| // 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); |
| 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"); |