1 files changed, 160 insertions, 149 deletions

diff --git a/mm/zswap.c b/mm/zswap.c
index 275b22cc8df4..eedc27894b10 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -76,9 +76,17 @@ static u64 zswap_duplicate_entry;
 * tunables
 **********************************/
 
+#define ZSWAP_PARAM_UNSET ""
+
 /* Enable/disable zswap (disabled by default) */
 static bool zswap_enabled;
-module_param_named(enabled, zswap_enabled, bool, 0644);
+static int zswap_enabled_param_set(const char *,
+				   const struct kernel_param *);
+static struct kernel_param_ops zswap_enabled_param_ops = {
+	.set =		zswap_enabled_param_set,
+	.get =		param_get_bool,
+};
+module_param_cb(enabled, &zswap_enabled_param_ops, &zswap_enabled, 0644);
 
 /* Crypto compressor to use */
 #define ZSWAP_COMPRESSOR_DEFAULT "lzo"
@@ -118,7 +126,7 @@ struct zswap_pool {
 	struct kref kref;
 	struct list_head list;
 	struct work_struct work;
-	struct notifier_block notifier;
+	struct hlist_node node;
 	char tfm_name[CRYPTO_MAX_ALG_NAME];
 };
 
@@ -176,6 +184,12 @@ static atomic_t zswap_pools_count = ATOMIC_INIT(0);
 /* used by param callback function */
 static bool zswap_init_started;
 
+/* fatal error during init */
+static bool zswap_init_failed;
+
+/* init completed, but couldn't create the initial pool */
+static bool zswap_has_pool;
+
 /*********************************
 * helpers and fwd declarations
 **********************************/
@@ -352,143 +366,58 @@ static struct zswap_entry *zswap_entry_find_get(struct rb_root *root,
 **********************************/
 static DEFINE_PER_CPU(u8 *, zswap_dstmem);
 
-static int __zswap_cpu_dstmem_notifier(unsigned long action, unsigned long cpu)
+static int zswap_dstmem_prepare(unsigned int cpu)
 {
 	u8 *dst;
 
-	switch (action) {
-	case CPU_UP_PREPARE:
-		dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
-		if (!dst) {
-			pr_err("can't allocate compressor buffer\n");
-			return NOTIFY_BAD;
-		}
-		per_cpu(zswap_dstmem, cpu) = dst;
-		break;
-	case CPU_DEAD:
-	case CPU_UP_CANCELED:
-		dst = per_cpu(zswap_dstmem, cpu);
-		kfree(dst);
-		per_cpu(zswap_dstmem, cpu) = NULL;
-		break;
-	default:
-		break;
+	dst = kmalloc_node(PAGE_SIZE * 2, GFP_KERNEL, cpu_to_node(cpu));
+	if (!dst) {
+		pr_err("can't allocate compressor buffer\n");
+		return -ENOMEM;
 	}
-	return NOTIFY_OK;
+	per_cpu(zswap_dstmem, cpu) = dst;
+	return 0;
 }
 
-static int zswap_cpu_dstmem_notifier(struct notifier_block *nb,
-				     unsigned long action, void *pcpu)
+static int zswap_dstmem_dead(unsigned int cpu)
 {
-	return __zswap_cpu_dstmem_notifier(action, (unsigned long)pcpu);
-}
+	u8 *dst;
 
-static struct notifier_block zswap_dstmem_notifier = {
-	.notifier_call =	zswap_cpu_dstmem_notifier,
-};
+	dst = per_cpu(zswap_dstmem, cpu);
+	kfree(dst);
+	per_cpu(zswap_dstmem, cpu) = NULL;
 
-static int __init zswap_cpu_dstmem_init(void)
-{
-	unsigned long cpu;
-
-	cpu_notifier_register_begin();
-	for_each_online_cpu(cpu)
-		if (__zswap_cpu_dstmem_notifier(CPU_UP_PREPARE, cpu) ==
-		    NOTIFY_BAD)
-			goto cleanup;
-	__register_cpu_notifier(&zswap_dstmem_notifier);
-	cpu_notifier_register_done();
 	return 0;
-
-cleanup:
-	for_each_online_cpu(cpu)
-		__zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu);
-	cpu_notifier_register_done();
-	return -ENOMEM;
-}
-
-static void zswap_cpu_dstmem_destroy(void)
-{
-	unsigned long cpu;
-
-	cpu_notifier_register_begin();
-	for_each_online_cpu(cpu)
-		__zswap_cpu_dstmem_notifier(CPU_UP_CANCELED, cpu);
-	__unregister_cpu_notifier(&zswap_dstmem_notifier);
-	cpu_notifier_register_done();
 }
 
