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-rw-r--r--mm/zswap.c1831
1 files changed, 882 insertions, 949 deletions
diff --git a/mm/zswap.c b/mm/zswap.c
index 69766f2c5a..6f8850c44b 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -71,8 +71,6 @@ static u64 zswap_reject_compress_poor;
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;
@@ -141,10 +139,6 @@ 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
@@ -168,6 +162,7 @@ struct crypto_acomp_ctx {
struct crypto_wait wait;
u8 *buffer;
struct mutex mutex;
+ bool is_sleepable;
};
/*
@@ -179,18 +174,24 @@ struct crypto_acomp_ctx {
struct zswap_pool {
struct zpool *zpools[ZSWAP_NR_ZPOOLS];
struct crypto_acomp_ctx __percpu *acomp_ctx;
- struct kref kref;
+ struct percpu_ref ref;
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_lru list_lru;
- struct mem_cgroup *next_shrink;
- struct shrinker *shrinker;
- atomic_t nr_stored;
};
+/* Global LRU lists shared by all zswap pools. */
+static struct list_lru zswap_list_lru;
+/* counter of pages stored in all zswap pools. */
+static atomic_t zswap_nr_stored = ATOMIC_INIT(0);
+
+/* 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
*
@@ -199,12 +200,6 @@ struct zswap_pool {
*
* 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.
@@ -217,7 +212,6 @@ struct zswap_pool {
struct zswap_entry {
struct rb_node rbnode;
swp_entry_t swpentry;
- int refcount;
unsigned int length;
struct zswap_pool *pool;
union {
@@ -228,17 +222,13 @@ struct zswap_entry {
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];
+static unsigned int nr_zswap_trees[MAX_SWAPFILES];
/* RCU-protected iteration */
static LIST_HEAD(zswap_pools);
@@ -265,15 +255,16 @@ static bool zswap_has_pool;
* helpers and fwd declarations
**********************************/
+static inline struct zswap_tree *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)->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 <
@@ -313,717 +304,10 @@ static void zswap_update_total_size(void)
zswap_pool_total_size = total;
}
-/* 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));
-}
-
-void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg)
-{
- struct zswap_pool *pool;
-
- /* lock out zswap pools list modification */
- spin_lock(&zswap_pools_lock);
- list_for_each_entry(pool, &zswap_pools, list) {
- if (pool->next_shrink == memcg)
- pool->next_shrink = mem_cgroup_iter(NULL, pool->next_shrink, NULL);
- }
- spin_unlock(&zswap_pools_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;
- 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);
-}
-
-/*********************************
-* zswap lruvec functions
-**********************************/
-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;
-
- VM_WARN_ON_ONCE(!folio_test_locked(folio));
- lruvec = folio_lruvec(folio);
- atomic_long_inc(&lruvec->zswap_lruvec_state.nr_zswap_protected);
-}
-
-/*********************************
-* lru functions
-**********************************/
-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() and list_lru_putback().
- */
- 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();
-}
-
-static void zswap_lru_putback(struct list_lru *list_lru,
- struct zswap_entry *entry)
-{
- int nid = entry_to_nid(entry);
- spinlock_t *lock = &list_lru->node[nid].lock;
- struct mem_cgroup *memcg;
- struct lruvec *lruvec;
-
- rcu_read_lock();
- memcg = mem_cgroup_from_entry(entry);
- spin_lock(lock);
- /* we cannot use list_lru_add here, because it increments node's lru count */
- list_lru_putback(list_lru, &entry->lru, nid, memcg);
- spin_unlock(lock);
-
- lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(entry_to_nid(entry)));
- /* increment the protection area to account for the LRU rotation. */
- atomic_long_inc(&lruvec->zswap_lruvec_state.nr_zswap_protected);
- rcu_read_unlock();
-}
-
-/*********************************
-* 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->length)
- atomic_dec(&zswap_same_filled_pages);
- else {
- zswap_lru_del(&entry->pool->list_lru, entry);
- zpool_free(zswap_find_zpool(entry), entry->handle);
- atomic_dec(&entry->pool->nr_stored);
- 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);
- 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;
-}
-
-/*********************************
-* shrinker functions
-**********************************/
-static enum lru_status shrink_memcg_cb(struct list_head *item, struct list_lru_one *l,
- spinlock_t *lock, void *arg);
-
-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;
- struct zswap_pool *pool = shrinker->private_data;
- 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(&pool->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(&pool->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 zswap_pool *pool = shrinker->private_data;
- 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 = get_zswap_pool_size(pool) >> PAGE_SHIFT;
- nr_stored = atomic_read(&pool->nr_stored);
- }
-
- if (!nr_stored)
- return 0;
-
- nr_protected =
- atomic_long_read(&lruvec->zswap_lruvec_state.nr_zswap_protected);
- nr_freeable = list_lru_shrink_count(&pool->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).
