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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * zswap.c - zswap driver file
4 *
5 * zswap is a backend for frontswap that takes pages that are in the process
6 * of being swapped out and attempts to compress and store them in a
7 * RAM-based memory pool. This can result in a significant I/O reduction on
8 * the swap device and, in the case where decompressing from RAM is faster
9 * than reading from the swap device, can also improve workload performance.
10 *
11 * Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com>
12*/
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/module.h>
17#include <linux/cpu.h>
18#include <linux/highmem.h>
19#include <linux/slab.h>
20#include <linux/spinlock.h>
21#include <linux/types.h>
22#include <linux/atomic.h>
23#include <linux/frontswap.h>
24#include <linux/rbtree.h>
25#include <linux/swap.h>
26#include <linux/crypto.h>
27#include <linux/mempool.h>
28#include <linux/zpool.h>
29
30#include <linux/mm_types.h>
31#include <linux/page-flags.h>
32#include <linux/swapops.h>
33#include <linux/writeback.h>
34#include <linux/pagemap.h>
35#include <linux/workqueue.h>
36
37/*********************************
38* statistics
39**********************************/
40/* Total bytes used by the compressed storage */
41static u64 zswap_pool_total_size;
42/* The number of compressed pages currently stored in zswap */
43static atomic_t zswap_stored_pages = ATOMIC_INIT(0);
44/* The number of same-value filled pages currently stored in zswap */
45static atomic_t zswap_same_filled_pages = ATOMIC_INIT(0);
46
47/*
48 * The statistics below are not protected from concurrent access for
49 * performance reasons so they may not be a 100% accurate. However,
50 * they do provide useful information on roughly how many times a
51 * certain event is occurring.
52*/
53
54/* Pool limit was hit (see zswap_max_pool_percent) */
55static u64 zswap_pool_limit_hit;
56/* Pages written back when pool limit was reached */
57static u64 zswap_written_back_pages;
58/* Store failed due to a reclaim failure after pool limit was reached */
59static u64 zswap_reject_reclaim_fail;
60/* Compressed page was too big for the allocator to (optimally) store */
61static u64 zswap_reject_compress_poor;
62/* Store failed because underlying allocator could not get memory */
63static u64 zswap_reject_alloc_fail;
64/* Store failed because the entry metadata could not be allocated (rare) */
65static u64 zswap_reject_kmemcache_fail;
66/* Duplicate store was encountered (rare) */
67static u64 zswap_duplicate_entry;
68
69/* Shrinker work queue */
70static struct workqueue_struct *shrink_wq;
71/* Pool limit was hit, we need to calm down */
72static bool zswap_pool_reached_full;
73
74/*********************************
75* tunables
76**********************************/
77
78#define ZSWAP_PARAM_UNSET ""
79
80/* Enable/disable zswap */
81static bool zswap_enabled = IS_ENABLED(CONFIG_ZSWAP_DEFAULT_ON);
82static int zswap_enabled_param_set(const char *,
83 const struct kernel_param *);
84static struct kernel_param_ops zswap_enabled_param_ops = {
85 .set = zswap_enabled_param_set,
86 .get = param_get_bool,
87};
88module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644);
89
90/* Crypto compressor to use */
91static char *zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
92static int zswap_compressor_param_set(const char *,
93 const struct kernel_param *);
94static struct kernel_param_ops zswap_compressor_param_ops = {
95 .set = zswap_compressor_param_set,
96 .get = param_get_charp,
97 .free = param_free_charp,
98};
99module_param_cb(compressor, &zswap_compressor_param_ops,
100 &zswap_compressor, 0644);
101
102/* Compressed storage zpool to use */
103static char *zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
104static int zswap_zpool_param_set(const char *, const struct kernel_param *);
105static struct kernel_param_ops zswap_zpool_param_ops = {
106 .set = zswap_zpool_param_set,
107 .get = param_get_charp,
108 .free = param_free_charp,
109};
110module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_type, 0644);
111
112/* The maximum percentage of memory that the compressed pool can occupy */
113static unsigned int zswap_max_pool_percent = 20;
114module_param_named(max_pool_percent, zswap_max_pool_percent, uint, 0644);
115
116/* The threshold for accepting new pages after the max_pool_percent was hit */
117static unsigned int zswap_accept_thr_percent = 90; /* of max pool size */
118module_param_named(accept_threshold_percent, zswap_accept_thr_percent,
119 uint, 0644);
120
121/* Enable/disable handling same-value filled pages (enabled by default) */
122static bool zswap_same_filled_pages_enabled = true;
123module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled,
124 bool, 0644);
125
126/*********************************
127* data structures
128**********************************/
129
130struct zswap_pool {
131 struct zpool *zpool;
132 struct crypto_comp * __percpu *tfm;
133 struct kref kref;
134 struct list_head list;
135 struct work_struct release_work;
136 struct work_struct shrink_work;
137 struct hlist_node node;
138 char tfm_name[CRYPTO_MAX_ALG_NAME];
139};
140
141/*
142 * struct zswap_entry
143 *
144 * This structure contains the metadata for tracking a single compressed
145 * page within zswap.
146 *
147 * rbnode - links the entry into red-black tree for the appropriate swap type
148 * offset - the swap offset for the entry. Index into the red-black tree.
149 * refcount - the number of outstanding reference to the entry. This is needed
150 * to protect against premature freeing of the entry by code
151 * concurrent calls to load, invalidate, and writeback. The lock
152 * for the zswap_tree structure that contains the entry must
153 * be held while changing the refcount. Since the lock must
154 * be held, there is no reason to also make refcount atomic.
155 * length - the length in bytes of the compressed page data. Needed during
156 * decompression. For a same value filled page length is 0.
157 * pool - the zswap_pool the entry's data is in
158 * handle - zpool allocation handle that stores the compressed page data
159 * value - value of the same-value filled pages which have same content
160 */
161struct zswap_entry {
162 struct rb_node rbnode;
163 pgoff_t offset;
164 int refcount;
165 unsigned int length;
166 struct zswap_pool *pool;
167 union {
168 unsigned long handle;
169 unsigned long value;
170 };
171};
172
173struct zswap_header {
174 swp_entry_t swpentry;
175};
176
177/*
178 * The tree lock in the zswap_tree struct protects a few things:
179 * - the rbtree
180 * - the refcount field of each entry in the tree
181 */
182struct zswap_tree {
183 struct rb_root rbroot;
184 spinlock_t lock;
185};
186
187static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
188
189/* RCU-protected iteration */
190static LIST_HEAD(zswap_pools);
191/* protects zswap_pools list modification */
192static DEFINE_SPINLOCK(zswap_pools_lock);
193/* pool counter to provide unique names to zpool */
194static atomic_t zswap_pools_count = ATOMIC_INIT(0);
195
196/* used by param callback function */
197static bool zswap_init_started;
198
199/* fatal error during init */
200static bool zswap_init_failed;
201
202/* init completed, but couldn't create the initial pool */
203static bool zswap_has_pool;
204
205/*********************************
206* helpers and fwd declarations
207**********************************/
208
209#define zswap_pool_debug(msg, p) \
210 pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name, \
211 zpool_get_type((p)->zpool))
212
213static int zswap_writeback_entry(struct zpool *pool, unsigned long handle);
214static int zswap_pool_get(struct zswap_pool *pool);
215static void zswap_pool_put(struct zswap_pool *pool);
216
217static const struct zpool_ops zswap_zpool_ops = {
218 .evict = zswap_writeback_entry
219};
220
221static bool zswap_is_full(void)
222{
223 return totalram_pages() * zswap_max_pool_percent / 100 <
224 DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
225}
226
227static bool zswap_can_accept(void)
228{
229 return totalram_pages() * zswap_accept_thr_percent / 100 *
230 zswap_max_pool_percent / 100 >
231 DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
232}
233
234static void zswap_update_total_size(void)
235{
236 struct zswap_pool *pool;
237 u64 total = 0;
238
239 rcu_read_lock();
240
241 list_for_each_entry_rcu(pool, &zswap_pools, list)
242 total += zpool_get_total_size(pool->zpool);
243
244 rcu_read_unlock();
245
246 zswap_pool_total_size = total;
247}
248
249/*********************************
250* zswap entry functions
251**********************************/
252static struct kmem_cache *zswap_entry_cache;
253
254static int __init zswap_entry_cache_create(void)
255{
256 zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
257 return zswap_entry_cache == NULL;
258}
259
260static void __init zswap_entry_cache_destroy(void)
261{
262 kmem_cache_destroy(zswap_entry_cache);
263}
264
265static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp)
266{
267 struct zswap_entry *entry;
268 entry = kmem_cache_alloc(zswap_entry_cache, gfp);
269 if (!entry)
270 return NULL;
271 entry->refcount = 1;
272 RB_CLEAR_NODE(&entry->rbnode);
273 return entry;
274}
275
276static void zswap_entry_cache_free(struct zswap_entry *entry)
277{
278 kmem_cache_free(zswap_entry_cache, entry);
279}
280
281/*********************************
282* rbtree functions
283**********************************/
284static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
285{
286 struct rb_node *node = root->rb_node;
287 struct zswap_entry *entry;
288
289 while (node) {
290 entry = rb_entry(node, struct zswap_entry, rbnode);
291 if (entry->offset > offset)
292 node = node->rb_left;
293 else if (entry->offset < offset)
294 node = node->rb_right;
295 else
296 return entry;
297 }
298 return NULL;
299}
300
301/*
302 * In the case that a entry with the same offset is found, a pointer to
303 * the existing entry is stored in dupentry and the function returns -EEXIST
304 */
305static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
306 struct zswap_entry **dupentry)
307{
308 struct rb_node **link = &root->rb_node, *parent = NULL;
309 struct zswap_entry *myentry;
310
311 while (*link) {
312 parent = *link;
313 myentry = rb_entry(parent, struct zswap_entry, rbnode);
314 if (myentry->offset > entry->offset)
315 link = &(*link)->rb_left;
316 else if (myentry->offset < entry->offset)
317 link = &(*link)->rb_right;
318 else {
319 *dupentry = myentry;
320 return -EEXIST;
321 }
322 }
323 rb_link_node(&entry->rbnode, parent, link);
324 rb_insert_color(&entry->rbnode, root);
325 return 0;
326}
327
328static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
329{
330 if (!RB_EMPTY_NODE(&entry->rbnode)) {
331 rb_erase(&entry->rbnode, root);
332 RB_CLEAR_NODE(&entry->rbnode);
333 }
334}
335
336/*
337 * Carries out the common pattern of freeing and entry's zpool allocation,
338 * freeing the entry itself, and decrementing the number of stored pages.
