2 * zswap.c - zswap driver file
4 * zswap is a backend for frontswap that takes pages that are in the process
5 * of being swapped out and attempts to compress and store them in a
6 * RAM-based memory pool. This can result in a significant I/O reduction on
7 * the swap device and, in the case where decompressing from RAM is faster
8 * than reading from the swap device, can also improve workload performance.
10 * Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com>
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version 2
15 * of the License, or (at your option) any later version.
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
23 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
25 #include <linux/module.h>
26 #include <linux/cpu.h>
27 #include <linux/highmem.h>
28 #include <linux/slab.h>
29 #include <linux/spinlock.h>
30 #include <linux/types.h>
31 #include <linux/atomic.h>
32 #include <linux/frontswap.h>
33 #include <linux/rbtree.h>
34 #include <linux/swap.h>
35 #include <linux/crypto.h>
36 #include <linux/mempool.h>
37 #include <linux/zpool.h>
39 #include <linux/mm_types.h>
40 #include <linux/page-flags.h>
41 #include <linux/swapops.h>
42 #include <linux/writeback.h>
43 #include <linux/pagemap.h>
45 /*********************************
47 **********************************/
48 /* Total bytes used by the compressed storage */
49 static u64 zswap_pool_total_size;
50 /* The number of compressed pages currently stored in zswap */
51 static atomic_t zswap_stored_pages = ATOMIC_INIT(0);
54 * The statistics below are not protected from concurrent access for
55 * performance reasons so they may not be a 100% accurate. However,
56 * they do provide useful information on roughly how many times a
57 * certain event is occurring.
60 /* Pool limit was hit (see zswap_max_pool_percent) */
61 static u64 zswap_pool_limit_hit;
62 /* Pages written back when pool limit was reached */
63 static u64 zswap_written_back_pages;
64 /* Store failed due to a reclaim failure after pool limit was reached */
65 static u64 zswap_reject_reclaim_fail;
66 /* Compressed page was too big for the allocator to (optimally) store */
67 static u64 zswap_reject_compress_poor;
68 /* Store failed because underlying allocator could not get memory */
69 static u64 zswap_reject_alloc_fail;
70 /* Store failed because the entry metadata could not be allocated (rare) */
71 static u64 zswap_reject_kmemcache_fail;
72 /* Duplicate store was encountered (rare) */
73 static u64 zswap_duplicate_entry;
75 /*********************************
77 **********************************/
79 /* Enable/disable zswap (disabled by default) */
80 static bool zswap_enabled;
81 module_param_named(enabled, zswap_enabled, bool, 0644);
83 /* Compressor to be used by zswap (fixed at boot for now) */
84 #define ZSWAP_COMPRESSOR_DEFAULT "lzo"
85 static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
86 module_param_named(compressor, zswap_compressor, charp, 0444);
88 /* The maximum percentage of memory that the compressed pool can occupy */
89 static unsigned int zswap_max_pool_percent = 20;
90 module_param_named(max_pool_percent,
91 zswap_max_pool_percent, uint, 0644);
93 /* Compressed storage to use */
94 #define ZSWAP_ZPOOL_DEFAULT "zbud"
95 static char *zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
96 module_param_named(zpool, zswap_zpool_type, charp, 0444);
98 /* zpool is shared by all of zswap backend */
99 static struct zpool *zswap_pool;
101 /*********************************
102 * compression functions
103 **********************************/
104 /* per-cpu compression transforms */
105 static struct crypto_comp * __percpu *zswap_comp_pcpu_tfms;
108 ZSWAP_COMPOP_COMPRESS,
109 ZSWAP_COMPOP_DECOMPRESS
112 static int zswap_comp_op(enum comp_op op, const u8 *src, unsigned int slen,
113 u8 *dst, unsigned int *dlen)
115 struct crypto_comp *tfm;
118 tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, get_cpu());
120 case ZSWAP_COMPOP_COMPRESS:
121 ret = crypto_comp_compress(tfm, src, slen, dst, dlen);