- */
- return mult_frac(nr_freeable, nr_backing, nr_stored);
-}
-
-static void zswap_alloc_shrinker(struct zswap_pool *pool)
-{
- pool->shrinker =
- shrinker_alloc(SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE, "mm-zswap");
- if (!pool->shrinker)
- return;
-
- pool->shrinker->private_data = pool;
- pool->shrinker->scan_objects = zswap_shrinker_scan;
- pool->shrinker->count_objects = zswap_shrinker_count;
- pool->shrinker->batch = 0;
- pool->shrinker->seeks = DEFAULT_SEEKS;
-}
-
-/*********************************
-* per-cpu code
-**********************************/
-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;
-
- 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;
-}
-
/*********************************
* 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 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;
- struct zswap_tree *tree;
- pgoff_t swpoffset;
- enum lru_status ret = LRU_REMOVED_RETRY;
- int writeback_result;
-
- /*
- * 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)];
- list_lru_isolate(l, item);
- /*
- * It's safe to drop the lock here because we return either
- * LRU_REMOVED_RETRY or LRU_RETRY.
- */
- spin_unlock(lock);
-
- /* Check for invalidate() race */
- spin_lock(&tree->lock);
- if (entry != zswap_rb_search(&tree->rbroot, swpoffset))
- goto unlock;
-
- /* Hold a reference to prevent a free during writeback */
- zswap_entry_get(entry);
- spin_unlock(&tree->lock);
-
- writeback_result = zswap_writeback_entry(entry, tree);
-
- spin_lock(&tree->lock);
- if (writeback_result) {
- zswap_reject_reclaim_fail++;
- zswap_lru_putback(&entry->pool->list_lru, entry);
- 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)
- *encountered_page_in_swapcache = true;
-
- goto put_unlock;
- }
- zswap_written_back_pages++;
-
- if (entry->objcg)
- count_objcg_event(entry->objcg, ZSWPWB);
-
- count_vm_event(ZSWPWB);
- /*
- * 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);
- spin_lock(lock);
- return ret;
-}
-
-static int shrink_memcg(struct mem_cgroup *memcg)
-{
- struct zswap_pool *pool;
- 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;
-
- pool = zswap_pool_current_get();
- if (!pool)
- return -EINVAL;
-
- for_each_node_state(nid, N_NORMAL_MEMORY) {
- unsigned long nr_to_walk = 1;
-
- shrunk += list_lru_walk_one(&pool->list_lru, nid, memcg,
- &shrink_memcg_cb, NULL, &nr_to_walk);
- }
- zswap_pool_put(pool);
- return shrunk ? 0 : -EAGAIN;
-}
-
-static void shrink_worker(struct work_struct *w)
-{
- struct zswap_pool *pool = container_of(w, typeof(*pool),
- shrink_work);
- struct mem_cgroup *memcg;
- int ret, failures = 0;
-
- /* global reclaim will select cgroup in a round-robin fashion. */
- do {
- spin_lock(&zswap_pools_lock);
- pool->next_shrink = mem_cgroup_iter(NULL, pool->next_shrink, NULL);
- memcg = pool->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_pools_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);
- pool->next_shrink = NULL;
- spin_unlock(&zswap_pools_lock);
-
- if (++failures == MAX_RECLAIM_RETRIES)
- break;
-
- goto resched;
- }
- spin_unlock(&zswap_pools_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_can_accept());
- zswap_pool_put(pool);
-}
+static void __zswap_pool_empty(struct percpu_ref *ref);
static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
{
@@ -1074,30 +358,21 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
if (ret)
goto error;
- zswap_alloc_shrinker(pool);
- if (!pool->shrinker)
- 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);
+ 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);
- if (list_lru_init_memcg(&pool->list_lru, pool->shrinker))
- goto lru_fail;
- shrinker_register(pool->shrinker);
- INIT_WORK(&pool->shrink_work, shrink_worker);
- atomic_set(&pool->nr_stored, 0);
zswap_pool_debug("created", pool);
return pool;
-lru_fail:
- list_lru_destroy(&pool->list_lru);
