| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Johannes Weiner | 3328 | 52.35% | 27 | 22.31% |
| Seth Jennings | 655 | 10.30% | 2 | 1.65% |
| Dan Streetman | 556 | 8.75% | 11 | 9.09% |
| Chengming Zhou | 416 | 6.54% | 18 | 14.88% |
| Yosry Ahmed | 233 | 3.67% | 14 | 11.57% |
| Domenico Cerasuolo | 201 | 3.16% | 5 | 4.13% |
| Chris Li | 173 | 2.72% | 1 | 0.83% |
| Srividya Desireddy | 158 | 2.49% | 1 | 0.83% |
| Barry Song | 138 | 2.17% | 4 | 3.31% |
| Nhat Pham | 124 | 1.95% | 5 | 4.13% |
| Liu Shixin | 99 | 1.56% | 3 | 2.48% |
| Vitaly Wool | 57 | 0.90% | 1 | 0.83% |
| Weijie Yang | 45 | 0.71% | 2 | 1.65% |
| Taejoon Song | 36 | 0.57% | 1 | 0.83% |
| Sebastian Andrzej Siewior | 33 | 0.52% | 2 | 1.65% |
| Matthew Wilcox | 25 | 0.39% | 5 | 4.13% |
| Joe Perches | 12 | 0.19% | 2 | 1.65% |
| Maciej S. Szmigiero | 11 | 0.17% | 1 | 0.83% |
| MinChan Kim | 9 | 0.14% | 1 | 0.83% |
| Ronald Monthero | 7 | 0.11% | 1 | 0.83% |
| Song Muchun | 6 | 0.09% | 1 | 0.83% |
| Huang Ying | 5 | 0.08% | 1 | 0.83% |
| Andrew Morton | 4 | 0.06% | 2 | 1.65% |
| Mel Gorman | 4 | 0.06% | 1 | 0.83% |
| David Hildenbrand | 4 | 0.06% | 1 | 0.83% |
| Li Wang | 4 | 0.06% | 1 | 0.83% |
| Dan Magenheimer | 3 | 0.05% | 1 | 0.83% |
| Neil Brown | 3 | 0.05% | 1 | 0.83% |
| Pavel Emelyanov | 2 | 0.03% | 1 | 0.83% |
| Christoph Hellwig | 2 | 0.03% | 1 | 0.83% |
| Hui Zhu | 2 | 0.03% | 1 | 0.83% |
| Arun K S | 1 | 0.02% | 1 | 0.83% |
| Thomas Gleixner | 1 | 0.02% | 1 | 0.83% |
| Total | 6357 | 121 |
// 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/swap.h> #include <linux/crypto.h> #include <linux/scatterlist.h> #include <linux/mempolicy.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 <linux/list_lru.h> #include "swap.h" #include "internal.h" /********************************* * statistics **********************************/ /* 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; /* Store failed due to compression algorithm failure */ static u64 zswap_reject_compress_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; /* 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 DEFINE_STATIC_KEY_MAYBE(CONFIG_ZSWAP_DEFAULT_ON, zswap_ever_enabled); 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 memory pressure-based shrinker. */ static bool zswap_shrinker_enabled = IS_ENABLED( CONFIG_ZSWAP_SHRINKER_DEFAULT_ON); module_param_named(shrinker_enabled, zswap_shrinker_enabled, bool, 0644); bool zswap_is_enabled(void) { return zswap_enabled; } bool zswap_never_enabled(void) { return !static_branch_maybe(CONFIG_ZSWAP_DEFAULT_ON, &zswap_ever_enabled); } /********************************* * data structures **********************************/ struct crypto_acomp_ctx { struct crypto_acomp *acomp; struct acomp_req *req; struct crypto_wait wait; u8 *buffer; struct mutex mutex; bool is_sleepable; }; /* * 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 *zpool; struct crypto_acomp_ctx __percpu *acomp_ctx; struct percpu_ref ref; struct list_head list; struct work_struct release_work; struct hlist_node node; char tfm_name[CRYPTO_MAX_ALG_NAME]; }; /* Global LRU lists shared by all zswap pools. */ static struct list_lru zswap_list_lru; /* The lock protects zswap_next_shrink updates. */ static DEFINE_SPINLOCK(zswap_shrink_lock); static struct mem_cgroup *zswap_next_shrink; static struct work_struct zswap_shrink_work; static struct shrinker *zswap_shrinker; /* * struct zswap_entry * * This structure contains the metadata for tracking a single compressed * page within zswap. * * swpentry - associated swap entry, the offset indexes into the red-black tree * 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 { swp_entry_t swpentry; unsigned int length; struct zswap_pool *pool; union { unsigned long handle; unsigned long value; }; struct obj_cgroup *objcg; struct list_head lru; }; static struct xarray *zswap_trees[MAX_SWAPFILES]; static unsigned int nr_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 **********************************/ static inline struct xarray *swap_zswap_tree(swp_entry_t swp) { return &zswap_trees[swp_type(swp)][swp_offset(swp) >> SWAP_ADDRESS_SPACE_SHIFT]; } #define zswap_pool_debug(msg, p) \ pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name, \ zpool_get_type((p)->zpool)) /********************************* * pool