123 case ZSWAP_COMPOP_DECOMPRESS:
124 ret = crypto_comp_decompress(tfm, src, slen, dst, dlen);
134 static int __init zswap_comp_init(void)
136 if (!crypto_has_comp(zswap_compressor, 0, 0)) {
137 pr_info("%s compressor not available\n", zswap_compressor);
138 /* fall back to default compressor */
139 zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
140 if (!crypto_has_comp(zswap_compressor, 0, 0))
141 /* can't even load the default compressor */
144 pr_info("using %s compressor\n", zswap_compressor);
146 /* alloc percpu transforms */
147 zswap_comp_pcpu_tfms = alloc_percpu(struct crypto_comp *);
148 if (!zswap_comp_pcpu_tfms)
153 static void __init zswap_comp_exit(void)
155 /* free percpu transforms */
156 free_percpu(zswap_comp_pcpu_tfms);
159 /*********************************
161 **********************************/
165 * This structure contains the metadata for tracking a single compressed
168 * rbnode - links the entry into red-black tree for the appropriate swap type
169 * refcount - the number of outstanding reference to the entry. This is needed
170 * to protect against premature freeing of the entry by code
171 * concurrent calls to load, invalidate, and writeback. The lock
172 * for the zswap_tree structure that contains the entry must
173 * be held while changing the refcount. Since the lock must
174 * be held, there is no reason to also make refcount atomic.
175 * offset - the swap offset for the entry. Index into the red-black tree.
176 * handle - zpool allocation handle that stores the compressed page data
177 * length - the length in bytes of the compressed page data. Needed during
181 struct rb_node rbnode;
185 unsigned long handle;
188 struct zswap_header {
189 swp_entry_t swpentry;
193 * The tree lock in the zswap_tree struct protects a few things:
195 * - the refcount field of each entry in the tree
198 struct rb_root rbroot;
202 static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
204 /*********************************
205 * zswap entry functions
206 **********************************/
207 static struct kmem_cache *zswap_entry_cache;
209 static int __init zswap_entry_cache_create(void)
211 zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
212 return zswap_entry_cache == NULL;
215 static void __init zswap_entry_cache_destroy(void)
217 kmem_cache_destroy(zswap_entry_cache);
220 static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp)
222 struct zswap_entry *entry;
223 entry = kmem_cache_alloc(zswap_entry_cache, gfp);
227 RB_CLEAR_NODE(&entry->rbnode);
231 static void zswap_entry_cache_free(struct zswap_entry *entry)
233 kmem_cache_free(zswap_entry_cache, entry);
236 /*********************************
238 **********************************/
239 static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
241 struct rb_node *node = root->rb_node;
242 struct zswap_entry *entry;
245 entry = rb_entry(node, struct zswap_entry, rbnode);
246 if (entry->offset > offset)
247 node = node->rb_left;
248 else if (entry->offset < offset)
249 node = node->rb_right;
257 * In the case that a entry with the same offset is found, a pointer to
258 * the existing entry is stored in dupentry and the function returns -EEXIST
260 static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
261 struct zswap_entry **dupentry)
263 struct rb_node **link = &root->rb_node, *parent = NULL;
264 struct zswap_entry *myentry;
268 myentry = rb_entry(parent, struct zswap_entry, rbnode);
269 if (myentry->offset > entry->offset)
270 link = &(*link)->rb_left;
271 else if (myentry->offset < entry->offset)
272 link = &(*link)->rb_right;
278 rb_link_node(&entry->rbnode, parent, link);
279 rb_insert_color(&entry->rbnode, root);
283 static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
285 if (!RB_EMPTY_NODE(&entry->rbnode)) {
286 rb_erase(&entry->rbnode, root);
287 RB_CLEAR_NODE(&entry->rbnode);
292 * Carries out the common pattern of freeing and entry's zpool allocation,
293 * freeing the entry itself, and decrementing the number of stored pages.
295 static void zswap_free_entry(struct zswap_entry *entry)
297 zpool_free(zswap_pool, entry->handle);
298 zswap_entry_cache_free(entry);
299 atomic_dec(&zswap_stored_pages);
300 zswap_pool_total_size = zpool_get_total_size(zswap_pool);
303 /* caller must hold the tree lock */
304 static void zswap_entry_get(struct zswap_entry *entry)
309 /* caller must hold the tree lock
310 * remove from the tree and free it, if nobody reference the entry
312 static void zswap_entry_put(struct zswap_tree *tree,
313 struct zswap_entry *entry)
315 int refcount = --entry->refcount;
317 BUG_ON(refcount < 0);
319 zswap_rb_erase(&tree->rbroot, entry);
320 zswap_free_entry(entry);
324 /* caller must hold the tree lock */
325 static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
328 struct zswap_entry *entry = NULL;
330 entry = zswap_rb_search(root, offset);
332 zswap_entry_get(entry);
337 /*********************************
339 **********************************/
340 static DEFINE_PER_CPU(u8 *, zswap_dstmem);
342 static int __zswap_cpu_notifier(unsigned long action, unsigned long cpu)
344 struct crypto_comp *tfm;
349 tfm = crypto_alloc_comp(zswap_compressor, 0, 0);
351 pr_err("can't allocate compressor transform\n");
354 *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = tfm;
355 dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
357 pr_err("can't allocate compressor buffer\n");
358 crypto_free_comp(tfm);
359 *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL;
362 per_cpu(zswap_dstmem, cpu) = dst;
365 case CPU_UP_CANCELED:
366 tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu);
368 crypto_free_comp(tfm);
369 *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL;
371 dst = per_cpu(zswap_dstmem, cpu);
373 per_cpu(zswap_dstmem, cpu) = NULL;
381 static int zswap_cpu_notifier(struct notifier_block *nb,
382 unsigned long action, void *pcpu)
384 unsigned long cpu = (unsigned long)pcpu;
385 return __zswap_cpu_notifier(action, cpu);
388 static struct notifier_block zswap_cpu_notifier_block = {
389 .notifier_call = zswap_cpu_notifier
392 static int __init zswap_cpu_init(void)
396 cpu_notifier_register_begin();
397 for_each_online_cpu(cpu)
398 if (__zswap_cpu_notifier(CPU_UP_PREPARE, cpu) != NOTIFY_OK)
400 __register_cpu_notifier(&zswap_cpu_notifier_block);
401 cpu_notifier_register_done();
405 for_each_online_cpu(cpu)
406 __zswap_cpu_notifier(CPU_UP_CANCELED, cpu);
407 cpu_notifier_register_done();
411 /*********************************
413 **********************************/
414 static bool zswap_is_full(void)
416 return totalram_pages * zswap_max_pool_percent / 100 <
417 DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
420 /*********************************
422 **********************************/
423 /* return enum for zswap_get_swap_cache_page */
424 enum zswap_get_swap_ret {
426 ZSWAP_SWAPCACHE_EXIST,
427 ZSWAP_SWAPCACHE_FAIL,
431 * zswap_get_swap_cache_page
433 * This is an adaption of read_swap_cache_async()
435 * This function tries to find a page with the given swap entry
436 * in the swapper_space address space (the swap cache). If the page
437 * is found, it is returned in retpage. Otherwise, a page is allocated,
438 * added to the swap cache, and returned in retpage.
440 * If success, the swap cache page is returned in retpage
441 * Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache
442 * Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated,
443 * the new page is added to swapcache and locked
444 * Returns ZSWAP_SWAPCACHE_FAIL on error
446 static int zswap_get_swap_cache_page(swp_entry_t entry,
447 struct page **retpage)
449 bool page_was_allocated;
451 *retpage = __read_swap_cache_async(entry, GFP_KERNEL,
452 NULL, 0, &page_was_allocated);
453 if (page_was_allocated)
454 return ZSWAP_SWAPCACHE_NEW;
456 return ZSWAP_SWAPCACHE_FAIL;
457 return ZSWAP_SWAPCACHE_EXIST;
461 * Attempts to free an entry by adding a page to the swap cache,
462 * decompressing the entry data into the page, and issuing a
463 * bio write to write the page back to the swap device.
465 * This can be thought of as a "resumed writeback" of the page
466 * to the swap device. We are basically resuming the same swap
467 * writeback path that was intercepted with the frontswap_store()
468 * in the first place. After the page has been decompressed into
469 * the swap cache, the compressed version stored by zswap can be
472 static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
474 struct zswap_header *zhdr;
475 swp_entry_t swpentry;
476 struct zswap_tree *tree;
478 struct zswap_entry *entry;
483 struct writeback_control wbc = {
484 .sync_mode = WB_SYNC_NONE,
487 /* extract swpentry from data */
488 zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
489 swpentry = zhdr->swpentry; /* here */
490 zpool_unmap_handle(pool, handle);
491 tree = zswap_trees[swp_type(swpentry)];
492 offset = swp_offset(swpentry);
494 /* find and ref zswap entry */
495 spin_lock(&tree->lock);
496 entry = zswap_entry_find_get(&tree->rbroot, offset);
498 /* entry was invalidated */
499 spin_unlock(&tree->lock);
502 spin_unlock(&tree->lock);
503 BUG_ON(offset != entry->offset);
505 /* try to allocate swap cache page */
506 switch (zswap_get_swap_cache_page(swpentry, &page)) {
507 case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
511 case ZSWAP_SWAPCACHE_EXIST:
512 /* page is already in the swap cache, ignore for now */
513 page_cache_release(page);
517 case ZSWAP_SWAPCACHE_NEW: /* page is locked */
520 src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
521 ZPOOL_MM_RO) + sizeof(struct zswap_header);
522 dst = kmap_atomic(page);
523 ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src,
524 entry->length, dst, &dlen);
526 zpool_unmap_handle(zswap_pool, entry->handle);
528 BUG_ON(dlen != PAGE_SIZE);
530 /* page is up to date */
531 SetPageUptodate(page);
534 /* move it to the tail of the inactive list after end_writeback */
535 SetPageReclaim(page);
537 /* start writeback */
538 __swap_writepage(page, &wbc, end_swap_bio_write);
539 page_cache_release(page);
540 zswap_written_back_pages++;
542 spin_lock(&tree->lock);
543 /* drop local reference */
544 zswap_entry_put(tree, entry);
547 * There are two possible situations for entry here:
548 * (1) refcount is 1(normal case), entry is valid and on the tree
549 * (2) refcount is 0, entry is freed and not on the tree
550 * because invalidate happened during writeback
551 * search the tree and free the entry if find entry
553 if (entry == zswap_rb_search(&tree->rbroot, offset))
554 zswap_entry_put(tree, entry);
555 spin_unlock(&tree->lock);
560 * if we get here due to ZSWAP_SWAPCACHE_EXIST
561 * a load may happening concurrently
562 * it is safe and okay to not free the entry
563 * if we free the entry in the following put
564 * it it either okay to return !0
567 spin_lock(&tree->lock);
568 zswap_entry_put(tree, entry);
569 spin_unlock(&tree->lock);
575 /*********************************
577 **********************************/
578 /* attempts to compress and store an single page */
579 static int zswap_frontswap_store(unsigned type, pgoff_t offset,
582 struct zswap_tree *tree = zswap_trees[type];
583 struct zswap_entry *entry, *dupentry;
585 unsigned int dlen = PAGE_SIZE, len;
586 unsigned long handle;
589 struct zswap_header *zhdr;
591 if (!zswap_enabled || !tree) {
596 /* reclaim space if needed */
