v4.19.13 snapshot.
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
new file mode 100644
index 0000000..9da6555
--- /dev/null
+++ b/mm/zsmalloc.c
@@ -0,0 +1,2540 @@
+/*
+ * zsmalloc memory allocator
+ *
+ * Copyright (C) 2011 Nitin Gupta
+ * Copyright (C) 2012, 2013 Minchan Kim
+ *
+ * This code is released using a dual license strategy: BSD/GPL
+ * You can choose the license that better fits your requirements.
+ *
+ * Released under the terms of 3-clause BSD License
+ * Released under the terms of GNU General Public License Version 2.0
+ */
+
+/*
+ * Following is how we use various fields and flags of underlying
+ * struct page(s) to form a zspage.
+ *
+ * Usage of struct page fields:
+ * page->private: points to zspage
+ * page->freelist(index): links together all component pages of a zspage
+ * For the huge page, this is always 0, so we use this field
+ * to store handle.
+ * page->units: first object offset in a subpage of zspage
+ *
+ * Usage of struct page flags:
+ * PG_private: identifies the first component page
+ * PG_owner_priv_1: identifies the huge component page
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/magic.h>
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/highmem.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <asm/tlbflush.h>
+#include <asm/pgtable.h>
+#include <linux/cpumask.h>
+#include <linux/cpu.h>
+#include <linux/vmalloc.h>
+#include <linux/preempt.h>
+#include <linux/spinlock.h>
+#include <linux/shrinker.h>
+#include <linux/types.h>
+#include <linux/debugfs.h>
+#include <linux/zsmalloc.h>
+#include <linux/zpool.h>
+#include <linux/mount.h>
+#include <linux/migrate.h>
+#include <linux/pagemap.h>
+#include <linux/fs.h>
+
+#define ZSPAGE_MAGIC 0x58
+
+/*
+ * 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> starts from 0.
+ *
+ * This is made more complicated by various memory models and PAE.
+ */
+
+#ifndef MAX_POSSIBLE_PHYSMEM_BITS
+#ifdef MAX_PHYSMEM_BITS
+#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS
+#else
+/*
+ * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
+ * be PAGE_SHIFT
+ */
+#define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG
+#endif
+#endif
+
+#define _PFN_BITS (MAX_POSSIBLE_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 FULLNESS_BITS 2
+#define CLASS_BITS 8
+#define ISOLATED_BITS 3
+#define MAGIC_VAL_BITS 8
+
+#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 >> CLASS_BITS)
+#define ZS_SIZE_CLASSES (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \
+ ZS_SIZE_CLASS_DELTA) + 1)
+
+enum fullness_group {
+ ZS_EMPTY,
+ ZS_ALMOST_EMPTY,
+ ZS_ALMOST_FULL,
+ ZS_FULL,
+ NR_ZS_FULLNESS,
+};
+
+enum zs_stat_type {
+ CLASS_EMPTY,
+ CLASS_ALMOST_EMPTY,
+ CLASS_ALMOST_FULL,
+ CLASS_FULL,
+ OBJ_ALLOCATED,
+ OBJ_USED,
+ NR_ZS_STAT_TYPE,
+};
+
+struct zs_size_stat {
+ unsigned long objs[NR_ZS_STAT_TYPE];
+};
+
+#ifdef CONFIG_ZSMALLOC_STAT
+static struct dentry *zs_stat_root;
+#endif
+
+#ifdef CONFIG_COMPACTION
+static struct vfsmount *zsmalloc_mnt;
+#endif
+
+/*
+ * 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;
+static size_t huge_class_size;
+
+struct size_class {
+ spinlock_t lock;
+ struct list_head fullness_list[NR_ZS_FULLNESS];
+ /*
+ * Size of objects stored in this class. Must be multiple
+ * of ZS_ALIGN.
+ */
+ int size;
+ int objs_per_zspage;
+ /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
+ int pages_per_zspage;
+
+ unsigned int index;
+ struct zs_size_stat stats;
+};
+
+/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
+static void SetPageHugeObject(struct page *page)
+{
+ SetPageOwnerPriv1(page);
+}
+
+static void ClearPageHugeObject(struct page *page)
+{
+ ClearPageOwnerPriv1(page);
+}
+
+static int PageHugeObject(struct page *page)
+{
+ return PageOwnerPriv1(page);
+}
+
+/*
+ * Placed within free objects to form a singly linked list.
+ * For every zspage, zspage->freeobj gives head of this list.
+ *
+ * This must be power of 2 and less than or equal to ZS_ALIGN
+ */
+struct link_free {
+ union {
+ /*
+ * Free object index;
+ * It's valid for non-allocated object
+ */
+ unsigned long next;
+ /*
+ * Handle of allocated object.
+ */
+ unsigned long handle;
+ };
+};
+
+struct zs_pool {
+ const char *name;
+
+ struct size_class *size_class[ZS_SIZE_CLASSES];
+ struct kmem_cache *handle_cachep;
+ struct kmem_cache *zspage_cachep;
+
+ atomic_long_t pages_allocated;
+
+ struct zs_pool_stats stats;
+
+ /* Compact classes */
+ struct shrinker shrinker;
+
+#ifdef CONFIG_ZSMALLOC_STAT
+ struct dentry *stat_dentry;
+#endif
+#ifdef CONFIG_COMPACTION
+ struct inode *inode;
+ struct work_struct free_work;
+#endif
+};
+
+struct zspage {
+ struct {
+ unsigned int fullness:FULLNESS_BITS;
+ unsigned int class:CLASS_BITS + 1;
+ unsigned int isolated:ISOLATED_BITS;
+ unsigned int magic:MAGIC_VAL_BITS;
+ };
+ unsigned int inuse;
+ unsigned int freeobj;
+ struct page *first_page;
+ struct list_head list; /* fullness list */
+#ifdef CONFIG_COMPACTION
+ rwlock_t lock;
+#endif
+};
+
+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 */
+};
+
+#ifdef CONFIG_COMPACTION
+static int zs_register_migration(struct zs_pool *pool);
+static void zs_unregister_migration(struct zs_pool *pool);
+static void migrate_lock_init(struct zspage *zspage);
+static void migrate_read_lock(struct zspage *zspage);
+static void migrate_read_unlock(struct zspage *zspage);
+static void kick_deferred_free(struct zs_pool *pool);
+static void init_deferred_free(struct zs_pool *pool);
+static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage);
+#else
+static int zsmalloc_mount(void) { return 0; }
+static void zsmalloc_unmount(void) {}
+static int zs_register_migration(struct zs_pool *pool) { return 0; }
+static void zs_unregister_migration(struct zs_pool *pool) {}
+static void migrate_lock_init(struct zspage *zspage) {}
+static void migrate_read_lock(struct zspage *zspage) {}
+static void migrate_read_unlock(struct zspage *zspage) {}
+static void kick_deferred_free(struct zs_pool *pool) {}
+static void init_deferred_free(struct zs_pool *pool) {}
+static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) {}
+#endif
+
+static int create_cache(struct zs_pool *pool)
+{
+ pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
+ 0, 0, NULL);
+ if (!pool->handle_cachep)
+ return 1;
+
+ pool->zspage_cachep = kmem_cache_create("zspage", sizeof(struct zspage),
+ 0, 0, NULL);
+ if (!pool->zspage_cachep) {
+ kmem_cache_destroy(pool->handle_cachep);
+ pool->handle_cachep = NULL;
+ return 1;
+ }
+
+ return 0;
+}
+
+static void destroy_cache(struct zs_pool *pool)
+{
+ kmem_cache_destroy(pool->handle_cachep);
+ kmem_cache_destroy(pool->zspage_cachep);
+}
+
+static unsigned long cache_alloc_handle(struct zs_pool *pool, gfp_t gfp)
+{
+ return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
+ gfp & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
+}
+
+static void cache_free_handle(struct zs_pool *pool, unsigned long handle)
+{
+ kmem_cache_free(pool->handle_cachep, (void *)handle);
+}
+
+static struct zspage *cache_alloc_zspage(struct zs_pool *pool, gfp_t flags)
+{
+ return kmem_cache_alloc(pool->zspage_cachep,
+ flags & ~(__GFP_HIGHMEM|__GFP_MOVABLE));
+}
+
+static void cache_free_zspage(struct zs_pool *pool, struct zspage *zspage)
+{
+ kmem_cache_free(pool->zspage_cachep, zspage);
+}
+
+static void record_obj(unsigned long handle, unsigned long obj)
+{
+ /*
+ * lsb of @obj represents handle lock while other bits
+ * represent object value the handle is pointing so
+ * updating shouldn't do store tearing.
