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2024-10-22 8ac6c7a54ed1b98d142dce24b11c6de6a1e239a5 
 kernel/mm/zswap.c
....@@ -1,3 +1,4 @@
1
+// SPDX-License-Identifier: GPL-2.0-or-later
12 /*
23  * zswap.c - zswap driver file
34  *
....@@ -8,16 +9,6 @@
89  * than reading from the swap device, can also improve workload performance.
910  *
1011  * Copyright (C) 2012  Seth Jennings <sjenning@linux.vnet.ibm.com>
11
- *
12
- * This program is free software; you can redistribute it and/or
13
- * modify it under the terms of the GNU General Public License
14
- * as published by the Free Software Foundation; either version 2
15
- * of the License, or (at your option) any later version.
16
- *
17
- * This program is distributed in the hope that it will be useful,
18
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
19
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
20
- * GNU General Public License for more details.
2112 */
2213 
2314 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
....@@ -41,6 +32,7 @@
4132 #include <linux/swapops.h>
4233 #include <linux/writeback.h>
4334 #include <linux/pagemap.h>
35
+#include <linux/workqueue.h>
4436 
4537 /*********************************
4638 * statistics
....@@ -74,14 +66,19 @@
7466 /* Duplicate store was encountered (rare) */
7567 static u64 zswap_duplicate_entry;
7668 
69
+/* Shrinker work queue */
70
+static struct workqueue_struct *shrink_wq;
71
+/* Pool limit was hit, we need to calm down */
72
+static bool zswap_pool_reached_full;
73
+
7774 /*********************************
7875 * tunables
7976 **********************************/
8077 
8178 #define ZSWAP_PARAM_UNSET ""
8279 
83
-/* Enable/disable zswap (disabled by default) */
84
-static bool zswap_enabled;
80
+/* Enable/disable zswap */
81
+static bool zswap_enabled = IS_ENABLED(CONFIG_ZSWAP_DEFAULT_ON);
8582 static int zswap_enabled_param_set(const char *,
8683 				   const struct kernel_param *);
8784 static struct kernel_param_ops zswap_enabled_param_ops = {
....@@ -91,8 +88,7 @@
9188 module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644);
9289 
9390 /* Crypto compressor to use */
94
-#define ZSWAP_COMPRESSOR_DEFAULT "lzo"
95
-static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
91
+static char *zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
9692 static int zswap_compressor_param_set(const char *,
9793 				      const struct kernel_param *);
9894 static struct kernel_param_ops zswap_compressor_param_ops = {
....@@ -104,8 +100,7 @@
104100 		&zswap_compressor, 0644);
105101 
106102 /* Compressed storage zpool to use */
107
-#define ZSWAP_ZPOOL_DEFAULT "zbud"
108
-static char *zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
103
+static char *zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
109104 static int zswap_zpool_param_set(const char *, const struct kernel_param *);
110105 static struct kernel_param_ops zswap_zpool_param_ops = {
111106 	.set =		zswap_zpool_param_set,
....@@ -117,6 +112,11 @@
117112 /* The maximum percentage of memory that the compressed pool can occupy */
118113 static unsigned int zswap_max_pool_percent = 20;
119114 module_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 */
117
+static unsigned int zswap_accept_thr_percent = 90; /* of max pool size */
118
+module_param_named(accept_threshold_percent, zswap_accept_thr_percent,
119
+		   uint, 0644);
120120 
121121 /* Enable/disable handling same-value filled pages (enabled by default) */
122122 static bool zswap_same_filled_pages_enabled = true;
....@@ -132,7 +132,8 @@
132132 	struct crypto_comp * __percpu *tfm;