- shrinker_free(pool->shrinker);
+ref_fail:
+ cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
error:
if (pool->acomp_ctx)
free_percpu(pool->acomp_ctx);
@@ -1155,29 +430,14 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
zswap_pool_debug("destroying", pool);
- shrinker_free(pool->shrinker);
cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
free_percpu(pool->acomp_ctx);
- list_lru_destroy(&pool->list_lru);
-
- spin_lock(&zswap_pools_lock);
- mem_cgroup_iter_break(NULL, pool->next_shrink);
- pool->next_shrink = NULL;
- spin_unlock(&zswap_pools_lock);
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),
@@ -1185,20 +445,23 @@ static void __zswap_pool_release(struct work_struct *work)
synchronize_rcu();
- /* nobody should have been able to get a kref... */
- WARN_ON(kref_get_unless_zero(&pool->kref));
+ /* 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 void __zswap_pool_empty(struct kref *kref)
+static struct zswap_pool *zswap_pool_current(void);
+
+static void __zswap_pool_empty(struct percpu_ref *ref)
{
struct zswap_pool *pool;
- pool = container_of(kref, typeof(*pool), kref);
+ pool = container_of(ref, typeof(*pool), ref);
- spin_lock(&zswap_pools_lock);
+ spin_lock_bh(&zswap_pools_lock);
WARN_ON(pool == zswap_pool_current());
@@ -1207,12 +470,75 @@ static void __zswap_pool_empty(struct kref *kref)
INIT_WORK(&pool->release_work, __zswap_pool_release);
schedule_work(&pool->release_work);
- spin_unlock(&zswap_pools_lock);
+ 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)
{
- kref_put(&pool->kref, __zswap_pool_empty);
+ 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;
+ /* 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;
}
/*********************************
@@ -1274,7 +600,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
return -EINVAL;
}
- spin_lock(&zswap_pools_lock);
+ spin_lock_bh(&zswap_pools_lock);
pool = zswap_pool_find_get(type, compressor);
if (pool) {
@@ -1283,17 +609,28 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
list_del_rcu(&pool->list);
}
- spin_unlock(&zswap_pools_lock);
+ 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(&zswap_pools_lock);
+ spin_lock_bh(&zswap_pools_lock);
if (!ret) {
put_pool = zswap_pool_current();
@@ -1308,7 +645,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
put_pool = pool;
}
- spin_unlock(&zswap_pools_lock);
+ spin_unlock_bh(&zswap_pools_lock);
if (!zswap_has_pool && !pool) {
/* if initial pool creation failed, and this pool creation also
@@ -1325,7 +662,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
* or the new pool we failed to add
*/
if (put_pool)
- zswap_pool_put(put_pool);
+ percpu_ref_kill(&put_pool->ref);
return ret;
}
@@ -1371,7 +708,368 @@ static int zswap_enabled_param_set(const char *val,
return ret;
}
-static void __zswap_load(struct zswap_entry *entry, struct page *page)
+/*********************************
+* 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);
+}
+
+/*********************************
+* 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 void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
+{
+ rb_erase(&entry->rbnode, root);
+ RB_CLEAR_NODE(&entry->rbnode);
+}
+
+/*********************************
+* 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;
+ RB_CLEAR_NODE(&entry->rbnode);
+ return entry;
+}
+
+static void zswap_entry_cache_free(struct zswap_entry *entry)
+{
+ kmem_cache_free(zswap_entry_cache, entry);
+}
+
+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_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(zswap_find_zpool(entry), entry->handle);
+ atomic_dec(&zswap_nr_stored);
+ 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);
+ zswap_update_total_size();
+}
+
+/*
+ * The caller hold the tree lock and search the entry from the tree,
+ * so it must be on the tree, remove it from the tree and free it.