functions **********************************/ static void __zswap_pool_empty(struct percpu_ref *ref); static struct zswap_pool *zswap_pool_create(char *type, char *compressor) { 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; /* unique name for each pool specifically required by zsmalloc */ snprintf(name, 38, "zswap%x", atomic_inc_return(&zswap_pools_count)); pool->zpool = zpool_create_pool(type, name, gfp); if (!pool->zpool) { pr_err("%s zpool not available\n", type); goto error; } pr_debug("using %s zpool\n", zpool_get_type(pool->zpool)); 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; /* being the current pool takes 1 ref; this func expects the * caller to always add the new pool as the current pool */ ret = percpu_ref_init(&pool->ref, __zswap_pool_empty, PERCPU_REF_ALLOW_REINIT, GFP_KERNEL); if (ret) goto ref_fail; INIT_LIST_HEAD(&pool->list); zswap_pool_debug("created", pool); return pool; ref_fail: cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node); error: if (pool->acomp_ctx) free_percpu(pool->acomp_ctx); if (pool->zpool) zpool_destroy_pool(pool->zpool); 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) { zswap_pool_debug("destroying", pool); cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node); free_percpu(pool->acomp_ctx); zpool_destroy_pool(pool->zpool); kfree(pool); } 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 ref... */ WARN_ON(!percpu_ref_is_zero(&pool->ref)); percpu_ref_exit(&pool->ref); /* pool is now off zswap_pools list and has no references. */ zswap_pool_destroy(pool); } static struct zswap_pool *zswap_pool_current(void); static void __zswap_pool_empty(struct percpu_ref *ref) { struct zswap_pool *pool; pool = container_of(ref, typeof(*pool), ref); spin_lock_bh(&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_bh(&zswap_pools_lock); } static int __must_check zswap_pool_get(struct zswap_pool *pool) { if (!pool) return 0; return percpu_ref_tryget(&pool->ref); } static void zswap_pool_put(struct zswap_pool *pool) { percpu_ref_put(&pool->ref); } 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; } /* 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; if (strcmp(zpool_get_type(pool->zpool), type)) continue; /* if we can't get it, it's about to be destroyed */ if (!zswap_pool_get(pool)) continue; return pool; } return NULL; } static unsigned long zswap_max_pages(void) { return totalram_pages() * zswap_max_pool_percent / 100; } static unsigned long zswap_accept_thr_pages(void) { return zswap_max_pages() * zswap_accept_thr_percent / 100; } unsigned long zswap_total_pages(void) { struct zswap_pool *pool; unsigned long total = 0; rcu_read_lock(); list_for_each_entry_rcu(pool, &zswap_pools, list) total += zpool_get_total_pages(pool->zpool); rcu_read_unlock(); return total; } static bool zswap_check_limits(void) { unsigned long cur_pages = zswap_total_pages(); unsigned long max_pages = zswap_max_pages(); if (cur_pages >= max_pages) { zswap_pool_limit_hit++; zswap_pool_reached_full = true; } else if (zswap_pool_reached_full && cur_pages <= zswap_accept_thr_pages()) { zswap_pool_reached_full = false; } return zswap_pool_reached_full; } /********************************* * 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_bh(&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_bh(&zswap_pools_lock); if (!pool) pool = zswap_pool_create(type, compressor); else { /* * Restore the initial ref dropped by percpu_ref_kill() * when the pool was decommissioned and switch it again * to percpu mode. */ percpu_ref_resurrect(&pool->ref); /* Drop the ref from zswap_pool_find_get(). */ zswap_pool_put(pool); } if (pool) ret = param_set_charp(s, kp); else ret = -EINVAL; spin_lock_bh(&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_bh(&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) percpu_ref_kill(&put_pool->ref); 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; } /********************************* * lru functions **********************************/ /* should be called under RCU */ #ifdef CONFIG_MEMCG static inline struct mem_cgroup *mem_cgroup_from_entry(struct zswap_entry *entry) { return entry->objcg ? obj_cgroup_memcg(entry->objcg) : NULL; } #else static inline struct mem_cgroup *mem_cgroup_from_entry(struct