597 if (zswap_is_full()) {
598 zswap_pool_limit_hit++;
599 if (zpool_shrink(zswap_pool, 1, NULL)) {
600 zswap_reject_reclaim_fail++;
607 entry = zswap_entry_cache_alloc(GFP_KERNEL);
609 zswap_reject_kmemcache_fail++;
615 dst = get_cpu_var(zswap_dstmem);
616 src = kmap_atomic(page);
617 ret = zswap_comp_op(ZSWAP_COMPOP_COMPRESS, src, PAGE_SIZE, dst, &dlen);
625 len = dlen + sizeof(struct zswap_header);
626 ret = zpool_malloc(zswap_pool, len, __GFP_NORETRY | __GFP_NOWARN,
628 if (ret == -ENOSPC) {
629 zswap_reject_compress_poor++;
633 zswap_reject_alloc_fail++;
636 zhdr = zpool_map_handle(zswap_pool, handle, ZPOOL_MM_RW);
637 zhdr->swpentry = swp_entry(type, offset);
638 buf = (u8 *)(zhdr + 1);
639 memcpy(buf, dst, dlen);
640 zpool_unmap_handle(zswap_pool, handle);
641 put_cpu_var(zswap_dstmem);
644 entry->offset = offset;
645 entry->handle = handle;
646 entry->length = dlen;
649 spin_lock(&tree->lock);
651 ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry);
652 if (ret == -EEXIST) {
653 zswap_duplicate_entry++;
654 /* remove from rbtree */
655 zswap_rb_erase(&tree->rbroot, dupentry);
656 zswap_entry_put(tree, dupentry);
658 } while (ret == -EEXIST);
659 spin_unlock(&tree->lock);
662 atomic_inc(&zswap_stored_pages);
663 zswap_pool_total_size = zpool_get_total_size(zswap_pool);
668 put_cpu_var(zswap_dstmem);
669 zswap_entry_cache_free(entry);
675 * returns 0 if the page was successfully decompressed
676 * return -1 on entry not found or error
678 static int zswap_frontswap_load(unsigned type, pgoff_t offset,
681 struct zswap_tree *tree = zswap_trees[type];
682 struct zswap_entry *entry;
688 spin_lock(&tree->lock);
689 entry = zswap_entry_find_get(&tree->rbroot, offset);
691 /* entry was written back */
692 spin_unlock(&tree->lock);
695 spin_unlock(&tree->lock);
699 src = (u8 *)zpool_map_handle(zswap_pool, entry->handle,
700 ZPOOL_MM_RO) + sizeof(struct zswap_header);
701 dst = kmap_atomic(page);
702 ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src, entry->length,
705 zpool_unmap_handle(zswap_pool, entry->handle);
708 spin_lock(&tree->lock);
709 zswap_entry_put(tree, entry);
710 spin_unlock(&tree->lock);
715 /* frees an entry in zswap */
716 static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
718 struct zswap_tree *tree = zswap_trees[type];
719 struct zswap_entry *entry;
722 spin_lock(&tree->lock);
723 entry = zswap_rb_search(&tree->rbroot, offset);
725 /* entry was written back */
726 spin_unlock(&tree->lock);
730 /* remove from rbtree */
731 zswap_rb_erase(&tree->rbroot, entry);
733 /* drop the initial reference from entry creation */
734 zswap_entry_put(tree, entry);
736 spin_unlock(&tree->lock);
739 /* frees all zswap entries for the given swap type */
740 static void zswap_frontswap_invalidate_area(unsigned type)
742 struct zswap_tree *tree = zswap_trees[type];
743 struct zswap_entry *entry, *n;
748 /* walk the tree and free everything */
749 spin_lock(&tree->lock);
750 rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
751 zswap_free_entry(entry);
752 tree->rbroot = RB_ROOT;
753 spin_unlock(&tree->lock);
755 zswap_trees[type] = NULL;
758 static const struct zpool_ops zswap_zpool_ops = {
759 .evict = zswap_writeback_entry
762 static void zswap_frontswap_init(unsigned type)
764 struct zswap_tree *tree;
766 tree = kzalloc(sizeof(struct zswap_tree), GFP_KERNEL);