+ */
+ WRITE_ONCE(*(unsigned long *)handle, obj);
+}
+
+/* zpool driver */
+
+#ifdef CONFIG_ZPOOL
+
+static void *zs_zpool_create(const char *name, gfp_t gfp,
+ const struct zpool_ops *zpool_ops,
+ struct zpool *zpool)
+{
+ /*
+ * Ignore global gfp flags: zs_malloc() may be invoked from
+ * different contexts and its caller must provide a valid
+ * gfp mask.
+ */
+ return zs_create_pool(name);
+}
+
+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, gfp);
+ return *handle ? 0 : -1;
+}
+static void zs_zpool_free(void *pool, unsigned long handle)
+{
+ zs_free(pool, handle);
+}
+
+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,
+ .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 bool is_zspage_isolated(struct zspage *zspage)
+{
+ return zspage->isolated;
+}
+
+static __maybe_unused int is_first_page(struct page *page)
+{
+ return PagePrivate(page);
+}
+
+/* Protected by class->lock */
+static inline int get_zspage_inuse(struct zspage *zspage)
+{
+ return zspage->inuse;
+}
+
+static inline void set_zspage_inuse(struct zspage *zspage, int val)
+{
+ zspage->inuse = val;
+}
+
+static inline void mod_zspage_inuse(struct zspage *zspage, int val)
+{
+ zspage->inuse += val;
+}
+
+static inline struct page *get_first_page(struct zspage *zspage)
+{
+ struct page *first_page = zspage->first_page;
+
+ VM_BUG_ON_PAGE(!is_first_page(first_page), first_page);
+ return first_page;
+}
+
+static inline int get_first_obj_offset(struct page *page)
+{
+ return page->units;
+}
+
+static inline void set_first_obj_offset(struct page *page, int offset)
+{
+ page->units = offset;
+}
+
+static inline unsigned int get_freeobj(struct zspage *zspage)
+{
+ return zspage->freeobj;
+}
+
+static inline void set_freeobj(struct zspage *zspage, unsigned int obj)
+{
+ zspage->freeobj = obj;
+}
+
+static void get_zspage_mapping(struct zspage *zspage,
+ unsigned int *class_idx,
+ enum fullness_group *fullness)
+{
+ BUG_ON(zspage->magic != ZSPAGE_MAGIC);
+
+ *fullness = zspage->fullness;
+ *class_idx = zspage->class;
+}
+
+static void set_zspage_mapping(struct zspage *zspage,
+ unsigned int class_idx,
+ enum fullness_group fullness)
+{
+ zspage->class = class_idx;
+ zspage->fullness = fullness;
+}
+
+/*
+ * 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_t(int, ZS_SIZE_CLASSES - 1, idx);
+}
+
+/* type can be of enum type zs_stat_type or fullness_group */
+static inline void zs_stat_inc(struct size_class *class,
+ int type, unsigned long cnt)
+{
+ class->stats.objs[type] += cnt;
+}
+
+/* type can be of enum type zs_stat_type or fullness_group */
+static inline void zs_stat_dec(struct size_class *class,
+ int type, unsigned long cnt)
+{
+ class->stats.objs[type] -= cnt;
+}
+
+/* type can be of enum type zs_stat_type or fullness_group */
+static inline unsigned long zs_stat_get(struct size_class *class,
+ int type)
+{
+ return class->stats.objs[type];
+}
+
+#ifdef CONFIG_ZSMALLOC_STAT
+
+static void __init zs_stat_init(void)
+{
+ if (!debugfs_initialized()) {
+ pr_warn("debugfs not available, stat dir not created\n");
+ return;
+ }
+
+ zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
+ if (!zs_stat_root)
+ pr_warn("debugfs 'zsmalloc' stat dir creation failed\n");
+}
+
+static void __exit zs_stat_exit(void)
+{
+ debugfs_remove_recursive(zs_stat_root);
+}
+
+static unsigned long zs_can_compact(struct size_class *class);
+
+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, freeable;
+ unsigned long total_class_almost_full = 0, total_class_almost_empty = 0;
+ unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
+ unsigned long total_freeable = 0;
+
+ seq_printf(s, " %5s %5s %11s %12s %13s %10s %10s %16s %8s\n",
+ "class", "size", "almost_full", "almost_empty",
+ "obj_allocated", "obj_used", "pages_used",
+ "pages_per_zspage", "freeable");
+
+ 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);
+ freeable = zs_can_compact(class);
+ spin_unlock(&class->lock);
+
+ objs_per_zspage = class->objs_per_zspage;
+ pages_used = obj_allocated / objs_per_zspage *
+ class->pages_per_zspage;
+
+ seq_printf(s, " %5u %5u %11lu %12lu %13lu"
+ " %10lu %10lu %16d %8lu\n",
+ i, class->size, class_almost_full, class_almost_empty,
+ obj_allocated, obj_used, pages_used,
+ class->pages_per_zspage, freeable);
+
+ 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;
+ total_freeable += freeable;
+ }
+
+ seq_puts(s, "\n");
+ seq_printf(s, " %5s %5s %11lu %12lu %13lu %10lu %10lu %16s %8lu\n",
+ "Total", "", total_class_almost_full,
+ total_class_almost_empty, total_objs,
+ total_used_objs, total_pages, "", total_freeable);
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(zs_stats_size);
+
+static void zs_pool_stat_create(struct zs_pool *pool, const char *name)
+{
+ struct dentry *entry;
+
+ if (!zs_stat_root) {
+ pr_warn("no root stat dir, not creating <%s> stat dir\n", name);
+ return;
+ }
+
+ entry = debugfs_create_dir(name, zs_stat_root);
+ if (!entry) {
+ pr_warn("debugfs dir <%s> creation failed\n", name);
+ return;
+ }
+ pool->stat_dentry = entry;
+
+ entry = debugfs_create_file("classes", S_IFREG | 0444,
+ pool->stat_dentry, pool,
+ &zs_stats_size_fops);
+ if (!entry) {
+ pr_warn("%s: debugfs file entry <%s> creation failed\n",
+ name, "classes");
+ debugfs_remove_recursive(pool->stat_dentry);
+ pool->stat_dentry = NULL;
+ }
+}
+
+static void zs_pool_stat_destroy(struct zs_pool *pool)
+{
+ debugfs_remove_recursive(pool->stat_dentry);
+}
+
+#else /* CONFIG_ZSMALLOC_STAT */
+static void __init zs_stat_init(void)
+{
+}
+
+static void __exit zs_stat_exit(void)
+{
+}
+
+static inline void zs_pool_stat_create(struct zs_pool *pool, const char *name)
+{
+}
+
+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 size_class *class,
+ struct zspage *zspage)
+{
+ int inuse, objs_per_zspage;
+ enum fullness_group fg;
+
+ inuse = get_zspage_inuse(zspage);
+ objs_per_zspage = class->objs_per_zspage;
+
+ if (inuse == 0)
+ fg = ZS_EMPTY;
+ else if (inuse == objs_per_zspage)
+ fg = ZS_FULL;
+ else if (inuse <= 3 * objs_per_zspage / 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 size_class *class,
+ struct zspage *zspage,
+ enum fullness_group fullness)
+{
+ struct zspage *head;
+
+ zs_stat_inc(class, fullness, 1);
+ head = list_first_entry_or_null(&class->fullness_list[fullness],
+ struct zspage, list);
+ /*
+ * We want to see more ZS_FULL pages and less almost empty/full.