-static int __zswap_cpu_comp_notifier(struct zswap_pool *pool,
-				     unsigned long action, unsigned long cpu)
+static int zswap_cpu_comp_prepare(unsigned int cpu, struct hlist_node *node)
 {
+	struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
 	struct crypto_comp *tfm;
 
-	switch (action) {
-	case CPU_UP_PREPARE:
-		if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
-			break;
-		tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
-		if (IS_ERR_OR_NULL(tfm)) {
-			pr_err("could not alloc crypto comp %s : %ld\n",
-			       pool->tfm_name, PTR_ERR(tfm));
-			return NOTIFY_BAD;
-		}
-		*per_cpu_ptr(pool->tfm, cpu) = tfm;
-		break;
-	case CPU_DEAD:
-	case CPU_UP_CANCELED:
-		tfm = *per_cpu_ptr(pool->tfm, cpu);
-		if (!IS_ERR_OR_NULL(tfm))
-			crypto_free_comp(tfm);
-		*per_cpu_ptr(pool->tfm, cpu) = NULL;
-		break;
-	default:
-		break;
-	}
-	return NOTIFY_OK;
-}
-
-static int zswap_cpu_comp_notifier(struct notifier_block *nb,
-				   unsigned long action, void *pcpu)
-{
-	unsigned long cpu = (unsigned long)pcpu;
-	struct zswap_pool *pool = container_of(nb, typeof(*pool), notifier);
-
-	return __zswap_cpu_comp_notifier(pool, action, cpu);
-}
+	if (WARN_ON(*per_cpu_ptr(pool->tfm, cpu)))
+		return 0;
 
-static int zswap_cpu_comp_init(struct zswap_pool *pool)
-{
-	unsigned long cpu;
-
-	memset(&pool->notifier, 0, sizeof(pool->notifier));
-	pool->notifier.notifier_call = zswap_cpu_comp_notifier;
-
-	cpu_notifier_register_begin();
-	for_each_online_cpu(cpu)
-		if (__zswap_cpu_comp_notifier(pool, CPU_UP_PREPARE, cpu) ==
-		    NOTIFY_BAD)
-			goto cleanup;
-	__register_cpu_notifier(&pool->notifier);
-	cpu_notifier_register_done();
+	tfm = crypto_alloc_comp(pool->tfm_name, 0, 0);
+	if (IS_ERR_OR_NULL(tfm)) {
+		pr_err("could not alloc crypto comp %s : %ld\n",
+		       pool->tfm_name, PTR_ERR(tfm));
+		return -ENOMEM;
+	}
+	*per_cpu_ptr(pool->tfm, cpu) = tfm;
 	return 0;
-
-cleanup:
-	for_each_online_cpu(cpu)
-		__zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu);
-	cpu_notifier_register_done();
-	return -ENOMEM;
 }
 
-static void zswap_cpu_comp_destroy(struct zswap_pool *pool)
+static int zswap_cpu_comp_dead(unsigned int cpu, struct hlist_node *node)
 {
-	unsigned long cpu;
+	struct zswap_pool *pool = hlist_entry(node, struct zswap_pool, node);
+	struct crypto_comp *tfm;
 
-	cpu_notifier_register_begin();
-	for_each_online_cpu(cpu)
-		__zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu);
-	__unregister_cpu_notifier(&pool->notifier);
-	cpu_notifier_register_done();
+	tfm = *per_cpu_ptr(pool->tfm, cpu);
+	if (!IS_ERR_OR_NULL(tfm))
+		crypto_free_comp(tfm);
+	*per_cpu_ptr(pool->tfm, cpu) = NULL;
+	return 0;
 }
 
 /*********************************
@@ -500,7 +429,8 @@ static struct zswap_pool *__zswap_pool_current(void)
 	struct zswap_pool *pool;
 
 	pool = list_first_or_null_rcu(&zswap_pools, typeof(*pool), list);
-	WARN_ON(!pool);
+	WARN_ONCE(!pool && zswap_has_pool,
+		  "%s: no page storage pool!\n", __func__);
 
 	return pool;
 }
@@ -519,7 +449,7 @@ static struct zswap_pool *zswap_pool_current_get(void)
 	rcu_read_lock();
 
 	pool = __zswap_pool_current();
-	if (!pool || !zswap_pool_get(pool))
+	if (!zswap_pool_get(pool))
 		pool = NULL;
 
 	rcu_read_unlock();
@@ -535,7 +465,9 @@ static struct zswap_pool *zswap_pool_last_get(void)
 