768 pr_err("alloc failed, zswap disabled for swap type %d\n", type);
772 tree->rbroot = RB_ROOT;
773 spin_lock_init(&tree->lock);
774 zswap_trees[type] = tree;
777 static struct frontswap_ops zswap_frontswap_ops = {
778 .store = zswap_frontswap_store,
779 .load = zswap_frontswap_load,
780 .invalidate_page = zswap_frontswap_invalidate_page,
781 .invalidate_area = zswap_frontswap_invalidate_area,
782 .init = zswap_frontswap_init
785 /*********************************
787 **********************************/
788 #ifdef CONFIG_DEBUG_FS
789 #include <linux/debugfs.h>
791 static struct dentry *zswap_debugfs_root;
793 static int __init zswap_debugfs_init(void)
795 if (!debugfs_initialized())
798 zswap_debugfs_root = debugfs_create_dir("zswap", NULL);
799 if (!zswap_debugfs_root)
802 debugfs_create_u64("pool_limit_hit", S_IRUGO,
803 zswap_debugfs_root, &zswap_pool_limit_hit);
804 debugfs_create_u64("reject_reclaim_fail", S_IRUGO,
805 zswap_debugfs_root, &zswap_reject_reclaim_fail);
806 debugfs_create_u64("reject_alloc_fail", S_IRUGO,
807 zswap_debugfs_root, &zswap_reject_alloc_fail);
808 debugfs_create_u64("reject_kmemcache_fail", S_IRUGO,
809 zswap_debugfs_root, &zswap_reject_kmemcache_fail);
810 debugfs_create_u64("reject_compress_poor", S_IRUGO,
811 zswap_debugfs_root, &zswap_reject_compress_poor);
812 debugfs_create_u64("written_back_pages", S_IRUGO,
813 zswap_debugfs_root, &zswap_written_back_pages);
814 debugfs_create_u64("duplicate_entry", S_IRUGO,
815 zswap_debugfs_root, &zswap_duplicate_entry);
816 debugfs_create_u64("pool_total_size", S_IRUGO,
817 zswap_debugfs_root, &zswap_pool_total_size);
818 debugfs_create_atomic_t("stored_pages", S_IRUGO,
819 zswap_debugfs_root, &zswap_stored_pages);
824 static void __exit zswap_debugfs_exit(void)
826 debugfs_remove_recursive(zswap_debugfs_root);
829 static int __init zswap_debugfs_init(void)
834 static void __exit zswap_debugfs_exit(void) { }
837 /*********************************
838 * module init and exit
839 **********************************/
840 static int __init init_zswap(void)
842 gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN;
844 pr_info("loading zswap\n");
846 zswap_pool = zpool_create_pool(zswap_zpool_type, "zswap", gfp,
848 if (!zswap_pool && strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
849 pr_info("%s zpool not available\n", zswap_zpool_type);
850 zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
851 zswap_pool = zpool_create_pool(zswap_zpool_type, "zswap", gfp,
855 pr_err("%s zpool not available\n", zswap_zpool_type);
856 pr_err("zpool creation failed\n");
859 pr_info("using %s pool\n", zswap_zpool_type);
861 if (zswap_entry_cache_create()) {
862 pr_err("entry cache creation failed\n");
865 if (zswap_comp_init()) {
866 pr_err("compressor initialization failed\n");
869 if (zswap_cpu_init()) {
870 pr_err("per-cpu initialization failed\n");
874 frontswap_register_ops(&zswap_frontswap_ops);
875 if (zswap_debugfs_init())
876 pr_warn("debugfs initialization failed\n");
881 zswap_entry_cache_destroy();
883 zpool_destroy_pool(zswap_pool);
887 /* must be late so crypto has time to come up */
888 late_initcall(init_zswap);
890 MODULE_LICENSE("GPL");
891 MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
892 MODULE_DESCRIPTION("Compressed cache for swap pages");