zswap_entry *entry) { return NULL; } #endif static inline int entry_to_nid(struct zswap_entry *entry) { return page_to_nid(virt_to_page(entry)); } static void zswap_lru_add(struct list_lru *list_lru, struct zswap_entry *entry) { atomic_long_t *nr_zswap_protected; unsigned long lru_size, old, new; int nid = entry_to_nid(entry); struct mem_cgroup *memcg; struct lruvec *lruvec; /* * Note that it is safe to use rcu_read_lock() here, even in the face of * concurrent memcg offlining. Thanks to the memcg->kmemcg_id indirection * used in list_lru lookup, only two scenarios are possible: * * 1. list_lru_add() is called before memcg->kmemcg_id is updated. The * new entry will be reparented to memcg's parent's list_lru. * 2. list_lru_add() is called after memcg->kmemcg_id is updated. The * new entry will be added directly to memcg's parent's list_lru. * * Similar reasoning holds for list_lru_del(). */ rcu_read_lock(); memcg = mem_cgroup_from_entry(entry); /* will always succeed */ list_lru_add(list_lru, &entry->lru, nid, memcg); /* Update the protection area */ lru_size = list_lru_count_one(list_lru, nid, memcg); lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid)); nr_zswap_protected = &lruvec->zswap_lruvec_state.nr_zswap_protected; old = atomic_long_inc_return(nr_zswap_protected); /* * Decay to avoid overflow and adapt to changing workloads. * This is based on LRU reclaim cost decaying heuristics. */ do { new = old > lru_size / 4 ? old / 2 : old; } while (!atomic_long_try_cmpxchg(nr_zswap_protected, &old, new)); rcu_read_unlock(); } static void zswap_lru_del(struct list_lru *list_lru, struct zswap_entry *entry) { int nid = entry_to_nid(entry); struct mem_cgroup *memcg; rcu_read_lock(); memcg = mem_cgroup_from_entry(entry); /* will always succeed */ list_lru_del(list_lru, &entry->lru, nid, memcg); rcu_read_unlock(); } void zswap_lruvec_state_init(struct lruvec *lruvec) { atomic_long_set(&lruvec->zswap_lruvec_state.nr_zswap_protected, 0); } void zswap_folio_swapin(struct folio *folio) { struct lruvec *lruvec; if (folio) { lruvec = folio_lruvec(folio); atomic_long_inc(&lruvec->zswap_lruvec_state.nr_zswap_protected); } } void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg) { /* lock out zswap shrinker walking memcg tree */ spin_lock(&zswap_shrink_lock); if (zswap_next_shrink == memcg) zswap_next_shrink = mem_cgroup_iter(NULL, zswap_next_shrink, NULL); spin_unlock(&zswap_shrink_lock); } /********************************* * zswap entry functions **********************************/ static struct kmem_cache *zswap_entry_cache; static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp, int nid) { struct zswap_entry *entry; entry = kmem_cache_alloc_node(zswap_entry_cache, gfp, nid); if (!entry) return NULL; return entry; } static void zswap_entry_cache_free(struct zswap_entry *entry) { kmem_cache_free(zswap_entry_cache, entry); } /* * 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_entry_free(struct zswap_entry *entry) { if (!entry->length) atomic_dec(&zswap_same_filled_pages); else { zswap_lru_del(&zswap_list_lru, entry); zpool_free(entry->pool->zpool, entry->handle); zswap_pool_put(entry->pool); } if (entry->objcg) { obj_cgroup_uncharge_zswap(entry->objcg, entry->length); obj_cgroup_put(entry->objcg); } zswap_entry_cache_free(entry); atomic_dec(&zswap_stored_pages); } /********************************* * compressed storage functions **********************************/ 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; int ret; mutex_init(&acomp_ctx->mutex); acomp_ctx->buffer = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu)); if (!acomp_ctx->buffer) return -ENOMEM; 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)); ret = PTR_ERR(acomp); goto acomp_fail; } acomp_ctx->acomp = acomp; acomp_ctx->is_sleepable = acomp_is_async(acomp); req = acomp_request_alloc(acomp_ctx->acomp); if (!req) { pr_err("could not alloc crypto acomp_request %s\n", pool->tfm_name); ret = -ENOMEM; goto req_fail; } 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); return 0; req_fail: crypto_free_acomp(acomp_ctx->acomp); acomp_fail: kfree(acomp_ctx->buffer); return ret; } 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); kfree(acomp_ctx->buffer); } return 0; } static bool zswap_compress(struct folio *folio, struct zswap_entry *entry) { struct crypto_acomp_ctx *acomp_ctx; struct scatterlist input, output; int comp_ret = 0, alloc_ret = 0; unsigned int dlen = PAGE_SIZE; unsigned long handle; struct zpool *zpool; char *buf; gfp_t gfp; u8 *dst; acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); mutex_lock(&acomp_ctx->mutex); dst = acomp_ctx->buffer; sg_init_table(&input, 1); sg_set_folio(&input, folio, PAGE_SIZE, 0); /* * We need PAGE_SIZE * 2 here since there maybe over-compression case, * and hardware-accelerators may won't check the dst buffer size, so * giving the dst buffer with enough length to avoid buffer overflow. */ 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. */ comp_ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait); dlen = acomp_ctx->req->dlen; if (comp_ret) goto unlock; zpool = entry->pool->zpool; gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM; if (zpool_malloc_support_movable(zpool)) gfp |= __GFP_HIGHMEM | __GFP_MOVABLE; alloc_ret = zpool_malloc(zpool, dlen, gfp, &handle); if (alloc_ret) goto unlock; buf = zpool_map_handle(zpool, handle, ZPOOL_MM_WO); memcpy(buf, dst, dlen); zpool_unmap_handle(zpool, handle); entry->handle = handle; entry->length = dlen; unlock: if (comp_ret == -ENOSPC || alloc_ret == -ENOSPC) zswap_reject_compress_poor++; else if (comp_ret) zswap_reject_compress_fail++; else if (alloc_ret) zswap_reject_alloc_fail++; mutex_unlock(&acomp_ctx->mutex); return comp_ret == 0 && alloc_ret == 0; } static void zswap_decompress(struct zswap_entry *entry, struct folio *folio) { struct zpool *zpool = entry->pool->zpool; struct scatterlist input, output; struct crypto_acomp_ctx *acomp_ctx; u8 *src; acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); mutex_lock(&acomp_ctx->mutex); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); /* * If zpool_map_handle is atomic, we cannot reliably utilize its mapped buffer * to do crypto_acomp_decompress() which might sleep. In such cases, we must * resort to copying the buffer to a temporary one. * Meanwhile, zpool_map_handle() might return a non-linearly mapped buffer, * such as a kmap address of high memory or even ever a vmap address. * However, sg_init_one is only equipped to handle linearly mapped low memory. * In such cases, we also must copy the buffer to a temporary and lowmem one. */ if ((acomp_ctx->is_sleepable && !zpool_can_sleep_mapped(zpool)) || !virt_addr_valid(src)) { memcpy(acomp_ctx->buffer, src, entry->length); src = acomp_ctx->buffer; zpool_unmap_handle(zpool, entry->handle); } sg_init_one(&input, src, entry->length); sg_init_table(&output, 1); sg_set_folio(&output, folio, PAGE_SIZE, 0); acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, PAGE_SIZE); BUG_ON(crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait)); BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE); mutex_unlock(&acomp_ctx->mutex); if (src != acomp_ctx->buffer) zpool_unmap_handle(zpool, entry->handle); } /********************************* * writeback code **********************************/ /* * Attempts to free an entry by adding a folio to the swap cache, * decompressing the entry data into the folio, and issuing a * bio write to write the folio back to the swap device. * * This can be thought of as a "resumed writeback" of the folio * 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 folio 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, swp_entry_t swpentry) { struct xarray *tree; pgoff_t offset = swp_offset(swpentry); struct folio *folio; struct mempolicy *mpol; bool folio_was_allocated; struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE, }; /* try to allocate swap cache folio */ mpol = get_task_policy(current); folio = __read_swap_cache_async(swpentry, GFP_KERNEL, mpol, NO_INTERLEAVE_INDEX, &folio_was_allocated, true); if (!folio) return -ENOMEM; /* * Found an existing folio, we raced with swapin or concurrent * shrinker. We generally writeback cold folios from zswap, and * swapin means the folio just became hot, so skip this folio. * For unlikely concurrent shrinker case, it will be unlinked * and freed when invalidated by the concurrent shrinker anyway. */ if (!folio_was_allocated) { folio_put(folio); return -EEXIST; } /* * folio is locked, and the swapcache is