--- /dev/null
+/*
+ * 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)
+{
+ if (pool->handle_cachep)
+ 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;
+
+ 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>");
Code Review / kvmfornfv.git / blobdiff