339 */
340static void zswap_free_entry(struct zswap_entry *entry)
341{
342 if (!entry->length)
343 atomic_dec(&zswap_same_filled_pages);
344 else {
345 zpool_free(entry->pool->zpool, entry->handle);
346 zswap_pool_put(entry->pool);
347 }
348 zswap_entry_cache_free(entry);
349 atomic_dec(&zswap_stored_pages);
350 zswap_update_total_size();
351}
352
353/* caller must hold the tree lock */
354static void zswap_entry_get(struct zswap_entry *entry)
355{
356 entry->refcount++;
357}
358
359/* caller must hold the tree lock
360* remove from the tree and free it, if nobody reference the entry
361*/
362static void zswap_entry_put(struct zswap_tree *tree,
363 struct zswap_entry *entry)
364{
365 int refcount = --entry->refcount;
366
367 BUG_ON(refcount < 0);
368 if (refcount == 0) {
369 zswap_rb_erase(&tree->rbroot, entry);
370 zswap_free_entry(entry);
371 }
372}
373
374/* caller must hold the tree lock */
375static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
376 pgoff_t offset)
377{
378 struct zswap_entry *entry;
379
380 entry = zswap_rb_search(root, offset);
381 if (entry)
382 zswap_entry_get(entry);
383
384 return entry;
385}
386
387/*********************************
388* per-cpu code
389**********************************/
390static DEFINE_PER_CPU(u8 *, zswap_dstmem);
391
392static int zswap_dstmem_prepare(unsigned int cpu)
393{
394 u8 *dst;
395
396 dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
397 if (!dst)
398 return -ENOMEM;
399
400 per_cpu(zswap_dstmem, cpu) = dst;
401 return 0;
402}
403
404static int zswap_dstmem_dead(unsigned int cpu)
405{
406 u8 *dst;
407
408 dst = per_cpu(zswap_dstmem, cpu);
409 kfree(dst);
410 per_cpu(zswap_dstmem, cpu) = NULL;
411
412 return 0;
413}
414
415static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
416{
417 struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
418 struct crypto_comp *tfm;
419
420 if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
421 return 0;
422
423 tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
424 if (IS_ERR_OR_NULL(tfm)) {
425 pr_err("could not alloc crypto comp %s : %ld\n",
426 pool->tfm_name, PTR_ERR(tfm));
427 return -ENOMEM;
428 }
429 *per_cpu_ptr(pool->tfm, cpu) = tfm;
430 return 0;
431}
432
433static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
434{
435 struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
436 struct crypto_comp *tfm;
437
438 tfm = *per_cpu_ptr(pool->tfm, cpu);
439 if (!IS_ERR_OR_NULL(tfm))
440 crypto_free_comp(tfm);
441 *per_cpu_ptr(pool->tfm, cpu) = NULL;
442 return 0;
443}
444
445/*********************************
446* pool functions
447**********************************/
448
449static struct zswap_pool *__zswap_pool_current(void)
450{
451 struct zswap_pool *pool;
452
453 pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);
454 WARN_ONCE(!pool && zswap_has_pool,
455 "%s: no page storage pool!\n", __func__);
456
457 return pool;
458}
459
460static struct zswap_pool *zswap_pool_current(void)
461{
462 assert_spin_locked(&zswap_pools_lock);
463
464 return __zswap_pool_current();
465}
466
467static struct zswap_pool *zswap_pool_current_get(void)
468{
469 struct zswap_pool *pool;
470
471 rcu_read_lock();
472
473 pool = __zswap_pool_current();
474 if (!zswap_pool_get(pool))
475 pool = NULL;
476
477 rcu_read_unlock();
478
479 return pool;
480}
481
482static struct zswap_pool *zswap_pool_last_get(void)
483{
484 struct zswap_pool *pool, *last = NULL;
485
486 rcu_read_lock();
487
488 list_for_each_entry_rcu(pool, &zswap_pools, list)
489 last = pool;
490 WARN_ONCE(!last && zswap_has_pool,
491 "%s: no page storage pool!\n", __func__);
492 if (!zswap_pool_get(last))
493 last = NULL;
494
495 rcu_read_unlock();
496
497 return last;
498}
499
500/* type and compressor must be null-terminated */
501static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor)
502{
503 struct zswap_pool *pool;
504
505 assert_spin_locked(&zswap_pools_lock);
506
507 list_for_each_entry_rcu(pool, &zswap_pools, list) {
508 if (strcmp(pool->tfm_name, compressor))
509 continue;
510 if (strcmp(zpool_get_type(pool->zpool), type))
511 continue;
512 /* if we can't get it, it's about to be destroyed */
513 if (!zswap_pool_get(pool))
514 continue;
515 return pool;
516 }
517
518 return NULL;
519}
520
521static void shrink_worker(struct work_struct *w)
522{
523 struct zswap_pool *pool = container_of(w, typeof(*pool),
524 shrink_work);
525
526 if (zpool_shrink(pool->zpool, 1, NULL))
527 zswap_reject_reclaim_fail++;
528 zswap_pool_put(pool);
529}
530
531static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
532{
533 struct zswap_pool *pool;
534 char name[38]; /* 'zswap' + 32 char (max) num + \0 */
535 gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
536 int ret;
537
538 if (!zswap_has_pool) {
539 /* if either are unset, pool initialization failed, and we
540 * need both params to be set correctly before trying to
541 * create a pool.
542 */
543 if (!strcmp(type, ZSWAP_PARAM_UNSET))
544 return NULL;
545 if (!strcmp(compressor, ZSWAP_PARAM_UNSET))
546 return NULL;
547 }
548
549 pool = kzalloc(sizeof(*pool), GFP_KERNEL);
550 if (!pool)
551 return NULL;
552
553 /* unique name for each pool specifically required by zsmalloc */
554 snprintf(name, 38, "zswap%x", atomic_inc_return(&zswap_pools_count));
555
556 pool->zpool = zpool_create_pool(type, name, gfp, &zswap_zpool_ops);
557 if (!pool->zpool) {
558 pr_err("%s zpool not available\n", type);
559 goto error;
560 }
561 pr_debug("using %s zpool\n", zpool_get_type(pool->zpool));
562
563 strlcpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
564 pool->tfm = alloc_percpu(struct crypto_comp *);
565 if (!pool->tfm) {
566 pr_err("percpu alloc failed\n");
567 goto error;
568 }
569
570 ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
571 &pool->node);
572 if (ret)
573 goto error;
574 pr_debug("using %s compressor\n", pool->tfm_name);
575
576 /* being the current pool takes 1 ref; this func expects the
577 * caller to always add the new pool as the current pool
578 */
579 kref_init(&pool->kref);
580 INIT_LIST_HEAD(&pool->list);
581 INIT_WORK(&pool->shrink_work, shrink_worker);
582
583 zswap_pool_debug("created", pool);
584
585 return pool;
586
587error:
588 free_percpu(pool->tfm);
589 if (pool->zpool)
590 zpool_destroy_pool(pool->zpool);
591 kfree(pool);
592 return NULL;
593}
594
595static __init struct zswap_pool *__zswap_pool_create_fallback(void)
596{
597 bool has_comp, has_zpool;
598
599 has_comp = crypto_has_comp(zswap_compressor, 0, 0);
600 if (!has_comp && strcmp(zswap_compressor,
601 CONFIG_ZSWAP_COMPRESSOR_DEFAULT)) {
602 pr_err("compressor %s not available, using default %s\n",
603 zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT);
604 param_free_charp(&zswap_compressor);
605 zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
606 has_comp = crypto_has_comp(zswap_compressor, 0, 0);
607 }
608 if (!has_comp) {
609 pr_err("default compressor %s not available\n",
610 zswap_compressor);
611 param_free_charp(&zswap_compressor);
612 zswap_compressor = ZSWAP_PARAM_UNSET;
613 }
614
615 has_zpool = zpool_has_pool(zswap_zpool_type);
616 if (!has_zpool && strcmp(zswap_zpool_type,
617 CONFIG_ZSWAP_ZPOOL_DEFAULT)) {
618 pr_err("zpool %s not available, using default %s\n",
619 zswap_zpool_type, CONFIG_ZSWAP_ZPOOL_DEFAULT);
620 param_free_charp(&zswap_zpool_type);
621 zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
622 has_zpool = zpool_has_pool(zswap_zpool_type);
623 }
624 if (!has_zpool) {
625 pr_err("default zpool %s not available\n",
626 zswap_zpool_type);
627 param_free_charp(&zswap_zpool_type);
628 zswap_zpool_type = ZSWAP_PARAM_UNSET;
629 }
630
631 if (!has_comp || !has_zpool)
632 return NULL;
633
634 return zswap_pool_create(zswap_zpool_type, zswap_compressor);
635}
636
637static void zswap_pool_destroy(struct zswap_pool *pool)
638{
639 zswap_pool_debug("destroying", pool);
640
641 cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
642 free_percpu(pool->tfm);
643 zpool_destroy_pool(pool->zpool);
644 kfree(pool);
645}
646
647static int __must_check zswap_pool_get(struct zswap_pool *pool)
648{
649 if (!pool)
650 return 0;
651
652 return kref_get_unless_zero(&pool->kref);
653}
654
655static void __zswap_pool_release(struct work_struct *work)
656{
657 struct zswap_pool *pool = container_of(work, typeof(*pool),
658 release_work);
659
660 synchronize_rcu();
661
662 /* nobody should have been able to get a kref... */
663 WARN_ON(kref_get_unless_zero(&pool->kref));
664
665 /* pool is now off zswap_pools list and has no references. */
666 zswap_pool_destroy(pool);
667}
668
669static void __zswap_pool_empty(struct kref *kref)
670{
671 struct zswap_pool *pool;
672
673 pool = container_of(kref, typeof(*pool), kref);
674
675 spin_lock(&zswap_pools_lock);
676
677 WARN_ON(pool == zswap_pool_current());
678
679 list_del_rcu(&pool->list);
680
681 INIT_WORK(&pool->release_work, __zswap_pool_release);
682 schedule_work(&pool->release_work);
683
684 spin_unlock(&zswap_pools_lock);
685}
686
687static void zswap_pool_put(struct zswap_pool *pool)
688{
689 kref_put(&pool->kref, __zswap_pool_empty);
690}
691
692/*********************************
693* param callbacks
694**********************************/
695
696/* val must be a null-terminated string */
697static int __zswap_param_set(const char *val, const struct kernel_param *kp,
698 char *type, char *compressor)
699{
700 struct zswap_pool *pool, *put_pool = NULL;
701 char *s = strstrip((char *)val);
702 int ret;
703
704 if (zswap_init_failed) {
705 pr_err("can't set param, initialization failed\n");
706 return -ENODEV;
707 }
708
709 /* no change required */
710 if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
711 return 0;
712
713 /* if this is load-time (pre-init) param setting,
714 * don't create a pool; that's done during init.
715 */
716 if (!zswap_init_started)
717 return param_set_charp(s, kp);
718
719 if (!type) {
720 if (!zpool_has_pool(s)) {
721 pr_err("zpool %s not available\n", s);
722 return -ENOENT;
723 }
724 type = s;
725 } else if (!compressor) {
726 if (!crypto_has_comp(s, 0, 0)) {
727 pr_err("compressor %s not available\n", s);
728 return -ENOENT;
729 }
730 compressor = s;
731 } else {
732 WARN_ON(1);
733 return -EINVAL;
734 }
735
736 spin_lock(&zswap_pools_lock);
737
738 pool = zswap_pool_find_get(type, compressor);
739 if (pool) {
740 zswap_pool_debug("using existing", pool);
741 WARN_ON(pool == zswap_pool_current());
742 list_del_rcu(&pool->list);
743 }
744
745 spin_unlock(&zswap_pools_lock);
746
747 if (!pool)
748 pool = zswap_pool_create(type, compressor);
749
750 if (pool)
751 ret = param_set_charp(s, kp);
752 else
753 ret = -EINVAL;
754
755 spin_lock(&zswap_pools_lock);
756
757 if (!ret) {
758 put_pool = zswap_pool_current();
759 list_add_rcu(&pool->list, &zswap_pools);
760 zswap_has_pool = true;
761 } else if (pool) {
762 /* add the possibly pre-existing pool to the end of the pools
763 * list; if it's new (and empty) then it'll be removed and
764 * destroyed by the put after we drop the lock
765 */
766 list_add_tail_rcu(&pool->list, &zswap_pools);
767 put_pool = pool;
768 }
769
770 spin_unlock(&zswap_pools_lock);
771
772 if (!zswap_has_pool && !pool) {
773 /* if initial pool creation failed, and this pool creation also
774 * failed, maybe both compressor and zpool params were bad.
775 * Allow changing this param, so pool creation will succeed
776 * when the other param is changed. We already verified this
777 * param is ok in the zpool_has_pool() or crypto_has_comp()
778 * checks above.