+ * Put pages with higher ->inuse first.
+ */
+ if (head) {
+ if (get_zspage_inuse(zspage) < get_zspage_inuse(head)) {
+ list_add(&zspage->list, &head->list);
+ return;
+ }
+ }
+ list_add(&zspage->list, &class->fullness_list[fullness]);
+}
+
+/*
+ * This function removes the given zspage from the freelist identified
+ * by <class, fullness_group>.
+ */
+static void remove_zspage(struct size_class *class,
+ struct zspage *zspage,
+ enum fullness_group fullness)
+{
+ VM_BUG_ON(list_empty(&class->fullness_list[fullness]));
+ VM_BUG_ON(is_zspage_isolated(zspage));
+
+ list_del_init(&zspage->list);
+ zs_stat_dec(class, fullness, 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 zspage *zspage)
+{
+ int class_idx;
+ enum fullness_group currfg, newfg;
+
+ get_zspage_mapping(zspage, &class_idx, &currfg);
+ newfg = get_fullness_group(class, zspage);
+ if (newfg == currfg)
+ goto out;
+
+ if (!is_zspage_isolated(zspage)) {
+ remove_zspage(class, zspage, currfg);
+ insert_zspage(class, zspage, newfg);
+ }
+
+ set_zspage_mapping(zspage, 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;
+}
+
+static struct zspage *get_zspage(struct page *page)
+{
+ struct zspage *zspage = (struct zspage *)page->private;
+
+ BUG_ON(zspage->magic != ZSPAGE_MAGIC);
+ return zspage;
+}
+
+static struct page *get_next_page(struct page *page)
+{
+ if (unlikely(PageHugeObject(page)))
+ return NULL;
+
+ return page->freelist;
+}
+
+/**
+ * obj_to_location - get (<page>, <obj_idx>) from encoded object value
+ * @obj: the encoded object value
+ * @page: page object resides in zspage
+ * @obj_idx: object index
+ */
+static void obj_to_location(unsigned long obj, struct page **page,
+ unsigned int *obj_idx)
+{
+ obj >>= OBJ_TAG_BITS;
+ *page = pfn_to_page(obj >> OBJ_INDEX_BITS);
+ *obj_idx = (obj & OBJ_INDEX_MASK);
+}
+
+/**
+ * location_to_obj - get obj value encoded from (<page>, <obj_idx>)
+ * @page: page object resides in zspage
+ * @obj_idx: object index
+ */
+static unsigned long location_to_obj(struct page *page, unsigned int obj_idx)
+{
+ unsigned long obj;
+
+ obj = page_to_pfn(page) << OBJ_INDEX_BITS;
+ obj |= obj_idx & OBJ_INDEX_MASK;
+ obj <<= OBJ_TAG_BITS;
+
+ return obj;
+}
+
+static unsigned long handle_to_obj(unsigned long handle)
+{
+ return *(unsigned long *)handle;
+}
+
+static unsigned long obj_to_head(struct page *page, void *obj)
+{
+ if (unlikely(PageHugeObject(page))) {
+ VM_BUG_ON_PAGE(!is_first_page(page), page);
+ return page->index;
+ } else
+ return *(unsigned long *)obj;
+}
+
+static inline int testpin_tag(unsigned long handle)
+{
+ return bit_spin_is_locked(HANDLE_PIN_BIT, (unsigned long *)handle);
+}
+
+static inline int trypin_tag(unsigned long handle)
+{
+ return bit_spin_trylock(HANDLE_PIN_BIT, (unsigned long *)handle);
+}
+
+static void pin_tag(unsigned long handle)
+{
+ bit_spin_lock(HANDLE_PIN_BIT, (unsigned long *)handle);
+}
+
+static void unpin_tag(unsigned long handle)
+{
+ bit_spin_unlock(HANDLE_PIN_BIT, (unsigned long *)handle);
+}
+
+static void reset_page(struct page *page)
+{
+ __ClearPageMovable(page);
+ ClearPagePrivate(page);
+ set_page_private(page, 0);
+ page_mapcount_reset(page);
+ ClearPageHugeObject(page);
+ page->freelist = NULL;
+}
+
+static int trylock_zspage(struct zspage *zspage)
+{
+ struct page *cursor, *fail;
+
+ for (cursor = get_first_page(zspage); cursor != NULL; cursor =
+ get_next_page(cursor)) {
+ if (!trylock_page(cursor)) {
+ fail = cursor;
+ goto unlock;
+ }
+ }
+
+ return 1;
+unlock:
+ for (cursor = get_first_page(zspage); cursor != fail; cursor =
+ get_next_page(cursor))
+ unlock_page(cursor);
+
+ return 0;
+}
+
+static void __free_zspage(struct zs_pool *pool, struct size_class *class,
+ struct zspage *zspage)
+{
+ struct page *page, *next;
+ enum fullness_group fg;
+ unsigned int class_idx;
+
+ get_zspage_mapping(zspage, &class_idx, &fg);
+
+ assert_spin_locked(&class->lock);
+
+ VM_BUG_ON(get_zspage_inuse(zspage));
+ VM_BUG_ON(fg != ZS_EMPTY);
+
+ next = page = get_first_page(zspage);
+ do {
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ next = get_next_page(page);
+ reset_page(page);
+ unlock_page(page);
+ dec_zone_page_state(page, NR_ZSPAGES);
+ put_page(page);
+ page = next;
+ } while (page != NULL);
+
+ cache_free_zspage(pool, zspage);
+
+ zs_stat_dec(class, OBJ_ALLOCATED, class->objs_per_zspage);
+ atomic_long_sub(class->pages_per_zspage,
+ &pool->pages_allocated);
+}
+
+static void free_zspage(struct zs_pool *pool, struct size_class *class,
+ struct zspage *zspage)
+{
+ VM_BUG_ON(get_zspage_inuse(zspage));
+ VM_BUG_ON(list_empty(&zspage->list));
+
+ if (!trylock_zspage(zspage)) {
+ kick_deferred_free(pool);
+ return;
+ }
+
+ remove_zspage(class, zspage, ZS_EMPTY);
+ __free_zspage(pool, class, zspage);
+}
+
+/* Initialize a newly allocated zspage */
+static void init_zspage(struct size_class *class, struct zspage *zspage)
+{
+ unsigned int freeobj = 1;
+ unsigned long off = 0;
+ struct page *page = get_first_page(zspage);
+
+ while (page) {
+ struct page *next_page;
+ struct link_free *link;
+ void *vaddr;
+
+ set_first_obj_offset(page, off);
+
+ vaddr = kmap_atomic(page);
+ link = (struct link_free *)vaddr + off / sizeof(*link);
+
+ while ((off += class->size) < PAGE_SIZE) {
+ link->next = freeobj++ << OBJ_TAG_BITS;
+ 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);
+ if (next_page) {
+ link->next = freeobj++ << OBJ_TAG_BITS;
+ } else {
+ /*
+ * Reset OBJ_TAG_BITS bit to last link to tell
+ * whether it's allocated object or not.
