diff options
Diffstat (limited to 'mm/zswap.c')
| -rw-r--r-- | mm/zswap.c | 1647 |
1 files changed, 1647 insertions, 0 deletions
diff --git a/mm/zswap.c b/mm/zswap.c new file mode 100644 index 0000000000..37d2b1cb2e --- /dev/null +++ b/mm/zswap.c @@ -0,0 +1,1647 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * zswap.c - zswap driver file + * + * zswap is a cache that takes pages that are in the process + * of being swapped out and attempts to compress and store them in a + * RAM-based memory pool. This can result in a significant I/O reduction on + * the swap device and, in the case where decompressing from RAM is faster + * than reading from the swap device, can also improve workload performance. + * + * Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com> +*/ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/cpu.h> +#include <linux/highmem.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/types.h> +#include <linux/atomic.h> +#include <linux/rbtree.h> +#include <linux/swap.h> +#include <linux/crypto.h> +#include <linux/scatterlist.h> +#include <linux/mempool.h> +#include <linux/zpool.h> +#include <crypto/acompress.h> +#include <linux/zswap.h> +#include <linux/mm_types.h> +#include <linux/page-flags.h> +#include <linux/swapops.h> +#include <linux/writeback.h> +#include <linux/pagemap.h> +#include <linux/workqueue.h> + +#include "swap.h" +#include "internal.h" + +/********************************* +* statistics +**********************************/ +/* Total bytes used by the compressed storage */ +u64 zswap_pool_total_size; +/* The number of compressed pages currently stored in zswap */ +atomic_t zswap_stored_pages = ATOMIC_INIT(0); +/* The number of same-value filled pages currently stored in zswap */ +static atomic_t zswap_same_filled_pages = ATOMIC_INIT(0); + +/* + * The statistics below are not protected from concurrent access for + * performance reasons so they may not be a 100% accurate. However, + * they do provide useful information on roughly how many times a + * certain event is occurring. +*/ + +/* Pool limit was hit (see zswap_max_pool_percent) */ +static u64 zswap_pool_limit_hit; +/* Pages written back when pool limit was reached */ +static u64 zswap_written_back_pages; +/* Store failed due to a reclaim failure after pool limit was reached */ +static u64 zswap_reject_reclaim_fail; +/* Compressed page was too big for the allocator to (optimally) store */ +static u64 zswap_reject_compress_poor; +/* Store failed because underlying allocator could not get memory */ +static u64 zswap_reject_alloc_fail; +/* Store failed because the entry metadata could not be allocated (rare) */ +static u64 zswap_reject_kmemcache_fail; +/* Duplicate store was encountered (rare) */ +static u64 zswap_duplicate_entry; + +/* Shrinker work queue */ +static struct workqueue_struct *shrink_wq; +/* Pool limit was hit, we need to calm down */ +static bool zswap_pool_reached_full; + +/********************************* +* tunables +**********************************/ + +#define ZSWAP_PARAM_UNSET "" + +static int zswap_setup(void); + +/* Enable/disable zswap */ +static bool zswap_enabled = IS_ENABLED(CONFIG_ZSWAP_DEFAULT_ON); +static int zswap_enabled_param_set(const char *, + const struct kernel_param *); +static const struct kernel_param_ops zswap_enabled_param_ops = { + .set = zswap_enabled_param_set, + .get = param_get_bool, +}; +module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644); + +/* Crypto compressor to use */ +static char *zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT; +static int zswap_compressor_param_set(const char *, + const struct kernel_param *); +static const struct kernel_param_ops zswap_compressor_param_ops = { + .set = zswap_compressor_param_set, + .get = param_get_charp, + .free = param_free_charp, +}; +module_param_cb(compressor, &zswap_compressor_param_ops, + &zswap_compressor, 0644); + +/* Compressed storage zpool to use */ +static char *zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT; +static int zswap_zpool_param_set(const char *, const struct kernel_param *); +static const struct kernel_param_ops zswap_zpool_param_ops = { + .set = zswap_zpool_param_set, + .get = param_get_charp, + .free = param_free_charp, +}; +module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_type, 0644); + +/* The maximum percentage of memory that the compressed pool can occupy */ +static unsigned int zswap_max_pool_percent = 20; +module_param_named(max_pool_percent, zswap_max_pool_percent, uint, 0644); + +/* The threshold for accepting new pages after the max_pool_percent was hit */ +static unsigned int zswap_accept_thr_percent = 90; /* of max pool size */ +module_param_named(accept_threshold_percent, zswap_accept_thr_percent, + uint, 0644); + +/* + * Enable/disable handling same-value filled pages (enabled by default). + * If disabled every page is considered non-same-value filled. + */ +static bool zswap_same_filled_pages_enabled = true; +module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled, + bool, 0644); + +/* Enable/disable handling non-same-value filled pages (enabled by default) */ +static bool zswap_non_same_filled_pages_enabled = true; +module_param_named(non_same_filled_pages_enabled, zswap_non_same_filled_pages_enabled, + bool, 0644); + +static bool zswap_exclusive_loads_enabled = IS_ENABLED( + CONFIG_ZSWAP_EXCLUSIVE_LOADS_DEFAULT_ON); +module_param_named(exclusive_loads, zswap_exclusive_loads_enabled, bool, 0644); + +/* Number of zpools in zswap_pool (empirically determined for scalability) */ +#define ZSWAP_NR_ZPOOLS 32 + +/********************************* +* data structures +**********************************/ + +struct crypto_acomp_ctx { + struct crypto_acomp *acomp; + struct acomp_req *req; + struct crypto_wait wait; + u8 *dstmem; + struct mutex *mutex; +}; + +/* + * The lock ordering is zswap_tree.lock -> zswap_pool.lru_lock. + * The only case where lru_lock is not acquired while holding tree.lock is + * when a zswap_entry is taken off the lru for writeback, in that case it + * needs to be verified that it's still valid in the tree. + */ +struct zswap_pool { + struct zpool *zpools[ZSWAP_NR_ZPOOLS]; + struct crypto_acomp_ctx __percpu *acomp_ctx; + struct kref kref; + struct list_head list; + struct work_struct release_work; + struct work_struct shrink_work; + struct hlist_node node; + char tfm_name[CRYPTO_MAX_ALG_NAME]; + struct list_head lru; + spinlock_t lru_lock; +}; + +/* + * struct zswap_entry + * + * This structure contains the metadata for tracking a single compressed + * page within zswap. + * + * rbnode - links the entry into red-black tree for the appropriate swap type + * swpentry - associated swap entry, the offset indexes into the red-black tree + * refcount - the number of outstanding reference to the entry. This is needed + * to protect against premature freeing of the entry by code + * concurrent calls to load, invalidate, and writeback. The lock + * for the zswap_tree structure that contains the entry must + * be held while changing the refcount. Since the lock must + * be held, there is no reason to also make refcount atomic. + * length - the length in bytes of the compressed page data. Needed during + * decompression. For a same value filled page length is 0, and both + * pool and lru are invalid and must be ignored. + * pool - the zswap_pool the entry's data is in + * handle - zpool allocation handle that stores the compressed page data + * value - value of the same-value filled pages which have same content + * objcg - the obj_cgroup that the compressed memory is charged to + * lru - handle to the pool's lru used to evict pages. + */ +struct zswap_entry { + struct rb_node rbnode; + swp_entry_t swpentry; + int refcount; + unsigned int length; + struct zswap_pool *pool; + union { + unsigned long handle; + unsigned long value; + }; + struct obj_cgroup *objcg; + struct list_head lru; +}; + +/* + * The tree lock in the zswap_tree struct protects a few things: + * - the rbtree + * - the refcount field of each entry in the tree + */ +struct zswap_tree { + struct rb_root rbroot; + spinlock_t lock; +}; + +static struct zswap_tree *zswap_trees[MAX_SWAPFILES]; + +/* RCU-protected iteration */ +static LIST_HEAD(zswap_pools); +/* protects zswap_pools list modification */ +static DEFINE_SPINLOCK(zswap_pools_lock); +/* pool counter to provide unique names to zpool */ +static atomic_t zswap_pools_count = ATOMIC_INIT(0); + +enum zswap_init_type { + ZSWAP_UNINIT, + ZSWAP_INIT_SUCCEED, + ZSWAP_INIT_FAILED +}; + +static enum zswap_init_type zswap_init_state; + +/* used to ensure the integrity of initialization */ +static DEFINE_MUTEX(zswap_init_lock); + +/* init completed, but couldn't create the initial pool */ +static bool zswap_has_pool; + +/********************************* +* helpers and fwd declarations +**********************************/ + +#define zswap_pool_debug(msg, p) \ + pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name, \ + zpool_get_type((p)->zpools[0])) + +static int zswap_writeback_entry(struct zswap_entry *entry, + struct zswap_tree *tree); +static int zswap_pool_get(struct zswap_pool *pool); +static void zswap_pool_put(struct zswap_pool *pool); + +static bool zswap_is_full(void) +{ + return totalram_pages() * zswap_max_pool_percent / 100 < + DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE); +} + +static bool zswap_can_accept(void) +{ + return totalram_pages() * zswap_accept_thr_percent / 100 * + zswap_max_pool_percent / 100 > + DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE); +} + +static void zswap_update_total_size(void) +{ + struct zswap_pool *pool; + u64 total = 0; + int i; + + rcu_read_lock(); + + list_for_each_entry_rcu(pool, &zswap_pools, list) + for (i = 0; i < ZSWAP_NR_ZPOOLS; i++) + total += zpool_get_total_size(pool->zpools[i]); + + rcu_read_unlock(); + + zswap_pool_total_size = total; +} + +/********************************* +* zswap entry functions +**********************************/ +static struct kmem_cache *zswap_entry_cache; + +static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp) +{ + struct zswap_entry *entry; + entry = kmem_cache_alloc(zswap_entry_cache, gfp); + if (!entry) + return NULL; + entry->refcount = 1; + RB_CLEAR_NODE(&entry->rbnode); + return entry; +} + +static void zswap_entry_cache_free(struct zswap_entry *entry) +{ + kmem_cache_free(zswap_entry_cache, entry); +} + +/********************************* +* rbtree functions +**********************************/ +static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset) +{ + struct rb_node *node = root->rb_node; + struct zswap_entry *entry; + pgoff_t entry_offset; + + while (node) { + entry = rb_entry(node, struct zswap_entry, rbnode); + entry_offset = swp_offset(entry->swpentry); + if (entry_offset > offset) + node = node->rb_left; + else if (entry_offset < offset) + node = node->rb_right; + else + return entry; + } + return NULL; +} + +/* + * In the case that a entry with the same offset is found, a pointer to + * the existing entry is stored in dupentry and the function returns -EEXIST + */ +static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry, + struct zswap_entry **dupentry) +{ + struct rb_node **link = &root->rb_node, *parent = NULL; + struct zswap_entry *myentry; + pgoff_t myentry_offset, entry_offset = swp_offset(entry->swpentry); + + while (*link) { + parent = *link; + myentry = rb_entry(parent, struct zswap_entry, rbnode); + myentry_offset = swp_offset(myentry->swpentry); + if (myentry_offset > entry_offset) + link = &(*link)->rb_left; + else if (myentry_offset < entry_offset) + link = &(*link)->rb_right; + else { + *dupentry = myentry; + return -EEXIST; + } + } + rb_link_node(&entry->rbnode, parent, link); + rb_insert_color(&entry->rbnode, root); + return 0; +} + +static bool zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry) +{ + if (!RB_EMPTY_NODE(&entry->rbnode)) { + rb_erase(&entry->rbnode, root); + RB_CLEAR_NODE(&entry->rbnode); + return true; + } + return false; +} + +static struct zpool *zswap_find_zpool(struct zswap_entry *entry) +{ + int i = 0; + + if (ZSWAP_NR_ZPOOLS > 1) + i = hash_ptr(entry, ilog2(ZSWAP_NR_ZPOOLS)); + + return entry->pool->zpools[i]; +} + +/* + * Carries out the common pattern of freeing and entry's zpool allocation, + * freeing the entry itself, and decrementing the number of stored pages. + */ +static void zswap_free_entry(struct zswap_entry *entry) +{ + if (entry->objcg) { + obj_cgroup_uncharge_zswap(entry->objcg, entry->length); + obj_cgroup_put(entry->objcg); + } + if (!entry->length) + atomic_dec(&zswap_same_filled_pages); + else { + spin_lock(&entry->pool->lru_lock); + list_del(&entry->lru); + spin_unlock(&entry->pool->lru_lock); + zpool_free(zswap_find_zpool(entry), entry->handle); + zswap_pool_put(entry->pool); + } + zswap_entry_cache_free(entry); + atomic_dec(&zswap_stored_pages); + zswap_update_total_size(); +} + +/* caller must hold the tree lock */ +static void zswap_entry_get(struct zswap_entry *entry) +{ + entry->refcount++; +} + +/* caller must hold the tree lock +* remove from the tree and free it, if nobody reference the entry +*/ +static void zswap_entry_put(struct zswap_tree *tree, + struct zswap_entry *entry) +{ + int refcount = --entry->refcount; + + WARN_ON_ONCE(refcount < 0); + if (refcount == 0) { + WARN_ON_ONCE(!RB_EMPTY_NODE(&entry->rbnode)); + zswap_free_entry(entry); + } +} + +/* caller must hold the tree lock */ +static struct zswap_entry *zswap_entry_find_get(struct rb_root *root, + pgoff_t offset) +{ + struct zswap_entry *entry; + + entry = zswap_rb_search(root, offset); + if (entry) + zswap_entry_get(entry); + + return entry; +} + +/********************************* +* per-cpu code +**********************************/ +static DEFINE_PER_CPU(u8 *, zswap_dstmem); +/* + * If users dynamically change the zpool type and compressor at runtime, i.e. + * zswap is running, zswap can have more than one zpool on one cpu, but they + * are sharing dtsmem. So we need this mutex to be per-cpu. + */ +static DEFINE_PER_CPU(struct mutex *, zswap_mutex); + +static int zswap_dstmem_prepare(unsigned int cpu) +{ + struct mutex *mutex; + u8 *dst; + + dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu)); + if (!dst) + return -ENOMEM; + + mutex = kmalloc_node(sizeof(*mutex), GFP_KERNEL, cpu_to_node(cpu)); + if (!mutex) { + kfree(dst); + return -ENOMEM; + } + + mutex_init(mutex); + per_cpu(zswap_dstmem, cpu) = dst; + per_cpu(zswap_mutex, cpu) = mutex; + return 0; +} + +static int zswap_dstmem_dead(unsigned int cpu) +{ + struct mutex *mutex; + u8 *dst; + + mutex = per_cpu(zswap_mutex, cpu); + kfree(mutex); + per_cpu(zswap_mutex, cpu) = NULL; + + dst = per_cpu(zswap_dstmem, cpu); + kfree(dst); + per_cpu(zswap_dstmem, cpu) = NULL; + + return 0; +} + +static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node) +{ + struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); + struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu); + struct crypto_acomp *acomp; + struct acomp_req *req; + + acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu)); + if (IS_ERR(acomp)) { + pr_err("could not alloc crypto acomp %s : %ld\n", + pool->tfm_name, PTR_ERR(acomp)); + return PTR_ERR(acomp); + } + acomp_ctx->acomp = acomp; + + req = acomp_request_alloc(acomp_ctx->acomp); + if (!req) { + pr_err("could not alloc crypto acomp_request %s\n", + pool->tfm_name); + crypto_free_acomp(acomp_ctx->acomp); + return -ENOMEM; + } + acomp_ctx->req = req; + + crypto_init_wait(&acomp_ctx->wait); + /* + * if the backend of acomp is async zip, crypto_req_done() will wakeup + * crypto_wait_req(); if the backend of acomp is scomp, the callback + * won't be called, crypto_wait_req() will return without blocking. + */ + acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, + crypto_req_done, &acomp_ctx->wait); + + acomp_ctx->mutex = per_cpu(zswap_mutex, cpu); + acomp_ctx->dstmem = per_cpu(zswap_dstmem, cpu); + + return 0; +} + +static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node) +{ + struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node); + struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu); + + if (!IS_ERR_OR_NULL(acomp_ctx)) { + if (!IS_ERR_OR_NULL(acomp_ctx->req)) + acomp_request_free(acomp_ctx->req); + if (!IS_ERR_OR_NULL(acomp_ctx->acomp)) + crypto_free_acomp(acomp_ctx->acomp); + } + + return 0; +} + +/********************************* +* pool functions +**********************************/ + +static struct zswap_pool *__zswap_pool_current(void) +{ + struct zswap_pool *pool; + + pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list); + WARN_ONCE(!pool && zswap_has_pool, + "%s: no page storage pool!