133133 	struct kref kref;
134134 	struct list_head list;
135
-	struct work_struct work;
135
+	struct work_struct release_work;
136
+	struct work_struct shrink_work;
136137 	struct hlist_node node;
137138 	char tfm_name[CRYPTO_MAX_ALG_NAME];
138139 };
....@@ -219,8 +220,15 @@
219220 
220221 static bool zswap_is_full(void)
221222 {
222
-	return totalram_pages * zswap_max_pool_percent / 100 <
223
-		DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
223
+	return totalram_pages() * zswap_max_pool_percent / 100 <
224
+			DIV_ROUND_UP(zswap_pool_total_size, PAGE_SIZE);
225
+}
226
+
227
+static 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);
224232 }
225233 
226234 static void zswap_update_total_size(void)
....@@ -510,6 +518,16 @@
510518 	return NULL;
511519 }
512520 
521
+static 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
+
513531 static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
514532 {
515533 	struct zswap_pool *pool;
....@@ -560,6 +578,7 @@
560578 	 */
561579 	kref_init(&pool->kref);
562580 	INIT_LIST_HEAD(&pool->list);
581
+	INIT_WORK(&pool->shrink_work, shrink_worker);
563582 
564583 	zswap_pool_debug("created", pool);
565584 
....@@ -578,11 +597,12 @@
578597 	bool has_comp, has_zpool;
579598 
580599 	has_comp = crypto_has_comp(zswap_compressor, 0, 0);
581
-	if (!has_comp && strcmp(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT)) {
600
+	if (!has_comp && strcmp(zswap_compressor,
601
+				CONFIG_ZSWAP_COMPRESSOR_DEFAULT)) {
582602 		pr_err("compressor %s not available, using default %s\n",
583
-		       zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT);
603
+		       zswap_compressor, CONFIG_ZSWAP_COMPRESSOR_DEFAULT);
584604 		param_free_charp(&zswap_compressor);
585
-		zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
605
+		zswap_compressor = CONFIG_ZSWAP_COMPRESSOR_DEFAULT;
586606 		has_comp = crypto_has_comp(zswap_compressor, 0, 0);
587607 	}
588608 	if (!has_comp) {
....@@ -593,11 +613,12 @@
593613 	}
594614 
595615 	has_zpool = zpool_has_pool(zswap_zpool_type);
596
-	if (!has_zpool && strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
616
+	if (!has_zpool && strcmp(zswap_zpool_type,
617
+				 CONFIG_ZSWAP_ZPOOL_DEFAULT)) {
597618 		pr_err("zpool %s not available, using default %s\n",
598
-		       zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT);
619
+		       zswap_zpool_type, CONFIG_ZSWAP_ZPOOL_DEFAULT);
599620 		param_free_charp(&zswap_zpool_type);
600
-		zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
621
+		zswap_zpool_type = CONFIG_ZSWAP_ZPOOL_DEFAULT;
601622 		has_zpool = zpool_has_pool(zswap_zpool_type);
602623 	}
603624 	if (!has_zpool) {
....@@ -633,7 +654,8 @@
633654 
634655 static void __zswap_pool_release(struct work_struct *work)
635656 {
636
-	struct zswap_pool *pool = container_of(work, typeof(*pool), work);
657
+	struct zswap_pool *pool = container_of(work, typeof(*pool),
658
+						release_work);
637659 
638660 	synchronize_rcu();
639661 
....@@ -656,8 +678,8 @@
656678 
657679 	list_del_rcu(&pool->list);
658680 
659
-	INIT_WORK(&pool->work, __zswap_pool_release);
660
-	schedule_work(&pool->work);
681
+	INIT_WORK(&pool->release_work, __zswap_pool_release);
682
+	schedule_work(&pool->release_work);
661683 
662684 	spin_unlock(&zswap_pools_lock);
663685 }
....@@ -865,7 +887,6 @@
865887 	/* extract swpentry from data */
866888 	zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO);
867889 	swpentry = zhdr->swpentry; /* here */
868
-	zpool_unmap_handle(pool, handle);
869890 	tree = zswap_trees[swp_type(swpentry)];
870891 	offset = swp_offset(swpentry);
871892 
