diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/Kconfig | 32 | ||||
| -rw-r--r-- | mm/Makefile | 2 | ||||
| -rw-r--r-- | mm/zpool.c | 364 | ||||
| -rw-r--r-- | mm/zsmalloc.c | 1221 |
4 files changed, 1619 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig index b2d1aed56439..7c13c134f646 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -504,3 +504,35 @@ config CMA_DEBUG messages for every CMA call as well as various messages while processing calls such as dma_alloc_from_contiguous(). This option does not affect warning and error messages. + +config ZPOOL + tristate "Common API for compressed memory storage" + default n + help + Compressed memory storage API. This allows using either zbud or + zsmalloc. + +config ZSMALLOC + bool "Memory allocator for compressed pages" + depends on MMU + default n + help + zsmalloc is a slab-based memory allocator designed to store + compressed RAM pages. zsmalloc uses virtual memory mapping + in order to reduce fragmentation. However, this results in a + non-standard allocator interface where a handle, not a pointer, is + returned by an alloc(). This handle must be mapped in order to + access the allocated space. + +config PGTABLE_MAPPING + bool "Use page table mapping to access object in zsmalloc" + depends on ZSMALLOC + help + By default, zsmalloc uses a copy-based object mapping method to + access allocations that span two pages. However, if a particular + architecture (ex, ARM) performs VM mapping faster than copying, + then you should select this. This causes zsmalloc to use page table + mapping rather than copying for object mapping. + + You can check speed with zsmalloc benchmark[1]. + [1] https://github.com/spartacus06/zsmalloc diff --git a/mm/Makefile b/mm/Makefile index 89244cb96221..0fa6442b4d4c 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -59,3 +59,5 @@ obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o obj-$(CONFIG_CLEANCACHE) += cleancache.o obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o +obj-$(CONFIG_ZPOOL) += zpool.o +obj-$(CONFIG_ZSMALLOC) += zsmalloc.o diff --git a/mm/zpool.c b/mm/zpool.c new file mode 100644 index 000000000000..739cdf0d183a --- /dev/null +++ b/mm/zpool.c @@ -0,0 +1,364 @@ +/* + * zpool memory storage api + * + * Copyright (C) 2014 Dan Streetman + * + * This is a common frontend for memory storage pool implementations. + * Typically, this is used to store compressed memory. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/list.h> +#include <linux/types.h> +#include <linux/mm.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/module.h> +#include <linux/zpool.h> + +struct zpool { + char *type; + + struct zpool_driver *driver; + void *pool; + struct zpool_ops *ops; + + struct list_head list; +}; + +static LIST_HEAD(drivers_head); +static DEFINE_SPINLOCK(drivers_lock); + +static LIST_HEAD(pools_head); +static DEFINE_SPINLOCK(pools_lock); + +/** + * zpool_register_driver() - register a zpool implementation. + * @driver: driver to register + */ +void zpool_register_driver(struct zpool_driver *driver) +{ + spin_lock(&drivers_lock); + atomic_set(&driver->refcount, 0); + list_add(&driver->list, &drivers_head); + spin_unlock(&drivers_lock); +} +EXPORT_SYMBOL(zpool_register_driver); + +/** + * zpool_unregister_driver() - unregister a zpool implementation. + * @driver: driver to unregister. + * + * Module usage counting is used to prevent using a driver + * while/after unloading, so if this is called from module + * exit function, this should never fail; if called from + * other than the module exit function, and this returns + * failure, the driver is in use and must remain available. + */ +int zpool_unregister_driver(struct zpool_driver *driver) +{ + int ret = 0, refcount; + + spin_lock(&drivers_lock); + refcount = atomic_read(&driver->refcount); + WARN_ON(refcount < 0); + if (refcount > 0) + ret = -EBUSY; + else + list_del(&driver->list); + spin_unlock(&drivers_lock); + + return ret; +} +EXPORT_SYMBOL(zpool_unregister_driver); + +/** + * zpool_evict() - evict callback from a zpool implementation. + * @pool: pool to evict from. + * @handle: handle to evict. + * + * This can be used by zpool implementations to call the + * user's evict zpool_ops struct evict callback. + */ +int zpool_evict(void *pool, unsigned long handle) +{ + struct zpool *zpool; + + spin_lock(&pools_lock); + list_for_each_entry(zpool, &pools_head, list) { + if (zpool->pool == pool) { + spin_unlock(&pools_lock); + if (!zpool->ops || !zpool->ops->evict) + return -EINVAL; + return zpool->ops->evict(zpool, handle); + } + } + spin_unlock(&pools_lock); + + return -ENOENT; +} +EXPORT_SYMBOL(zpool_evict); + +static struct zpool_driver *zpool_get_driver(char *type) +{ + struct zpool_driver *driver; + + spin_lock(&drivers_lock); + list_for_each_entry(driver, &drivers_head, list) { + if (!strcmp(driver->type, type)) { + bool got = try_module_get(driver->owner); + + if (got) + atomic_inc(&driver->refcount); + spin_unlock(&drivers_lock); + return got ? driver : NULL; + } + } + + spin_unlock(&drivers_lock); + return NULL; +} + +static void zpool_put_driver(struct zpool_driver *driver) +{ + atomic_dec(&driver->refcount); + module_put(driver->owner); +} + +/** + * zpool_create_pool() - Create a new zpool + * @type The type of the zpool to create (e.g. zbud, zsmalloc) + * @gfp The GFP flags to use when allocating the pool. + * @ops The optional ops callback. + * + * This creates a new zpool of the specified type. The gfp flags will be + * used when allocating memory, if the implementation supports it. If the + * ops param is NULL, then the created zpool will not be shrinkable. + * + * Implementations must guarantee this to be thread-safe. + * + * Returns: New zpool on success, NULL on failure. + */ +struct zpool *zpool_create_pool(char *type, gfp_t gfp, struct zpool_ops *ops) +{ + struct zpool_driver *driver; + struct zpool *zpool; + + pr_info("creating pool type %s\n", type); + + driver = zpool_get_driver(type); + + if (!driver) { + request_module("zpool-%s", type); + driver = zpool_get_driver(type); + } + + if (!driver) { + pr_err("no driver for type %s\n", type); + return NULL; + } + + zpool = kmalloc(sizeof(*zpool), gfp); + if (!zpool) { + pr_err("couldn't create zpool - out of memory\n"); + zpool_put_driver(driver); + return NULL; + } + + zpool->type = driver->type; + zpool->driver = driver; + zpool->pool = driver->create(gfp, ops); + zpool->ops = ops; + + if (!zpool->pool) { + pr_err("couldn't create %s pool\n", type); + zpool_put_driver(driver); + kfree(zpool); + return NULL; + } + + pr_info("created %s pool\n", type); + + spin_lock(&pools_lock); + list_add(&zpool->list, &pools_head); + spin_unlock(&pools_lock); + + return zpool; +} + +/** + * zpool_destroy_pool() - Destroy a zpool + * @pool The zpool to destroy. + * + * Implementations must guarantee this to be thread-safe, + * however only when destroying different pools. The same + * pool should only be destroyed once, and should not be used + * after it is destroyed. + * + * This destroys an existing zpool. The zpool should not be in use. + */ +void zpool_destroy_pool(struct zpool *zpool) +{ + pr_info("destroying pool type %s\n", zpool->type); + + spin_lock(&pools_lock); + list_del(&zpool->list); + spin_unlock(&pools_lock); + zpool->driver->destroy(zpool->pool); + zpool_put_driver(zpool->driver); + kfree(zpool); +} + +/** + * zpool_get_type() - Get the type of the zpool + * @pool The zpool to check + * + * This returns the type of the pool. + * + * Implementations must guarantee this to be thread-safe. + * + * Returns: The type of zpool. + */ +char *zpool_get_type(struct zpool *zpool) +{ + return zpool->type; +} + +/** + * zpool_malloc() - Allocate memory + * @pool The zpool to allocate from. + * @size The amount of memory to allocate. + * @gfp The GFP flags to use when allocating memory. + * @handle Pointer to the handle to set + * + * This allocates the requested amount of memory from the pool. + * The gfp flags will be used when allocating memory, if the + * implementation supports it. The provided @handle will be + * set to the allocated object handle. + * + * Implementations must guarantee this to be thread-safe. + * + * Returns: 0 on success, negative value on error. + */ +int zpool_malloc(struct zpool *zpool, size_t size, gfp_t gfp, + unsigned long *handle) +{ + return zpool->driver->malloc(zpool->pool, size, gfp, handle); +} + +/** + * zpool_free() - Free previously allocated memory + * @pool The zpool that allocated the memory. + * @handle The handle to the memory to free. + * + * This frees previously allocated memory. This does not guarantee + * that the pool will actually free memory, only that the memory + * in the pool will become available for use by the pool. + * + * Implementations must guarantee this to be thread-safe, + * however only when freeing different handles. The same + * handle should only be freed once, and should not be used + * after freeing. + */ +void