mm/zswap.c

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