+ */
+static void zswap_invalidate_entry(struct zswap_tree *tree,
+ struct zswap_entry *entry)
+{
+ zswap_rb_erase(&tree->rbroot, entry);
+ zswap_entry_free(entry);
+}
+
+/*********************************
+* 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_page(&input, &folio->page, 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 = zswap_find_zpool(entry);
+ 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 page *page)
{
struct zpool *zpool = zswap_find_zpool(entry);
struct scatterlist input, output;
@@ -1382,7 +1080,17 @@ static void __zswap_load(struct zswap_entry *entry, struct page *page)
mutex_lock(&acomp_ctx->mutex);
src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
- if (!zpool_can_sleep_mapped(zpool)) {
+ /*
+ * 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);
@@ -1396,7 +1104,7 @@ static void __zswap_load(struct zswap_entry *entry, struct page *page)
BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE);
mutex_unlock(&acomp_ctx->mutex);
- if (zpool_can_sleep_mapped(zpool))
+ if (src != acomp_ctx->buffer)
zpool_unmap_handle(zpool, entry->handle);
}
@@ -1416,9 +1124,9 @@ static void __zswap_load(struct zswap_entry *entry, struct page *page)
* freed.
*/
static int zswap_writeback_entry(struct zswap_entry *entry,
- struct zswap_tree *tree)
+ swp_entry_t swpentry)
{
- swp_entry_t swpentry = entry->swpentry;
+ struct zswap_tree *tree;
struct folio *folio;
struct mempolicy *mpol;
bool folio_was_allocated;
@@ -1434,9 +1142,11 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
return -ENOMEM;
/*
- * Found an existing folio, we raced with load/swapin. We generally
- * writeback cold folios from zswap, and swapin means the folio just
- * became hot. Skip this folio and let the caller find another one.
+ * 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);
@@ -1445,22 +1155,34 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
/*
* folio 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 folio with old compressed data.
+ * 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);
spin_lock(&tree->lock);
- if (zswap_rb_search(&tree->rbroot, swp_offset(entry->swpentry)) != entry) {
+ if (zswap_rb_search(&tree->rbroot, swp_offset(swpentry)) != entry) {
spin_unlock(&tree->lock);
delete_from_swap_cache(folio);
folio_unlock(folio);
folio_put(folio);
return -ENOMEM;
}
+
+ /* Safe to deref entry after the entry is verified above. */
+ zswap_rb_erase(&tree->rbroot, entry);
spin_unlock(&tree->lock);
- __zswap_load(entry, &folio->page);
+ zswap_decompress(entry, &folio->page);
+
+ 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);
@@ -1475,6 +1197,274 @@ static int zswap_writeback_entry(struct zswap_entry *entry,
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_pool_total_size >> PAGE_SHIFT;
+ nr_stored = atomic_read(&zswap_nr_stored);
+ }
+
+ 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).
