zswap: dynamic pool creation

Add dynamic creation of pools.  Move the static crypto compression per-cpu
transforms into each pool.  Add a pointer to zswap_entry to the pool it's
in.

This is required by the following patch which enables changing the zswap
zpool and compressor params at runtime.

[akpm@linux-foundation.org: fix merge snafus]
Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Acked-by: Seth Jennings <sjennings@variantweb.net>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 405 insertions, 143 deletions

diff --git a/mm/zswap.c b/mm/zswap.c
index 48a1d081e2a5..f9ba9bb1c1b8 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -99,66 +99,19 @@ module_param_named(zpool, zswap_zpool_type, charp, 0444);
 static struct zpool *zswap_pool;
 
 /*********************************
-* compression functions
+* data structures
 **********************************/
-/* per-cpu compression transforms */
-static struct crypto_comp * __percpu *zswap_comp_pcpu_tfms;
 
-enum comp_op {
-        ZSWAP_COMPOP_COMPRESS,
-        ZSWAP_COMPOP_DECOMPRESS
+struct zswap_pool {
+        struct zpool *zpool;
+        struct crypto_comp * __percpu *tfm;
+        struct kref kref;
+        struct list_head list;
+        struct rcu_head rcu_head;
+        struct notifier_block notifier;
+        char tfm_name[CRYPTO_MAX_ALG_NAME];
 };
 
-static int zswap_comp_op(enum comp_op op, const u8 *src, unsigned int slen,
-                                u8 *dst, unsigned int *dlen)
-{
-        struct crypto_comp *tfm;
-        int ret;
-
-        tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, get_cpu());
-        switch (op) {
-        case ZSWAP_COMPOP_COMPRESS:
-                ret = crypto_comp_compress(tfm, src, slen, dst, dlen);
-                break;
-        case ZSWAP_COMPOP_DECOMPRESS:
-                ret = crypto_comp_decompress(tfm, src, slen, dst, dlen);
-                break;
-        default:
-                ret = -EINVAL;
-        }
-
-        put_cpu();
-        return ret;
-}
-
-static int __init zswap_comp_init(void)
-{
-        if (!crypto_has_comp(zswap_compressor, 0, 0)) {
-                pr_info("%s compressor not available\n", zswap_compressor);
-                /* fall back to default compressor */
-                zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
-                if (!crypto_has_comp(zswap_compressor, 0, 0))
-                        /* can't even load the default compressor */
-                        return -ENODEV;
-        }
-        pr_info("using %s compressor\n", zswap_compressor);
-
-        /* alloc percpu transforms */
-        zswap_comp_pcpu_tfms = alloc_percpu(struct crypto_comp *);
-        if (!zswap_comp_pcpu_tfms)
-                return -ENOMEM;
-        return 0;
-}
-
-static void __init zswap_comp_exit(void)
-{
-        /* free percpu transforms */
-        free_percpu(zswap_comp_pcpu_tfms);
-}
-
-/*********************************
-* data structures
-**********************************/
 /*
  * struct zswap_entry
  *
@@ -166,22 +119,24 @@ static void __init zswap_comp_exit(void)
  * page within zswap.
  *
  * rbnode - links the entry into red-black tree for the appropriate swap type
+ * offset - the swap offset for the entry.  Index 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.
- * offset - the swap offset for the entry.  Index into the red-black tree.
- * handle - zpool allocation handle that stores the compressed page data
  * length - the length in bytes of the compressed page data.  Needed during
  *          decompression
+ * pool - the zswap_pool the entry's data is in
+ * handle - zpool allocation handle that stores the compressed page data
  */
 struct zswap_entry {
         struct rb_node rbnode;
         pgoff_t offset;
         int refcount;
         unsigned int length;
+        struct zswap_pool *pool;
         unsigned long handle;
 };
 
@@ -201,6 +156,48 @@ struct zswap_tree {
 
 static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
 
+/* RCU-protected iteration */
+static LIST_HEAD(zswap_pools);
+/* protects zswap_pools list modification */
+static DEFINE_SPINLOCK(zswap_pools_lock);
+
+/*********************************
+* helpers and fwd declarations
+**********************************/
+
+#define zswap_pool_debug(msg, p)                                \
+        pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name,         \
+                 zpool_get_type((p)->zpool))
+
+static int zswap_writeback_entry(struct zpool *pool, unsigned long handle);
+static int zswap_pool_get(struct zswap_pool *pool);
+static void zswap_pool_put(struct zswap_pool *pool);
+
+static const struct zpool_ops zswap_zpool_ops = {
+        .evict = zswap_writeback_entry
+};
+
+static bool zswap_is_full(void)
+{
+        return totalram_pages * zswap_max_pool_percent / 100 <
+                DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
+}
+
+static void zswap_update_total_size(void)
+{
+        struct zswap_pool *pool;
+        u64 total = 0;
+
+        rcu_read_lock();
+
+        list_for_each_entry_rcu(pool, &zswap_pools, list)
+                total += zpool_get_total_size(pool->zpool);
+
+        rcu_read_unlock();
+
+        zswap_pool_total_size = total;
+}
+
 /*********************************
 * zswap entry functions
 **********************************/
@@ -294,10 +291,11 @@ static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
  */
 static void zswap_free_entry(struct zswap_entry *entry)
 {
-        zpool_free(zswap_pool, entry->handle);
+        zpool_free(entry->pool->zpool, entry->handle);
+        zswap_pool_put(entry->pool);
         zswap_entry_cache_free(entry);
         atomic_dec(&zswap_stored_pages);
-        zswap_pool_total_size = zpool_get_total_size(zswap_pool);
+        zswap_update_total_size();
 }
 
 /* caller must hold the tree lock */
@@ -339,35 +337,21 @@ static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
 **********************************/
 static DEFINE_PER_CPU(u8 *, zswap_dstmem);
 
-static int __zswap_cpu_notifier(unsigned long action, unsigned long cpu)
+static int __zswap_cpu_dstmem_notifier(unsigned long action, unsigned long cpu)
 {
-        struct crypto_comp *tfm;
         u8 *dst;
 
         switch (action) {
         case CPU_UP_PREPARE:
-                tfm = crypto_alloc_comp(zswap_compressor, 0, 0);
-                if (IS_ERR(tfm)) {
-                        pr_err("can't allocate compressor transform\n");
-                        return NOTIFY_BAD;
-                }
-                *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = tfm;
                 dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
                 if (!dst) {
                         pr_err("can't allocate compressor buffer\n");
-                        crypto_free_comp(tfm);
-                        *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL;
                         return NOTIFY_BAD;
                 }
                 per_cpu(zswap_dstmem, cpu) = dst;
                 break;
         case CPU_DEAD:
         case CPU_UP_CANCELED:
-                tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu);
-                if (tfm) {
-                        crypto_free_comp(tfm);
-                        *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL;
-                }
                 dst = per_cpu(zswap_dstmem, cpu);
                 kfree(dst);
                 per_cpu(zswap_dstmem, cpu) = NULL;
@@ -378,43 +362,303 @@ static int __zswap_cpu_notifier(unsigned long action, unsigned long cpu)
         return NOTIFY_OK;
 }
 
-static int zswap_cpu_notifier(struct notifier_block *nb,
-                                unsigned long action, void *pcpu)
+static int zswap_cpu_dstmem_notifier(struct notifier_block *nb,
+                                     unsigned long action, void *pcpu)
 {
-        unsigned long cpu = (unsigned long)pcpu;
-        return __zswap_cpu_notifier(action, cpu);
+        return __zswap_cpu_dstmem_notifier(action, (unsigned long)pcpu);
 }
 
-static struct notifier_block zswap_cpu_notifier_block = {
-        .notifier_call = zswap_cpu_notifier
+static struct notifier_block zswap_dstmem_notifier = {
+        .notifier_call =        zswap_cpu_dstmem_notifier,
 };
 