\n", __func__); + + return pool; +} + +static struct zswap_pool *zswap_pool_current(void) +{ + assert_spin_locked(&zswap_pools_lock); + + return __zswap_pool_current(); +} + +static struct zswap_pool *zswap_pool_current_get(void) +{ + struct zswap_pool *pool; + + rcu_read_lock(); + + pool = __zswap_pool_current(); + if (!zswap_pool_get(pool)) + pool = NULL; + + rcu_read_unlock(); + + return pool; +} + +static struct zswap_pool *zswap_pool_last_get(void) +{ + struct zswap_pool *pool, *last = NULL; + + rcu_read_lock(); + + list_for_each_entry_rcu(pool, &zswap_pools, list) + last = pool; + WARN_ONCE(!last && zswap_has_pool, + "%s: no page storage pool!\n", __func__); + if (!zswap_pool_get(last)) + last = NULL; + + rcu_read_unlock(); + + return last; +} + +/* type and compressor must be null-terminated */ +static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor) +{ + struct zswap_pool *pool; + + assert_spin_locked(&zswap_pools_lock); + + list_for_each_entry_rcu(pool, &zswap_pools, list) { + if (strcmp(pool->tfm_name, compressor)) + continue; + /* all zpools share the same type */ + if (strcmp(zpool_get_type(pool->zpools[0]), type)) + continue; + /* if we can't get it, it's about to be destroyed */ + if (!zswap_pool_get(pool)) + continue; + return pool; + } + + return NULL; +} + +/* + * If the entry is still valid in the tree, drop the initial ref and remove it + * from the tree. This function must be called with an additional ref held, + * otherwise it may race with another invalidation freeing the entry. + */ +static void zswap_invalidate_entry(struct zswap_tree *tree, + struct zswap_entry *entry) +{ + if (zswap_rb_erase(&tree->rbroot, entry)) + zswap_entry_put(tree, entry); +} + +static int zswap_reclaim_entry(struct zswap_pool *pool) +{ + struct zswap_entry *entry; + struct zswap_tree *tree; + pgoff_t swpoffset; + int ret; + + /* Get an entry off the LRU */ + spin_lock(&pool->lru_lock); + if (list_empty(&pool->lru)) { + spin_unlock(&pool->lru_lock); + return -EINVAL; + } + entry = list_last_entry(&pool->lru, struct zswap_entry, lru); + list_del_init(&entry->lru); + /* + * Once the lru lock is dropped, the entry might get freed. The + * swpoffset is copied to the stack, and entry isn't deref'd again + * until the entry is verified to still be alive in the tree. + */ + swpoffset = swp_offset(entry->swpentry); + tree = zswap_trees[swp_type(entry->swpentry)]; + spin_unlock(&pool->lru_lock); + + /* Check for invalidate() race */ + spin_lock(&tree->lock); + if (entry != zswap_rb_search(&tree->rbroot, swpoffset)) { + ret = -EAGAIN; + goto unlock; + } + /* Hold a reference to prevent a free during writeback */ + zswap_entry_get(entry); + spin_unlock(&tree->lock); + + ret = zswap_writeback_entry(entry, tree); + + spin_lock(&tree->lock); + if (ret) { + /* Writeback failed, put entry back on LRU */ + spin_lock(&pool->lru_lock); + list_move(&entry->lru, &pool->lru); + spin_unlock(&pool->lru_lock); + goto put_unlock; + } + + /* + * Writeback started successfully, the page now belongs to the + * swapcache. Drop the entry from zswap - unless invalidate already + * took it out while we had the tree->lock released for IO. + */ + zswap_invalidate_entry(tree, entry); + +put_unlock: + /* Drop local reference */ + zswap_entry_put(tree, entry); +unlock: + spin_unlock(&tree->lock); + return ret ? -EAGAIN : 0; +} + +static void shrink_worker(struct work_struct *w) +{ + struct zswap_pool *pool = container_of(w, typeof(*pool), + shrink_work); + int ret, failures = 0; + + do { + ret = zswap_reclaim_entry(pool); + if (ret) { + zswap_reject_reclaim_fail++; + if (ret != -EAGAIN) + break; + if (++failures == MAX_RECLAIM_RETRIES) + break; + } + cond_resched(); + } while (!zswap_can_accept()); + zswap_pool_put(pool); +} + +static struct zswap_pool *zswap_pool_create(char *type, char *compressor) +{ + int i; + struct zswap_pool *pool; + char name[38]; /* 'zswap' + 32 char (max) num + \0 */ + gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM; + int ret; + + if (!zswap_has_pool) { + /* if either are unset, pool initialization failed, and we + * need both params to be set correctly before trying to + * create a pool. + */ + if (!strcmp(type, ZSWAP_PARAM_UNSET)) + return NULL; + if (!strcmp(compressor, ZSWAP_PARAM_UNSET)) + return NULL; + } + + pool = kzalloc(sizeof(*pool), GFP_KERNEL); + if (!pool) + return NULL; + + for (i = 0; i < ZSWAP_NR_ZPOOLS; i++) { + /* unique name for each pool specifically required by zsmalloc */ + snprintf(name, 38, "zswap%x", + atomic_inc_return(&zswap_pools_count)); + + pool->zpools[i] = zpool_create_pool(type, name, gfp); + if (!pool->zpools[i]) { + pr_err("%s zpool not available\n", type); + goto error; + } + } + pr_debug("using %s zpool\n", zpool_get_type(pool->zpools[0])); + + strscpy(pool->tfm_name, compressor, sizeof(pool->tfm_name)); + + pool->acomp_ctx = alloc_percpu(*pool->acomp_ctx); + if (!pool->acomp_ctx) { + pr_err("percpu alloc failed\n"); + goto error; + } + + ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE, + &pool->node); + if (ret) + goto error; + pr_debug("using %s compressor\n", pool->tfm_name); + + /* being the current pool takes 1 ref; this func expects the + * caller to always add the new pool as the current pool + */ + kref_init(&pool->kref); + INIT_LIST_HEAD(&pool->list); + INIT_LIST_HEAD(&pool->lru); + spin_lock_init(&pool->lru_lock); + INIT_WORK(&pool->shrink_work, shrink_worker); + + zswap_pool_debug("created", pool); + + return pool; + +error: + if (pool->acomp_ctx) + free_percpu(pool->acomp_ctx); + while (i--) + zpool_destroy_pool(pool->zpools[i]); + kfree(pool); + return NULL; +} + +static struct zswap_pool *__zswap_pool_create_fallback(void) +{ + bool has_comp, has_zpool; + + has_comp = crypto_has_acomp(zswap_compressor, 0, 0); + if (!has_comp && strcmp(zswap_compressor, + CONFIG_ZSWAP_COMPRESSOR_DEFAULT)) { + pr_err("compressor %s not available, using default %s\n", + zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT); + param_free_charp(&zswap_compressor); + zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT; + has_comp = crypto_has_acomp(zswap_compressor, 0, 0); + } + if (!has_comp) { + pr_err("default compressor %s not available\n", + zswap_compressor); + param_free_charp(&zswap_compressor); + zswap_compressor = ZSWAP_PARAM_UNSET; + } + + has_zpool = zpool_has_pool(zswap_zpool_type); + if (!has_zpool && strcmp(zswap_zpool_type, + CONFIG_ZSWAP_ZPOOL_DEFAULT)) { + pr_err("zpool %s not available, using default %s\n", + zswap_zpool_type, CONFIG_ZSWAP_ZPOOL_DEFAULT); + param_free_charp(&zswap_zpool_type); + zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT; + has_zpool = zpool_has_pool(zswap_zpool_type); + } + if (!has_zpool) { + pr_err("default zpool %s not available\n", + zswap_zpool_type); + param_free_charp(&zswap_zpool_type); + zswap_zpool_type = ZSWAP_PARAM_UNSET; + } + + if (!has_comp || !has_zpool) + return NULL; + + return zswap_pool_create(zswap_zpool_type, zswap_compressor); +} + +static void zswap_pool_destroy(struct zswap_pool *pool) +{ + int i; + + zswap_pool_debug("destroying", pool); + + cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node); + free_percpu(pool->acomp_ctx); + for (i = 0; i < ZSWAP_NR_ZPOOLS; i++) + zpool_destroy_pool(pool->zpools[i]); + kfree(pool); +} + +static int __must_check zswap_pool_get(struct zswap_pool *pool) +{ + if (!pool) + return 0; + + return kref_get_unless_zero(&pool->kref); +} + +static void __zswap_pool_release(struct work_struct *work) +{ + struct zswap_pool *pool = container_of(work, typeof(*pool), + release_work); + + synchronize_rcu(); + + /* nobody should have been able to get a kref... */ + WARN_ON(kref_get_unless_zero(&pool->kref)); + + /* pool is now off zswap_pools list and has no references. */ + zswap_pool_destroy(pool); +} + +static void __zswap_pool_empty(struct kref *kref) +{ + struct zswap_pool *pool; + + pool = container_of(kref, typeof(*pool), kref); + + spin_lock(&zswap_pools_lock); + + WARN_ON(pool == zswap_pool_current()); + + list_del_rcu(&pool->list); + + INIT_WORK(&pool->release_work, __zswap_pool_release); + schedule_work(&pool->release_work); + + spin_unlock(&zswap_pools_lock); +} + +static void zswap_pool_put(struct zswap_pool *pool) +{ + kref_put(&pool->kref, __zswap_pool_empty); +} + +/********************************* +* param callbacks +**********************************/ + +static bool zswap_pool_changed(const char *s, const struct kernel_param *kp) +{ + /* no change required */ + if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool) + return false; + return true; +} + +/* val must be a null-terminated string */ +static int __zswap_param_set(const char *val, const struct kernel_param *kp, + char *type, char *compressor) +{ + struct zswap_pool *pool, *put_pool = NULL; + char *s = strstrip((char *)val); + int ret = 0; + bool new_pool = false; + + mutex_lock(&zswap_init_lock); + switch (zswap_init_state) { + case ZSWAP_UNINIT: + /* if this is load-time (pre-init) param setting, + * don't create a pool; that's done during init. + */ + ret = param_set_charp(s, kp); + break; + case ZSWAP_INIT_SUCCEED: + new_pool = zswap_pool_changed(s, kp); + break; + case ZSWAP_INIT_FAILED: + pr_err("can't set param, initialization failed\n"); + ret = -ENODEV; + } + mutex_unlock(&zswap_init_lock); + + /* no need to create a new pool, return directly */ + if (!new_pool) + return ret; + + if (!type) { + if (!zpool_has_pool(s)) { + pr_err("zpool %s not available\n", s); + return -ENOENT; + } + type = s; + } else if (!compressor) { + if (!crypto_has_acomp(s, 0, 0)) { + pr_err("compressor %s not available\n", s); + return -ENOENT; + } + compressor = s; + } else { + WARN_ON(1); + return -EINVAL; + } + + spin_lock(&zswap_pools_lock); + + pool = zswap_pool_find_get(type, compressor); + if (pool) { + zswap_pool_debug("using existing", pool); + WARN_ON(pool == zswap_pool_current()); + list_del_rcu(&pool->list); + } + + spin_unlock(&zswap_pools_lock); + + if (!pool) + pool = zswap_pool_create(type, compressor); + + if (pool) + ret = param_set_charp(s, kp); + else + ret = -EINVAL; + + spin_lock(&zswap_pools_lock); + + if (!ret) { + put_pool = zswap_pool_current(); + list_add_rcu(&pool->list, &zswap_pools); + zswap_has_pool = true; + } else if (pool) { + /* add the possibly pre-existing pool to the end of the pools + * list; if it's new (and empty) then it'll be removed and + * destroyed by the put after we drop the lock + */ + list_add_tail_rcu(&pool->list, &zswap_pools); + put_pool = pool; + } + + spin_unlock(&zswap_pools_lock); + + if (!zswap_has_pool && !pool) { + /* if initial pool creation failed, and this pool creation also + * failed, maybe both compressor and zpool params were bad. + * Allow changing this param, so pool creation will succeed + * when the other param is changed. We already verified this + * param is ok in the zpool_has_pool() or crypto_has_acomp() + * checks above. + */ + ret = param_set_charp(s, kp); + } + + /* drop the ref from either the old current pool, + * or the new pool we failed to add + */ + if (put_pool) + zswap_pool_put(put_pool); + + return ret; +} + +static int zswap_compressor_param_set(const char *val, + const struct kernel_param *kp) +{ + return __zswap_param_set(val, kp, zswap_zpool_type, NULL); +} + +static int