zpool_free(struct zpool *zpool, unsigned long handle) +{ + zpool->driver->free(zpool->pool, handle); +} + +/** + * zpool_shrink() - Shrink the pool size + * @pool The zpool to shrink. + * @pages The number of pages to shrink the pool. + * @reclaimed The number of pages successfully evicted. + * + * This attempts to shrink the actual memory size of the pool + * by evicting currently used handle(s). If the pool was + * created with no zpool_ops, or the evict call fails for any + * of the handles, this will fail. If non-NULL, the @reclaimed + * parameter will be set to the number of pages reclaimed, + * which may be more than the number of pages requested. + * + * Implementations must guarantee this to be thread-safe. + * + * Returns: 0 on success, negative value on error/failure. + */ +int zpool_shrink(struct zpool *zpool, unsigned int pages, + unsigned int *reclaimed) +{ + return zpool->driver->shrink(zpool->pool, pages, reclaimed); +} + +/** + * zpool_map_handle() - Map a previously allocated handle into memory + * @pool The zpool that the handle was allocated from + * @handle The handle to map + * @mm How the memory should be mapped + * + * This maps a previously allocated handle into memory. The @mm + * param indicates to the implementation how the memory will be + * used, i.e. read-only, write-only, read-write. If the + * implementation does not support it, the memory will be treated + * as read-write. + * + * This may hold locks, disable interrupts, and/or preemption, + * and the zpool_unmap_handle() must be called to undo those + * actions. The code that uses the mapped handle should complete + * its operatons on the mapped handle memory quickly and unmap + * as soon as possible. As the implementation may use per-cpu + * data, multiple handles should not be mapped concurrently on + * any cpu. + * + * Returns: A pointer to the handle's mapped memory area. + */ +void *zpool_map_handle(struct zpool *zpool, unsigned long handle, + enum zpool_mapmode mapmode) +{ + return zpool->driver->map(zpool->pool, handle, mapmode); +} + +/** + * zpool_unmap_handle() - Unmap a previously mapped handle + * @pool The zpool that the handle was allocated from + * @handle The handle to unmap + * + * This unmaps a previously mapped handle. Any locks or other + * actions that the implementation took in zpool_map_handle() + * will be undone here. The memory area returned from + * zpool_map_handle() should no longer be used after this. + */ +void zpool_unmap_handle(struct zpool *zpool, unsigned long handle) +{ + zpool->driver->unmap(zpool->pool, handle); +} + +/** + * zpool_get_total_size() - The total size of the pool + * @pool The zpool to check + * + * This returns the total size in bytes of the pool. + * + * Returns: Total size of the zpool in bytes. + */ +u64 zpool_get_total_size(struct zpool *zpool) +{ + return zpool->driver->total_size(zpool->pool); +} + +static int __init init_zpool(void) +{ + pr_info("loaded\n"); + return 0; +} + +static void __exit exit_zpool(void) +{ + pr_info("unloaded\n"); +} + +module_init(init_zpool); +module_exit(exit_zpool); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>"); +MODULE_DESCRIPTION("Common API for compressed memory storage"); diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c new file mode 100644 index 000000000000..7031e12fcf2b --- /dev/null +++ b/mm/zsmalloc.c @@ -0,0 +1,1221 @@ +/* + * 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 + */ + + +/* + * This allocator is designed for use with zcache and zram. Thus, the + * allocator is supposed to work well under low memory conditions. In + * particular, it never attempts higher order page allocation which is + * very likely to fail under memory pressure. On the other hand, if we + * just use single (0-order) pages, it would suffer from very high + * fragmentation -- any object of size PAGE_SIZE/2 or larger would occupy + * an entire page. This was one of the major issues with its predecessor + * (xvmalloc). + * + * To overcome these issues, zsmalloc allocates a bunch of 0-order pages + * and links them together using various 'struct page' fields. These linked + * pages act as a single higher-order page i.e. an object can span 0-order + * page boundaries. The code refers to these linked pages as a single entity + * called zspage. + * + * 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 + * 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/bitops.h> +#include <linux/errno.h> +#include <linux/highmem.h> +#include <linux/init.