+ */
+ link->next = -1UL << OBJ_TAG_BITS;
+ }
+ kunmap_atomic(vaddr);
+ page = next_page;
+ off %= PAGE_SIZE;
+ }
+
+ set_freeobj(zspage, 0);
+}
+
+static void create_page_chain(struct size_class *class, struct zspage *zspage,
+ struct page *pages[])
+{
+ int i;
+ struct page *page;
+ struct page *prev_page = NULL;
+ int nr_pages = class->pages_per_zspage;
+
+ /*
+ * Allocate individual pages and link them together as:
+ * 1. all pages are linked together using page->freelist
+ * 2. each sub-page point to zspage using page->private
+ *
+ * we set PG_private to identify the first page (i.e. no other sub-page
+ * has this flag set).
+ */
+ for (i = 0; i < nr_pages; i++) {
+ page = pages[i];
+ set_page_private(page, (unsigned long)zspage);
+ page->freelist = NULL;
+ if (i == 0) {
+ zspage->first_page = page;
+ SetPagePrivate(page);
+ if (unlikely(class->objs_per_zspage == 1 &&
+ class->pages_per_zspage == 1))
+ SetPageHugeObject(page);
+ } else {
+ prev_page->freelist = page;
+ }
+ prev_page = page;
+ }
+}
+
+/*
+ * Allocate a zspage for the given size class
+ */
+static struct zspage *alloc_zspage(struct zs_pool *pool,
+ struct size_class *class,
+ gfp_t gfp)
+{
+ int i;
+ struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE];
+ struct zspage *zspage = cache_alloc_zspage(pool, gfp);
+
+ if (!zspage)
+ return NULL;
+
+ memset(zspage, 0, sizeof(struct zspage));
+ zspage->magic = ZSPAGE_MAGIC;
+ migrate_lock_init(zspage);
+
+ for (i = 0; i < class->pages_per_zspage; i++) {
+ struct page *page;
+
+ page = alloc_page(gfp);
+ if (!page) {
+ while (--i >= 0) {
+ dec_zone_page_state(pages[i], NR_ZSPAGES);
+ __free_page(pages[i]);
+ }
+ cache_free_zspage(pool, zspage);
+ return NULL;
+ }
+
+ inc_zone_page_state(page, NR_ZSPAGES);
+ pages[i] = page;
+ }
+
+ create_page_chain(class, zspage, pages);
+ init_zspage(class, zspage);
+
+ return zspage;
+}
+
+static struct zspage *find_get_zspage(struct size_class *class)
+{
+ int i;
+ struct zspage *zspage;
+
+ for (i = ZS_ALMOST_FULL; i >= ZS_EMPTY; i--) {
+ zspage = list_first_entry_or_null(&class->fullness_list[i],
+ struct zspage, list);
+ if (zspage)
+ break;
+ }
+
+ return zspage;
+}
+
+#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;
+ 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_prepare(unsigned int cpu)
+{
+ struct mapping_area *area;
+
+ area = &per_cpu(zs_map_area, cpu);
+ return __zs_cpu_up(area);
+}
+
+static int zs_cpu_dead(unsigned int cpu)
+{
+ struct mapping_area *area;
+
+ area = &per_cpu(zs_map_area, cpu);
+ __zs_cpu_down(area);
+ return 0;
+}
+
+static bool can_merge(struct size_class *prev, int pages_per_zspage,
+ int objs_per_zspage)
+{
+ if (prev->pages_per_zspage == pages_per_zspage &&
+ prev->objs_per_zspage == objs_per_zspage)
+ return true;
+
+ return false;
+}
+
+static bool zspage_full(struct size_class *class, struct zspage *zspage)
+{
+ return get_zspage_inuse(zspage) == class->objs_per_zspage;
+}
+
+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
+ * @mm: maping mode to use
+ *
+ * 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 zspage *zspage;
+ struct page *page;
+ unsigned long obj, off;
+ unsigned int obj_idx;
+
+ unsigned int class_idx;
+ enum fullness_group fg;
+ struct size_class *class;
+ struct mapping_area *area;
+ struct page *pages[2];
+ void *ret;
+
+ /*
+ * 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);
+ zspage = get_zspage(page);
+
+ /* migration cannot move any subpage in this zspage */
+ migrate_read_lock(zspage);
+
+ get_zspage_mapping(zspage, &class_idx, &fg);
+ class = pool->size_class[class_idx];
+ off = (class->size * obj_idx) & ~PAGE_MASK;
+
+ 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 (likely(!PageHugeObject(page)))
+ ret += ZS_HANDLE_SIZE;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(zs_map_object);
+
+void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
+{
+ struct zspage *zspage;
+ struct page *page;
+ unsigned long obj, off;
+ unsigned int obj_idx;
+
+ unsigned int class_idx;
+ enum fullness_group fg;
+ struct size_class *class;
+ struct mapping_area *area;
+
+ obj = handle_to_obj(handle);
+ obj_to_location(obj, &page, &obj_idx);
+ zspage = get_zspage(page);
+ get_zspage_mapping(zspage, &class_idx, &fg);
+ class = pool->size_class[class_idx];
+ off = (class->size * obj_idx) & ~PAGE_MASK;
+
+ 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);
+
+ migrate_read_unlock(zspage);
+ unpin_tag(handle);
+}
+EXPORT_SYMBOL_GPL(zs_unmap_object);
+
+/**
+ * zs_huge_class_size() - Returns the size (in bytes) of the first huge
+ * zsmalloc &size_class.
+ * @pool: zsmalloc pool to use
+ *
+ * The function returns the size of the first huge class - any object of equal
+ * or bigger size will be stored in zspage consisting of a single physical
+ * page.
+ *
+ * Context: Any context.
+ *
+ * Return: the size (in bytes) of the first huge zsmalloc &size_class.
+ */
+size_t zs_huge_class_size(struct zs_pool *pool)
+{
+ return huge_class_size;
+}
+EXPORT_SYMBOL_GPL(zs_huge_class_size);
+
+static unsigned long obj_malloc(struct size_class *class,
+ struct zspage *zspage, unsigned long handle)
+{
+ int i, nr_page, offset;
+ unsigned long obj;
+ struct link_free *link;
+
+ struct page *m_page;
+ unsigned long m_offset;
+ void *vaddr;
+
+ handle |= OBJ_ALLOCATED_TAG;
+ obj = get_freeobj(zspage);
+
+ offset = obj * class->size;
+ nr_page = offset >> PAGE_SHIFT;
+ m_offset = offset & ~PAGE_MASK;
+ m_page = get_first_page(zspage);
+
+ for (i = 0; i < nr_page; i++)
+ m_page = get_next_page(m_page);
+
+ vaddr = kmap_atomic(m_page);
+ link = (struct link_free *)vaddr + m_offset / sizeof(*link);
+ set_freeobj(zspage, link->next >> OBJ_TAG_BITS);
+ if (likely(!PageHugeObject(m_page)))
+ /* record handle in the header of allocated chunk */
+ link->handle = handle;
+ else
+ /* record handle to page->index */
+ zspage->first_page->index = handle;
+
+ kunmap_atomic(vaddr);
+ mod_zspage_inuse(zspage, 1);
+ zs_stat_inc(class, OBJ_USED, 1);
+
+ obj = location_to_obj(m_page, obj);
+
+ return obj;
+}
+
+
+/**
+ * zs_malloc - Allocate block of given size from pool.