+ */
+ 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;
+
+ /* 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_can_accept());
+}
+
static int zswap_is_page_same_filled(void *ptr, unsigned long *value)
{
unsigned long *page;
@@ -1508,23 +1498,11 @@ static void zswap_fill_page(void *ptr, unsigned long value)
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_tree *tree = swap_zswap_tree(swp);
struct zswap_entry *entry, *dupentry;
- struct scatterlist input, output;
- struct crypto_acomp_ctx *acomp_ctx;
struct obj_cgroup *objcg = NULL;
struct mem_cgroup *memcg = 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));
@@ -1533,24 +1511,8 @@ bool zswap_store(struct folio *folio)
if (folio_test_large(folio))
return false;
- if (!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);
-
if (!zswap_enabled)
- return false;
+ goto check_old;
objcg = get_obj_cgroup_from_folio(folio);
if (objcg && !obj_cgroup_may_zswap(objcg)) {
@@ -1577,17 +1539,19 @@ bool zswap_store(struct folio *folio)
}
/* allocate entry */
- entry = zswap_entry_cache_alloc(GFP_KERNEL, page_to_nid(page));
+ entry = zswap_entry_cache_alloc(GFP_KERNEL, folio_nid(folio));
if (!entry) {
zswap_reject_kmemcache_fail++;
goto reject;
}
if (zswap_same_filled_pages_enabled) {
- src = kmap_local_page(page);
+ unsigned long value;
+ u8 *src;
+
+ src = kmap_local_folio(folio, 0);
if (zswap_is_page_same_filled(src, &value)) {
kunmap_local(src);
- entry->swpentry = swp_entry(type, offset);
entry->length = 0;
entry->value = value;
atomic_inc(&zswap_same_filled_pages);
@@ -1606,74 +1570,18 @@ bool zswap_store(struct folio *folio)
if (objcg) {
memcg = get_mem_cgroup_from_objcg(objcg);
- if (memcg_list_lru_alloc(memcg, &entry->pool->list_lru, GFP_KERNEL)) {
+ if (memcg_list_lru_alloc(memcg, &zswap_list_lru, GFP_KERNEL)) {
mem_cgroup_put(memcg);
goto put_pool;
}
mem_cgroup_put(memcg);
}
- /* compress */
- 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_page(&input, &folio->page, 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.
- */
- ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
- dlen = acomp_ctx->req->dlen;
-
- if (ret) {
- zswap_reject_compress_fail++;
- 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;
+ if (!zswap_compress(folio, entry))
+ goto put_pool;
insert_entry:
+ entry->swpentry = swp;
entry->objcg = objcg;
if (objcg) {
obj_cgroup_charge_zswap(objcg, entry->length);
@@ -1684,20 +1592,17 @@ insert_entry:
/* 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.
+ * The folio may have been dirtied again, invalidate the
+ * possibly stale entry before inserting the new entry.
*/
- while (zswap_rb_insert(&tree->rbroot, entry, &dupentry) == -EEXIST) {
- WARN_ON(1);
- zswap_duplicate_entry++;
+ if (zswap_rb_insert(&tree->rbroot, entry, &dupentry) == -EEXIST) {
zswap_invalidate_entry(tree, dupentry);
+ WARN_ON(zswap_rb_insert(&tree->rbroot, entry, &dupentry));
}
if (entry->length) {
INIT_LIST_HEAD(&entry->lru);
- zswap_lru_add(&entry->pool->list_lru, entry);
- atomic_inc(&entry->pool->nr_stored);
+ zswap_lru_add(&zswap_list_lru, entry);
+ atomic_inc(&zswap_nr_stored);
}
spin_unlock(&tree->lock);
@@ -1708,8 +1613,6 @@ insert_entry:
return true;
-put_dstmem:
- mutex_unlock(&acomp_ctx->mutex);
put_pool:
zswap_pool_put(entry->pool);
freepage:
@@ -1717,38 +1620,60 @@ freepage:
reject:
if (objcg)
obj_cgroup_put(objcg);
+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.