 	list_for_each_entry_rcu(pool, &zswap_pools, list)
 		last = pool;
-	if (!WARN_ON(!last) && !zswap_pool_get(last))
+	WARN_ONCE(!last && zswap_has_pool,
+		  "%s: no page storage pool!\n", __func__);
+	if (!zswap_pool_get(last))
 		last = NULL;
 
 	rcu_read_unlock();
@@ -569,6 +501,18 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
 	struct zswap_pool *pool;
 	char name[38]; /* 'zswap' + 32 char (max) num + \0 */
 	gfp_t gfp = __GFP_NORETRY | __GFP_NOWARN | __GFP_KSWAPD_RECLAIM;
+	int ret;
+
+	if (!zswap_has_pool) {
+		/* if either are unset, pool initialization failed, and we
+		 * need both params to be set correctly before trying to
+		 * create a pool.
+		 */
+		if (!strcmp(type, ZSWAP_PARAM_UNSET))
+			return NULL;
+		if (!strcmp(compressor, ZSWAP_PARAM_UNSET))
+			return NULL;
+	}
 
 	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
 	if (!pool) {
@@ -593,7 +537,9 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
 		goto error;
 	}
 
-	if (zswap_cpu_comp_init(pool))
+	ret = cpuhp_state_add_instance(CPUHP_MM_ZSWP_POOL_PREPARE,
+				       &pool->node);
+	if (ret)
 		goto error;
 	pr_debug("using %s compressor\n", pool->tfm_name);
 
@@ -617,29 +563,41 @@ error:
 
 static __init struct zswap_pool *__zswap_pool_create_fallback(void)
 {
-	if (!crypto_has_comp(zswap_compressor, 0, 0)) {
-		if (!strcmp(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT)) {
-			pr_err("default compressor %s not available\n",
-			       zswap_compressor);
-			return NULL;
-		}
+	bool has_comp, has_zpool;
+
+	has_comp = crypto_has_comp(zswap_compressor, 0, 0);
+	if (!has_comp && strcmp(zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT)) {
 		pr_err("compressor %s not available, using default %s\n",
 		       zswap_compressor, ZSWAP_COMPRESSOR_DEFAULT);
 		param_free_charp(&zswap_compressor);
 		zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT;
+		has_comp = crypto_has_comp(zswap_compressor, 0, 0);
 	}
-	if (!zpool_has_pool(zswap_zpool_type)) {
-		if (!strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
-			pr_err("default zpool %s not available\n",
-			       zswap_zpool_type);
-			return NULL;
-		}
+	if (!has_comp) {
+		pr_err("default compressor %s not available\n",
+		       zswap_compressor);
+		param_free_charp(&zswap_compressor);
+		zswap_compressor = ZSWAP_PARAM_UNSET;
+	}
+
+	has_zpool = zpool_has_pool(zswap_zpool_type);
+	if (!has_zpool && strcmp(zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT)) {
 		pr_err("zpool %s not available, using default %s\n",
 		       zswap_zpool_type, ZSWAP_ZPOOL_DEFAULT);
 		param_free_charp(&zswap_zpool_type);
 		zswap_zpool_type = ZSWAP_ZPOOL_DEFAULT;
+		has_zpool = zpool_has_pool(zswap_zpool_type);
+	}
+	if (!has_zpool) {
+		pr_err("default zpool %s not available\n",
+		       zswap_zpool_type);
+		param_free_charp(&zswap_zpool_type);
+		zswap_zpool_type = ZSWAP_PARAM_UNSET;
 	}
 
+	if (!has_comp || !has_zpool)
+		return NULL;
+
 	return zswap_pool_create(zswap_zpool_type, zswap_compressor);
 }
 
@@ -647,7 +605,7 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
 {
 	zswap_pool_debug("destroying", pool);
 
-	zswap_cpu_comp_destroy(pool);
+	cpuhp_state_remove_instance(CPUHP_MM_ZSWP_POOL_PREPARE, &pool->node);
 	free_percpu(pool->tfm);
 	zpool_destroy_pool(pool->zpool);
 	kfree(pool);
@@ -655,6 +613,9 @@ static void zswap_pool_destroy(struct zswap_pool *pool)
 
 static int __must_check zswap_pool_get(struct zswap_pool *pool)
 {
+	if (!pool)
+		return 0;
+
 	return kref_get_unless_zero(&pool->kref);
 }
 
@@ -706,8 +667,13 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
 	char *s = strstrip((char *)val);
 	int ret;
 
+	if (zswap_init_failed) {
+		pr_err("can't set param, initialization failed\n");
+		return -ENODEV;
+	}
+
 	/* no change required */
-	if (!strcmp(s, *(char **)kp->arg))
+	if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
 		return 0;
 