....@@ -875,6 +896,7 @@
875896 	if (!entry) {
876897 		/* entry was invalidated */
877898 		spin_unlock(&tree->lock);
899
+		zpool_unmap_handle(pool, handle);
878900 		return 0;
879901 	}
880902 	spin_unlock(&tree->lock);
....@@ -895,15 +917,13 @@
895917 	case ZSWAP_SWAPCACHE_NEW: /* page is locked */
896918 		/* decompress */
897919 		dlen = PAGE_SIZE;
898
-		src = (u8 *)zpool_map_handle(entry->pool->zpool, entry->handle,
899
-				ZPOOL_MM_RO) + sizeof(struct zswap_header);
920
+		src = (u8 *)zhdr + sizeof(struct zswap_header);
900921 		dst = kmap_atomic(page);
901922 		tfm = *get_cpu_ptr(entry->pool->tfm);
902923 		ret = crypto_comp_decompress(tfm, src, entry->length,
903924 					     dst, &dlen);
904925 		put_cpu_ptr(entry->pool->tfm);
905926 		kunmap_atomic(dst);
906
-		zpool_unmap_handle(entry->pool->zpool, entry->handle);
907927 		BUG_ON(ret);
908928 		BUG_ON(dlen != PAGE_SIZE);
909929 
....@@ -949,22 +969,7 @@
949969 	spin_unlock(&tree->lock);
950970 
951971 end:
952
-	return ret;
953
-}
954
-
955
-static int zswap_shrink(void)
956
-{
957
-	struct zswap_pool *pool;
958
-	int ret;
959
-
960
-	pool = zswap_pool_last_get();
961
-	if (!pool)
962
-		return -ENOENT;
963
-
964
-	ret = zpool_shrink(pool->zpool, 1, NULL);
965
-
966
-	zswap_pool_put(pool);
967
-
972
+	zpool_unmap_handle(pool, handle);
968973 	return ret;
969974 }
970975 
....@@ -1006,6 +1011,7 @@
10061011 	char *buf;
10071012 	u8 *src, *dst;
10081013 	struct zswap_header zhdr = { .swpentry = swp_entry(type, offset) };
1014
+	gfp_t gfp;
10091015 
10101016 	/* THP isn't supported */
10111017 	if (PageTransHuge(page)) {
....@@ -1020,21 +1026,23 @@
10201026 
10211027 	/* reclaim space if needed */
10221028 	if (zswap_is_full()) {
1023
-		zswap_pool_limit_hit++;
1024
-		if (zswap_shrink()) {
1025
-			zswap_reject_reclaim_fail++;
1026
-			ret = -ENOMEM;
1027
-			goto reject;
1028
-		}
1029
+		struct zswap_pool *pool;
10291030 
1030
-		/* A second zswap_is_full() check after
1031
-		 * zswap_shrink() to make sure it's now
1032
-		 * under the max_pool_percent
1033
-		 */
1034
-		if (zswap_is_full()) {
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()) {
10351042 			ret = -ENOMEM;
10361043 			goto reject;
1037
-		}
1044
+		} else
1045
+			zswap_pool_reached_full = false;
10381046 	}
10391047 
10401048 	/* allocate entry */
....@@ -1079,9 +1087,10 @@
10791087 
10801088 	/* store */
10811089 	hlen = zpool_evictable(entry->pool->zpool) ? sizeof(zhdr) : 0;
1082
-	ret = zpool_malloc(entry->pool->zpool, hlen + dlen,
1083
-			   __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM,
1084
-			   &handle);
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);
10851094 	if (ret == -ENOSPC) {
10861095 		zswap_reject_compress_poor++;
10871096 		goto put_dstmem;
....@@ -1262,8 +1271,6 @@
12621271 		return -ENODEV;
12631272 
12641273 	zswap_debugfs_root = debugfs_create_dir("zswap", NULL);
1265
-	if (!zswap_debugfs_root)
1266
-		return -ENOMEM;
12671274 
12681275 	debugfs_create_u64("pool_limit_hit", 0444,
12691276 			   zswap_debugfs_root, &zswap_pool_limit_hit);
....@@ -1342,11 +1349,18 @@
13421349 		zswap_enabled = false;
13431350 	}
13441351 
1352
+	shrink_wq = create_workqueue("zswap-shrink");
1353
+	if (!shrink_wq)
1354
+		goto fallback_fail;
1355
+
13451356 	frontswap_register_ops(&zswap_frontswap_ops);
13461357 	if (zswap_debugfs_init())
13471358 		pr_warn("debugfs initialization failed\n");
13481359 	return 0;
13491360 
1361
+fallback_fail:
1362
+	if (pool)
1363
+		zswap_pool_destroy(pool);
13501364 hp_fail:
13511365 	cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
13521366 dstmem_fail: