/* * zswap.c - zswap driver file * * zswap is a backend for frontswap 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> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. */ #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/frontswap.h> #include <linux/rbtree.h> #include <linux/swap.h> #include <linux/crypto.h> #include <linux/mempool.h> #include <linux/zbud.h> #include <linux/mm_types.h> #include <linux/page-flags.h> #include <linux/swapops.h> #include <linux/writeback.h> #include <linux/pagemap.h> /********************************* * statistics **********************************/ /* Number of memory pages used by the compressed pool */ static u64 zswap_pool_pages; /* The number of compressed pages currently stored in zswap */ static atomic_t zswap_stored_pages = ATOMIC_INIT(0); /* * The statistics below are not protected from concurrent access for * performance reasons so they may not be a 100% accurate. However, * they do provide useful information on roughly how many times a * certain event is occurring. */ /* Pool limit was hit (see zswap_max_pool_percent) */ static u64 zswap_pool_limit_hit; /* Pages written back when pool limit was reached */ static u64 zswap_written_back_pages; /* Store failed due to a reclaim failure after pool limit was reached */ static u64 zswap_reject_reclaim_fail; /* Compressed page was too big for the allocator to (optimally) store */ static u64 zswap_reject_compress_poor; /* Store failed because underlying allocator could not get memory */ static u64 zswap_reject_alloc_fail; /* Store failed because the entry metadata could not be allocated (rare) */ static u64 zswap_reject_kmemcache_fail; /* Duplicate store was encountered (rare) */ static u64 zswap_duplicate_entry; /********************************* * tunables **********************************/ /* Enable/disable zswap (disabled by default, fixed at boot for now) */ static bool zswap_enabled __read_mostly; module_param_named(enabled, zswap_enabled, bool, 0); /* Compressor to be used by zswap (fixed at boot for now) */ #define ZSWAP_COMPRESSOR_DEFAULT "lzo" static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT; module_param_named(compressor, zswap_compressor, charp, 0); /* 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); /********************************* * compression functions **********************************/ /* per-cpu compression transforms */ static struct crypto_comp * __percpu *zswap_comp_pcpu_tfms; enum comp_op { ZSWAP_COMPOP_COMPRESS, ZSWAP_COMPOP_DECOMPRESS }; 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 zswap_comp_exit(void) { /* free percpu transforms */ if (zswap_comp_pcpu_tfms) free_percpu(zswap_comp_pcpu_tfms); } /********************************* * data structures **********************************/ /* * struct zswap_entry * * This structure contains the metadata for tracking a single compressed * page within zswap. * * rbnode - links the entry into red-black tree for the appropriate swap type * refcount - the number of outstanding reference to the entry. This is needed * to protect against premature freeing of the entry by code * concurent 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 - zsmalloc allocation handle that stores the compressed page data * length - the length in bytes of the compressed page data. Needed during * decompression */ struct zswap_entry { struct rb_node rbnode; pgoff_t offset; int refcount; unsigned int length; unsigned long handle; }; struct zswap_header { swp_entry_t swpentry; }; /* * 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; struct zbud_pool *pool; }; static struct zswap_tree *zswap_trees[MAX_SWAPFILES]; /********************************* * zswap entry functions **********************************/ static struct kmem_cache *zswap_entry_cache; static int zswap_entry_cache_create(void) { zswap_entry_cache = KMEM_CACHE(zswap_entry, 0); return (zswap_entry_cache == NULL); } static void zswap_entry_cache_destory(void) { kmem_cache_destroy(zswap_entry_cache); } static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp) { struct zswap_entry *entry; entry = kmem_cache_alloc(zswap_entry_cache, gfp); if (!entry) return NULL; entry->refcount = 1; return entry; } static void zswap_entry_cache_free(struct zswap_entry *entry) { kmem_cache_free(zswap_entry_cache, entry); } /* caller must hold the tree lock */ static void zswap_entry_get(struct zswap_entry *entry) { entry->refcount++; } /* caller must hold the tree lock */ static int zswap_entry_put(struct zswap_entry *entry) { entry->refcount--; return entry->refcount; } /********************************* * 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; while (node) { entry = rb_entry(node, struct zswap_entry, rbnode); 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; while (*link) { parent = *link; myentry = rb_entry(parent, struct zswap_entry, rbnode); 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; } /********************************* * per-cpu code **********************************/ static DEFINE_PER_CPU(u8 *, zswap_dstmem); static int __zswap_cpu_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(PAGE_SIZE * 2, GFP_KERNEL); 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; break; default: break; } return NOTIFY_OK; } static int zswap_cpu_notifier(struct notifier_block *nb, unsigned long action, void *pcpu) { unsigned long cpu = (unsigned long)pcpu; return __zswap_cpu_notifier(action, cpu); } static struct notifier_block zswap_cpu_notifier_block = { .notifier_call = zswap_cpu_notifier }; static int zswap_cpu_init(void) { unsigned long cpu; get_online_cpus(); for_each_online_cpu(cpu) if (__zswap_cpu_notifier(CPU_UP_PREPARE, cpu) != NOTIFY_OK) goto cleanup; register_cpu_notifier(&zswap_cpu_notifier_block); put_online_cpus(); return 0; cleanup: for_each_online_cpu(cpu) __zswap_cpu_notifier(CPU_UP_CANCELED, cpu); put_online_cpus(); return -ENOMEM; } /********************************* * helpers **********************************/ static bool zswap_is_full(void) { return (totalram_pages * zswap_max_pool_percent / 100 < zswap_pool_pages); } /* * Carries out the common pattern of freeing and entry's zsmalloc allocation, * freeing the entry itself, and decrementing the number of stored pages. */ static void zswap_free_entry(struct zswap_tree *tree, struct zswap_entry *entry) { zbud_free(tree->pool, entry->handle); zswap_entry_cache_free(entry); atomic_dec(&zswap_stored_pages); zswap_pool_pages = zbud_get_pool_size(tree->pool); } /********************************* * writeback code **********************************/ /* return enum for zswap_get_swap_cache_page */ enum zswap_get_swap_ret { ZSWAP_SWAPCACHE_NEW, ZSWAP_SWAPCACHE_EXIST, ZSWAP_SWAPCACHE_NOMEM }; /* * zswap_get_swap_cache_page * * This is an adaption of read_swap_cache_async() * * This function tries to find a page with the given swap entry * in the swapper_space address space (the swap cache). If the page * is found, it is returned in retpage. Otherwise, a page is allocated, * added to the swap cache, and returned in retpage. * * If success, the swap cache page is returned in retpage * Returns 0 if page was already in the swap cache, page is not locked * Returns 1 if the new page needs to be populated, page is locked * Returns <0 on error */ static int zswap_get_swap_cache_page(swp_entry_t entry, struct page **retpage) { struct page *found_page, *new_page = NULL; struct address_space *swapper_space = &swapper_spaces[swp_type(entry)]; int err; *retpage = NULL; do { /* * First check the swap cache. Since this is normally * called after lookup_swap_cache() failed, re-calling * that would confuse statistics. */ found_page = find_get_page(swapper_space, entry.val); if (found_page) break; /* * Get a new page to read into from swap. */ if (!new_page) { new_page = alloc_page(GFP_KERNEL); if (!new_page) break; /* Out of memory */ } /* * call radix_tree_preload() while we can wait. */ err = radix_tree_preload(GFP_KERNEL); if (err) break; /* * Swap entry may have been freed since our caller observed it. */ err = swapcache_prepare(entry); if (err == -EEXIST) { /* seems racy */ radix_tree_preload_end(); continue; } if (err) { /* swp entry is obsolete ? */ radix_tree_preload_end(); break; } /* May fail (-ENOMEM) if radix-tree node allocation failed. */ __set_page_locked(new_page); SetPageSwapBacked(new_page); err = __add_to_swap_cache(new_page, entry); if (likely(!err)) { radix_tree_preload_end(); lru_cache_add_anon(new_page); *retpage = new_page; return ZSWAP_SWAPCACHE_NEW; } radix_tree_preload_end(); ClearPageSwapBacked(new_page); __clear_page_locked(new_page); /* * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ swapcache_free(entry, NULL); } while (err != -ENOMEM); if (new_page) page_cache_release(new_page); if (!found_page) return ZSWAP_SWAPCACHE_NOMEM; *retpage = found_page; return ZSWAP_SWAPCACHE_EXIST; } /* * Attempts to free an entry by adding a page to the swap cache, * decompressing the entry data into the page, and issuing a * bio write to write the page back to the swap device. * * This can be thought of as a "resumed writeback" of the page * to the swap device. We are basically resuming the same swap * writeback path that was intercepted with the frontswap_store() * in the first place. After the page has been decompressed into * the swap cache, the compressed version stored by zswap can be * freed. */ static int zswap_writeback_entry(struct zbud_pool *pool, unsigned long handle) { struct zswap_header *zhdr; swp_entry_t swpentry; struct zswap_tree *tree; pgoff_t offset; struct zswap_entry *entry; struct page *page; u8 *src, *dst; unsigned int dlen; int ret, refcount; struct writeback_control wbc = { .sync_mode = WB_SYNC_NONE, }; /* extract swpentry from data */ zhdr = zbud_map(pool, handle); swpentry = zhdr->swpentry; /* here */ zbud_unmap(pool, handle); tree = zswap_trees[swp_type(swpentry)]; offset = swp_offset(swpentry); BUG_ON(pool != tree->pool); /* find and ref zswap entry */ spin_lock(&tree->lock); entry = zswap_rb_search(&tree->rbroot, offset); if (!entry) { /* entry was invalidated */ spin_unlock(&tree->lock); return 0; } zswap_entry_get(entry); spin_unlock(&tree->lock); BUG_ON(offset != entry->offset); /* try to allocate swap cache page */ switch (zswap_get_swap_cache_page(swpentry, &page)) { case ZSWAP_SWAPCACHE_NOMEM: /* no memory */ ret = -ENOMEM; goto fail; case ZSWAP_SWAPCACHE_EXIST: /* page is unlocked */ /* page is already in the swap cache, ignore for now */ page_cache_release(page); ret = -EEXIST; goto fail; case ZSWAP_SWAPCACHE_NEW: /* page is locked */ /* decompress */ dlen = PAGE_SIZE; src = (u8 *)zbud_map(tree->pool, entry->handle) + sizeof(struct zswap_header); dst = kmap_atomic(page); ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src, entry->length, dst, &dlen); kunmap_atomic(dst); zbud_unmap(tree->pool, entry->handle); BUG_ON(ret); BUG_ON(dlen != PAGE_SIZE); /* page is up to date */ SetPageUptodate(page); } /* start writeback */ __swap_writepage(page, &wbc, end_swap_bio_write); page_cache_release(page); zswap_written_back_pages++; spin_lock(&tree->lock); /* drop local reference */ zswap_entry_put(entry); /* drop the initial reference from entry creation */ refcount = zswap_entry_put(entry); /* * There are three possible values for refcount here: * (1) refcount is 1, load is in progress, unlink from rbtree, * load will free * (2) refcount is 0, (normal case) entry is valid, * remove from rbtree and free entry * (3) refcount is -1, invalidate happened during writeback, * free entry */ if (refcount >= 0) { /* no invalidate yet, remove from rbtree */ rb_erase(&entry->rbnode, &tree->rbroot); } spin_unlock(&tree->lock); if (refcount <= 0) { /* free the entry */ zswap_free_entry(tree, entry); return 0; } return -EAGAIN; fail: spin_lock(&tree->lock); zswap_entry_put(entry); spin_unlock(&tree->lock); return ret; } /********************************* * frontswap hooks **********************************/ /* attempts to compress and store an single page */ static int zswap_frontswap_store(unsigned type, pgoff_t offset, struct page *page) { struct zswap_tree *tree = zswap_trees[type]; struct zswap_entry *entry, *dupentry; int ret; unsigned int dlen = PAGE_SIZE, len; unsigned long handle; char *buf; u8 *src, *dst; struct zswap_header *zhdr; if (!tree) { ret = -ENODEV; goto reject; } /* reclaim space if needed */ if (zswap_is_full()) { zswap_pool_limit_hit++; if (zbud_reclaim_page(tree->pool, 8)) { zswap_reject_reclaim_fail++; ret = -ENOMEM; goto reject; } } /* allocate entry */ entry = zswap_entry_cache_alloc(GFP_KERNEL); if (!entry) { zswap_reject_kmemcache_fail++; ret = -ENOMEM; goto reject; } /* compress */ dst = get_cpu_var(zswap_dstmem); src = kmap_atomic(page); ret = zswap_comp_op(ZSWAP_COMPOP_COMPRESS, src, PAGE_SIZE, dst, &dlen); kunmap_atomic(src); if (ret) { ret = -EINVAL; goto freepage; } /* store */ len = dlen + sizeof(struct zswap_header); ret = zbud_alloc(tree->pool, len, __GFP_NORETRY | __GFP_NOWARN, &handle); if (ret == -ENOSPC) { zswap_reject_compress_poor++; goto freepage; } if (ret) { zswap_reject_alloc_fail++; goto freepage; } zhdr = zbud_map(tree->pool, handle); zhdr->swpentry = swp_entry(type, offset); buf = (u8 *)(zhdr + 1); memcpy(buf, dst, dlen); zbud_unmap(tree->pool, handle); put_cpu_var(zswap_dstmem); /* populate entry */ entry->offset = offset; entry->handle = handle; entry->length = dlen; /* map */ spin_lock(&tree->lock); do { ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry); if (ret == -EEXIST) { zswap_duplicate_entry++; /* remove from rbtree */ rb_erase(&dupentry->rbnode, &tree->rbroot); if (!zswap_entry_put(dupentry)) { /* free */ zswap_free_entry(tree, dupentry); } } } while (ret == -EEXIST); spin_unlock(&tree->lock); /* update stats */ atomic_inc(&zswap_stored_pages); zswap_pool_pages = zbud_get_pool_size(tree->pool); return 0; freepage: put_cpu_var(zswap_dstmem); zswap_entry_cache_free(entry); reject: return ret; } /* * returns 0 if the page was successfully decompressed * return -1 on entry not found or error */ static int zswap_frontswap_load(unsigned type, pgoff_t offset, struct page *page) { struct zswap_tree *tree = zswap_trees[type]; struct zswap_entry *entry; u8 *src, *dst; unsigned int dlen; int refcount, ret; /* find */ spin_lock(&tree->lock); entry = zswap_rb_search(&tree->rbroot, offset); if (!entry) { /* entry was written back */ spin_unlock(&tree->lock); return -1; } zswap_entry_get(entry); spin_unlock(&tree->lock); /* decompress */ dlen = PAGE_SIZE; src = (u8 *)zbud_map(tree->pool, entry->handle) + sizeof(struct zswap_header); dst = kmap_atomic(page); ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src, entry->length, dst, &dlen); kunmap_atomic(dst); zbud_unmap(tree->pool, entry->handle); BUG_ON(ret); spin_lock(&tree->lock); refcount = zswap_entry_put(entry); if (likely(refcount)) { spin_unlock(&tree->lock); return 0; } spin_unlock(&tree->lock); /* * We don't have to unlink from the rbtree because * zswap_writeback_entry() or zswap_frontswap_invalidate page() * has already done this for us if we are the last reference. */ /* free */ zswap_free_entry(tree, entry); return 0; } /* frees an entry in zswap */ static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset) { struct zswap_tree *tree = zswap_trees[type]; struct zswap_entry *entry; int refcount; /* find */ spin_lock(&tree->lock); entry = zswap_rb_search(&tree->rbroot, offset); if (!entry) { /* entry was written back */ spin_unlock(&tree->lock); return; } /* remove from rbtree */ rb_erase(&entry->rbnode, &tree->rbroot); /* drop the initial reference from entry creation */ refcount = zswap_entry_put(entry); spin_unlock(&tree->lock); if (refcount) { /* writeback in progress, writeback will free */ return; } /* free */ zswap_free_entry(tree, entry); } /* frees all zswap entries for the given swap type */ static void zswap_frontswap_invalidate_area(unsigned type) { struct zswap_tree *tree = zswap_trees[type]; struct rb_node *node; struct zswap_entry *entry; if (!tree) return; /* walk the tree and free everything */ spin_lock(&tree->lock); /* * TODO: Even though this code should not be executed because * the try_to_unuse() in swapoff should have emptied the tree, * it is very wasteful to rebalance the tree after every * removal when we are freeing the whole tree. * * If post-order traversal code is ever added to the rbtree * implementation, it should be used here. */ while ((node = rb_first(&tree->rbroot))) { entry = rb_entry(node, struct zswap_entry, rbnode); rb_erase(&entry->rbnode, &tree->rbroot); zbud_free(tree->pool, entry->handle); zswap_entry_cache_free(entry); atomic_dec(&zswap_stored_pages); } tree->rbroot = RB_ROOT; spin_unlock(&tree->lock); } static struct zbud_ops zswap_zbud_ops = { .evict = zswap_writeback_entry }; static void zswap_frontswap_init(unsigned type) { struct zswap_tree *tree; tree = kzalloc(sizeof(struct zswap_tree), GFP_KERNEL); if (!tree) goto err; tree->pool = zbud_create_pool(GFP_KERNEL, &zswap_zbud_ops); if (!tree->pool) goto freetree; tree->rbroot = RB_ROOT; spin_lock_init(&tree->lock); zswap_trees[type] = tree; return; freetree: kfree(tree); err: pr_err("alloc failed, zswap disabled for swap type %d\n", type); } static struct frontswap_ops zswap_frontswap_ops = { .store = zswap_frontswap_store, .load = zswap_frontswap_load, .invalidate_page = zswap_frontswap_invalidate_page, .invalidate_area = zswap_frontswap_invalidate_area, .init = zswap_frontswap_init }; /********************************* * debugfs functions **********************************/ #ifdef CONFIG_DEBUG_FS #include <linux/debugfs.h> static struct dentry *zswap_debugfs_root; static int __init zswap_debugfs_init(void) { if (!debugfs_initialized()) return -ENODEV; zswap_debugfs_root = debugfs_create_dir("zswap", NULL); if (!zswap_debugfs_root) return -ENOMEM; debugfs_create_u64("pool_limit_hit", S_IRUGO, zswap_debugfs_root, &zswap_pool_limit_hit); debugfs_create_u64("reject_reclaim_fail", S_IRUGO, zswap_debugfs_root, &zswap_reject_reclaim_fail); debugfs_create_u64("reject_alloc_fail", S_IRUGO, zswap_debugfs_root, &zswap_reject_alloc_fail); debugfs_create_u64("reject_kmemcache_fail", S_IRUGO, zswap_debugfs_root, &zswap_reject_kmemcache_fail); debugfs_create_u64("reject_compress_poor", S_IRUGO, zswap_debugfs_root, &zswap_reject_compress_poor); debugfs_create_u64("written_back_pages", S_IRUGO, zswap_debugfs_root, &zswap_written_back_pages); debugfs_create_u64("duplicate_entry", S_IRUGO, zswap_debugfs_root, &zswap_duplicate_entry); debugfs_create_u64("pool_pages", S_IRUGO, zswap_debugfs_root, &zswap_pool_pages); debugfs_create_atomic_t("stored_pages", S_IRUGO, zswap_debugfs_root, &zswap_stored_pages); return 0; } static void __exit zswap_debugfs_exit(void) { debugfs_remove_recursive(zswap_debugfs_root); } #else static int __init zswap_debugfs_init(void) { return 0; } static void __exit zswap_debugfs_exit(void) { } #endif /********************************* * module init and exit **********************************/ static int __init init_zswap(void) { if (!zswap_enabled) return 0; pr_info("loading zswap\n"); if (zswap_entry_cache_create()) { pr_err("entry cache creation failed\n"); goto error; } if (zswap_comp_init()) { pr_err("compressor initialization failed\n"); goto compfail; } if (zswap_cpu_init()) { pr_err("per-cpu initialization failed\n"); goto pcpufail; } frontswap_register_ops(&zswap_frontswap_ops); if (zswap_debugfs_init()) pr_warn("debugfs initialization failed\n"); return 0; pcpufail: zswap_comp_exit(); compfail: zswap_entry_cache_destory(); error: return -ENOMEM; } /* must be late so crypto has time to come up */ late_initcall(init_zswap); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Seth Jennings <sjenning@linux.vnet.ibm.com>"); MODULE_DESCRIPTION("Compressed cache for swap pages");