+ */
+ spin_lock(&tree->lock);
+ entry = zswap_rb_search(&tree->rbroot, offset);
+ if (entry)
+ zswap_invalidate_entry(tree, entry);
+ spin_unlock(&tree->lock);
return false;
shrink:
- pool = zswap_pool_last_get();
- if (pool && !queue_work(shrink_wq, &pool->shrink_work))
- zswap_pool_put(pool);
+ queue_work(shrink_wq, &zswap_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];
+ bool swapcache = folio_test_swapcache(folio);
+ struct zswap_tree *tree = swap_zswap_tree(swp);
struct zswap_entry *entry;
u8 *dst;
VM_WARN_ON_ONCE(!folio_test_locked(folio));
- /* find */
spin_lock(&tree->lock);
- entry = zswap_entry_find_get(&tree->rbroot, offset);
+ entry = zswap_rb_search(&tree->rbroot, offset);
if (!entry) {
spin_unlock(&tree->lock);
return false;
}
+ /*
+ * 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)
+ zswap_rb_erase(&tree->rbroot, entry);
spin_unlock(&tree->lock);
if (entry->length)
- __zswap_load(entry, page);
+ zswap_decompress(entry, page);
else {
dst = kmap_local_page(page);
zswap_fill_page(dst, entry->value);
@@ -1759,67 +1684,64 @@ bool zswap_load(struct folio *folio)
if (entry->objcg)
count_objcg_event(entry->objcg, ZSWPIN);
- spin_lock(&tree->lock);
- if (zswap_exclusive_loads_enabled) {
- zswap_invalidate_entry(tree, entry);
+ if (swapcache) {
+ zswap_entry_free(entry);
folio_mark_dirty(folio);
- } else if (entry->length) {
- zswap_lru_del(&entry->pool->list_lru, entry);
- zswap_lru_add(&entry->pool->list_lru, entry);
}
- zswap_entry_put(tree, entry);
- spin_unlock(&tree->lock);
return true;
}
-void zswap_invalidate(int type, pgoff_t offset)
+void zswap_invalidate(swp_entry_t swp)
{
- struct zswap_tree *tree = zswap_trees[type];
+ pgoff_t offset = swp_offset(swp);
+ struct zswap_tree *tree = swap_zswap_tree(swp);
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);
+ if (entry)
+ zswap_invalidate_entry(tree, entry);
spin_unlock(&tree->lock);
}
-void zswap_swapon(int type)
+int zswap_swapon(int type, unsigned long nr_pages)
{
- struct zswap_tree *tree;
+ struct zswap_tree *trees, *tree;
+ unsigned int nr, i;
- tree = kzalloc(sizeof(*tree), GFP_KERNEL);
- if (!tree) {
+ 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;
+ return -ENOMEM;
}
- tree->rbroot = RB_ROOT;
- spin_lock_init(&tree->lock);
- zswap_trees[type] = tree;
+ for (i = 0; i < nr; i++) {
+ tree = trees + i;
+ tree->rbroot = RB_ROOT;
+ spin_lock_init(&tree->lock);
+ }
+
+ nr_zswap_trees[type] = nr;
+ zswap_trees[type] = trees;
+ return 0;
}
void zswap_swapoff(int type)
{
- struct zswap_tree *tree = zswap_trees[type];
- struct zswap_entry *entry, *n;
+ struct zswap_tree *trees = zswap_trees[type];
+ unsigned int i;
- if (!tree)
+ if (!trees)
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);
+ /* try_to_unuse() invalidated all the entries already */
+ for (i = 0; i < nr_zswap_trees[type]; i++)
+ WARN_ON_ONCE(!RB_EMPTY_ROOT(&trees[i].rbroot));
+
+ kvfree(trees);
+ nr_zswap_trees[type] = 0;
zswap_trees[type] = NULL;
}
@@ -1852,8 +1774,6 @@ static int zswap_debugfs_init(void)
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,
@@ -1891,6 +1811,20 @@ static int zswap_setup(void)
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,
@@ -1902,18 +1836,17 @@ static int zswap_setup(void)
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);
+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: