &(*head)->lru);
*head = page;
zs_stat_inc(class, fullness == ZS_ALMOST_EMPTY ?
CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
}
/*
* 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 page->first_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 *(unsigned long *)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->first_page
*
* 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)
page->first_page = 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;
int class_idx;
enum fullness_group fullness;
BUG_ON(!obj);
obj &= ~OBJ_ALLOCATED_TAG;
obj_to_location(obj, &f_page, &f_objidx);
first_page = get_first_page(f_page);
get_zspage_mapping(first_page, &class_idx, &fullness);
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 src, unsigned long dst,
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;
/* how many of objects are migrated */
int nr_migrated;
};
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 nr_migrated = 0;
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(used_obj, free_obj, class);
index++;
record_obj(handle, free_obj);
unpin_tag(handle);
obj_free(pool, class, used_obj);
nr_migrated++;
}
/* Remember last position in this iteration */
cc->s_page = s_page;
cc->index = index;
cc->nr_migrated = nr_migrated;
return ret;
}
static struct page *alloc_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;
}
static void 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);
}
}
static struct page *isolate_source_page(struct size_class *class)
{
struct page *page;
page = class->fullness_list[ZS_ALMOST_EMPTY];
if (page)
remove_zspage(page, class, ZS_ALMOST_EMPTY);
return page;
}
static unsigned long __zs_compact(struct zs_pool *pool,
struct size_class *class)
{
int nr_to_migrate;
struct zs_compact_control cc;
struct page *src_page;
struct page *dst_page = NULL;
unsigned long nr_total_migrated = 0;
cond_resched();
spin_lock(&class->lock);
while ((src_page = isolate_source_page(class))) {
BUG_ON(!is_first_page(src_page));
/* The goal is to migrate all live objects in source page */
nr_to_migrate = src_page->inuse;
cc.index = 0;
cc.s_page = src_page;
while ((dst_page = alloc_target_page(class))) {
cc.d_page = dst_page;
/*
* If there is no more space in dst_page, try to
* allocate another zspage.
*/
if (!migrate_zspage(pool, class, &cc))
break;
putback_zspage(pool, class, dst_page);
nr_total_migrated += cc.nr_migrated;
nr_to_migrate -= cc.nr_migrated;
}
/* Stop if we couldn't find slot */
if (dst_page == NULL)
break;
putback_zspage(pool, class, dst_page);
putback_zspage(pool, class, src_page);
spin_unlock(&class->lock);
nr_total_migrated += cc.nr_migrated;
cond_resched();
spin_lock(&class->lock);
}
if (src_page)
putback_zspage(pool, class, src_page);
spin_unlock(&class->lock);
return nr_total_migrated;
}
unsigned long zs_compact(struct zs_pool *pool)
{
int i;
unsigned long nr_migrated = 0;
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;
nr_migrated += __zs_compact(pool, class);
}
return nr_migrated;
}
EXPORT_SYMBOL_GPL(zs_compact);
/**
* 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(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;
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_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>");