779 */
780 ret = param_set_charp(s, kp);
781 }
782
783 /* drop the ref from either the old current pool,
784 * or the new pool we failed to add
785 */
786 if (put_pool)
787 zswap_pool_put(put_pool);
788
789 return ret;
790}
791
792static int zswap_compressor_param_set(const char *val,
793 const struct kernel_param *kp)
794{
795 return __zswap_param_set(val, kp, zswap_zpool_type, NULL);
796}
797
798static int zswap_zpool_param_set(const char *val,
799 const struct kernel_param *kp)
800{
801 return __zswap_param_set(val, kp, NULL, zswap_compressor);
802}
803
804static int zswap_enabled_param_set(const char *val,
805 const struct kernel_param *kp)
806{
807 if (zswap_init_failed) {
808 pr_err("can't enable, initialization failed\n");
809 return -ENODEV;
810 }
811 if (!zswap_has_pool && zswap_init_started) {
812 pr_err("can't enable, no pool configured\n");
813 return -ENODEV;
814 }
815
816 return param_set_bool(val, kp);
817}
818
819/*********************************
820* writeback code
821**********************************/
822/* return enum for zswap_get_swap_cache_page */
823enum zswap_get_swap_ret {
824 ZSWAP_SWAPCACHE_NEW,
825 ZSWAP_SWAPCACHE_EXIST,
826 ZSWAP_SWAPCACHE_FAIL,
827};
828
829/*
830 * zswap_get_swap_cache_page
831 *
832 * This is an adaption of read_swap_cache_async()
833 *
834 * This function tries to find a page with the given swap entry
835 * in the swapper_space address space (the swap cache). If the page
836 * is found, it is returned in retpage. Otherwise, a page is allocated,
837 * added to the swap cache, and returned in retpage.
838 *
839 * If success, the swap cache page is returned in retpage
840 * Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache
841 * Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated,
842 * the new page is added to swapcache and locked
843 * Returns ZSWAP_SWAPCACHE_FAIL on error
844 */
845static int zswap_get_swap_cache_page(swp_entry_t entry,
846 struct page **retpage)
847{
848 bool page_was_allocated;
849
850 *retpage = __read_swap_cache_async(entry, GFP_KERNEL,
851 NULL, 0, &page_was_allocated);
852 if (page_was_allocated)
853 return ZSWAP_SWAPCACHE_NEW;
854 if (!*retpage)
855 return ZSWAP_SWAPCACHE_FAIL;
856 return ZSWAP_SWAPCACHE_EXIST;
857}
858
859/*
860 * Attempts to free an entry by adding a page to the swap cache,
861 * decompressing the entry data into the page, and issuing a
862 * bio write to write the page back to the swap device.
863 *
864 * This can be thought of as a "resumed writeback" of the page
865 * to the swap device. We are basically resuming the same swap
866 * writeback path that was intercepted with the frontswap_store()
867 * in the first place. After the page has been decompressed into
868 * the swap cache, the compressed version stored by zswap can be
869 * freed.
870 */
871static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
872{
873 struct zswap_header *zhdr;
874 swp_entry_t swpentry;
875 struct zswap_tree *tree;
876 pgoff_t offset;
877 struct zswap_entry *entry;
878 struct page *page;
879 struct crypto_comp *tfm;
880 u8 *src, *dst;
881 unsigned int dlen;
882 int ret;
883 struct writeback_control wbc = {
884 .sync_mode = WB_SYNC_NONE,
885 };
886
887 /* extract swpentry from data */
888 zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
889 swpentry = zhdr->swpentry; /* here */
890 tree = zswap_trees[swp_type(swpentry)];
891 offset = swp_offset(swpentry);
892
893 /* find and ref zswap entry */
894 spin_lock(&tree->lock);
895 entry = zswap_entry_find_get(&tree->rbroot, offset);
896 if (!entry) {
897 /* entry was invalidated */
898 spin_unlock(&tree->lock);
899 zpool_unmap_handle(pool, handle);
900 return 0;
901 }
902 spin_unlock(&tree->lock);
903 BUG_ON(offset != entry->offset);
904
905 /* try to allocate swap cache page */
906 switch (zswap_get_swap_cache_page(swpentry, &page)) {
907 case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
908 ret = -ENOMEM;
909 goto fail;
910
911 case ZSWAP_SWAPCACHE_EXIST:
912 /* page is already in the swap cache, ignore for now */
913 put_page(page);
914 ret = -EEXIST;
915 goto fail;
916
917 case ZSWAP_SWAPCACHE_NEW: /* page is locked */
918 /* decompress */
919 dlen = PAGE_SIZE;
920 src = (u8 *)zhdr + sizeof(struct zswap_header);
921 dst = kmap_atomic(page);
922 tfm = *get_cpu_ptr(entry->pool->tfm);
923 ret = crypto_comp_decompress(tfm, src, entry->length,
924 dst, &dlen);
925 put_cpu_ptr(entry->pool->tfm);
926 kunmap_atomic(dst);
927 BUG_ON(ret);
928 BUG_ON(dlen != PAGE_SIZE);
929
930 /* page is up to date */
931 SetPageUptodate(page);
932 }
933
934 /* move it to the tail of the inactive list after end_writeback */
935 SetPageReclaim(page);
936
937 /* start writeback */
938 __swap_writepage(page, &wbc, end_swap_bio_write);
939 put_page(page);
940 zswap_written_back_pages++;
941
942 spin_lock(&tree->lock);
943 /* drop local reference */
944 zswap_entry_put(tree, entry);
945
946 /*
947 * There are two possible situations for entry here:
948 * (1) refcount is 1(normal case), entry is valid and on the tree
949 * (2) refcount is 0, entry is freed and not on the tree
950 * because invalidate happened during writeback
951 * search the tree and free the entry if find entry
952 */
953 if (entry == zswap_rb_search(&tree->rbroot, offset))
954 zswap_entry_put(tree, entry);
955 spin_unlock(&tree->lock);
956
957 goto end;
958
959 /*
960 * if we get here due to ZSWAP_SWAPCACHE_EXIST
961 * a load may happening concurrently
962 * it is safe and okay to not free the entry
963 * if we free the entry in the following put
964 * it it either okay to return !0
965 */
966fail:
967 spin_lock(&tree->lock);
968 zswap_entry_put(tree, entry);
969 spin_unlock(&tree->lock);
970
971end:
972 zpool_unmap_handle(pool, handle);
973 return ret;
974}
975
976static int zswap_is_page_same_filled(void *ptr, unsigned long *value)
977{
978 unsigned int pos;
979 unsigned long *page;
980
981 page = (unsigned long *)ptr;
982 for (pos = 1; pos < PAGE_SIZE / sizeof(*page); pos++) {
983 if (page[pos] != page[0])
984 return 0;
985 }
986 *value = page[0];
987 return 1;
988}
989
990static void zswap_fill_page(void *ptr, unsigned long value)
991{
992 unsigned long *page;
993
994 page = (unsigned long *)ptr;
995 memset_l(page, value, PAGE_SIZE / sizeof(unsigned long));
996}
997
998/*********************************
999* frontswap hooks
1000**********************************/
1001/* attempts to compress and store an single page */
1002static int zswap_frontswap_store(unsigned type, pgoff_t offset,
1003 struct page *page)
1004{
1005 struct zswap_tree *tree = zswap_trees[type];
1006 struct zswap_entry *entry, *dupentry;
1007 struct crypto_comp *tfm;
1008 int ret;
1009 unsigned int hlen, dlen = PAGE_SIZE;
1010 unsigned long handle, value;
1011 char *buf;
1012 u8 *src, *dst;
1013 struct zswap_header zhdr = { .swpentry = swp_entry(type, offset) };
1014 gfp_t gfp;
1015
1016 /* THP isn't supported */
1017 if (PageTransHuge(page)) {
1018 ret = -EINVAL;
1019 goto reject;
1020 }
1021
1022 if (!zswap_enabled || !tree) {
1023 ret = -ENODEV;
1024 goto reject;
1025 }
1026
1027 /* reclaim space if needed */
1028 if (zswap_is_full()) {
1029 struct zswap_pool *pool;
1030
1031 zswap_pool_limit_hit++;
1032 zswap_pool_reached_full = true;
1033 pool = zswap_pool_last_get();
1034 if (pool)
1035 queue_work(shrink_wq, &pool->shrink_work);
1036 ret = -ENOMEM;
1037 goto reject;
1038 }
1039
1040 if (zswap_pool_reached_full) {
1041 if (!zswap_can_accept()) {
1042 ret = -ENOMEM;
1043 goto reject;
1044 } else
1045 zswap_pool_reached_full = false;
1046 }
1047
1048 /* allocate entry */
1049 entry = zswap_entry_cache_alloc(GFP_KERNEL);
1050 if (!entry) {
1051 zswap_reject_kmemcache_fail++;
1052 ret = -ENOMEM;
1053 goto reject;
1054 }
1055
1056 if (zswap_same_filled_pages_enabled) {
1057 src = kmap_atomic(page);
1058 if (zswap_is_page_same_filled(src, &value)) {
1059 kunmap_atomic(src);
1060 entry->offset = offset;
1061 entry->length = 0;
1062 entry->value = value;
1063 atomic_inc(&zswap_same_filled_pages);
1064 goto insert_entry;
1065 }
1066 kunmap_atomic(src);
1067 }
1068
1069 /* if entry is successfully added, it keeps the reference */
1070 entry->pool = zswap_pool_current_get();
1071 if (!entry->pool) {
1072 ret = -EINVAL;
1073 goto freepage;
1074 }
1075
1076 /* compress */
1077 dst = get_cpu_var(zswap_dstmem);
1078 tfm = *get_cpu_ptr(entry->pool->tfm);
1079 src = kmap_atomic(page);
1080 ret = crypto_comp_compress(tfm, src, PAGE_SIZE, dst, &dlen);
1081 kunmap_atomic(src);
1082 put_cpu_ptr(entry->pool->tfm);
1083 if (ret) {
1084 ret = -EINVAL;
1085 goto put_dstmem;
1086 }
1087
1088 /* store */
1089 hlen = zpool_evictable(entry->pool->zpool) ? sizeof(zhdr) : 0;
1090 gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
1091 if (zpool_malloc_support_movable(entry->pool->zpool))
1092 gfp |= __GFP_HIGHMEM | __GFP_MOVABLE;
1093 ret = zpool_malloc(entry->pool->zpool, hlen + dlen, gfp, &handle);
1094 if (ret == -ENOSPC) {
1095 zswap_reject_compress_poor++;
1096 goto put_dstmem;
1097 }
1098 if (ret) {
1099 zswap_reject_alloc_fail++;
1100 goto put_dstmem;
1101 }
1102 buf = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_RW);
1103 memcpy(buf, &zhdr, hlen);
1104 memcpy(buf + hlen, dst, dlen);
1105 zpool_unmap_handle(entry->pool->zpool, handle);
1106 put_cpu_var(zswap_dstmem);
1107
1108 /* populate entry */
1109 entry->offset = offset;
1110 entry->handle = handle;
1111 entry->length = dlen;
1112
1113insert_entry:
1114 /* map */
1115 spin_lock(&tree->lock);
1116 do {
1117 ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry);
1118 if (ret == -EEXIST) {
1119 zswap_duplicate_entry++;
1120 /* remove from rbtree */
1121 zswap_rb_erase(&tree->rbroot, dupentry);
1122 zswap_entry_put(tree, dupentry);
1123 }
1124 } while (ret == -EEXIST);
1125 spin_unlock(&tree->lock);
1126
1127 /* update stats */
1128 atomic_inc(&zswap_stored_pages);
1129 zswap_update_total_size();
1130
1131 return 0;
1132
1133put_dstmem:
1134 put_cpu_var(zswap_dstmem);
1135 zswap_pool_put(entry->pool);
1136freepage:
1137 zswap_entry_cache_free(entry);
1138reject:
1139 return ret;
1140}
1141
1142/*
1143 * returns 0 if the page was successfully decompressed
1144 * return -1 on entry not found or error
1145*/
1146static int zswap_frontswap_load(unsigned type, pgoff_t offset,
1147 struct page *page)
1148{
1149 struct zswap_tree *tree = zswap_trees[type];
1150 struct zswap_entry *entry;
1151 struct crypto_comp *tfm;
1152 u8 *src, *dst;
1153 unsigned int dlen;
1154 int ret;
1155
1156 /* find */
1157 spin_lock(&tree->lock);
1158 entry = zswap_entry_find_get(&tree->rbroot, offset);
1159 if (!entry) {
1160 /* entry was written back */
1161 spin_unlock(&tree->lock);
1162 return -1;
1163 }
1164 spin_unlock(&tree->lock);
1165
1166 if (!entry->length) {
1167 dst = kmap_atomic(page);
1168 zswap_fill_page(dst, entry->value);
1169 kunmap_atomic(dst);
1170 goto freeentry;
1171 }
1172
1173 /* decompress */
1174 dlen = PAGE_SIZE;
1175 src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO);
1176 if (zpool_evictable(entry->pool->zpool))
1177 src += sizeof(struct zswap_header);
1178 dst = kmap_atomic(page);
1179 tfm = *get_cpu_ptr(entry->pool->tfm);
1180 ret = crypto_comp_decompress(tfm, src, entry->length, dst, &dlen);
1181 put_cpu_ptr(entry->pool->tfm);
1182 kunmap_atomic(dst);
1183 zpool_unmap_handle(entry->pool->zpool, entry->handle);
1184 BUG_ON(ret);
1185
1186freeentry:
1187 spin_lock(&tree->lock);
1188 zswap_entry_put(tree, entry);
1189 spin_unlock(&tree->lock);
1190
1191 return 0;
1192}
1193
1194/* frees an entry in zswap */
1195static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
1196{
1197 struct zswap_tree *tree = zswap_trees[type];
1198 struct zswap_entry *entry;
1199
1200 /* find */
1201 spin_lock(&tree->lock);
1202 entry = zswap_rb_search(&tree->rbroot, offset);
1203 if (!entry) {
1204 /* entry was written back */
1205 spin_unlock(&tree->lock);
1206 return;
1207 }
1208
1209 /* remove from rbtree */
1210 zswap_rb_erase(&tree->rbroot, entry);
1211
1212 /* drop the initial reference from entry creation */
1213 zswap_entry_put(tree, entry);
1214
1215 spin_unlock(&tree->lock);
1216}
1217
1218/* frees all zswap entries for the given swap type */
1219static void zswap_frontswap_invalidate_area(unsigned type)
1220{
1221 struct zswap_tree *tree = zswap_trees[type];
1222 struct zswap_entry *entry, *n;
1223
1224 if (!tree)
1225 return;
1226
1227 /* walk the tree and free everything */
1228 spin_lock(&tree->lock);
1229 rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
1230 zswap_free_entry(entry);
1231 tree->rbroot = RB_ROOT;
1232 spin_unlock(&tree->lock);
1233 kfree(tree);
1234 zswap_trees[type] = NULL;
1235}
1236
1237static void zswap_frontswap_init(unsigned type)
1238{
1239 struct zswap_tree *tree;
1240
1241 tree = kzalloc(sizeof(*tree), GFP_KERNEL);
1242 if (!tree) {
1243 pr_err("alloc failed, zswap disabled for swap type %d\n", type);
1244 return;
1245 }
1246
1247 tree->rbroot = RB_ROOT;
1248 spin_lock_init(&tree->lock);
1249 zswap_trees[type] = tree;
1250}
1251
1252static struct frontswap_ops zswap_frontswap_ops = {
1253 .store = zswap_frontswap_store,
1254 .load = zswap_frontswap_load,
1255 .invalidate_page = zswap_frontswap_invalidate_page,
1256 .invalidate_area = zswap_frontswap_invalidate_area,
1257 .init = zswap_frontswap_init
1258};
1259
1260/*********************************
1261* debugfs functions
1262**********************************/
1263#ifdef CONFIG_DEBUG_FS
1264#include <linux/debugfs.h>
1265
1266static struct dentry *zswap_debugfs_root;
1267
1268static int __init zswap_debugfs_init(void)
1269{
1270 if (!debugfs_initialized())
1271 return -ENODEV;
1272
1273 zswap_debugfs_root = debugfs_create_dir("zswap", NULL);
1274
1275 debugfs_create_u64("pool_limit_hit", 0444,
1276 zswap_debugfs_root, &zswap_pool_limit_hit);
1277 debugfs_create_u64("reject_reclaim_fail", 0444,
1278 zswap_debugfs_root, &zswap_reject_reclaim_fail);
1279 debugfs_create_u64("reject_alloc_fail", 0444,
1280 zswap_debugfs_root, &zswap_reject_alloc_fail);
1281 debugfs_create_u64("reject_kmemcache_fail", 0444,
1282 zswap_debugfs_root, &zswap_reject_kmemcache_fail);
1283 debugfs_create_u64("reject_compress_poor", 0444,
1284 zswap_debugfs_root, &zswap_reject_compress_poor);
1285 debugfs_create_u64("written_back_pages", 0444,
1286 zswap_debugfs_root, &zswap_written_back_pages);
1287 debugfs_create_u64("duplicate_entry", 0444,
1288 zswap_debugfs_root, &zswap_duplicate_entry);
1289 debugfs_create_u64("pool_total_size", 0444,
1290 zswap_debugfs_root, &zswap_pool_total_size);
1291 debugfs_create_atomic_t("stored_pages", 0444,
1292 zswap_debugfs_root, &zswap_stored_pages);
1293 debugfs_create_atomic_t("same_filled_pages", 0444,
1294 zswap_debugfs_root, &zswap_same_filled_pages);
1295
1296 return 0;
1297}
1298
1299static void __exit zswap_debugfs_exit(void)
1300{
1301 debugfs_remove_recursive(zswap_debugfs_root);
1302}
1303#else
1304static int __init zswap_debugfs_init(void)
1305{
1306 return 0;
1307}
1308
1309static void __exit zswap_debugfs_exit(void) { }
1310#endif
1311
1312/*********************************
1313* module init and exit
1314**********************************/
1315static int __init init_zswap(void)
1316{
1317 struct zswap_pool *pool;
1318 int ret;
1319
1320 zswap_init_started = true;
1321
1322 if (zswap_entry_cache_create()) {
1323 pr_err("entry cache creation failed\n");
1324 goto cache_fail;
1325 }
1326
1327 ret = cpuhp_setup_state(CPUHP_MM_ZSWP_MEM_PREPARE, "mm/zswap:prepare",
1328 zswap_dstmem_prepare, zswap_dstmem_dead);
1329 if (ret) {
1330 pr_err("dstmem alloc failed\n");
1331 goto dstmem_fail;
1332 }
1333
1334 ret = cpuhp_setup_state_multi(CPUHP_MM_ZSWP_POOL_PREPARE,
1335 "mm/zswap_pool:prepare",
1336 zswap_cpu_comp_prepare,
1337 zswap_cpu_comp_dead);
1338 if (ret)
1339 goto hp_fail;
1340
1341 pool = __zswap_pool_create_fallback();
1342 if (pool) {
1343 pr_info("loaded using pool %s/%s\n", pool->tfm_name,
1344 zpool_get_type(pool->zpool));
1345 list_add(&pool->list, &zswap_pools);
1346 zswap_has_pool = true;
1347 } else {
1348 pr_err("pool creation failed\n");
1349 zswap_enabled = false;
1350 }
1351
1352 shrink_wq = create_workqueue("zswap-shrink");
1353 if (!shrink_wq)
1354 goto fallback_fail;
1355
1356 frontswap_register_ops(&zswap_frontswap_ops);
1357 if (zswap_debugfs_init())
1358 pr_warn("debugfs initialization failed\n");
1359 return 0;
1360
1361fallback_fail:
1362 if (pool)
1363 zswap_pool_destroy(pool);
1364hp_fail:
1365 cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
1366dstmem_fail:
1367 zswap_entry_cache_destroy();
1368cache_fail:
1369 /* if built-in, we aren't unloaded on failure; don't allow use */
1370 zswap_init_failed = true;
1371 zswap_enabled = false;
1372 return -ENOMEM;
1373}
1374/* must be late so crypto has time to come up */
1375late_initcall(init_zswap);
1376
1377MODULE_LICENSE("GPL");
1378MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
1379MODULE_DESCRIPTION("Compressed cache for swap pages");
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * zswap.c - zswap driver file
4 *
5 * zswap is a backend for frontswap that takes pages that are in the process
6 * of being swapped out and attempts to compress and store them in a
7 * RAM-based memory pool. This can result in a significant I/O reduction on
8 * the swap device and, in the case where decompressing from RAM is faster
9 * than reading from the swap device, can also improve workload performance.
10 *
11 * Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com>
12*/
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/module.h>
17#include <linux/cpu.h>
18#include <linux/highmem.h>
19#include <linux/slab.h>
20#include <linux/spinlock.h>
21#include <linux/types.h>
22#include <linux/atomic.h>
23#include <linux/frontswap.h>
24#include <linux/rbtree.h>
25#include <linux/swap.h>
26#include <linux/crypto.h>
27#include <linux/scatterlist.h>
28#include <linux/mempool.h>
29#include <linux/zpool.h>
30#include <crypto/acompress.h>
31
32#include <linux/mm_types.h>
33#include <linux/page-flags.h>
34#include <linux/swapops.h>
35#include <linux/writeback.h>
36#include <linux/pagemap.h>
37#include <linux/workqueue.h>
38
39#include "swap.h"
40
41/*********************************
42* statistics
43**********************************/
44/* Total bytes used by the compressed storage */
45u64 zswap_pool_total_size;
46/* The number of compressed pages currently stored in zswap */
47atomic_t zswap_stored_pages = ATOMIC_INIT(0);
48/* The number of same-value filled pages currently stored in zswap */
49static atomic_t zswap_same_filled_pages = ATOMIC_INIT(0);
50
51/*
52 * The statistics below are not protected from concurrent access for
53 * performance reasons so they may not be a 100% accurate. However,
54 * they do provide useful information on roughly how many times a
55 * certain event is occurring.
56*/
57
58/* Pool limit was hit (see zswap_max_pool_percent) */
59static u64 zswap_pool_limit_hit;
60/* Pages written back when pool limit was reached */
61static u64 zswap_written_back_pages;
62/* Store failed due to a reclaim failure after pool limit was reached */
63static u64 zswap_reject_reclaim_fail;
64/* Compressed page was too big for the allocator to (optimally) store */
65static u64 zswap_reject_compress_poor;
66/* Store failed because underlying allocator could not get memory */
67static u64 zswap_reject_alloc_fail;
68/* Store failed because the entry metadata could not be allocated (rare) */
69static u64 zswap_reject_kmemcache_fail;
70/* Duplicate store was encountered (rare) */
71static u64 zswap_duplicate_entry;
72
73/* Shrinker work queue */
74static struct workqueue_struct *shrink_wq;
75/* Pool limit was hit, we need to calm down */
76static bool zswap_pool_reached_full;
77
78/*********************************
79* tunables
80**********************************/
81
82#define ZSWAP_PARAM_UNSET ""
83
84/* Enable/disable zswap */
85static bool zswap_enabled = IS_ENABLED(CONFIG_ZSWAP_DEFAULT_ON);
86static int zswap_enabled_param_set(const char *,
87 const struct kernel_param *);
88static const struct kernel_param_ops zswap_enabled_param_ops = {
89 .set = zswap_enabled_param_set,
90 .get = param_get_bool,
91};
92module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644);
93
94/* Crypto compressor to use */
95static char *zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
96static int zswap_compressor_param_set(const char *,
97 const struct kernel_param *);
98static const struct kernel_param_ops zswap_compressor_param_ops = {
99 .set = zswap_compressor_param_set,
100 .get = param_get_charp,
101 .free = param_free_charp,
102};
103module_param_cb(compressor, &zswap_compressor_param_ops,
104 &zswap_compressor, 0644);
105
106/* Compressed storage zpool to use */
107static char *zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
108static int zswap_zpool_param_set(const char *, const struct kernel_param *);
109static const struct kernel_param_ops zswap_zpool_param_ops = {
110 .set = zswap_zpool_param_set,
111 .get = param_get_charp,
112 .free = param_free_charp,
113};
114module_param_cb(zpool, &zswap_zpool_param_ops, &zswap_zpool_type, 0644);
115
116/* The maximum percentage of memory that the compressed pool can occupy */
117static unsigned int zswap_max_pool_percent = 20;
118module_param_named(max_pool_percent, zswap_max_pool_percent, uint, 0644);
119
120/* The threshold for accepting new pages after the max_pool_percent was hit */
121static unsigned int zswap_accept_thr_percent = 90; /* of max pool size */
122module_param_named(accept_threshold_percent, zswap_accept_thr_percent,
123 uint, 0644);
124
125/*
126 * Enable/disable handling same-value filled pages (enabled by default).
127 * If disabled every page is considered non-same-value filled.
128 */
129static bool zswap_same_filled_pages_enabled = true;
130module_param_named(same_filled_pages_enabled, zswap_same_filled_pages_enabled,
131 bool, 0644);
132
133/* Enable/disable handling non-same-value filled pages (enabled by default) */
134static bool zswap_non_same_filled_pages_enabled = true;
135module_param_named(non_same_filled_pages_enabled, zswap_non_same_filled_pages_enabled,
136 bool, 0644);
137
138/*********************************
139* data structures
140**********************************/
141
142struct crypto_acomp_ctx {
143 struct crypto_acomp *acomp;
144 struct acomp_req *req;
145 struct crypto_wait wait;
146 u8 *dstmem;
147 struct mutex *mutex;
148};
149
150struct zswap_pool {
151 struct zpool *zpool;
152 struct crypto_acomp_ctx __percpu *acomp_ctx;
153 struct kref kref;
154 struct list_head list;
155 struct work_struct release_work;
156 struct work_struct shrink_work;
157 struct hlist_node node;
158 char tfm_name[CRYPTO_MAX_ALG_NAME];
159};
160
161/*
162 * struct zswap_entry
163 *
164 * This structure contains the metadata for tracking a single compressed
165 * page within zswap.
166 *
167 * rbnode - links the entry into red-black tree for the appropriate swap type
168 * offset - the swap offset for the entry. Index into the red-black tree.
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 * length - the length in bytes of the compressed page data. Needed during
176 * decompression. For a same value filled page length is 0.
177 * pool - the zswap_pool the entry's data is in
178 * handle - zpool allocation handle that stores the compressed page data
179 * value - value of the same-value filled pages which have same content
180 */
181struct zswap_entry {
182 struct rb_node rbnode;
183 pgoff_t offset;
184 int refcount;
185 unsigned int length;
186 struct zswap_pool *pool;
187 union {
188 unsigned long handle;
189 unsigned long value;
190 };
191 struct obj_cgroup *objcg;
192};
193
194struct zswap_header {
195 swp_entry_t swpentry;
196};
197
198/*
199 * The tree lock in the zswap_tree struct protects a few things:
200 * - the rbtree
201 * - the refcount field of each entry in the tree
202 */
203struct zswap_tree {
204 struct rb_root rbroot;
205 spinlock_t lock;
206};
207
208static struct zswap_tree *zswap_trees[MAX_SWAPFILES];
209
210/* RCU-protected iteration */
211static LIST_HEAD(zswap_pools);
212/* protects zswap_pools list modification */
213static DEFINE_SPINLOCK(zswap_pools_lock);
214/* pool counter to provide unique names to zpool */
215static atomic_t zswap_pools_count = ATOMIC_INIT(0);
216
217/* used by param callback function */
218static bool zswap_init_started;
219
220/* fatal error during init */
221static bool zswap_init_failed;
222
223/* init completed, but couldn't create the initial pool */
224static bool zswap_has_pool;
225
226/*********************************
227* helpers and fwd declarations
228**********************************/
229
230#define zswap_pool_debug(msg, p) \
231 pr_debug("%s pool %s/%s\n", msg, (p)->tfm_name, \
232 zpool_get_type((p)->zpool))
233
234static int zswap_writeback_entry(struct zpool *pool, unsigned long handle);
235static int zswap_pool_get(struct zswap_pool *pool);
236static void zswap_pool_put(struct zswap_pool *pool);
237
238static const struct zpool_ops zswap_zpool_ops = {
239 .evict = zswap_writeback_entry
240};
241
242static bool zswap_is_full(void)
243{
244 return totalram_pages() * zswap_max_pool_percent / 100 <
245 DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
246}
247
248static bool zswap_can_accept(void)
249{
250 return totalram_pages() * zswap_accept_thr_percent / 100 *
251 zswap_max_pool_percent / 100 >
252 DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
253}
254
255static void zswap_update_total_size(void)
256{
257 struct zswap_pool *pool;
258 u64 total = 0;
259
260 rcu_read_lock();
261
262 list_for_each_entry_rcu(pool, &zswap_pools, list)
263 total += zpool_get_total_size(pool->zpool);
264
265 rcu_read_unlock();
266
267 zswap_pool_total_size = total;
268}
269
270/*********************************
271* zswap entry functions
272**********************************/
273static struct kmem_cache *zswap_entry_cache;
274
275static int __init zswap_entry_cache_create(void)
276{
277 zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
278 return zswap_entry_cache == NULL;
279}
280
281static void __init zswap_entry_cache_destroy(void)
282{
283 kmem_cache_destroy(zswap_entry_cache);
284}
285
286static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp)
287{
288 struct zswap_entry *entry;
289 entry = kmem_cache_alloc(zswap_entry_cache, gfp);
290 if (!entry)
291 return NULL;
292 entry->refcount = 1;
293 RB_CLEAR_NODE(&entry->rbnode);
294 return entry;
295}
296
297static void zswap_entry_cache_free(struct zswap_entry *entry)
298{
299 kmem_cache_free(zswap_entry_cache, entry);
300}
301
302/*********************************
303* rbtree functions
304**********************************/
305static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset)
306{
307 struct rb_node *node = root->rb_node;
308 struct zswap_entry *entry;
309
310 while (node) {
311 entry = rb_entry(node, struct zswap_entry, rbnode);
312 if (entry->offset > offset)
313 node = node->rb_left;
314 else if (entry->offset < offset)
315 node = node->rb_right;
316 else
317 return entry;
318 }
319 return NULL;
320}
321
322/*
323 * In the case that a entry with the same offset is found, a pointer to
324 * the existing entry is stored in dupentry and the function returns -EEXIST
325 */
326static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry,
327 struct zswap_entry **dupentry)
328{
329 struct rb_node **link = &root->rb_node, *parent = NULL;
330 struct zswap_entry *myentry;
331
332 while (*link) {
333 parent = *link;
334 myentry = rb_entry(parent, struct zswap_entry, rbnode);
335 if (myentry->offset > entry->offset)
336 link = &(*link)->rb_left;
337 else if (myentry->offset < entry->offset)
338 link = &(*link)->rb_right;
339 else {
340 *dupentry = myentry;
341 return -EEXIST;
342 }
343 }
344 rb_link_node(&entry->rbnode, parent, link);
345 rb_insert_color(&entry->rbnode, root);
346 return 0;
347}
348
349static void zswap_rb_erase(struct rb_root *root, struct zswap_entry *entry)
350{
351 if (!RB_EMPTY_NODE(&entry->rbnode)) {
352 rb_erase(&entry->rbnode, root);
353 RB_CLEAR_NODE(&entry->rbnode);
354 }
355}
356
357/*
358 * Carries out the common pattern of freeing and entry's zpool allocation,
359 * freeing the entry itself, and decrementing the number of stored pages.
360 */
361static void zswap_free_entry(struct zswap_entry *entry)
362{
363 if (entry->objcg) {
364 obj_cgroup_uncharge_zswap(entry->objcg, entry->length);
365 obj_cgroup_put(entry->objcg);
366 }
367 if (!entry->length)
368 atomic_dec(&zswap_same_filled_pages);
369 else {
370 zpool_free(entry->pool->zpool, entry->handle);
371 zswap_pool_put(entry->pool);
372 }
373 zswap_entry_cache_free(entry);
374 atomic_dec(&zswap_stored_pages);
375 zswap_update_total_size();
376}
377
378/* caller must hold the tree lock */
379static void zswap_entry_get(struct zswap_entry *entry)
380{
381 entry->refcount++;
382}
383
384/* caller must hold the tree lock
385* remove from the tree and free it, if nobody reference the entry
386*/
387static void zswap_entry_put(struct zswap_tree *tree,
388 struct zswap_entry *entry)
389{
390 int refcount = --entry->refcount;
391
392 BUG_ON(refcount < 0);
393 if (refcount == 0) {
394 zswap_rb_erase(&tree->rbroot, entry);
395 zswap_free_entry(entry);
396 }
397}
398
399/* caller must hold the tree lock */
400static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
401 pgoff_t offset)
402{
403 struct zswap_entry *entry;
404
405 entry = zswap_rb_search(root, offset);
406 if (entry)
407 zswap_entry_get(entry);
408
409 return entry;
410}
411
412/*********************************
413* per-cpu code
414**********************************/
415static DEFINE_PER_CPU(u8 *, zswap_dstmem);
416/*
417 * If users dynamically change the zpool type and compressor at runtime, i.e.
418 * zswap is running, zswap can have more than one zpool on one cpu, but they
419 * are sharing dtsmem. So we need this mutex to be per-cpu.
420 */
421static DEFINE_PER_CPU(struct mutex *, zswap_mutex);
422
423static int zswap_dstmem_prepare(unsigned int cpu)
424{
425 struct mutex *mutex;
426 u8 *dst;
427
428 dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
429 if (!dst)
430 return -ENOMEM;
431
432 mutex = kmalloc_node(sizeof(*mutex), GFP_KERNEL, cpu_to_node(cpu));
433 if (!mutex) {
434 kfree(dst);
435 return -ENOMEM;
436 }
437
438 mutex_init(mutex);
439 per_cpu(zswap_dstmem, cpu) = dst;
440 per_cpu(zswap_mutex, cpu) = mutex;
441 return 0;
442}
443
444static int zswap_dstmem_dead(unsigned int cpu)
445{
446 struct mutex *mutex;
447 u8 *dst;
448
449 mutex = per_cpu(zswap_mutex, cpu);
450 kfree(mutex);
451 per_cpu(zswap_mutex, cpu) = NULL;
452
453 dst = per_cpu(zswap_dstmem, cpu);
454 kfree(dst);
455 per_cpu(zswap_dstmem, cpu) = NULL;
456
457 return 0;
458}
459
460static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
461{
462 struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
463 struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
464 struct crypto_acomp *acomp;
465 struct acomp_req *req;
466
467 acomp = crypto_alloc_acomp_node(pool->tfm_name, 0, 0, cpu_to_node(cpu));
468 if (IS_ERR(acomp)) {
469 pr_err("could not alloc crypto acomp %s : %ld\n",
470 pool->tfm_name, PTR_ERR(acomp));
471 return PTR_ERR(acomp);
472 }
473 acomp_ctx->acomp = acomp;
474
475 req = acomp_request_alloc(acomp_ctx->acomp);
476 if (!req) {
477 pr_err("could not alloc crypto acomp_request %s\n",
478 pool->tfm_name);
479 crypto_free_acomp(acomp_ctx->acomp);
480 return -ENOMEM;
481 }
482 acomp_ctx->req = req;
483
484 crypto_init_wait(&acomp_ctx->wait);
485 /*
486 * if the backend of acomp is async zip, crypto_req_done() will wakeup
487 * crypto_wait_req(); if the backend of acomp is scomp, the callback
488 * won't be called, crypto_wait_req() will return without blocking.
489 */
490 acomp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
491 crypto_req_done, &acomp_ctx->wait);
492
493 acomp_ctx->mutex = per_cpu(zswap_mutex, cpu);
494 acomp_ctx->dstmem = per_cpu(zswap_dstmem, cpu);
495
496 return 0;
497}
498
499static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
500{
501 struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
502 struct crypto_acomp_ctx *acomp_ctx = per_cpu_ptr(pool->acomp_ctx, cpu);
503
504 if (!IS_ERR_OR_NULL(acomp_ctx)) {
505 if (!IS_ERR_OR_NULL(acomp_ctx->req))
506 acomp_request_free(acomp_ctx->req);
507 if (!IS_ERR_OR_NULL(acomp_ctx->acomp))
508 crypto_free_acomp(acomp_ctx->acomp);
509 }
510
511 return 0;
512}
513
514/*********************************
515* pool functions
516**********************************/
517
518static struct zswap_pool *__zswap_pool_current(void)
519{
520 struct zswap_pool *pool;
521
522 pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);
523 WARN_ONCE(!pool && zswap_has_pool,
524 "%s: no page storage pool!\n", __func__);
525
526 return pool;
527}
528
529static struct zswap_pool *zswap_pool_current(void)
530{
531 assert_spin_locked(&zswap_pools_lock);
532
533 return __zswap_pool_current();
534}
535
536static struct zswap_pool *zswap_pool_current_get(void)
537{
538 struct zswap_pool *pool;
539
540 rcu_read_lock();
541
542 pool = __zswap_pool_current();
543 if (!zswap_pool_get(pool))
544 pool = NULL;
545
546 rcu_read_unlock();
547
548 return pool;
549}
550
551static struct zswap_pool *zswap_pool_last_get(void)
552{
553 struct zswap_pool *pool, *last = NULL;
554
555 rcu_read_lock();
556
557 list_for_each_entry_rcu(pool, &zswap_pools, list)
558 last = pool;
559 WARN_ONCE(!last && zswap_has_pool,
560 "%s: no page storage pool!\n", __func__);
561 if (!zswap_pool_get(last))
562 last = NULL;
563
564 rcu_read_unlock();
565
566 return last;
567}
568
569/* type and compressor must be null-terminated */
570static struct zswap_pool *zswap_pool_find_get(char *type, char *compressor)
571{
572 struct zswap_pool *pool;
573
574 assert_spin_locked(&zswap_pools_lock);
575
576 list_for_each_entry_rcu(pool, &zswap_pools, list) {
577 if (strcmp(pool->tfm_name, compressor))
578 continue;
579 if (strcmp(zpool_get_type(pool->zpool), type))
580 continue;
581 /* if we can't get it, it's about to be destroyed */
582 if (!zswap_pool_get(pool))
583 continue;
584 return pool;
585 }
586
587 return NULL;
588}
589
590static void shrink_worker(struct work_struct *w)
591{
592 struct zswap_pool *pool = container_of(w, typeof(*pool),
593 shrink_work);
594
595 if (zpool_shrink(pool->zpool, 1, NULL))
596 zswap_reject_reclaim_fail++;
597 zswap_pool_put(pool);
598}
599
600static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
601{
602 struct zswap_pool *pool;
603 char name[38]; /* 'zswap' + 32 char (max) num + \0 */
604 gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
605 int ret;
606
607 if (!zswap_has_pool) {
608 /* if either are unset, pool initialization failed, and we
609 * need both params to be set correctly before trying to
610 * create a pool.
611 */
612 if (!strcmp(type, ZSWAP_PARAM_UNSET))
613 return NULL;
614 if (!strcmp(compressor, ZSWAP_PARAM_UNSET))
615 return NULL;
616 }
617
618 pool = kzalloc(sizeof(*pool), GFP_KERNEL);
619 if (!pool)
620 return NULL;
621
622 /* unique name for each pool specifically required by zsmalloc */
623 snprintf(name, 38, "zswap%x", atomic_inc_return(&zswap_pools_count));
624
625 pool->zpool = zpool_create_pool(type, name, gfp, &zswap_zpool_ops);
626 if (!pool->zpool) {
627 pr_err("%s zpool not available\n", type);
628 goto error;
629 }
630 pr_debug("using %s zpool\n", zpool_get_type(pool->zpool));
631
632 strscpy(pool->tfm_name, compressor, sizeof(pool->tfm_name));
633
634 pool->acomp_ctx = alloc_percpu(*pool->acomp_ctx);
635 if (!pool->acomp_ctx) {
636 pr_err("percpu alloc failed\n");
637 goto error;
638 }
639
640 ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
641 &pool->node);
642 if (ret)
643 goto error;
644 pr_debug("using %s compressor\n", pool->tfm_name);
645
646 /* being the current pool takes 1 ref; this func expects the
647 * caller to always add the new pool as the current pool
648 */
649 kref_init(&pool->kref);
650 INIT_LIST_HEAD(&pool->list);
651 INIT_WORK(&pool->shrink_work, shrink_worker);
652
653 zswap_pool_debug("created", pool);
654
655 return pool;
656
657error:
658 if (pool->acomp_ctx)
659 free_percpu(pool->acomp_ctx);
660 if (pool->zpool)
661 zpool_destroy_pool(pool->zpool);
662 kfree(pool);
663 return NULL;
664}
665
666static __init struct zswap_pool *__zswap_pool_create_fallback(void)
667{
668 bool has_comp, has_zpool;
669
670 has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
671 if (!has_comp && strcmp(zswap_compressor,
672 CONFIG_ZSWAP_COMPRESSOR_DEFAULT)) {
673 pr_err("compressor %s not available, using default %s\n",
674 zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT);
675 param_free_charp(&zswap_compressor);
676 zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
677 has_comp = crypto_has_acomp(zswap_compressor, 0, 0);
678 }
679 if (!has_comp) {
680 pr_err("default compressor %s not available\n",
681 zswap_compressor);
682 param_free_charp(&zswap_compressor);
683 zswap_compressor = ZSWAP_PARAM_UNSET;
684 }
685
686 has_zpool = zpool_has_pool(zswap_zpool_type);
687 if (!has_zpool && strcmp(zswap_zpool_type,
688 CONFIG_ZSWAP_ZPOOL_DEFAULT)) {
689 pr_err("zpool %s not available, using default %s\n",
690 zswap_zpool_type, CONFIG_ZSWAP_ZPOOL_DEFAULT);
691 param_free_charp(&zswap_zpool_type);
692 zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
693 has_zpool = zpool_has_pool(zswap_zpool_type);
694 }
695 if (!has_zpool) {
696 pr_err("default zpool %s not available\n",
697 zswap_zpool_type);
698 param_free_charp(&zswap_zpool_type);
699 zswap_zpool_type = ZSWAP_PARAM_UNSET;
700 }
701
702 if (!has_comp || !has_zpool)
703 return NULL;
704
705 return zswap_pool_create(zswap_zpool_type, zswap_compressor);
706}
707
708static void zswap_pool_destroy(struct zswap_pool *pool)
709{
710 zswap_pool_debug("destroying", pool);
711
712 cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
713 free_percpu(pool->acomp_ctx);
714 zpool_destroy_pool(pool->zpool);
715 kfree(pool);
716}
717
718static int __must_check zswap_pool_get(struct zswap_pool *pool)
719{
720 if (!pool)
721 return 0;
722
723 return kref_get_unless_zero(&pool->kref);
724}
725
726static void __zswap_pool_release(struct work_struct *work)
727{
728 struct zswap_pool *pool = container_of(work, typeof(*pool),
729 release_work);
730
731 synchronize_rcu();
732
733 /* nobody should have been able to get a kref... */
734 WARN_ON(kref_get_unless_zero(&pool->kref));
735
736 /* pool is now off zswap_pools list and has no references. */
737 zswap_pool_destroy(pool);
738}
739
740static void __zswap_pool_empty(struct kref *kref)
741{
742 struct zswap_pool *pool;
743
744 pool = container_of(kref, typeof(*pool), kref);
745
746 spin_lock(&zswap_pools_lock);
747
748 WARN_ON(pool == zswap_pool_current());
749
750 list_del_rcu(&pool->list);
751
752 INIT_WORK(&pool->release_work, __zswap_pool_release);
753 schedule_work(&pool->release_work);
754
755 spin_unlock(&zswap_pools_lock);
756}
757
758static void zswap_pool_put(struct zswap_pool *pool)
759{
760 kref_put(&pool->kref, __zswap_pool_empty);
761}
762
763/*********************************
764* param callbacks
765**********************************/
766
767/* val must be a null-terminated string */
768static int __zswap_param_set(const char *val, const struct kernel_param *kp,
769 char *type, char *compressor)
770{
771 struct zswap_pool *pool, *put_pool = NULL;
772 char *s = strstrip((char *)val);
773 int ret;
774
775 if (zswap_init_failed) {
776 pr_err("can't set param, initialization failed\n");
777 return -ENODEV;
778 }
779
780 /* no change required */
781 if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
782 return 0;
783
784 /* if this is load-time (pre-init) param setting,
785 * don't create a pool; that's done during init.
786 */
787 if (!zswap_init_started)
788 return param_set_charp(s, kp);
789
790 if (!type) {
791 if (!zpool_has_pool(s)) {
792 pr_err("zpool %s not available\n", s);
793 return -ENOENT;
794 }
795 type = s;
796 } else if (!compressor) {
797 if (!crypto_has_acomp(s, 0, 0)) {
798 pr_err("compressor %s not available\n", s);
799 return -ENOENT;
800 }
801 compressor = s;
802 } else {
803 WARN_ON(1);
804 return -EINVAL;
805 }
806
807 spin_lock(&zswap_pools_lock);
808
809 pool = zswap_pool_find_get(type, compressor);
810 if (pool) {
811 zswap_pool_debug("using existing", pool);
812 WARN_ON(pool == zswap_pool_current());
813 list_del_rcu(&pool->list);
814 }
815
816 spin_unlock(&zswap_pools_lock);
817
818 if (!pool)
819 pool = zswap_pool_create(type, compressor);
820
821 if (pool)
822 ret = param_set_charp(s, kp);
823 else
824 ret = -EINVAL;
825
826 spin_lock(&zswap_pools_lock);
827
828 if (!ret) {
829 put_pool = zswap_pool_current();
830 list_add_rcu(&pool->list, &zswap_pools);
831 zswap_has_pool = true;
832 } else if (pool) {
833 /* add the possibly pre-existing pool to the end of the pools
834 * list; if it's new (and empty) then it'll be removed and
835 * destroyed by the put after we drop the lock
836 */
837 list_add_tail_rcu(&pool->list, &zswap_pools);
838 put_pool = pool;
839 }
840
841 spin_unlock(&zswap_pools_lock);
842
843 if (!zswap_has_pool && !pool) {
844 /* if initial pool creation failed, and this pool creation also
845 * failed, maybe both compressor and zpool params were bad.
846 * Allow changing this param, so pool creation will succeed
847 * when the other param is changed. We already verified this
848 * param is ok in the zpool_has_pool() or crypto_has_acomp()
849 * checks above.