+ * @pool: pool to allocate from
+ * @size: size of block to allocate
+ * @gfp: gfp flags when allocating object
+ *
+ * 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, gfp_t gfp)
+{
+ unsigned long handle, obj;
+ struct size_class *class;
+ enum fullness_group newfg;
+ struct zspage *zspage;
+
+ if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
+ return 0;
+
+ handle = cache_alloc_handle(pool, gfp);
+ 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);
+ zspage = find_get_zspage(class);
+ if (likely(zspage)) {
+ obj = obj_malloc(class, zspage, handle);
+ /* Now move the zspage to another fullness group, if required */
+ fix_fullness_group(class, zspage);
+ record_obj(handle, obj);
+ spin_unlock(&class->lock);
+
+ return handle;
+ }
+
+ spin_unlock(&class->lock);
+
+ zspage = alloc_zspage(pool, class, gfp);
+ if (!zspage) {
+ cache_free_handle(pool, handle);
+ return 0;
+ }
+
+ spin_lock(&class->lock);
+ obj = obj_malloc(class, zspage, handle);
+ newfg = get_fullness_group(class, zspage);
+ insert_zspage(class, zspage, newfg);
+ set_zspage_mapping(zspage, class->index, newfg);
+ record_obj(handle, obj);
+ atomic_long_add(class->pages_per_zspage,
+ &pool->pages_allocated);
+ zs_stat_inc(class, OBJ_ALLOCATED, class->objs_per_zspage);
+
+ /* We completely set up zspage so mark them as movable */
+ SetZsPageMovable(pool, zspage);
+ spin_unlock(&class->lock);
+
+ return handle;
+}
+EXPORT_SYMBOL_GPL(zs_malloc);
+
+static void obj_free(struct size_class *class, unsigned long obj)
+{
+ struct link_free *link;
+ struct zspage *zspage;
+ struct page *f_page;
+ unsigned long f_offset;
+ unsigned int f_objidx;
+ void *vaddr;
+
+ obj &= ~OBJ_ALLOCATED_TAG;
+ obj_to_location(obj, &f_page, &f_objidx);
+ f_offset = (class->size * f_objidx) & ~PAGE_MASK;
+ zspage = get_zspage(f_page);
+
+ vaddr = kmap_atomic(f_page);
+
+ /* Insert this object in containing zspage's freelist */
+ link = (struct link_free *)(vaddr + f_offset);
+ link->next = get_freeobj(zspage) << OBJ_TAG_BITS;
+ kunmap_atomic(vaddr);
+ set_freeobj(zspage, f_objidx);
+ mod_zspage_inuse(zspage, -1);
+ zs_stat_dec(class, OBJ_USED, 1);
+}
+
+void zs_free(struct zs_pool *pool, unsigned long handle)
+{
+ struct zspage *zspage;
+ struct page *f_page;
+ unsigned long obj;
+ unsigned int f_objidx;
+ int class_idx;
+ struct size_class *class;
+ enum fullness_group fullness;
+ bool isolated;
+
+ if (unlikely(!handle))
+ return;
+
+ pin_tag(handle);
+ obj = handle_to_obj(handle);
+ obj_to_location(obj, &f_page, &f_objidx);
+ zspage = get_zspage(f_page);
+
+ migrate_read_lock(zspage);
+
+ get_zspage_mapping(zspage, &class_idx, &fullness);
+ class = pool->size_class[class_idx];
+
+ spin_lock(&class->lock);
+ obj_free(class, obj);
+ fullness = fix_fullness_group(class, zspage);
+ if (fullness != ZS_EMPTY) {
+ migrate_read_unlock(zspage);
+ goto out;
+ }
+
+ isolated = is_zspage_isolated(zspage);
+ migrate_read_unlock(zspage);
+ /* If zspage is isolated, zs_page_putback will free the zspage */
+ if (likely(!isolated))
+ free_zspage(pool, class, zspage);
+out:
+
+ spin_unlock(&class->lock);
+ unpin_tag(handle);
+ cache_free_handle(pool, handle);
+}
+EXPORT_SYMBOL_GPL(zs_free);
+
+static void zs_object_copy(struct size_class *class, unsigned long dst,
+ unsigned long src)
+{
+ struct page *s_page, *d_page;
+ unsigned int 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 = (class->size * s_objidx) & ~PAGE_MASK;
+ d_off = (class->size * d_objidx) & ~PAGE_MASK;
+
+ 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);
+ 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);
+ 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 size_class *class,
+ struct page *page, int *obj_idx)
+{
+ unsigned long head;
+ int offset = 0;
+ int index = *obj_idx;
+ unsigned long handle = 0;
+ void *addr = kmap_atomic(page);
+
+ offset = get_first_obj_offset(page);
+ offset += class->size * index;
+
+ while (offset < PAGE_SIZE) {
+ head = obj_to_head(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);
+
+ *obj_idx = index;
+
+ return handle;
+}
+
+struct zs_compact_control {
+ /* Source spage 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 obj_idx;
+};
+
+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;
+ int obj_idx = cc->obj_idx;
+ int ret = 0;
+
+ while (1) {
+ handle = find_alloced_obj(class, s_page, &obj_idx);
+ if (!handle) {
+ s_page = get_next_page(s_page);
+ if (!s_page)
+ break;
+ obj_idx = 0;
+ continue;
+ }
+
+ /* Stop if there is no more space */
+ if (zspage_full(class, get_zspage(d_page))) {
+ unpin_tag(handle);
+ ret = -ENOMEM;
+ break;
+ }
+
+ used_obj = handle_to_obj(handle);
+ free_obj = obj_malloc(class, get_zspage(d_page), handle);
+ zs_object_copy(class, free_obj, used_obj);
+ obj_idx++;
+ /*
+ * record_obj updates handle's value to free_obj and it will
+ * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which
+ * breaks synchronization using pin_tag(e,g, zs_free) so
+ * let's keep the lock bit.
+ */
+ free_obj |= BIT(HANDLE_PIN_BIT);
+ record_obj(handle, free_obj);
+ unpin_tag(handle);
+ obj_free(class, used_obj);
+ }
+
+ /* Remember last position in this iteration */
+ cc->s_page = s_page;
+ cc->obj_idx = obj_idx;
+
+ return ret;
+}
+
+static struct zspage *isolate_zspage(struct size_class *class, bool source)
+{
+ int i;
+ struct zspage *zspage;
+ enum fullness_group fg[2] = {ZS_ALMOST_EMPTY, ZS_ALMOST_FULL};
+
+ if (!source) {
+ fg[0] = ZS_ALMOST_FULL;
+ fg[1] = ZS_ALMOST_EMPTY;
+ }
+
+ for (i = 0; i < 2; i++) {
+ zspage = list_first_entry_or_null(&class->fullness_list[fg[i]],
+ struct zspage, list);
+ if (zspage) {
+ VM_BUG_ON(is_zspage_isolated(zspage));
+ remove_zspage(class, zspage, fg[i]);
+ return zspage;
+ }
+ }
+
+ return zspage;
+}
+
+/*
+ * putback_zspage - add @zspage into right class's fullness list
+ * @class: destination class
+ * @zspage: target page
+ *
+ * Return @zspage's fullness_group
+ */
+static enum fullness_group putback_zspage(struct size_class *class,
+ struct zspage *zspage)
+{
+ enum fullness_group fullness;
+
+ VM_BUG_ON(is_zspage_isolated(zspage));
+
+ fullness = get_fullness_group(class, zspage);
+ insert_zspage(class, zspage, fullness);
+ set_zspage_mapping(zspage, class->index, fullness);
+
+ return fullness;
+}
+
+#ifdef CONFIG_COMPACTION
+/*
+ * To prevent zspage destroy during migration, zspage freeing should
+ * hold locks of all pages in the zspage.