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/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) + +/* + * Object location (<PFN>, <obj_idx>) is encoded as + * as single (void *) 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) +#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_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)) +#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) +#define ZS_SIZE_CLASSES ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / \ + ZS_SIZE_CLASS_DELTA + 1) + +/* + * 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 +}; + +/* + * 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; + + 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 { + /* Handle of next free chunk (encodes <PFN, obj_idx>) */ + void *next; +}; + +struct zs_pool { + struct size_class *size_class[ZS_SIZE_CLASSES]; + + gfp_t flags; /* allocation flags used when growing pool */ + atomic_long_t pages_allocated; +}; + +/* + * 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) + +/* + * By default, zsmalloc uses a copy-based object mapping method to access + * allocations that span two pages. However, if a particular architecture + * performs VM mapping faster than copying, then it should be added here + * so that USE_PGTABLE_MAPPING is defined. This causes zsmalloc to use + * page table mapping rather than copying for object mapping. +*/ +#if defined(CONFIG_ARM) && !defined(MODULE) +#define USE_PGTABLE_MAPPING +#endif + +struct mapping_area { +#ifdef USE_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 */ +}; + +/* zpool driver */ + +#ifdef CONFIG_ZPOOL + +static void *zs_zpool_create(gfp_t gfp, struct zpool_ops *zpool_ops) +{ + return zs_create_pool(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 */ + +/* 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; +} + +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 idx; +} + +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 <= max_objects / fullness_threshold_frac) + fg = ZS_ALMOST_EMPTY; + else + fg = ZS_ALMOST_FULL; + + return fg; +} + +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; +} + +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); +} + +static enum fullness_group fix_fullness_group(struct zs_pool *pool, + struct page *page) +{ + int class_idx; + struct size_class *class; + 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; + + class = pool->size_class[class_idx]; + 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 - Zp % size_class + * 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; + else + next = list_entry(page->lru.next, struct page, lru); + + return next; +} + +/* + * Encode <page, obj_idx> as a single handle value. + * On hardware platforms with physical memory starting at 0x0 the pfn + * could be 0 so we ensure that the handle will never be 0 by adjusting the + * encoded obj_idx value before encoding. + */ +static void *obj_location_to_handle(struct page *page, unsigned long obj_idx) +{ + unsigned long handle; + + if (!page) { + BUG_ON(obj_idx); + return NULL; + } + + handle = page_to_pfn(page) << OBJ_INDEX_BITS; + handle |= ((obj_idx + 1) & OBJ_INDEX_MASK); + + return (void *)handle; +} + +/* + * 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 + * obj_location_to_handle(). + */ +static void obj_handle_to_location(unsigned long handle, struct page **page, + unsigned long *obj_idx) +{ + *page = pfn_to_page(handle >> OBJ_INDEX_BITS); + *obj_idx = (handle & OBJ_INDEX_MASK) - 1; +} + +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 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 = obj_location_to_handle(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 = obj_location_to_handle(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) + first_page->private = (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 = obj_location_to_handle(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 USE_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 /* USE_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 = (char *)__get_free_page(GFP_KERNEL); + if (!area->vm_buf) + return -ENOMEM; + return 0; +} + +static inline void __zs_cpu_down(struct mapping_area *area) +{ + if (area->vm_buf) + free_page((unsigned long)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 = area->vm_buf; + + /* no write fastpath */ + if (area->vm_mm == ZS_MM_RO) + goto out; + + 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 /* USE_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 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 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 __exit zs_exit(void) +{ +#ifdef CONFIG_ZPOOL + zpool_unregister_driver(&zs_zpool_driver); +#endif + zs_unregister_cpu_notifier(); +} + +static int __init zs_init(void) +{ + int ret = zs_register_cpu_notifier(); + + if (ret) { + zs_unregister_cpu_notifier(); + return ret; + } + +#ifdef CONFIG_ZPOOL + zpool_register_driver(&zs_zpool_driver); +#endif + return 0; +} + +static unsigned int get_maxobj_per_zspage(int size, int pages_per_zspage) +{ + return pages_per_zspage * PAGE_SIZE / size; +} + +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; +} + +/** + * 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(gfp_t flags) +{ + int i, ovhd_size; + struct zs_pool *pool; + + ovhd_size = roundup(sizeof(*pool), PAGE_SIZE); + pool = kzalloc(ovhd_size, GFP_KERNEL); + if (!pool) + return NULL; + + /* + * 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; + struct size_class *prev_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 (i < ZS_SIZE_CLASSES - 1) { + prev_class = pool->size_class[i + 1]; + 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; + spin_lock_init(&class->lock); + pool->size_class[i] = class; + } + + pool->flags = flags; + + 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; + + 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); + } + kfree(pool); +} +EXPORT_SYMBOL_GPL(zs_destroy_pool); + +/** + * 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 obj; + struct link_free *link; + struct size_class *class; + void *vaddr; + + struct page *first_page, *m_page; + unsigned long m_objidx, m_offset; + + if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE)) + return 0; + + 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)) + 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); + } + + obj = (unsigned long)first_page->freelist; + obj_handle_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; + memset(link, POISON_INUSE, sizeof(*link)); + kunmap_atomic(vaddr); + + first_page->inuse++; + /* Now move the zspage to another fullness group, if required */ + fix_fullness_group(pool, first_page); + spin_unlock(&class->lock); + + return obj; +} +EXPORT_SYMBOL_GPL(zs_malloc); + +void zs_free(struct zs_pool *pool, unsigned long obj) +{ + struct link_free *link; + struct page *first_page, *f_page; + unsigned long f_objidx, f_offset; + void *vaddr; + + int class_idx; + struct size_class *class; + enum fullness_group fullness; + + if (unlikely(!obj)) + return; + + obj_handle_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]; + f_offset = obj_idx_to_offset(f_page, f_objidx, class->size); + + spin_lock(&class->lock); + + /* Insert this object in containing zspage's freelist */ + vaddr = kmap_atomic(f_page); + link = (struct link_free *)(vaddr + f_offset); + link->next = first_page->freelist; + kunmap_atomic(vaddr); + first_page->freelist = (void *)obj; + + first_page->inuse--; + fullness = fix_fullness_group(pool, first_page); + spin_unlock(&class->lock); + + if (fullness == ZS_EMPTY) { + atomic_long_sub(class->pages_per_zspage, + &pool->pages_allocated); + free_zspage(first_page); + } +} +EXPORT_SYMBOL_GPL(zs_free); + +/** + * 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_idx, off; + + unsigned int class_idx; + enum fullness_group fg; + struct size_class *class; + struct mapping_area *area; + struct page *pages[2]; + + 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()); + + obj_handle_to_location(handle, &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); + return area->vm_addr + off; + } + + /* this object spans two pages */ + pages[0] = page; + pages[1] = get_next_page(page); + BUG_ON(!pages[1]); + + return __zs_map_object(area, pages, off, class->size); +} +EXPORT_SYMBOL_GPL(zs_map_object); + +void zs_unmap_object(struct zs_pool *pool, unsigned long handle) +{ + struct page *page; + unsigned long 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_location(handle, &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); + 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); +} +EXPORT_SYMBOL_GPL(zs_unmap_object); + +unsigned long zs_get_total_pages(struct zs_pool *pool) +{ + return atomic_long_read(&pool->pages_allocated); +} +EXPORT_SYMBOL_GPL(zs_get_total_pages); + +module_init(zs_init); +module_exit(zs_exit); + +MODULE_LICENSE("Dual BSD/GPL"); +MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>"); |