-static int __init zswap_cpu_init(void)
+static int __init zswap_cpu_dstmem_init(void)
+{
+        unsigned long cpu;
+
+        cpu_notifier_register_begin();
+        for_each_online_cpu(cpu)
+                if (__zswap_cpu_dstmem_notifier(CPU_UP_PREPARE, cpu) ==
+                    NOTIFY_BAD)
+                        goto cleanup;
+        __register_cpu_notifier(&zswap_dstmem_notifier);
+        cpu_notifier_register_done();
+        return 0;
+
+cleanup:
+        for_each_online_cpu(cpu)
+                __zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu);
+        cpu_notifier_register_done();
+        return -ENOMEM;
+}
+
+static void zswap_cpu_dstmem_destroy(void)
+{
+        unsigned long cpu;
+
+        cpu_notifier_register_begin();
+        for_each_online_cpu(cpu)
+                __zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu);
+        __unregister_cpu_notifier(&zswap_dstmem_notifier);
+        cpu_notifier_register_done();
+}
+
+static int __zswap_cpu_comp_notifier(struct zswap_pool *pool,
+                                     unsigned long action, unsigned long cpu)
+{
+        struct crypto_comp *tfm;
+
+        switch (action) {
+        case CPU_UP_PREPARE:
+                if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
+                        break;
+                tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
+                if (IS_ERR_OR_NULL(tfm)) {
+                        pr_err("could not alloc crypto comp %s : %ld\n",
+                               pool->tfm_name, PTR_ERR(tfm));
+                        return NOTIFY_BAD;
+                }
+                *per_cpu_ptr(pool->tfm, cpu) = tfm;
+                break;
+        case CPU_DEAD:
+        case CPU_UP_CANCELED:
+                tfm = *per_cpu_ptr(pool->tfm, cpu);
+                if (!IS_ERR_OR_NULL(tfm))
+                        crypto_free_comp(tfm);
+                *per_cpu_ptr(pool->tfm, cpu) = NULL;
+                break;
+        default:
+                break;
+        }
+        return NOTIFY_OK;
+}
+
+static int zswap_cpu_comp_notifier(struct notifier_block *nb,
+                                   unsigned long action, void *pcpu)
+{
+        unsigned long cpu = (unsigned long)pcpu;
+        struct zswap_pool *pool = container_of(nb, typeof(*pool), notifier);
+
+        return __zswap_cpu_comp_notifier(pool, action, cpu);
+}
+
+static int zswap_cpu_comp_init(struct zswap_pool *pool)
 {
         unsigned long cpu;
 
+        memset(&pool->notifier, 0, sizeof(pool->notifier));
+        pool->notifier.notifier_call = zswap_cpu_comp_notifier;
+
         cpu_notifier_register_begin();
         for_each_online_cpu(cpu)
-                if (__zswap_cpu_notifier(CPU_UP_PREPARE, cpu) != NOTIFY_OK)
+                if (__zswap_cpu_comp_notifier(pool, CPU_UP_PREPARE, cpu) ==
+                    NOTIFY_BAD)
                         goto cleanup;
-        __register_cpu_notifier(&zswap_cpu_notifier_block);
+        __register_cpu_notifier(&pool->notifier);
         cpu_notifier_register_done();
         return 0;
 
 cleanup:
         for_each_online_cpu(cpu)
-                __zswap_cpu_notifier(CPU_UP_CANCELED, cpu);
+                __zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu);
         cpu_notifier_register_done();
         return -ENOMEM;
 }
 
+static void zswap_cpu_comp_destroy(struct zswap_pool *pool)
+{
+        unsigned long cpu;
+
+        cpu_notifier_register_begin();
+        for_each_online_cpu(cpu)
+                __zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu);
+        __unregister_cpu_notifier(&pool->notifier);
+        cpu_notifier_register_done();
+}
+
 /*********************************
-* helpers
+* pool functions
 **********************************/
-static bool zswap_is_full(void)
+
+static struct zswap_pool *__zswap_pool_current(void)
 {
-        return totalram_pages * zswap_max_pool_percent / 100 <
-                DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
+        struct zswap_pool *pool;
+
+        pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);
+        WARN_ON(!pool);
+
+        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 (!pool || !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;
+        if (!WARN_ON(!last) && !zswap_pool_get(last))
+                last = NULL;
+
+        rcu_read_unlock();
+
+        return last;
+}
+
+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 (strncmp(pool->tfm_name, compressor, sizeof(pool->tfm_name)))
+                        continue;
+                if (strncmp(zpool_get_type(pool->zpool), type,
+                            sizeof(zswap_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 struct zswap_pool *zswap_pool_create(char *type, char *compressor)
+{
+        struct zswap_pool *pool;
+        gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN;
+
+        pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+        if (!pool) {
+                pr_err("pool alloc failed\n");
+                return NULL;
+        }
+
+        pool->zpool = zpool_create_pool(type, "zswap", gfp, &zswap_zpool_ops);
+        if (!pool->zpool) {
+                pr_err("%s zpool not available\n", type);
+                goto error;
+        }
+        pr_debug("using %s zpool\n", zpool_get_type(pool->zpool));
+
+        strlcpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
+        pool->tfm = alloc_percpu(struct crypto_comp *);
+        if (!pool->tfm) {
+                pr_err("percpu alloc failed\n");
+                goto error;
+        }
+
+        if (zswap_cpu_comp_init(pool))
+                goto error;
+        pr_debug("using %s compressor\n", pool->tfm_name);
+
+        /* being the current pool takes 1 ref; this func expects the
+         * caller to always add the new pool as the current pool
+         */
+        kref_init(&pool->kref);
+        INIT_LIST_HEAD(&pool->list);
+
+        zswap_pool_debug("created", pool);
+
+        return pool;
+
+error:
+        free_percpu(pool->tfm);
+        if (pool->zpool)
+                zpool_destroy_pool(pool->zpool);
+        kfree(pool);
+        return NULL;
+}
+
+static struct zswap_pool *__zswap_pool_create_fallback(void)
+{
+        if (!crypto_has_comp(zswap_compressor, 0, 0)) {
+                pr_err("compressor %s not available, using default %s\n",
+                       zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT);
+                strncpy(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT,
+                        sizeof(zswap_compressor));
+        }
+        if (!zpool_has_pool(zswap_zpool_type)) {
+                pr_err("zpool %s not available, using default %s\n",
+                       zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT);
+                strncpy(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT,
+                        sizeof(zswap_zpool_type));
+        }
+
+        return zswap_pool_create(zswap_zpool_type, zswap_compressor);
+}
+
+static void zswap_pool_destroy(struct zswap_pool *pool)
+{
+        zswap_pool_debug("destroying", pool);
+
+        zswap_cpu_comp_destroy(pool);
+        free_percpu(pool->tfm);
+        zpool_destroy_pool(pool->zpool);
+        kfree(pool);
+}
+
+static int __must_check zswap_pool_get(struct zswap_pool *pool)
+{
+        return kref_get_unless_zero(&pool->kref);
+}
+
+static void __zswap_pool_release(struct rcu_head *head)
+{
+        struct zswap_pool *pool = container_of(head, typeof(*pool), rcu_head);
+
+        /* nobody should have been able to get a kref... */
+        WARN_ON(kref_get_unless_zero(&pool->kref));
+
+        /* pool is now off zswap_pools list and has no references. */
+        zswap_pool_destroy(pool);
+}
+
+static void __zswap_pool_empty(struct kref *kref)
+{
+        struct zswap_pool *pool;
+
+        pool = container_of(kref, typeof(*pool), kref);
+
+        spin_lock(&zswap_pools_lock);
+
+        WARN_ON(pool == zswap_pool_current());
+
+        list_del_rcu(&pool->list);
+        call_rcu(&pool->rcu_head, __zswap_pool_release);
+
+        spin_unlock(&zswap_pools_lock);
+}
+
+static void zswap_pool_put(struct zswap_pool *pool)
+{
+        kref_put(&pool->kref, __zswap_pool_empty);
 }
 
 /*********************************
@@ -477,6 +721,7 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
         pgoff_t offset;
         struct zswap_entry *entry;
         struct page *page;
+        struct crypto_comp *tfm;
         u8 *src, *dst;
         unsigned int dlen;
         int ret;
@@ -517,13 +762,15 @@ static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
         case ZSWAP_SWAPCACHE_NEW: /* page is locked */
                 /* decompress */
                 dlen = PAGE_SIZE;
-                src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
+                src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
                                 ZPOOL_MM_RO) + sizeof(struct zswap_header);
                 dst = kmap_atomic(page);
-                ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src,
-                                entry->length, dst, &dlen);
+                tfm = *get_cpu_ptr(entry->pool->tfm);
+                ret = crypto_comp_decompress(tfm, src, entry->length,
+                                             dst, &dlen);
+                put_cpu_ptr(entry->pool->tfm);
                 kunmap_atomic(dst);
-                zpool_unmap_handle(zswap_pool, entry->handle);
+                zpool_unmap_handle(entry->pool->zpool, entry->handle);
                 BUG_ON(ret);
                 BUG_ON(dlen != PAGE_SIZE);
 
@@ -572,6 +819,22 @@ end:
         return ret;
 }
 
+static int zswap_shrink(void)
+{
+        struct zswap_pool *pool;
+        int ret;
+
+        pool = zswap_pool_last_get();
+        if (!pool)
+                return -ENOENT;
+
+        ret = zpool_shrink(pool->zpool, 1, NULL);
+
+        zswap_pool_put(pool);
+
+        return ret;
+}
+
 /*********************************
 * frontswap hooks
 **********************************/
@@ -581,6 +844,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
 {
         struct zswap_tree *tree = zswap_trees[type];
         struct zswap_entry *entry, *dupentry;
+        struct crypto_comp *tfm;
         int ret;
         unsigned int dlen = PAGE_SIZE, len;
         unsigned long handle;
@@ -596,7 +860,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
         /* reclaim space if needed */
         if (zswap_is_full()) {
                 zswap_pool_limit_hit++;
-                if (zpool_shrink(zswap_pool, 1, NULL)) {
+                if (zswap_shrink()) {
                         zswap_reject_reclaim_fail++;
                         ret = -ENOMEM;
                         goto reject;
@@ -611,33 +875,42 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
                 goto reject;
         }
 
+        /* if entry is successfully added, it keeps the reference */
+        entry->pool = zswap_pool_current_get();
+        if (!entry->pool) {
+                ret = -EINVAL;
+                goto freepage;
+        }
+
         /* compress */
         dst = get_cpu_var(zswap_dstmem);
+        tfm = *get_cpu_ptr(entry->pool->tfm);
         src = kmap_atomic(page);
-        ret = zswap_comp_op(ZSWAP_COMPOP_COMPRESS, src, PAGE_SIZE, dst, &dlen);
+        ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen);
         kunmap_atomic(src);
+        put_cpu_ptr(entry->pool->tfm);
         if (ret) {
                 ret = -EINVAL;
-                goto freepage;
+                goto put_dstmem;
         }
 
         /* store */
         len = dlen + sizeof(struct zswap_header);
-        ret = zpool_malloc(zswap_pool, len, __GFP_NORETRY | __GFP_NOWARN,
-                &handle);
+        ret = zpool_malloc(entry->pool->zpool, len,
+                           __GFP_NORETRY | __GFP_NOWARN, &handle);
         if (ret == -ENOSPC) {
                 zswap_reject_compress_poor++;
-                goto freepage;
+                goto put_dstmem;
         }
         if (ret) {
                 zswap_reject_alloc_fail++;
-                goto freepage;
+                goto put_dstmem;
         }
-        zhdr = zpool_map_handle(zswap_pool, handle, ZPOOL_MM_RW);
+        zhdr = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_RW);
         zhdr->swpentry = swp_entry(type, offset);
         buf = (u8 *)(zhdr + 1);
         memcpy(buf, dst, dlen);
-        zpool_unmap_handle(zswap_pool, handle);
+        zpool_unmap_handle(entry->pool->zpool, handle);
         put_cpu_var(zswap_dstmem);
 
         /* populate entry */
@@ -660,12 +933,14 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
 
         /* update stats */
         atomic_inc(&zswap_stored_pages);
-        zswap_pool_total_size = zpool_get_total_size(zswap_pool);
+        zswap_update_total_size();
 
         return 0;
 
-freepage:
+put_dstmem:
         put_cpu_var(zswap_dstmem);
+        zswap_pool_put(entry->pool);
+freepage:
         zswap_entry_cache_free(entry);
 reject:
         return ret;
@@ -680,6 +955,7 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
 {
         struct zswap_tree *tree = zswap_trees[type];
         struct zswap_entry *entry;
+        struct crypto_comp *tfm;
         u8 *src, *dst;
         unsigned int dlen;
         int ret;
@@ -696,13 +972,14 @@ static int zswap_frontswap_load(unsigned type, pgoff_t offset,
 
         /* decompress */
         dlen = PAGE_SIZE;
-        src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
+        src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
                         ZPOOL_MM_RO) + sizeof(struct zswap_header);
         dst = kmap_atomic(page);
-        ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src, entry->length,
-                dst, &dlen);
+        tfm = *get_cpu_ptr(entry->pool->tfm);
+        ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen);
+        put_cpu_ptr(entry->pool->tfm);
         kunmap_atomic(dst);
-        zpool_unmap_handle(zswap_pool, entry->handle);
+        zpool_unmap_handle(entry->pool->zpool, entry->handle);
         BUG_ON(ret);
 
         spin_lock(&tree->lock);
@@ -755,10 +1032,6 @@ static void zswap_frontswap_invalidate_area(unsigned type)
         zswap_trees[type] = NULL;
 }
 
-static const struct zpool_ops zswap_zpool_ops = {
-        .evict = zswap_writeback_entry
-};
-
 static void zswap_frontswap_init(unsigned type)
 {
         struct zswap_tree *tree;
@@ -839,49 +1112,38 @@ static void __exit zswap_debugfs_exit(void) { }
 **********************************/
 static int __init init_zswap(void)
 {
-        gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN;
-
-        pr_info("loading zswap\n");
-
-        zswap_pool = zpool_create_pool(zswap_zpool_type, "zswap", gfp,
-                                        &zswap_zpool_ops);
-        if (!zswap_pool && strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
-                pr_info("%s zpool not available\n", zswap_zpool_type);
-                zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
-                zswap_pool = zpool_create_pool(zswap_zpool_type, "zswap", gfp,
-                                        &zswap_zpool_ops);
-        }
-        if (!zswap_pool) {
-                pr_err("%s zpool not available\n", zswap_zpool_type);
-                pr_err("zpool creation failed\n");
-                goto error;
-        }
-        pr_info("using %s pool\n", zswap_zpool_type);
+        struct zswap_pool *pool;
 
         if (zswap_entry_cache_create()) {
                 pr_err("entry cache creation failed\n");
-                goto cachefail;
+                goto cache_fail;
         }
-        if (zswap_comp_init()) {
-                pr_err("compressor initialization failed\n");
-                goto compfail;
+
+        if (zswap_cpu_dstmem_init()) {
+                pr_err("dstmem alloc failed\n");
+                goto dstmem_fail;
         }
-        if (zswap_cpu_init()) {
-                pr_err("per-cpu initialization failed\n");
-                goto pcpufail;
+
+        pool = __zswap_pool_create_fallback();
+        if (!pool) {
+                pr_err("pool creation failed\n");
+                goto pool_fail;
         }
+        pr_info("loaded using pool %s/%s\n", pool->tfm_name,
+                zpool_get_type(pool->zpool));
+
+        list_add(&pool->list, &zswap_pools);
 
         frontswap_register_ops(&zswap_frontswap_ops);
         if (zswap_debugfs_init())
                 pr_warn("debugfs initialization failed\n");
         return 0;
-pcpufail:
-        zswap_comp_exit();
-compfail:
+
+pool_fail:
+        zswap_cpu_dstmem_destroy();
+dstmem_fail:
         zswap_entry_cache_destroy();
-cachefail:
-        zpool_destroy_pool(zswap_pool);
-error:
+cache_fail:
         return -ENOMEM;
 }
 /* must be late so crypto has time to come up */