+ */
+static void lock_zspage(struct zspage *zspage)
+{
+ struct page *page = get_first_page(zspage);
+
+ do {
+ lock_page(page);
+ } while ((page = get_next_page(page)) != NULL);
+}
+
+static struct dentry *zs_mount(struct file_system_type *fs_type,
+ int flags, const char *dev_name, void *data)
+{
+ static const struct dentry_operations ops = {
+ .d_dname = simple_dname,
+ };
+
+ return mount_pseudo(fs_type, "zsmalloc:", NULL, &ops, ZSMALLOC_MAGIC);
+}
+
+static struct file_system_type zsmalloc_fs = {
+ .name = "zsmalloc",
+ .mount = zs_mount,
+ .kill_sb = kill_anon_super,
+};
+
+static int zsmalloc_mount(void)
+{
+ int ret = 0;
+
+ zsmalloc_mnt = kern_mount(&zsmalloc_fs);
+ if (IS_ERR(zsmalloc_mnt))
+ ret = PTR_ERR(zsmalloc_mnt);
+
+ return ret;
+}
+
+static void zsmalloc_unmount(void)
+{
+ kern_unmount(zsmalloc_mnt);
+}
+
+static void migrate_lock_init(struct zspage *zspage)
+{
+ rwlock_init(&zspage->lock);
+}
+
+static void migrate_read_lock(struct zspage *zspage)
+{
+ read_lock(&zspage->lock);
+}
+
+static void migrate_read_unlock(struct zspage *zspage)
+{
+ read_unlock(&zspage->lock);
+}
+
+static void migrate_write_lock(struct zspage *zspage)
+{
+ write_lock(&zspage->lock);
+}
+
+static void migrate_write_unlock(struct zspage *zspage)
+{
+ write_unlock(&zspage->lock);
+}
+
+/* Number of isolated subpage for *page migration* in this zspage */
+static void inc_zspage_isolation(struct zspage *zspage)
+{
+ zspage->isolated++;
+}
+
+static void dec_zspage_isolation(struct zspage *zspage)
+{
+ zspage->isolated--;
+}
+
+static void replace_sub_page(struct size_class *class, struct zspage *zspage,
+ struct page *newpage, struct page *oldpage)
+{
+ struct page *page;
+ struct page *pages[ZS_MAX_PAGES_PER_ZSPAGE] = {NULL, };
+ int idx = 0;
+
+ page = get_first_page(zspage);
+ do {
+ if (page == oldpage)
+ pages[idx] = newpage;
+ else
+ pages[idx] = page;
+ idx++;
+ } while ((page = get_next_page(page)) != NULL);
+
+ create_page_chain(class, zspage, pages);
+ set_first_obj_offset(newpage, get_first_obj_offset(oldpage));
+ if (unlikely(PageHugeObject(oldpage)))
+ newpage->index = oldpage->index;
+ __SetPageMovable(newpage, page_mapping(oldpage));
+}
+
+static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
+{
+ struct zs_pool *pool;
+ struct size_class *class;
+ int class_idx;
+ enum fullness_group fullness;
+ struct zspage *zspage;
+ struct address_space *mapping;
+
+ /*
+ * Page is locked so zspage couldn't be destroyed. For detail, look at
+ * lock_zspage in free_zspage.
+ */
+ VM_BUG_ON_PAGE(!PageMovable(page), page);
+ VM_BUG_ON_PAGE(PageIsolated(page), page);
+
+ zspage = get_zspage(page);
+
+ /*
+ * Without class lock, fullness could be stale while class_idx is okay
+ * because class_idx is constant unless page is freed so we should get
+ * fullness again under class lock.
+ */
+ get_zspage_mapping(zspage, &class_idx, &fullness);
+ mapping = page_mapping(page);
+ pool = mapping->private_data;
+ class = pool->size_class[class_idx];
+
+ spin_lock(&class->lock);
+ if (get_zspage_inuse(zspage) == 0) {
+ spin_unlock(&class->lock);
+ return false;
+ }
+
+ /* zspage is isolated for object migration */
+ if (list_empty(&zspage->list) && !is_zspage_isolated(zspage)) {
+ spin_unlock(&class->lock);
+ return false;
+ }
+
+ /*
+ * If this is first time isolation for the zspage, isolate zspage from
+ * size_class to prevent further object allocation from the zspage.
+ */
+ if (!list_empty(&zspage->list) && !is_zspage_isolated(zspage)) {
+ get_zspage_mapping(zspage, &class_idx, &fullness);
+ remove_zspage(class, zspage, fullness);
+ }
+
+ inc_zspage_isolation(zspage);
+ spin_unlock(&class->lock);
+
+ return true;
+}
+
+static int zs_page_migrate(struct address_space *mapping, struct page *newpage,
+ struct page *page, enum migrate_mode mode)
+{
+ struct zs_pool *pool;
+ struct size_class *class;
+ int class_idx;
+ enum fullness_group fullness;
+ struct zspage *zspage;
+ struct page *dummy;
+ void *s_addr, *d_addr, *addr;
+ int offset, pos;
+ unsigned long handle, head;
+ unsigned long old_obj, new_obj;
+ unsigned int obj_idx;
+ int ret = -EAGAIN;
+
+ /*
+ * We cannot support the _NO_COPY case here, because copy needs to
+ * happen under the zs lock, which does not work with
+ * MIGRATE_SYNC_NO_COPY workflow.
+ */
+ if (mode == MIGRATE_SYNC_NO_COPY)
+ return -EINVAL;
+
+ VM_BUG_ON_PAGE(!PageMovable(page), page);
+ VM_BUG_ON_PAGE(!PageIsolated(page), page);
+
+ zspage = get_zspage(page);
+
+ /* Concurrent compactor cannot migrate any subpage in zspage */
+ migrate_write_lock(zspage);
+ get_zspage_mapping(zspage, &class_idx, &fullness);
+ pool = mapping->private_data;
+ class = pool->size_class[class_idx];
+ offset = get_first_obj_offset(page);
+
+ spin_lock(&class->lock);
+ if (!get_zspage_inuse(zspage)) {
+ /*
+ * Set "offset" to end of the page so that every loops
+ * skips unnecessary object scanning.
+ */
+ offset = PAGE_SIZE;
+ }
+
+ pos = offset;
+ s_addr = kmap_atomic(page);
+ while (pos < PAGE_SIZE) {
+ head = obj_to_head(page, s_addr + pos);
+ if (head & OBJ_ALLOCATED_TAG) {
+ handle = head & ~OBJ_ALLOCATED_TAG;
+ if (!trypin_tag(handle))
+ goto unpin_objects;
+ }
+ pos += class->size;
+ }
+
+ /*
+ * Here, any user cannot access all objects in the zspage so let's move.
