/* * 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 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. * * For simplicity, zsmalloc can only allocate objects of size up to PAGE_SIZE * since this satisfies the requirements of all its current users (in the * worst case, page is incompressible and is thus stored "as-is" i.e. in * uncompressed form). For allocation requests larger than this size, failure * is returned (see zs_malloc). * * Additionally, zs_malloc() does not return a dereferenceable pointer. * Instead, it returns an opaque handle (unsigned long) which encodes actual * location of the allocated object. The reason for this indirection is that * zsmalloc does not keep zspages permanently mapped since that would cause * issues on 32-bit systems where the VA region for kernel space mappings * is very small. So, before using the allocating memory, the object has to * be mapped using zs_map_object() to get a usable pointer and subsequently * unmapped using zs_unmap_object(). * * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * 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 (, ) is encoded as * as single (unsigned long) handle value. * * Note that object index is relative to system * page 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 254 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 = 1/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; /* stats */ u64 pages_allocated; 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 ) */ void *next; }; struct zs_pool { struct size_class size_class[ZS_SIZE_CLASSES]; gfp_t flags; /* allocation flags used when growing pool */ }; /* * 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 */ }; /* 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 idx; } /* * 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 <= 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 . */ 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; } /* * This function removes the given zspage from the freelist identified * by . */ 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); } /* * 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 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(page); else next = list_entry(page->lru.next, struct page, lru); return next; } /* * Encode 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 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, objs_on_page; /* * 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; link = (struct link_free *)kmap_atomic(page) + off / sizeof(*link); objs_on_page = (PAGE_SIZE - off) / class->size; for (i = 1; i <= objs_on_page; i++) { off += class->size; if (off < 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(link); page = next_page; off = (off + class->size) % 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 = 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 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 = (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 /* 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 void zs_exit(void) { int cpu; for_each_online_cpu(cpu) zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu); unregister_cpu_notifier(&zs_cpu_nb); } static int zs_init(void) { int cpu, ret; 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)) goto fail; } return 0; fail: zs_exit(); return notifier_to_errno(ret); } /** * 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; for (i = 0; i < ZS_SIZE_CLASSES; i++) { int size; 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; class = &pool->size_class[i]; class->size = size; class->index = i; spin_lock_init(&class->lock); class->pages_per_zspage = get_pages_per_zspage(size); } pool->flags = flags; return pool; } 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]; 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(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; int class_idx; struct size_class *class; struct page *first_page, *m_page; unsigned long m_objidx, m_offset; if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE)) return 0; class_idx = get_size_class_index(size); class = &pool->size_class[class_idx]; BUG_ON(class_idx != class->index); 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); spin_lock(&class->lock); class->pages_allocated += class->pages_per_zspage; } 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); link = (struct link_free *)kmap_atomic(m_page) + m_offset / sizeof(*link); first_page->freelist = link->next; memset(link, POISON_INUSE, sizeof(*link)); kunmap_atomic(link); 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; 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 */ link = (struct link_free *)((unsigned char *)kmap_atomic(f_page) + f_offset); link->next = first_page->freelist; kunmap_atomic(link); first_page->freelist = (void *)obj; first_page->inuse--; fullness = fix_fullness_group(pool, first_page); if (fullness == ZS_EMPTY) class->pages_allocated -= class->pages_per_zspage; spin_unlock(&class->lock); if (fullness == ZS_EMPTY) 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); u64 zs_get_total_size_bytes(struct zs_pool *pool) { int i; u64 npages = 0; for (i = 0; i < ZS_SIZE_CLASSES; i++) npages += pool->size_class[i].pages_allocated; return npages << PAGE_SHIFT; } EXPORT_SYMBOL_GPL(zs_get_total_size_bytes); module_init(zs_init); module_exit(zs_exit); MODULE_LICENSE("Dual BSD/GPL"); MODULE_AUTHOR("Nitin Gupta ");