now secured against * concurrent swapping to and from the slot, and concurrent * swapoff so we can safely dereference the zswap tree here. * Verify that the swap entry hasn't been invalidated and recycled * behind our backs, to avoid overwriting a new swap folio with * old compressed data. Only when this is successful can the entry * be dereferenced. */ tree = swap_zswap_tree(swpentry); if (entry != xa_cmpxchg(tree, offset, entry, NULL, GFP_KERNEL)) { delete_from_swap_cache(folio); folio_unlock(folio); folio_put(folio); return -ENOMEM; } zswap_decompress(entry, folio); count_vm_event(ZSWPWB); if (entry->objcg) count_objcg_event(entry->objcg, ZSWPWB); zswap_entry_free(entry); /* folio is up to date */ folio_mark_uptodate(folio); /* move it to the tail of the inactive list after end_writeback */ folio_set_reclaim(folio); /* start writeback */ __swap_writepage(folio, &wbc); folio_put(folio); return 0; } /********************************* * shrinker functions **********************************/ static enum lru_status shrink_memcg_cb(struct list_head *item, struct list_lru_one *l, spinlock_t *lock, void *arg) { struct zswap_entry *entry = container_of(item, struct zswap_entry, lru); bool *encountered_page_in_swapcache = (bool *)arg; swp_entry_t swpentry; enum lru_status ret = LRU_REMOVED_RETRY; int writeback_result; /* * As soon as we drop the LRU lock, the entry can be freed by * a concurrent invalidation. This means the following: * * 1. We extract the swp_entry_t to the stack, allowing * zswap_writeback_entry() to pin the swap entry and * then validate the zwap entry against that swap entry's * tree using pointer value comparison. Only when that * is successful can the entry be dereferenced. * * 2. Usually, objects are taken off the LRU for reclaim. In * this case this isn't possible, because if reclaim fails * for whatever reason, we have no means of knowing if the * entry is alive to put it back on the LRU. * * So rotate it before dropping the lock. If the entry is * written back or invalidated, the free path will unlink * it. For failures, rotation is the right thing as well. * * Temporary failures, where the same entry should be tried * again immediately, almost never happen for this shrinker. * We don't do any trylocking; -ENOMEM comes closest, * but that's extremely rare and doesn't happen spuriously * either. Don't bother distinguishing this case. */ list_move_tail(item, &l->list); /* * Once the lru lock is dropped, the entry might get freed. The * swpentry is copied to the stack, and entry isn't deref'd again * until the entry is verified to still be alive in the tree. */ swpentry = entry->swpentry; /* * It's safe to drop the lock here because we return either * LRU_REMOVED_RETRY or LRU_RETRY. */ spin_unlock(lock); writeback_result = zswap_writeback_entry(entry, swpentry); if (writeback_result) { zswap_reject_reclaim_fail++; ret = LRU_RETRY; /* * Encountering a page already in swap cache is a sign that we are shrinking * into the warmer region. We should terminate shrinking (if we're in the dynamic * shrinker context). */ if (writeback_result == -EEXIST && encountered_page_in_swapcache) { ret = LRU_STOP; *encountered_page_in_swapcache = true; } } else { zswap_written_back_pages++; } spin_lock(lock); return ret; } static unsigned long zswap_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) { struct lruvec *lruvec = mem_cgroup_lruvec(sc->memcg, NODE_DATA(sc->nid)); unsigned long shrink_ret, nr_protected, lru_size; bool encountered_page_in_swapcache = false; if (!zswap_shrinker_enabled || !mem_cgroup_zswap_writeback_enabled(sc->memcg)) { sc->nr_scanned = 0; return SHRINK_STOP; } nr_protected = atomic_long_read(&lruvec->zswap_lruvec_state.nr_zswap_protected); lru_size = list_lru_shrink_count(&zswap_list_lru, sc); /* * Abort if we are shrinking into the protected region. * * This short-circuiting is necessary because if we have too many multiple * concurrent reclaimers getting the freeable zswap object counts at the * same time (before any of them made reasonable progress), the total * number of reclaimed objects might be more than the number of unprotected * objects (i.e the reclaimers will reclaim into the protected area of the * zswap LRU). */ if (nr_protected >= lru_size - sc->nr_to_scan) { sc->nr_scanned = 0; return SHRINK_STOP; } shrink_ret = list_lru_shrink_walk(&zswap_list_lru, sc, &shrink_memcg_cb, &encountered_page_in_swapcache); if (encountered_page_in_swapcache) return SHRINK_STOP; return shrink_ret ? shrink_ret : SHRINK_STOP; } static unsigned long zswap_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc) { struct mem_cgroup *memcg = sc->memcg; struct lruvec *lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(sc->nid)); unsigned long nr_backing, nr_stored, nr_freeable, nr_protected; if (!zswap_shrinker_enabled || !mem_cgroup_zswap_writeback_enabled(memcg)) return 0; /* * The shrinker resumes swap writeback, which will enter block * and may enter fs. XXX: Harmonize with vmscan.c __GFP_FS * rules (may_enter_fs()), which apply on a per-folio basis. */ if (!gfp_has_io_fs(sc->gfp_mask)) return 0; /* * For memcg, use the cgroup-wide ZSWAP stats since we don't * have them per-node and thus per-lruvec. Careful if memcg is * runtime-disabled: we can get sc->memcg == NULL, which is ok * for the lruvec, but not for memcg_page_state(). * * Without memcg, use the zswap pool-wide metrics. */ if (!mem_cgroup_disabled()) { mem_cgroup_flush_stats(memcg); nr_backing = memcg_page_state(memcg, MEMCG_ZSWAP_B) >> PAGE_SHIFT; nr_stored = memcg_page_state(memcg, MEMCG_ZSWAPPED); } else { nr_backing = zswap_total_pages(); nr_stored = atomic_read(&zswap_stored_pages); } if (!nr_stored) return 0; nr_protected = atomic_long_read(&lruvec->zswap_lruvec_state.nr_zswap_protected); nr_freeable = list_lru_shrink_count(&zswap_list_lru, sc); /* * Subtract the lru size by an estimate of the number of pages * that should be protected. */ nr_freeable = nr_freeable > nr_protected ? nr_freeable - nr_protected : 0; /* * Scale the number of freeable pages by the memory saving factor. * This ensures that the better zswap compresses memory, the fewer * pages we will evict to swap (as it will otherwise incur IO for * relatively small memory saving). * * The memory saving factor calculated here takes same-filled pages into * account, but those are not freeable since they almost occupy no * space. Hence, we may scale nr_freeable down a little bit more than we * should if we have a lot of same-filled pages. */ return mult_frac(nr_freeable, nr_backing, nr_stored); } static struct shrinker *zswap_alloc_shrinker(void) { struct shrinker *shrinker; shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE, "mm-zswap"); if (!shrinker) return NULL; shrinker->scan_objects = zswap_shrinker_scan; shrinker->count_objects = zswap_shrinker_count; shrinker->batch = 0; shrinker->seeks = DEFAULT_SEEKS; return shrinker; } static int shrink_memcg(struct mem_cgroup *memcg) { int nid, shrunk = 0; if (!mem_cgroup_zswap_writeback_enabled(memcg)) return -EINVAL; /* * Skip zombies because their LRUs are reparented and we would be * reclaiming from the parent instead of the dead memcg. */ if (memcg && !mem_cgroup_online(memcg)) return -ENOENT; for_each_node_state(nid, N_NORMAL_MEMORY) { unsigned long nr_to_walk = 1; shrunk += list_lru_walk_one(&zswap_list_lru, nid, memcg, &shrink_memcg_cb, NULL, &nr_to_walk); } return shrunk ? 0 : -EAGAIN; } static void shrink_worker(struct work_struct *w) { struct mem_cgroup *memcg; int ret, failures = 0; unsigned long thr; /* Reclaim down to the accept threshold */ thr = zswap_accept_thr_pages(); /* global reclaim will select cgroup in a round-robin fashion. */ do { spin_lock(&zswap_shrink_lock); zswap_next_shrink = mem_cgroup_iter(NULL, zswap_next_shrink, NULL); memcg = zswap_next_shrink; /* * We need to retry if we have gone through a full round trip, or if we * got an offline memcg (or else we risk undoing the effect of the * zswap memcg offlining cleanup callback). This is not catastrophic * per se, but it will keep the now offlined memcg hostage for a while. * * Note that if we got an online memcg, we will keep the extra * reference in case the original reference obtained by mem_cgroup_iter * is dropped by the zswap memcg offlining callback, ensuring that the * memcg is not killed when we are reclaiming. */ if (!memcg) { spin_unlock(&zswap_shrink_lock); if (++failures == MAX_RECLAIM_RETRIES) break; goto resched; } if (!mem_cgroup_tryget_online(memcg)) { /* drop the reference from mem_cgroup_iter() */ mem_cgroup_iter_break(NULL, memcg); zswap_next_shrink = NULL; spin_unlock(&zswap_shrink_lock); if (++failures == MAX_RECLAIM_RETRIES) break; goto resched; } spin_unlock(&zswap_shrink_lock); ret = shrink_memcg(memcg); /* drop the extra reference */ mem_cgroup_put(memcg); if (ret == -EINVAL) break; if (ret && ++failures == MAX_RECLAIM_RETRIES) break; resched: cond_resched(); } while (zswap_total_pages() > thr); } /********************************* * same-filled functions **********************************/ static bool zswap_is_folio_same_filled(struct folio *folio, unsigned long *value) { unsigned long *data; unsigned long val; unsigned int pos, last_pos = PAGE_SIZE / sizeof(*data) - 1; bool ret = false; data = kmap_local_folio(folio, 0); val = data[0]; if (val != data[last_pos]) goto out; for (pos = 1; pos < last_pos; pos++) { if (val != data[pos]) goto out; } *value = val; ret = true; out: kunmap_local(data); return ret; } static void zswap_fill_folio(struct folio *folio, unsigned long value) { unsigned long *data = kmap_local_folio(folio, 0); memset_l(data, value, PAGE_SIZE / sizeof(unsigned long)); kunmap_local(data); } /********************************* * main API **********************************/ bool zswap_store(struct folio *folio) { swp_entry_t swp = folio->swap; pgoff_t offset = swp_offset(swp); struct xarray *tree = swap_zswap_tree(swp); struct zswap_entry *entry, *old; struct obj_cgroup *objcg = NULL; struct mem_cgroup *memcg = NULL; unsigned long value; 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) goto check_old; /* Check cgroup limits */ objcg = get_obj_cgroup_from_folio(folio); if (objcg && !obj_cgroup_may_zswap(objcg)) { memcg = get_mem_cgroup_from_objcg(objcg); if (shrink_memcg(memcg)) { mem_cgroup_put(memcg); goto reject; } mem_cgroup_put(memcg); } if (zswap_check_limits()) goto reject; /* allocate entry */ entry = zswap_entry_cache_alloc(GFP_KERNEL, folio_nid(folio)); if (!entry) { zswap_reject_kmemcache_fail++; goto reject; } if (zswap_is_folio_same_filled(folio, &value)) { entry->length = 0; entry->value = value; atomic_inc(&zswap_same_filled_pages); goto store_entry; } /* if entry is successfully added, it keeps the reference */ entry->pool = zswap_pool_current_get(); if (!entry->pool) goto freepage; if (objcg) { memcg = get_mem_cgroup_from_objcg(objcg); if (memcg_list_lru_alloc(memcg, &zswap_list_lru, GFP_KERNEL)) { mem_cgroup_put(memcg); goto put_pool; } mem_cgroup_put(memcg); } if (!zswap_compress(folio, entry)) goto put_pool; store_entry: entry->swpentry = swp; entry->objcg = objcg; old = xa_store(tree, offset, entry, GFP_KERNEL); if (xa_is_err(old)) { int err = xa_err(old); WARN_ONCE(err != -ENOMEM, "unexpected xarray error: %d\n", err); zswap_reject_alloc_fail++; goto store_failed; } /* * We may have had an existing entry that became stale when * the folio was redirtied and now the new version is being * swapped out. Get rid of the old. */ if (old) zswap_entry_free(old); if (objcg) { obj_cgroup_charge_zswap(objcg, entry->length); count_objcg_event(objcg, ZSWPOUT); } /* * We finish initializing the entry while it's already in xarray. * This is safe because: * * 1. Concurrent stores and invalidations are excluded by folio lock. * * 2. Writeback is excluded by the entry not being on the LRU yet. * The publishing order matters to prevent writeback from seeing * an incoherent entry. */ if (entry->length) { INIT_LIST_HEAD(&entry->lru); zswap_lru_add(&zswap_list_lru, entry); } /* update stats */ atomic_inc(&zswap_stored_pages); count_vm_event(ZSWPOUT); return true; store_failed: if (!entry->length) atomic_dec(&zswap_same_filled_pages); else { zpool_free(entry->pool->zpool, entry->handle); put_pool: zswap_pool_put(entry->pool); } freepage: zswap_entry_cache_free(entry); reject: obj_cgroup_put(objcg); if (zswap_pool_reached_full) queue_work(shrink_wq, &zswap_shrink_work); check_old: /* * If the zswap store fails or zswap is disabled, we must invalidate the * possibly stale entry which was previously stored at this offset. * Otherwise, writeback could overwrite the new data in the swapfile. */ entry = xa_erase(tree, offset); if (entry) zswap_entry_free(entry); return false; } bool zswap_load(struct folio *folio) { swp_entry_t swp = folio->swap; pgoff_t offset = swp_offset(swp); bool swapcache = folio_test_swapcache(folio); struct xarray *tree = swap_zswap_tree(swp); struct zswap_entry *entry; VM_WARN_ON_ONCE(!folio_test_locked(folio)); if (zswap_never_enabled()) return false; /* * Large folios should not be swapped in while zswap is being used, as * they are not properly handled. Zswap does not properly load large * folios, and a large folio may only be partially in zswap. * * Return true without marking the folio uptodate so that an IO error is * emitted (e.g. do_swap_page() will sigbus). */ if (WARN_ON_ONCE(folio_test_large(folio))) return true; /* * When reading into the swapcache, invalidate our entry. The * swapcache can be the authoritative owner of the page and * its mappings, and the pressure that results from having two * in-memory copies outweighs any benefits of caching the * compression work. * * (Most swapins go through the swapcache. The notable * exception is the singleton fault on SWP_SYNCHRONOUS_IO * files, which reads into a private page and may free it if * the fault fails. We remain the primary owner of the entry.) */ if (swapcache) entry = xa_erase(tree, offset); else entry = xa_load(tree, offset); if (!entry) return false; if (entry->length) zswap_decompress(entry, folio); else zswap_fill_folio(folio, entry->value); count_vm_event(ZSWPIN); if (entry->objcg) count_objcg_event(entry->objcg, ZSWPIN); if (swapcache) { zswap_entry_free(entry); folio_mark_dirty(folio); } folio_mark_uptodate(folio); return true; } void zswap_invalidate(swp_entry_t swp) { pgoff_t offset = swp_offset(swp); struct xarray *tree = swap_zswap_tree(swp); struct zswap_entry *entry; entry = xa_erase(tree, offset); if (entry) zswap_entry_free(entry); } int zswap_swapon(int type, unsigned long nr_pages) { struct xarray *trees, *tree; unsigned int nr, i; nr = DIV_ROUND_UP(nr_pages, SWAP_ADDRESS_SPACE_PAGES); trees = kvcalloc(nr, sizeof(*tree), GFP_KERNEL); if (!trees) { pr_err("alloc failed, zswap disabled for swap type %d\n", type); return -ENOMEM; } for (i = 0; i < nr; i++) xa_init(trees + i); nr_zswap_trees[type] = nr; zswap_trees[type] = trees; return 0; } void zswap_swapoff(int type) { struct xarray *trees = zswap_trees[type]; unsigned int i; if (!trees) return; /* try_to_unuse() invalidated all the entries already */ for (i = 0; i < nr_zswap_trees[type]; i++) WARN_ON_ONCE(!xa_empty(trees + i)); kvfree(trees); nr_zswap_trees[type] = 0; zswap_trees[type] = NULL; } /********************************* * debugfs functions **********************************/ #ifdef CONFIG_DEBUG_FS #include <linux/debugfs.h> static struct dentry *zswap_debugfs_root; static int debugfs_get_total_size(void *data, u64 *val) { *val = zswap_total_pages() * PAGE_SIZE; return 0; } DEFINE_DEBUGFS_ATTRIBUTE(total_size_fops, debugfs_get_total_size, NULL, "%llu\n"); 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_fail", 0444, zswap_debugfs_root, &zswap_reject_compress_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_file("pool_total_size", 0444, zswap_debugfs_root, NULL, &total_size_fops); 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_multi(CPUHP_MM_ZSWP_POOL_PREPARE, "mm/zswap_pool:prepare", zswap_cpu_comp_prepare, zswap_cpu_comp_dead); if (ret) goto hp_fail; shrink_wq = alloc_workqueue("zswap-shrink", WQ_UNBOUND|WQ_MEM_RECLAIM, 1); if (!shrink_wq) goto shrink_wq_fail; zswap_shrinker = zswap_alloc_shrinker(); if (!zswap_shrinker) goto shrinker_fail; if (list_lru_init_memcg(&zswap_list_lru, zswap_shrinker)) goto lru_fail; shrinker_register(zswap_shrinker); INIT_WORK(&zswap_shrink_work, shrink_worker); pool = __zswap_pool_create_fallback(); if (pool) { pr_info("loaded using pool %s/%s\n", pool->tfm_name, zpool_get_type(pool->zpool)); list_add(&pool->list, &zswap_pools); zswap_has_pool = true; static_branch_enable(&zswap_ever_enabled); } else { pr_err("pool creation failed\n"); zswap_enabled = false; } if (zswap_debugfs_init()) pr_warn("debugfs initialization failed\n"); zswap_init_state = ZSWAP_INIT_SUCCEED; return 0; lru_fail: shrinker_free(zswap_shrinker); shrinker_fail: destroy_workqueue(shrink_wq); shrink_wq_fail: cpuhp_remove_multi_state(CPUHP_MM_ZSWP_POOL_PREPARE); hp_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");
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