+ */
+ d_addr = kmap_atomic(newpage);
+ memcpy(d_addr, s_addr, PAGE_SIZE);
+ kunmap_atomic(d_addr);
+
+ for (addr = s_addr + offset; addr < s_addr + pos;
+ addr += class->size) {
+ head = obj_to_head(page, addr);
+ if (head & OBJ_ALLOCATED_TAG) {
+ handle = head & ~OBJ_ALLOCATED_TAG;
+ if (!testpin_tag(handle))
+ BUG();
+
+ old_obj = handle_to_obj(handle);
+ obj_to_location(old_obj, &dummy, &obj_idx);
+ new_obj = (unsigned long)location_to_obj(newpage,
+ obj_idx);
+ new_obj |= BIT(HANDLE_PIN_BIT);
+ record_obj(handle, new_obj);
+ }
+ }
+
+ replace_sub_page(class, zspage, newpage, page);
+ get_page(newpage);
+
+ dec_zspage_isolation(zspage);
+
+ /*
+ * Page migration is done so let's putback isolated zspage to
+ * the list if @page is final isolated subpage in the zspage.
+ */
+ if (!is_zspage_isolated(zspage))
+ putback_zspage(class, zspage);
+
+ reset_page(page);
+ put_page(page);
+ page = newpage;
+
+ ret = MIGRATEPAGE_SUCCESS;
+unpin_objects:
+ for (addr = s_addr + offset; addr < s_addr + pos;
+ addr += class->size) {
+ head = obj_to_head(page, addr);
+ if (head & OBJ_ALLOCATED_TAG) {
+ handle = head & ~OBJ_ALLOCATED_TAG;
+ if (!testpin_tag(handle))
+ BUG();
+ unpin_tag(handle);
+ }
+ }
+ kunmap_atomic(s_addr);
+ spin_unlock(&class->lock);
+ migrate_write_unlock(zspage);
+
+ return ret;
+}
+
+static void zs_page_putback(struct page *page)
+{
+ struct zs_pool *pool;
+ struct size_class *class;
+ int class_idx;
+ enum fullness_group fg;
+ struct address_space *mapping;
+ struct zspage *zspage;
+
+ VM_BUG_ON_PAGE(!PageMovable(page), page);
+ VM_BUG_ON_PAGE(!PageIsolated(page), page);
+
+ zspage = get_zspage(page);
+ get_zspage_mapping(zspage, &class_idx, &fg);
+ mapping = page_mapping(page);
+ pool = mapping->private_data;
+ class = pool->size_class[class_idx];
+
+ spin_lock(&class->lock);
+ dec_zspage_isolation(zspage);
+ if (!is_zspage_isolated(zspage)) {
+ fg = putback_zspage(class, zspage);
+ /*
+ * Due to page_lock, we cannot free zspage immediately
+ * so let's defer.
+ */
+ if (fg == ZS_EMPTY)
+ schedule_work(&pool->free_work);
+ }
+ spin_unlock(&class->lock);
+}
+
+static const struct address_space_operations zsmalloc_aops = {
+ .isolate_page = zs_page_isolate,
+ .migratepage = zs_page_migrate,
+ .putback_page = zs_page_putback,
+};
+
+static int zs_register_migration(struct zs_pool *pool)
+{
+ pool->inode = alloc_anon_inode(zsmalloc_mnt->mnt_sb);
+ if (IS_ERR(pool->inode)) {
+ pool->inode = NULL;
+ return 1;
+ }
+
+ pool->inode->i_mapping->private_data = pool;
+ pool->inode->i_mapping->a_ops = &zsmalloc_aops;
+ return 0;
+}
+
+static void zs_unregister_migration(struct zs_pool *pool)
+{
+ flush_work(&pool->free_work);
+ iput(pool->inode);
+}
+
+/*
+ * Caller should hold page_lock of all pages in the zspage
+ * In here, we cannot use zspage meta data.
+ */
+static void async_free_zspage(struct work_struct *work)
+{
+ int i;
+ struct size_class *class;
+ unsigned int class_idx;
+ enum fullness_group fullness;
+ struct zspage *zspage, *tmp;
+ LIST_HEAD(free_pages);
+ struct zs_pool *pool = container_of(work, struct zs_pool,
+ free_work);
+
+ for (i = 0; i < ZS_SIZE_CLASSES; i++) {
+ class = pool->size_class[i];
+ if (class->index != i)
+ continue;
+
+ spin_lock(&class->lock);
+ list_splice_init(&class->fullness_list[ZS_EMPTY], &free_pages);
+ spin_unlock(&class->lock);
+ }
+
+
+ list_for_each_entry_safe(zspage, tmp, &free_pages, list) {
+ list_del(&zspage->list);
+ lock_zspage(zspage);
+
+ get_zspage_mapping(zspage, &class_idx, &fullness);
+ VM_BUG_ON(fullness != ZS_EMPTY);
+ class = pool->size_class[class_idx];
+ spin_lock(&class->lock);
+ __free_zspage(pool, pool->size_class[class_idx], zspage);
+ spin_unlock(&class->lock);
+ }
+};
+
+static void kick_deferred_free(struct zs_pool *pool)
+{
+ schedule_work(&pool->free_work);
+}
+
+static void init_deferred_free(struct zs_pool *pool)
+{
+ INIT_WORK(&pool->free_work, async_free_zspage);
+}
+
+static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage)
+{
+ struct page *page = get_first_page(zspage);
+
+ do {
+ WARN_ON(!trylock_page(page));
+ __SetPageMovable(page, pool->inode->i_mapping);
+ unlock_page(page);
+ } while ((page = get_next_page(page)) != NULL);
+}
+#endif
+
+/*
+ *
+ * Based on the number of unused allocated objects calculate
+ * and return the number of pages that we can free.
+ */
+static unsigned long zs_can_compact(struct size_class *class)
+{
+ unsigned long obj_wasted;
+ unsigned long obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
+ unsigned long obj_used = zs_stat_get(class, OBJ_USED);
+
+ if (obj_allocated <= obj_used)
+ return 0;
+
+ obj_wasted = obj_allocated - obj_used;
+ obj_wasted /= class->objs_per_zspage;
+
+ return obj_wasted * class->pages_per_zspage;
+}
+
+static void __zs_compact(struct zs_pool *pool, struct size_class *class)
+{
+ struct zs_compact_control cc;
+ struct zspage *src_zspage;
+ struct zspage *dst_zspage = NULL;
+
+ spin_lock(&class->lock);
+ while ((src_zspage = isolate_zspage(class, true))) {
+
+ if (!zs_can_compact(class))
+ break;
+
+ cc.obj_idx = 0;
+ cc.s_page = get_first_page(src_zspage);
+
+ while ((dst_zspage = isolate_zspage(class, false))) {
+ cc.d_page = get_first_page(dst_zspage);
+ /*
+ * If there is no more space in dst_page, resched
+ * and see if anyone had allocated another zspage.