850 */
851 ret = param_set_charp(s, kp);
852 }
853
854 /* drop the ref from either the old current pool,
855 * or the new pool we failed to add
856 */
857 if (put_pool)
858 zswap_pool_put(put_pool);
859
860 return ret;
861}
862
863static int zswap_compressor_param_set(const char *val,
864 const struct kernel_param *kp)
865{
866 return __zswap_param_set(val, kp, zswap_zpool_type, NULL);
867}
868
869static int zswap_zpool_param_set(const char *val,
870 const struct kernel_param *kp)
871{
872 return __zswap_param_set(val, kp, NULL, zswap_compressor);
873}
874
875static int zswap_enabled_param_set(const char *val,
876 const struct kernel_param *kp)
877{
878 if (zswap_init_failed) {
879 pr_err("can't enable, initialization failed\n");
880 return -ENODEV;
881 }
882 if (!zswap_has_pool && zswap_init_started) {
883 pr_err("can't enable, no pool configured\n");
884 return -ENODEV;
885 }
886
887 return param_set_bool(val, kp);
888}
889
890/*********************************
891* writeback code
892**********************************/
893/* return enum for zswap_get_swap_cache_page */
894enum zswap_get_swap_ret {
895 ZSWAP_SWAPCACHE_NEW,
896 ZSWAP_SWAPCACHE_EXIST,
897 ZSWAP_SWAPCACHE_FAIL,
898};
899
900/*
901 * zswap_get_swap_cache_page
902 *
903 * This is an adaption of read_swap_cache_async()
904 *
905 * This function tries to find a page with the given swap entry
906 * in the swapper_space address space (the swap cache). If the page
907 * is found, it is returned in retpage. Otherwise, a page is allocated,
908 * added to the swap cache, and returned in retpage.
909 *
910 * If success, the swap cache page is returned in retpage
911 * Returns ZSWAP_SWAPCACHE_EXIST if page was already in the swap cache
912 * Returns ZSWAP_SWAPCACHE_NEW if the new page needs to be populated,
913 * the new page is added to swapcache and locked
914 * Returns ZSWAP_SWAPCACHE_FAIL on error
915 */
916static int zswap_get_swap_cache_page(swp_entry_t entry,
917 struct page **retpage)
918{
919 bool page_was_allocated;
920
921 *retpage = __read_swap_cache_async(entry, GFP_KERNEL,
922 NULL, 0, &page_was_allocated);
923 if (page_was_allocated)
924 return ZSWAP_SWAPCACHE_NEW;
925 if (!*retpage)
926 return ZSWAP_SWAPCACHE_FAIL;
927 return ZSWAP_SWAPCACHE_EXIST;
928}
929
930/*
931 * Attempts to free an entry by adding a page to the swap cache,
932 * decompressing the entry data into the page, and issuing a
933 * bio write to write the page back to the swap device.
934 *
935 * This can be thought of as a "resumed writeback" of the page
936 * to the swap device. We are basically resuming the same swap
937 * writeback path that was intercepted with the frontswap_store()
938 * in the first place. After the page has been decompressed into
939 * the swap cache, the compressed version stored by zswap can be
940 * freed.
941 */
942static int zswap_writeback_entry(struct zpool *pool, unsigned long handle)
943{
944 struct zswap_header *zhdr;
945 swp_entry_t swpentry;
946 struct zswap_tree *tree;
947 pgoff_t offset;
948 struct zswap_entry *entry;
949 struct page *page;
950 struct scatterlist input, output;
951 struct crypto_acomp_ctx *acomp_ctx;
952
953 u8 *src, *tmp = NULL;
954 unsigned int dlen;
955 int ret;
956 struct writeback_control wbc = {
957 .sync_mode = WB_SYNC_NONE,
958 };
959
960 if (!zpool_can_sleep_mapped(pool)) {
961 tmp = kmalloc(PAGE_SIZE, GFP_KERNEL);
962 if (!tmp)
963 return -ENOMEM;
964 }
965
966 /* extract swpentry from data */
967 zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
968 swpentry = zhdr->swpentry; /* here */
969 tree = zswap_trees[swp_type(swpentry)];
970 offset = swp_offset(swpentry);
971 zpool_unmap_handle(pool, handle);
972
973 /* find and ref zswap entry */
974 spin_lock(&tree->lock);
975 entry = zswap_entry_find_get(&tree->rbroot, offset);
976 if (!entry) {
977 /* entry was invalidated */
978 spin_unlock(&tree->lock);
979 kfree(tmp);
980 return 0;
981 }
982 spin_unlock(&tree->lock);
983 BUG_ON(offset != entry->offset);
984
985 /* try to allocate swap cache page */
986 switch (zswap_get_swap_cache_page(swpentry, &page)) {
987 case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */
988 ret = -ENOMEM;
989 goto fail;
990
991 case ZSWAP_SWAPCACHE_EXIST:
992 /* page is already in the swap cache, ignore for now */
993 put_page(page);
994 ret = -EEXIST;
995 goto fail;
996
997 case ZSWAP_SWAPCACHE_NEW: /* page is locked */
998 /* decompress */
999 acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
1000 dlen = PAGE_SIZE;
1001
1002 zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
1003 src = (u8 *)zhdr + sizeof(struct zswap_header);
1004 if (!zpool_can_sleep_mapped(pool)) {
1005 memcpy(tmp, src, entry->length);
1006 src = tmp;
1007 zpool_unmap_handle(pool, handle);
1008 }
1009
1010 mutex_lock(acomp_ctx->mutex);
1011 sg_init_one(&input, src, entry->length);
1012 sg_init_table(&output, 1);
1013 sg_set_page(&output, page, PAGE_SIZE, 0);
1014 acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
1015 ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
1016 dlen = acomp_ctx->req->dlen;
1017 mutex_unlock(acomp_ctx->mutex);
1018
1019 if (!zpool_can_sleep_mapped(pool))
1020 kfree(tmp);
1021 else
1022 zpool_unmap_handle(pool, handle);
1023
1024 BUG_ON(ret);
1025 BUG_ON(dlen != PAGE_SIZE);
1026
1027 /* page is up to date */
1028 SetPageUptodate(page);
1029 }
1030
1031 /* move it to the tail of the inactive list after end_writeback */
1032 SetPageReclaim(page);
1033
1034 /* start writeback */
1035 __swap_writepage(page, &wbc);
1036 put_page(page);
1037 zswap_written_back_pages++;
1038
1039 spin_lock(&tree->lock);
1040 /* drop local reference */
1041 zswap_entry_put(tree, entry);
1042
1043 /*
1044 * There are two possible situations for entry here:
1045 * (1) refcount is 1(normal case), entry is valid and on the tree
1046 * (2) refcount is 0, entry is freed and not on the tree
1047 * because invalidate happened during writeback
1048 * search the tree and free the entry if find entry
1049 */
1050 if (entry == zswap_rb_search(&tree->rbroot, offset))
1051 zswap_entry_put(tree, entry);
1052 spin_unlock(&tree->lock);
1053
1054 return ret;
1055
1056fail:
1057 if (!zpool_can_sleep_mapped(pool))
1058 kfree(tmp);
1059
1060 /*
1061 * if we get here due to ZSWAP_SWAPCACHE_EXIST
1062 * a load may be happening concurrently.
1063 * it is safe and okay to not free the entry.
1064 * if we free the entry in the following put
1065 * it is also okay to return !0
1066 */
1067 spin_lock(&tree->lock);
1068 zswap_entry_put(tree, entry);
1069 spin_unlock(&tree->lock);
1070
1071 return ret;
1072}
1073
1074static int zswap_is_page_same_filled(void *ptr, unsigned long *value)
1075{
1076 unsigned int pos;
1077 unsigned long *page;
1078
1079 page = (unsigned long *)ptr;
1080 for (pos = 1; pos < PAGE_SIZE / sizeof(*page); pos++) {
1081 if (page[pos] != page[0])
1082 return 0;
1083 }
1084 *value = page[0];
1085 return 1;
1086}
1087
1088static void zswap_fill_page(void *ptr, unsigned long value)
1089{
1090 unsigned long *page;
1091
1092 page = (unsigned long *)ptr;
1093 memset_l(page, value, PAGE_SIZE / sizeof(unsigned long));
1094}
1095
1096/*********************************
1097* frontswap hooks
1098**********************************/
1099/* attempts to compress and store an single page */
1100static int zswap_frontswap_store(unsigned type, pgoff_t offset,
1101 struct page *page)
1102{
1103 struct zswap_tree *tree = zswap_trees[type];
1104 struct zswap_entry *entry, *dupentry;
1105 struct scatterlist input, output;
1106 struct crypto_acomp_ctx *acomp_ctx;
1107 struct obj_cgroup *objcg = NULL;
1108 struct zswap_pool *pool;
1109 int ret;
1110 unsigned int hlen, dlen = PAGE_SIZE;
1111 unsigned long handle, value;
1112 char *buf;
1113 u8 *src, *dst;
1114 struct zswap_header zhdr = { .swpentry = swp_entry(type, offset) };
1115 gfp_t gfp;
1116
1117 /* THP isn't supported */
1118 if (PageTransHuge(page)) {
1119 ret = -EINVAL;
1120 goto reject;
1121 }
1122
1123 if (!zswap_enabled || !tree) {
1124 ret = -ENODEV;
1125 goto reject;
1126 }
1127
1128 objcg = get_obj_cgroup_from_page(page);
1129 if (objcg && !obj_cgroup_may_zswap(objcg))
1130 goto shrink;
1131
1132 /* reclaim space if needed */
1133 if (zswap_is_full()) {
1134 zswap_pool_limit_hit++;
1135 zswap_pool_reached_full = true;
1136 goto shrink;
1137 }
1138
1139 if (zswap_pool_reached_full) {
1140 if (!zswap_can_accept()) {
1141 ret = -ENOMEM;
1142 goto reject;
1143 } else
1144 zswap_pool_reached_full = false;
1145 }
1146
1147 /* allocate entry */
1148 entry = zswap_entry_cache_alloc(GFP_KERNEL);
1149 if (!entry) {
1150 zswap_reject_kmemcache_fail++;
1151 ret = -ENOMEM;
1152 goto reject;
1153 }
1154
1155 if (zswap_same_filled_pages_enabled) {
1156 src = kmap_atomic(page);
1157 if (zswap_is_page_same_filled(src, &value)) {
1158 kunmap_atomic(src);
1159 entry->offset = offset;
1160 entry->length = 0;
1161 entry->value = value;
1162 atomic_inc(&zswap_same_filled_pages);
1163 goto insert_entry;
1164 }
1165 kunmap_atomic(src);
1166 }
1167
1168 if (!zswap_non_same_filled_pages_enabled) {
1169 ret = -EINVAL;
1170 goto freepage;
1171 }
1172
1173 /* if entry is successfully added, it keeps the reference */
1174 entry->pool = zswap_pool_current_get();
1175 if (!entry->pool) {
1176 ret = -EINVAL;
1177 goto freepage;
1178 }
1179
1180 /* compress */
1181 acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
1182
1183 mutex_lock(acomp_ctx->mutex);
1184
1185 dst = acomp_ctx->dstmem;
1186 sg_init_table(&input, 1);
1187 sg_set_page(&input, page, PAGE_SIZE, 0);
1188
1189 /* zswap_dstmem is of size (PAGE_SIZE * 2). Reflect same in sg_list */
1190 sg_init_one(&output, dst, PAGE_SIZE * 2);
1191 acomp_request_set_params(acomp_ctx->req, &input, &output, PAGE_SIZE, dlen);
1192 /*
1193 * it maybe looks a little bit silly that we send an asynchronous request,
1194 * then wait for its completion synchronously. This makes the process look
1195 * synchronous in fact.
1196 * Theoretically, acomp supports users send multiple acomp requests in one
1197 * acomp instance, then get those requests done simultaneously. but in this
1198 * case, frontswap actually does store and load page by page, there is no
1199 * existing method to send the second page before the first page is done
1200 * in one thread doing frontswap.
1201 * but in different threads running on different cpu, we have different
1202 * acomp instance, so multiple threads can do (de)compression in parallel.
1203 */
1204 ret = crypto_wait_req(crypto_acomp_compress(acomp_ctx->req), &acomp_ctx->wait);
1205 dlen = acomp_ctx->req->dlen;
1206
1207 if (ret) {
1208 ret = -EINVAL;
1209 goto put_dstmem;
1210 }
1211
1212 /* store */
1213 hlen = zpool_evictable(entry->pool->zpool) ? sizeof(zhdr) : 0;
1214 gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
1215 if (zpool_malloc_support_movable(entry->pool->zpool))
1216 gfp |= __GFP_HIGHMEM | __GFP_MOVABLE;
1217 ret = zpool_malloc(entry->pool->zpool, hlen + dlen, gfp, &handle);
1218 if (ret == -ENOSPC) {
1219 zswap_reject_compress_poor++;
1220 goto put_dstmem;
1221 }
1222 if (ret) {
1223 zswap_reject_alloc_fail++;
1224 goto put_dstmem;
1225 }
1226 buf = zpool_map_handle(entry->pool->zpool, handle, ZPOOL_MM_WO);
1227 memcpy(buf, &zhdr, hlen);
1228 memcpy(buf + hlen, dst, dlen);
1229 zpool_unmap_handle(entry->pool->zpool, handle);
1230 mutex_unlock(acomp_ctx->mutex);
1231
1232 /* populate entry */
1233 entry->offset = offset;
1234 entry->handle = handle;
1235 entry->length = dlen;
1236
1237insert_entry:
1238 entry->objcg = objcg;
1239 if (objcg) {
1240 obj_cgroup_charge_zswap(objcg, entry->length);
1241 /* Account before objcg ref is moved to tree */
1242 count_objcg_event(objcg, ZSWPOUT);
1243 }
1244
1245 /* map */
1246 spin_lock(&tree->lock);
1247 do {
1248 ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry);
1249 if (ret == -EEXIST) {
1250 zswap_duplicate_entry++;
1251 /* remove from rbtree */
1252 zswap_rb_erase(&tree->rbroot, dupentry);
1253 zswap_entry_put(tree, dupentry);
1254 }
1255 } while (ret == -EEXIST);
1256 spin_unlock(&tree->lock);
1257
1258 /* update stats */
1259 atomic_inc(&zswap_stored_pages);
1260 zswap_update_total_size();
1261 count_vm_event(ZSWPOUT);
1262
1263 return 0;
1264
1265put_dstmem:
1266 mutex_unlock(acomp_ctx->mutex);
1267 zswap_pool_put(entry->pool);
1268freepage:
1269 zswap_entry_cache_free(entry);
1270reject:
1271 if (objcg)
1272 obj_cgroup_put(objcg);
1273 return ret;
1274
1275shrink:
1276 pool = zswap_pool_last_get();
1277 if (pool)
1278 queue_work(shrink_wq, &pool->shrink_work);
1279 ret = -ENOMEM;
1280 goto reject;
1281}
1282
1283/*
1284 * returns 0 if the page was successfully decompressed
1285 * return -1 on entry not found or error
1286*/
1287static int zswap_frontswap_load(unsigned type, pgoff_t offset,
1288 struct page *page)
1289{
1290 struct zswap_tree *tree = zswap_trees[type];
1291 struct zswap_entry *entry;
1292 struct scatterlist input, output;
1293 struct crypto_acomp_ctx *acomp_ctx;
1294 u8 *src, *dst, *tmp;
1295 unsigned int dlen;
1296 int ret;
1297
1298 /* find */
1299 spin_lock(&tree->lock);
1300 entry = zswap_entry_find_get(&tree->rbroot, offset);
1301 if (!entry) {
1302 /* entry was written back */
1303 spin_unlock(&tree->lock);
1304 return -1;
1305 }
1306 spin_unlock(&tree->lock);
1307
1308 if (!entry->length) {
1309 dst = kmap_atomic(page);
1310 zswap_fill_page(dst, entry->value);
1311 kunmap_atomic(dst);
1312 ret = 0;
1313 goto stats;
1314 }
1315
1316 if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
1317 tmp = kmalloc(entry->length, GFP_KERNEL);
1318 if (!tmp) {
1319 ret = -ENOMEM;
1320 goto freeentry;
1321 }
1322 }
1323
1324 /* decompress */
1325 dlen = PAGE_SIZE;
1326 src = zpool_map_handle(entry->pool->zpool, entry->handle, ZPOOL_MM_RO);
1327 if (zpool_evictable(entry->pool->zpool))
1328 src += sizeof(struct zswap_header);
1329
1330 if (!zpool_can_sleep_mapped(entry->pool->zpool)) {
1331 memcpy(tmp, src, entry->length);
1332 src = tmp;
1333 zpool_unmap_handle(entry->pool->zpool, entry->handle);
1334 }
1335
1336 acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx);
1337 mutex_lock(acomp_ctx->mutex);
1338 sg_init_one(&input, src, entry->length);
1339 sg_init_table(&output, 1);
1340 sg_set_page(&output, page, PAGE_SIZE, 0);
1341 acomp_request_set_params(acomp_ctx->req, &input, &output, entry->length, dlen);
1342 ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);
1343 mutex_unlock(acomp_ctx->mutex);
1344
1345 if (zpool_can_sleep_mapped(entry->pool->zpool))
1346 zpool_unmap_handle(entry->pool->zpool, entry->handle);
1347 else
1348 kfree(tmp);
1349
1350 BUG_ON(ret);
1351stats:
1352 count_vm_event(ZSWPIN);
1353 if (entry->objcg)
1354 count_objcg_event(entry->objcg, ZSWPIN);
1355freeentry:
1356 spin_lock(&tree->lock);
1357 zswap_entry_put(tree, entry);
1358 spin_unlock(&tree->lock);
1359
1360 return ret;
1361}
1362
1363/* frees an entry in zswap */
1364static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset)
1365{
1366 struct zswap_tree *tree = zswap_trees[type];
1367 struct zswap_entry *entry;
1368
1369 /* find */
1370 spin_lock(&tree->lock);
1371 entry = zswap_rb_search(&tree->rbroot, offset);
1372 if (!entry) {
1373 /* entry was written back */
1374 spin_unlock(&tree->lock);
1375 return;
1376 }
1377
1378 /* remove from rbtree */
1379 zswap_rb_erase(&tree->rbroot, entry);
1380
1381 /* drop the initial reference from entry creation */
1382 zswap_entry_put(tree, entry);
1383
1384 spin_unlock(&tree->lock);
1385}
1386
1387/* frees all zswap entries for the given swap type */
1388static void zswap_frontswap_invalidate_area(unsigned type)
1389{
1390 struct zswap_tree *tree = zswap_trees[type];
1391 struct zswap_entry *entry, *n;
1392
1393 if (!tree)
1394 return;
1395
1396 /* walk the tree and free everything */
1397 spin_lock(&tree->lock);
1398 rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode)
1399 zswap_free_entry(entry);
1400 tree->rbroot = RB_ROOT;
1401 spin_unlock(&tree->lock);
1402 kfree(tree);
1403 zswap_trees[type] = NULL;
1404}
1405
1406static void zswap_frontswap_init(unsigned type)
1407{
1408 struct zswap_tree *tree;
1409
1410 tree = kzalloc(sizeof(*tree), GFP_KERNEL);
1411 if (!tree) {
1412 pr_err("alloc failed, zswap disabled for swap type %d\n", type);
1413 return;
1414 }
1415
1416 tree->rbroot = RB_ROOT;
1417 spin_lock_init(&tree->lock);
1418 zswap_trees[type] = tree;
1419}
1420
1421static const struct frontswap_ops zswap_frontswap_ops = {
1422 .store = zswap_frontswap_store,
1423 .load = zswap_frontswap_load,
1424 .invalidate_page = zswap_frontswap_invalidate_page,
1425 .invalidate_area = zswap_frontswap_invalidate_area,
1426 .init = zswap_frontswap_init
1427};
1428
1429/*********************************
1430* debugfs functions
1431**********************************/
1432#ifdef CONFIG_DEBUG_FS
1433#include <linux/debugfs.h>
1434
1435static struct dentry *zswap_debugfs_root;
1436
1437static int __init zswap_debugfs_init(void)
1438{
1439 if (!debugfs_initialized())
1440 return -ENODEV;
1441
1442 zswap_debugfs_root = debugfs_create_dir("zswap", NULL);
1443
1444 debugfs_create_u64("pool_limit_hit", 0444,
1445 zswap_debugfs_root, &zswap_pool_limit_hit);
1446 debugfs_create_u64("reject_reclaim_fail", 0444,
1447 zswap_debugfs_root, &zswap_reject_reclaim_fail);
1448 debugfs_create_u64("reject_alloc_fail", 0444,
1449 zswap_debugfs_root, &zswap_reject_alloc_fail);
1450 debugfs_create_u64("reject_kmemcache_fail", 0444,
1451 zswap_debugfs_root, &zswap_reject_kmemcache_fail);
1452 debugfs_create_u64("reject_compress_poor", 0444,
1453 zswap_debugfs_root, &zswap_reject_compress_poor);
1454 debugfs_create_u64("written_back_pages", 0444,
1455 zswap_debugfs_root, &zswap_written_back_pages);
1456 debugfs_create_u64("duplicate_entry", 0444,
1457 zswap_debugfs_root, &zswap_duplicate_entry);
1458 debugfs_create_u64("pool_total_size", 0444,
1459 zswap_debugfs_root, &zswap_pool_total_size);
1460 debugfs_create_atomic_t("stored_pages", 0444,
1461 zswap_debugfs_root, &zswap_stored_pages);
1462 debugfs_create_atomic_t("same_filled_pages", 0444,
1463 zswap_debugfs_root, &zswap_same_filled_pages);
1464
1465 return 0;
1466}
1467#else
1468static int __init zswap_debugfs_init(void)
1469{
1470 return 0;
1471}
1472#endif
1473
1474/*********************************
1475* module init and exit
1476**********************************/
1477static int __init init_zswap(void)
1478{
1479 struct zswap_pool *pool;
1480 int ret;
1481
1482 zswap_init_started = true;
1483
1484 if (zswap_entry_cache_create()) {
1485 pr_err("entry cache creation failed\n");
1486 goto cache_fail;
1487 }
1488
1489 ret = cpuhp_setup_state(CPUHP_MM_ZSWP_MEM_PREPARE, "mm/zswap:prepare",
1490 zswap_dstmem_prepare, zswap_dstmem_dead);
1491 if (ret) {
1492 pr_err("dstmem alloc failed\n");
1493 goto dstmem_fail;
1494 }
1495
1496 ret = cpuhp_setup_state_multi(CPUHP_MM_ZSWP_POOL_PREPARE,
1497 "mm/zswap_pool:prepare",
1498 zswap_cpu_comp_prepare,
1499 zswap_cpu_comp_dead);
1500 if (ret)
1501 goto hp_fail;
1502
1503 pool = __zswap_pool_create_fallback();
1504 if (pool) {
1505 pr_info("loaded using pool %s/%s\n", pool->tfm_name,
1506 zpool_get_type(pool->zpool));
1507 list_add(&pool->list, &zswap_pools);
1508 zswap_has_pool = true;
1509 } else {
1510 pr_err("pool creation failed\n");
1511 zswap_enabled = false;
1512 }
1513
1514 shrink_wq = create_workqueue("zswap-shrink");
1515 if (!shrink_wq)
1516 goto fallback_fail;
1517
1518 ret = frontswap_register_ops(&zswap_frontswap_ops);
1519 if (ret)
1520 goto destroy_wq;
1521 if (zswap_debugfs_init())
1522 pr_warn("debugfs initialization failed\n");
1523 return 0;
1524
1525destroy_wq:
1526 destroy_workqueue(shrink_wq);
1527fallback_fail:
1528 if (pool)
1529 zswap_pool_destroy(pool);
1530hp_fail:
1531 cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
1532dstmem_fail:
1533 zswap_entry_cache_destroy();
1534cache_fail:
1535 /* if built-in, we aren't unloaded on failure; don't allow use */
1536 zswap_init_failed = true;
1537 zswap_enabled = false;
1538 return -ENOMEM;
1539}
1540/* must be late so crypto has time to come up */
1541late_initcall(init_zswap);
1542
1543MODULE_LICENSE("GPL");
1544MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
1545MODULE_DESCRIPTION("Compressed cache for swap pages");