 	/* if this is load-time (pre-init) param setting,
@@ -738,21 +704,26 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
 	pool = zswap_pool_find_get(type, compressor);
 	if (pool) {
 		zswap_pool_debug("using existing", pool);
+		WARN_ON(pool == zswap_pool_current());
 		list_del_rcu(&pool->list);
-	} else {
-		spin_unlock(&zswap_pools_lock);
-		pool = zswap_pool_create(type, compressor);
-		spin_lock(&zswap_pools_lock);
 	}
 
+	spin_unlock(&zswap_pools_lock);
+
+	if (!pool)
+		pool = zswap_pool_create(type, compressor);
+
 	if (pool)
 		ret = param_set_charp(s, kp);
 	else
 		ret = -EINVAL;
 
+	spin_lock(&zswap_pools_lock);
+
 	if (!ret) {
 		put_pool = zswap_pool_current();
 		list_add_rcu(&pool->list, &zswap_pools);
+		zswap_has_pool = true;
 	} else if (pool) {
 		/* add the possibly pre-existing pool to the end of the pools
 		 * list; if it's new (and empty) then it'll be removed and
@@ -764,6 +735,17 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
 
 	spin_unlock(&zswap_pools_lock);
 
+	if (!zswap_has_pool && !pool) {
+		/* if initial pool creation failed, and this pool creation also
+		 * failed, maybe both compressor and zpool params were bad.
+		 * Allow changing this param, so pool creation will succeed
+		 * when the other param is changed. We already verified this
+		 * param is ok in the zpool_has_pool() or crypto_has_comp()
+		 * checks above.
+		 */
+		ret = param_set_charp(s, kp);
+	}
+
 	/* drop the ref from either the old current pool,
 	 * or the new pool we failed to add
 	 */
@@ -785,6 +767,21 @@ static int zswap_zpool_param_set(const char *val,
 	return __zswap_param_set(val, kp, NULL, zswap_compressor);
 }
 
+static int zswap_enabled_param_set(const char *val,
+				   const struct kernel_param *kp)
+{
+	if (zswap_init_failed) {
+		pr_err("can't enable, initialization failed\n");
+		return -ENODEV;
+	}
+	if (!zswap_has_pool && zswap_init_started) {
+		pr_err("can't enable, no pool configured\n");
+		return -ENODEV;
+	}
+
+	return param_set_bool(val, kp);
+}
+
 /*********************************
 * writeback code
 **********************************/
@@ -1238,6 +1235,7 @@ static void __exit zswap_debugfs_exit(void) { }
 static int __init init_zswap(void)
 {
 	struct zswap_pool *pool;
+	int ret;
 
 	zswap_init_started = true;
 
@@ -1246,31 +1244,44 @@ static int __init init_zswap(void)
 		goto cache_fail;
 	}
 
-	if (zswap_cpu_dstmem_init()) {
+	ret = cpuhp_setup_state(CPUHP_MM_ZSWP_MEM_PREPARE, "mm/zswap:prepare",
+				zswap_dstmem_prepare, zswap_dstmem_dead);
+	if (ret) {
 		pr_err("dstmem alloc failed\n");
 		goto dstmem_fail;
 	}
 
+	ret = cpuhp_setup_state_multi(CPUHP_MM_ZSWP_POOL_PREPARE,
+				      "mm/zswap_pool:prepare",
+				      zswap_cpu_comp_prepare,
+				      zswap_cpu_comp_dead);
+	if (ret)
+		goto hp_fail;
+
 	pool = __zswap_pool_create_fallback();
-	if (!pool) {
+	if (pool) {
+		pr_info("loaded using pool %s/%s\n", pool->tfm_name,
+			zpool_get_type(pool->zpool));
+		list_add(&pool->list, &zswap_pools);
+		zswap_has_pool = true;
+	} else {
 		pr_err("pool creation failed\n");
-		goto pool_fail;
+		zswap_enabled = false;
 	}
-	pr_info("loaded using pool %s/%s\n", pool->tfm_name,
-		zpool_get_type(pool->zpool));
-
-	list_add(&pool->list, &zswap_pools);
 
 	frontswap_register_ops(&zswap_frontswap_ops);
 	if (zswap_debugfs_init())
 		pr_warn("debugfs initialization failed\n");
 	return 0;
 
-pool_fail:
-	zswap_cpu_dstmem_destroy();
+hp_fail:
+	cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
 dstmem_fail:
 	zswap_entry_cache_destroy();
 cache_fail:
+	/* if built-in, we aren't unloaded on failure; don't allow use */
+	zswap_init_failed = true;
+	zswap_enabled = false;
 	return -ENOMEM;
 }
 /* must be late so crypto has time to come up */