zswap_zpool_param_set(const char *val, + const struct kernel_param *kp) +{ + return __zswap_param_set(val, kp, NULL, zswap_compressor); +} + +static int zswap_enabled_param_set(const char *val, + const struct kernel_param *kp) +{ + int ret = -ENODEV; + + /* if this is load-time (pre-init) param setting, only set param. */ + if (system_state != SYSTEM_RUNNING) + return param_set_bool(val, kp); + + mutex_lock(&zswap_init_lock); + switch (zswap_init_state) { + case ZSWAP_UNINIT: + if (zswap_setup()) + break; + fallthrough; + case ZSWAP_INIT_SUCCEED: + if (!zswap_has_pool) + pr_err("can't enable, no pool configured\n"); + else + ret = param_set_bool(val, kp); + break; + case ZSWAP_INIT_FAILED: + pr_err("can't enable, initialization failed\n"); + } + mutex_unlock(&zswap_init_lock); + + return ret; +} + +/********************************* +* writeback code +**********************************/ +/* + * Attempts to free an entry by adding a page to the swap cache, + * decompressing the entry data into the page, and issuing a + * bio write to write the page back to the swap device. + * + * This can be thought of as a "resumed writeback" of the page + * to the swap device. We are basically resuming the same swap + * writeback path that was intercepted with the zswap_store() + * in the first place. After the page has been decompressed into + * the swap cache, the compressed version stored by zswap can be + * freed. + */ +static int zswap_writeback_entry(struct zswap_entry *entry, + struct zswap_tree *tree) +{ + swp_entry_t swpentry = entry->swpentry; + struct page *page; + struct scatterlist input, output; + struct crypto_acomp_ctx *acomp_ctx; + struct zpool *pool = zswap_find_zpool(entry); + bool page_was_allocated; + u8 *src, *tmp = NULL; + unsigned int dlen; + int ret; + struct writeback_control wbc = { + .sync_mode = WB_SYNC_NONE, + }; + + if (!zpool_can_sleep_mapped(pool)) { + tmp = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!tmp) + return -ENOMEM; + } + + /* try to allocate swap cache page */ + page = __read_swap_cache_async(swpentry, GFP_KERNEL, NULL, 0, + &page_was_allocated); + if (!page) { + ret = -ENOMEM; + goto fail; + } + + /* Found an existing page, we raced with load/swapin */ + if (!page_was_allocated) { + put_page(page); + ret = -EEXIST; + goto fail; + } + + /* + * Page is locked, and the swapcache is now secured against + * concurrent swapping to and from the slot. Verify that the + * swap entry hasn't been invalidated and recycled behind our + * backs (our zswap_entry reference doesn't prevent that), to + * avoid overwriting a new swap page with old compressed data. + */ + spin_lock(&tree->lock); + if (zswap_rb_search(&tree->rbroot, swp_offset(entry->swpentry)) != entry) { + spin_unlock(&tree->lock); + delete_from_swap_cache(page_folio(page)); + ret = -ENOMEM; + goto fail; + } + spin_unlock(&tree->lock); + + /* decompress */ + acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); + dlen = PAGE_SIZE; + + src = zpool_map_handle(pool, entry->handle, ZPOOL_MM_RO); + if (!zpool_can_sleep_mapped(pool)) { + memcpy(tmp, src, entry->length); + src = tmp; + zpool_unmap_handle(pool, entry->handle); + } + + mutex_lock(acomp_ctx->mutex); + sg_init_one(&input, src, entry->length); + sg_init_table(&output, 1); + sg_set_page(&output, page, PAGE_SIZE, 0); + acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen); + ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait); + dlen = acomp_ctx->req->dlen; + mutex_unlock(acomp_ctx->mutex); + + if (!zpool_can_sleep_mapped(pool)) + kfree(tmp); + else + zpool_unmap_handle(pool, entry->handle); + + BUG_ON(ret); + BUG_ON(dlen != PAGE_SIZE); + + /* page is up to date */ + SetPageUptodate(page); + + /* move it to the tail of the inactive list after end_writeback */ + SetPageReclaim(page); + + /* start writeback */ + __swap_writepage(page, &wbc); + put_page(page); + zswap_written_back_pages++; + + return ret; + +fail: + if (!zpool_can_sleep_mapped(pool)) + kfree(tmp); + + /* + * If we get here because the page is already in swapcache, a + * load may be happening concurrently. It is safe and okay to + * not free the entry. It is also okay to return !0. + */ + return ret; +} + +static int zswap_is_page_same_filled(void *ptr, unsigned long *value) +{ + unsigned long *page; + unsigned long val; + unsigned int pos, last_pos = PAGE_SIZE / sizeof(*page) - 1; + + page = (unsigned long *)ptr; + val = page[0]; + + if (val != page[last_pos]) + return 0; + + for (pos = 1; pos < last_pos; pos++) { + if (val != page[pos]) + return 0; + } + + *value = val; + + return 1; +} + +static void zswap_fill_page(void *ptr, unsigned long value) +{ + unsigned long *page; + + page = (unsigned long *)ptr; + memset_l(page, value, PAGE_SIZE / sizeof(unsigned long)); +} + +bool zswap_store(struct folio *folio) +{ + swp_entry_t swp = folio->swap; + int type = swp_type(swp); + pgoff_t offset = swp_offset(swp); + struct page *page = &folio->page; + struct zswap_tree *tree = zswap_trees[type]; + struct zswap_entry *entry, *dupentry; + struct scatterlist input, output; + struct crypto_acomp_ctx *acomp_ctx; + struct obj_cgroup *objcg = NULL; + struct zswap_pool *pool; + struct zpool *zpool; + unsigned int dlen = PAGE_SIZE; + unsigned long handle, value; + char *buf; + u8 *src, *dst; + gfp_t gfp; + int ret; + + VM_WARN_ON_ONCE(!folio_test_locked(folio)); + VM_WARN_ON_ONCE(!folio_test_swapcache(folio)); + + /* Large folios aren't supported */ + if (folio_test_large(folio)) + return false; + + if (!zswap_enabled || !tree) + return false; + + /* + * If this is a duplicate, it must be removed before attempting to store + * it, otherwise, if the store fails the old page won't be removed from + * the tree, and it might be written back overriding the new data. + */ + spin_lock(&tree->lock); + dupentry = zswap_rb_search(&tree->rbroot, offset); + if (dupentry) { + zswap_duplicate_entry++; + zswap_invalidate_entry(tree, dupentry); + } + spin_unlock(&tree->lock); + + /* + * XXX: zswap reclaim does not work with cgroups yet. Without a + * cgroup-aware entry LRU, we will push out entries system-wide based on + * local cgroup limits. + */ + objcg = get_obj_cgroup_from_folio(folio); + if (objcg && !obj_cgroup_may_zswap(objcg)) + goto reject; + + /* reclaim space if needed */ + if (zswap_is_full()) { + zswap_pool_limit_hit++; + zswap_pool_reached_full = true; + goto shrink; + } + + if (zswap_pool_reached_full) { + if (!zswap_can_accept()) + goto shrink; + else + zswap_pool_reached_full = false; + } + + /* allocate entry */ + entry = zswap_entry_cache_alloc(GFP_KERNEL); + if (!entry) { + zswap_reject_kmemcache_fail++; + goto reject; + } + + if (zswap_same_filled_pages_enabled) { + src = kmap_atomic(page); + if (zswap_is_page_same_filled(src, &value)) { + kunmap_atomic(src); + entry->swpentry = swp_entry(type, offset); + entry->length = 0; + entry->value = value; + atomic_inc(&zswap_same_filled_pages); + goto insert_entry; + } + kunmap_atomic(src); + } + + if (!zswap_non_same_filled_pages_enabled) + goto freepage; + + /* if entry is successfully added, it keeps the reference */ + entry->pool = zswap_pool_current_get(); + if (!entry->pool) + goto freepage; + + /* compress */ + acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); + + mutex_lock(acomp_ctx->mutex); + + dst = acomp_ctx->dstmem; + sg_init_table(&input, 1); + sg_set_page(&input, page, PAGE_SIZE, 0); + + /* zswap_dstmem is of size (PAGE_SIZE * 2). Reflect same in sg_list */ + sg_init_one(&output, dst, PAGE_SIZE * 2); + acomp_request_set_params(acomp_ctx->req, &input, &output, PAGE_SIZE, dlen); + /* + * it maybe looks a little bit silly that we send an asynchronous request, + * then wait for its completion synchronously. This makes the process look + * synchronous in fact. + * Theoretically, acomp supports users send multiple acomp requests in one + * acomp instance, then get those requests done simultaneously. but in this + * case, zswap actually does store and load page by page, there is no + * existing method to send the second page before the first page is done + * in one thread doing zwap. + * but in different threads running on different cpu, we have different + * acomp instance, so multiple threads can do (de)compression in parallel. + */ + ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait); + dlen = acomp_ctx->req->dlen; + + if (ret) + goto put_dstmem; + + /* store */ + zpool = zswap_find_zpool(entry); + gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM; + if (zpool_malloc_support_movable(zpool)) + gfp |= __GFP_HIGHMEM | __GFP_MOVABLE; + ret = zpool_malloc(zpool, dlen, gfp, &handle); + if (ret == -ENOSPC) { + zswap_reject_compress_poor++; + goto put_dstmem; + } + if (ret) { + zswap_reject_alloc_fail++; + goto put_dstmem; + } + buf = zpool_map_handle(zpool, handle, ZPOOL_MM_WO); + memcpy(buf, dst, dlen); + zpool_unmap_handle(zpool, handle); + mutex_unlock(acomp_ctx->mutex); + + /* populate entry */ + entry->swpentry = swp_entry(type, offset); + entry->handle = handle; + entry->length = dlen; + +insert_entry: + entry->objcg = objcg; + if (objcg) { + obj_cgroup_charge_zswap(objcg, entry->length); + /* Account before objcg ref is moved to tree */ + count_objcg_event(objcg, ZSWPOUT); + } + + /* map */ + spin_lock(&tree->lock); + /* + * A duplicate entry should have been removed at the beginning of this + * function. Since the swap entry should be pinned, if a duplicate is + * found again here it means that something went wrong in the swap + * cache. + */ + while (zswap_rb_insert(&tree->rbroot, entry, &dupentry) == -EEXIST) { + WARN_ON(1); + zswap_duplicate_entry++; + zswap_invalidate_entry(tree, dupentry); + } + if (entry->length) { + spin_lock(&entry->pool->lru_lock); + list_add(&entry->lru, &entry->pool->lru); + spin_unlock(&entry->pool->lru_lock); + } + spin_unlock(&tree->lock); + + /* update stats */ + atomic_inc(&zswap_stored_pages); + zswap_update_total_size(); + count_vm_event(ZSWPOUT); + + return true; + +put_dstmem: + mutex_unlock(acomp_ctx->mutex); + zswap_pool_put(entry->pool); +freepage: + zswap_entry_cache_free(entry); +reject: + if (objcg) + obj_cgroup_put(objcg); + return false; + +shrink: + pool = zswap_pool_last_get(); + if (pool && !queue_work(shrink_wq, &pool->shrink_work)) + zswap_pool_put(pool); + goto reject; +} + +bool zswap_load(struct folio *folio) +{ + swp_entry_t swp = folio->swap; + int type = swp_type(swp); + pgoff_t offset = swp_offset(swp); + struct page *page = &folio->page; + struct zswap_tree *tree = zswap_trees[type]; + struct zswap_entry *entry; + struct scatterlist input, output; + struct crypto_acomp_ctx *acomp_ctx; + u8 *src, *dst, *tmp; + struct zpool *zpool; + unsigned int dlen; + bool ret; + + VM_WARN_ON_ONCE(!folio_test_locked(folio)); + + /* find */ + spin_lock(&tree->lock); + entry = zswap_entry_find_get(&tree->rbroot, offset); + if (!entry) { + spin_unlock(&tree->lock); + return false; + } + spin_unlock(&tree->lock); + + if (!entry->length) { + dst = kmap_atomic(page); + zswap_fill_page(dst, entry->value); + kunmap_atomic(dst); + ret = true; + goto stats; + } + + zpool = zswap_find_zpool(entry); + if (!zpool_can_sleep_mapped(zpool)) { + tmp = kmalloc(entry->length, GFP_KERNEL); + if (!tmp) { + ret = false; + goto freeentry; + } + } + + /* decompress */ + dlen = PAGE_SIZE; + src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); + + if (!zpool_can_sleep_mapped(zpool)) { + memcpy(tmp, src, entry->length); + src = tmp; + zpool_unmap_handle(zpool, entry->handle); + } + + acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); + mutex_lock(acomp_ctx->mutex); + sg_init_one(&input, src, entry->length); + sg_init_table(&output, 1); + sg_set_page(&output, page, PAGE_SIZE, 0); + acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen); + if (crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait)) + WARN_ON(1); + mutex_unlock(acomp_ctx->mutex); + + if (zpool_can_sleep_mapped(zpool)) + zpool_unmap_handle(zpool, entry->handle); + else + kfree(tmp); + + ret = true; +stats: + count_vm_event(ZSWPIN); + if (entry->objcg) + count_objcg_event(entry->objcg, ZSWPIN); +freeentry: + spin_lock(&tree->lock); + if (ret && zswap_exclusive_loads_enabled) { + zswap_invalidate_entry(tree, entry); + folio_mark_dirty(folio); + } else if (entry->length) { + spin_lock(&entry->pool->lru_lock); + list_move(&entry->lru, &entry->pool->lru); + spin_unlock(&entry->pool->lru_lock); + } + zswap_entry_put(tree, entry); + spin_unlock(&tree->lock); + + return ret; +} + +void zswap_invalidate(int type, pgoff_t offset) +{ + struct zswap_tree *tree = zswap_trees[type]; + struct zswap_entry *entry; + + /* find */ + spin_lock(&tree->lock); + entry = zswap_rb_search(&tree->rbroot, offset); + if (!entry) { + /* entry was written back */ + spin_unlock(&tree->lock); + return; + } + zswap_invalidate_entry(tree, entry); + spin_unlock(&tree->lock); +} + +void zswap_swapon(int type) +{ + struct zswap_tree *tree; + + tree = kzalloc(sizeof(*tree), GFP_KERNEL); + if (!tree) { + pr_err("alloc failed, zswap disabled for swap type %d\n", type); + return; + } + + tree->rbroot = RB_ROOT; + spin_lock_init(&tree->lock); + zswap_trees[type] = tree; +} + +void zswap_swapoff(int type) +{ + struct zswap_tree *tree = zswap_trees[type]; + struct zswap_entry *entry, *n; + + if (!tree) + return; + + /* walk the tree and free everything */ + spin_lock(&tree->lock); + rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode) + zswap_free_entry(entry); + tree->rbroot = RB_ROOT; + spin_unlock(&tree->lock); + kfree(tree); + zswap_trees[type] = NULL; +} + +/********************************* +* debugfs functions +**********************************/ +#ifdef CONFIG_DEBUG_FS +#include <linux/debugfs.h> + +static struct dentry *zswap_debugfs_root; + +static int zswap_debugfs_init(void) +{ + if (!debugfs_initialized()) + return -ENODEV; + + zswap_debugfs_root = debugfs_create_dir("zswap", NULL); + + debugfs_create_u64("pool_limit_hit", 0444, + zswap_debugfs_root, &zswap_pool_limit_hit); + debugfs_create_u64("reject_reclaim_fail", 0444, + zswap_debugfs_root, &zswap_reject_reclaim_fail); + debugfs_create_u64("reject_alloc_fail", 0444, + zswap_debugfs_root, &zswap_reject_alloc_fail); + debugfs_create_u64("reject_kmemcache_fail", 0444, + zswap_debugfs_root, &zswap_reject_kmemcache_fail); + debugfs_create_u64("reject_compress_poor", 0444, + zswap_debugfs_root, &zswap_reject_compress_poor); + debugfs_create_u64("written_back_pages", 0444, + zswap_debugfs_root, &zswap_written_back_pages); + debugfs_create_u64("duplicate_entry", 0444, + zswap_debugfs_root, &zswap_duplicate_entry); + debugfs_create_u64("pool_total_size", 0444, + zswap_debugfs_root, &zswap_pool_total_size); + debugfs_create_atomic_t("stored_pages", 0444, + zswap_debugfs_root, &zswap_stored_pages); + debugfs_create_atomic_t("same_filled_pages", 0444, + zswap_debugfs_root, &zswap_same_filled_pages); + + return 0; +} +#else +static int zswap_debugfs_init(void) +{ + return 0; +} +#endif + +/********************************* +* module init and exit +**********************************/ +static int zswap_setup(void) +{ + struct zswap_pool *pool; + int ret; + + zswap_entry_cache = KMEM_CACHE(zswap_entry, 0); + if (!zswap_entry_cache) { + pr_err("entry cache creation failed\n"); + goto cache_fail; + } + + ret = cpuhp_setup_state(CPUHP_MM_ZSWP_MEM_PREPARE, "mm/zswap:prepare", + zswap_dstmem_prepare, zswap_dstmem_dead); + if (ret) { + pr_err("dstmem alloc failed\n"); + goto dstmem_fail; + } + + ret = cpuhp_setup_state_multi(CPUHP_MM_ZSWP_POOL_PREPARE, + "mm/zswap_pool:prepare", + zswap_cpu_comp_prepare, + zswap_cpu_comp_dead); + if (ret) + goto hp_fail; + + pool = __zswap_pool_create_fallback(); + if (pool) { + pr_info("loaded using pool %s/%s\n", pool->tfm_name, + zpool_get_type(pool->zpools[0])); + list_add(&pool->list, &zswap_pools); + zswap_has_pool = true; + } else { + pr_err("pool creation failed\n"); + zswap_enabled = false; + } + + shrink_wq = create_workqueue("zswap-shrink"); + if (!shrink_wq) + goto fallback_fail; + + if (zswap_debugfs_init()) + pr_warn("debugfs initialization failed\n"); + zswap_init_state = ZSWAP_INIT_SUCCEED; + return 0; + +fallback_fail: + if (pool) + zswap_pool_destroy(pool); +hp_fail: + cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE); +dstmem_fail: + kmem_cache_destroy(zswap_entry_cache); +cache_fail: + /* if built-in, we aren't unloaded on failure; don't allow use */ + zswap_init_state = ZSWAP_INIT_FAILED; + zswap_enabled = false; + return -ENOMEM; +} + +static int __init zswap_init(void) +{ + if (!zswap_enabled) + return 0; + return zswap_setup(); +} +/* must be late so crypto has time to come up */ +late_initcall(zswap_init); + +MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>"); +MODULE_DESCRIPTION("Compressed cache for swap pages"); |