+ */
+ if (!migrate_zspage(pool, class, &cc))
+ break;
+
+ putback_zspage(class, dst_zspage);
+ }
+
+ /* Stop if we couldn't find slot */
+ if (dst_zspage == NULL)
+ break;
+
+ putback_zspage(class, dst_zspage);
+ if (putback_zspage(class, src_zspage) == ZS_EMPTY) {
+ free_zspage(pool, class, src_zspage);
+ pool->stats.pages_compacted += class->pages_per_zspage;
+ }
+ spin_unlock(&class->lock);
+ cond_resched();
+ spin_lock(&class->lock);
+ }
+
+ if (src_zspage)
+ putback_zspage(class, src_zspage);
+
+ spin_unlock(&class->lock);
+}
+
+unsigned long zs_compact(struct zs_pool *pool)
+{
+ int i;
+ struct size_class *class;
+
+ for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
+ class = pool->size_class[i];
+ if (!class)
+ continue;
+ if (class->index != i)
+ continue;
+ __zs_compact(pool, class);
+ }
+
+ return pool->stats.pages_compacted;
+}
+EXPORT_SYMBOL_GPL(zs_compact);
+
+void zs_pool_stats(struct zs_pool *pool, struct zs_pool_stats *stats)
+{
+ memcpy(stats, &pool->stats, sizeof(struct zs_pool_stats));
+}
+EXPORT_SYMBOL_GPL(zs_pool_stats);
+
+static unsigned long zs_shrinker_scan(struct shrinker *shrinker,
+ struct shrink_control *sc)
+{
+ unsigned long pages_freed;
+ struct zs_pool *pool = container_of(shrinker, struct zs_pool,
+ shrinker);
+
+ pages_freed = pool->stats.pages_compacted;
+ /*
+ * Compact classes and calculate compaction delta.
+ * Can run concurrently with a manually triggered
+ * (by user) compaction.
+ */
+ pages_freed = zs_compact(pool) - pages_freed;
+
+ return pages_freed ? pages_freed : SHRINK_STOP;
+}
+
+static unsigned long zs_shrinker_count(struct shrinker *shrinker,
+ struct shrink_control *sc)
+{
+ int i;
+ struct size_class *class;
+ unsigned long pages_to_free = 0;
+ struct zs_pool *pool = container_of(shrinker, struct zs_pool,
+ shrinker);
+
+ for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
+ class = pool->size_class[i];
+ if (!class)
+ continue;
+ if (class->index != i)
+ continue;
+
+ pages_to_free += zs_can_compact(class);
+ }
+
+ return pages_to_free;
+}
+
+static void zs_unregister_shrinker(struct zs_pool *pool)
+{
+ unregister_shrinker(&pool->shrinker);
+}
+
+static int zs_register_shrinker(struct zs_pool *pool)
+{
+ pool->shrinker.scan_objects = zs_shrinker_scan;
+ pool->shrinker.count_objects = zs_shrinker_count;
+ pool->shrinker.batch = 0;
+ pool->shrinker.seeks = DEFAULT_SEEKS;
+
+ return register_shrinker(&pool->shrinker);
+}
+
+/**
+ * zs_create_pool - Creates an allocation pool to work from.
+ * @name: pool name to be created
+ *
+ * This function must be called before anything when using
+ * the zsmalloc allocator.
+ *
+ * On success, a pointer to the newly created pool is returned,
+ * otherwise NULL.
+ */
+struct zs_pool *zs_create_pool(const char *name)
+{
+ int i;
+ struct zs_pool *pool;
+ struct size_class *prev_class = NULL;
+
+ pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+ if (!pool)
+ return NULL;
+
+ init_deferred_free(pool);
+
+ pool->name = kstrdup(name, GFP_KERNEL);
+ if (!pool->name)
+ goto err;
+
+ if (create_cache(pool))
+ goto err;
+
+ /*
+ * Iterate reversely, 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;
+ int objs_per_zspage;
+ struct size_class *class;
+ int fullness = 0;
+
+ 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);
+ objs_per_zspage = pages_per_zspage * PAGE_SIZE / size;
+
+ /*
+ * We iterate from biggest down to smallest classes,
+ * so huge_class_size holds the size of the first huge
+ * class. Any object bigger than or equal to that will
+ * endup in the huge class.
+ */
+ if (pages_per_zspage != 1 && objs_per_zspage != 1 &&
+ !huge_class_size) {
+ huge_class_size = size;
+ /*
+ * The object uses ZS_HANDLE_SIZE bytes to store the
+ * handle. We need to subtract it, because zs_malloc()
+ * unconditionally adds handle size before it performs
+ * size class search - so object may be smaller than
+ * huge class size, yet it still can end up in the huge
+ * class because it grows by ZS_HANDLE_SIZE extra bytes
+ * right before class lookup.
+ */
+ huge_class_size -= (ZS_HANDLE_SIZE - 1);
+ }
+
+ /*
+ * 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, pages_per_zspage, objs_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;
+ class->objs_per_zspage = objs_per_zspage;
+ spin_lock_init(&class->lock);
+ pool->size_class[i] = class;
+ for (fullness = ZS_EMPTY; fullness < NR_ZS_FULLNESS;
+ fullness++)
+ INIT_LIST_HEAD(&class->fullness_list[fullness]);
+
+ prev_class = class;
+ }
+
+ /* debug only, don't abort if it fails */
+ zs_pool_stat_create(pool, name);
+
+ if (zs_register_migration(pool))
+ goto err;
+
+ /*
+ * Not critical since shrinker is only used to trigger internal
+ * defragmentation of the pool which is pretty optional thing. If
+ * registration fails we still can use the pool normally and user can
+ * trigger compaction manually. Thus, ignore return code.
+ */
+ zs_register_shrinker(pool);
+
+ return pool;
+
+err:
+ zs_destroy_pool(pool);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(zs_create_pool);
+
+void zs_destroy_pool(struct zs_pool *pool)
+{
+ int i;
+
+ zs_unregister_shrinker(pool);
+ zs_unregister_migration(pool);
+ zs_pool_stat_destroy(pool);
+
+ for (i = 0; i < ZS_SIZE_CLASSES; i++) {
+ int fg;
+ struct size_class *class = pool->size_class[i];
+
+ if (!class)
+ continue;
+
+ if (class->index != i)
+ continue;
+
+ for (fg = ZS_EMPTY; fg < NR_ZS_FULLNESS; fg++) {
+ if (!list_empty(&class->fullness_list[fg])) {
+ pr_info("Freeing non-empty class with size %db, fullness group %d\n",
+ class->size, fg);
+ }
+ }
+ kfree(class);
+ }
+
+ destroy_cache(pool);
+ kfree(pool->name);
+ kfree(pool);
+}
+EXPORT_SYMBOL_GPL(zs_destroy_pool);
+
+static int __init zs_init(void)
+{
+ int ret;
+
+ ret = zsmalloc_mount();
+ if (ret)
+ goto out;
+
+ ret = cpuhp_setup_state(CPUHP_MM_ZS_PREPARE, "mm/zsmalloc:prepare",
+ zs_cpu_prepare, zs_cpu_dead);
+ if (ret)
+ goto hp_setup_fail;
+
+#ifdef CONFIG_ZPOOL
+ zpool_register_driver(&zs_zpool_driver);
+#endif
+
+ zs_stat_init();
+
+ return 0;
+
+hp_setup_fail:
+ zsmalloc_unmount();
+out:
+ return ret;
+}
+
+static void __exit zs_exit(void)
+{
+#ifdef CONFIG_ZPOOL
+ zpool_unregister_driver(&zs_zpool_driver);
+#endif
+ zsmalloc_unmount();
+ cpuhp_remove_state(CPUHP_MM_ZS_PREPARE);
+
+ zs_stat_exit();
+}
+
+module_init(zs_init);
+module_exit(zs_exit);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");