[failures] mm-zswap-delay-the-initializaton-of-zswap-until-the-first-enablement.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: mm/zswap: delay the initializaton of zswap until the first enablement
has been removed from the -mm tree.  Its filename was
     mm-zswap-delay-the-initializaton-of-zswap-until-the-first-enablement.patch

This patch was dropped because it had testing failures

------------------------------------------------------
From: Liu Shixin <liushixin2@huawei.com>
Subject: mm/zswap: delay the initializaton of zswap until the first enablement
Date: Thu, 25 Aug 2022 22:20:36 +0800

In the initialization of zswap, about 18MB memory will be allocated for
zswap_pool in my machine.  Since not all users use zswap, the memory may
be wasted.  Save the memory for these users by delaying the initialization
of zswap to first enablement.

[akpm@linux-foundation.org: s/init_zswap/zswap_init/]
Link: https://lkml.kernel.org/r/20220825142037.3214152-3-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/zswap.c |   50 ++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 40 insertions(+), 10 deletions(-)

--- a/mm/zswap.c~mm-zswap-delay-the-initializaton-of-zswap-until-the-first-enablement
+++ a/mm/zswap.c
@@ -81,6 +81,8 @@ static bool zswap_pool_reached_full;
 
 #define ZSWAP_PARAM_UNSET ""
 
+static int zswap_setup(void);
+
 /* Enable/disable zswap */
 static bool zswap_enabled = IS_ENABLED(CONFIG_ZSWAP_DEFAULT_ON);
 static int zswap_enabled_param_set(const char *,
@@ -220,6 +222,8 @@ static atomic_t zswap_pools_count = ATOM
 
 /* init state */
 static int zswap_init_state;
+/* used to ensure the integrity of initialization */
+static DEFINE_MUTEX(zswap_init_lock);
 
 /* init completed, but couldn't create the initial pool */
 static bool zswap_has_pool;
@@ -273,13 +277,13 @@ static void zswap_update_total_size(void
 **********************************/
 static struct kmem_cache *zswap_entry_cache;
 
-static int __init zswap_entry_cache_create(void)
+static int zswap_entry_cache_create(void)
 {
 	zswap_entry_cache = KMEM_CACHE(zswap_entry, 0);
 	return zswap_entry_cache == NULL;
 }
 
-static void __init zswap_entry_cache_destroy(void)
+static void zswap_entry_cache_destroy(void)
 {
 	kmem_cache_destroy(zswap_entry_cache);
 }
@@ -664,7 +668,7 @@ error:
 	return NULL;
 }
 
-static __init struct zswap_pool *__zswap_pool_create_fallback(void)
+static struct zswap_pool *__zswap_pool_create_fallback(void)
 {
 	bool has_comp, has_zpool;
 
@@ -782,11 +786,17 @@ static int __zswap_param_set(const char
 	if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
 		return 0;
 
-	/* if this is load-time (pre-init) param setting,
+	/*
+	 * if zswap has not been initialized,
 	 * don't create a pool; that's done during init.
 	 */
-	if (zswap_init_state == ZSWAP_UNINIT)
-		return param_set_charp(s, kp);
+	mutex_lock(&zswap_init_lock);
+	if (zswap_init_state == ZSWAP_UNINIT) {
+		ret = param_set_charp(s, kp);
+		mutex_unlock(&zswap_init_lock);
+		return ret;
+	}
+	mutex_unlock(&zswap_init_lock);
 
 	if (!type) {
 		if (!zpool_has_pool(s)) {
@@ -876,6 +886,14 @@ static int zswap_zpool_param_set(const c
 static int zswap_enabled_param_set(const char *val,
 				   const struct kernel_param *kp)
 {
+	if (system_state == SYSTEM_RUNNING) {
+		mutex_lock(&zswap_init_lock);
+		if (zswap_setup()) {
+			mutex_unlock(&zswap_init_lock);
+			return -ENODEV;
+		}
+		mutex_unlock(&zswap_init_lock);
+	}
 	if (zswap_init_state == ZSWAP_INIT_FAILED) {
 		pr_err("can't enable, initialization failed\n");
 		return -ENODEV;
@@ -1432,7 +1450,7 @@ static const struct frontswap_ops zswap_
 
 static struct dentry *zswap_debugfs_root;
 
-static int __init zswap_debugfs_init(void)
+static int zswap_debugfs_init(void)
 {
 	if (!debugfs_initialized())
 		return -ENODEV;
@@ -1463,7 +1481,7 @@ static int __init zswap_debugfs_init(voi
 	return 0;
 }
 #else
-static int __init zswap_debugfs_init(void)
+static int zswap_debugfs_init(void)
 {
 	return 0;
 }
@@ -1472,11 +1490,14 @@ static int __init zswap_debugfs_init(voi
 /*********************************
 * module init and exit
 **********************************/
-static int __init init_zswap(void)
+static int zswap_setup(void)
 {
 	struct zswap_pool *pool;
 	int ret;
 
+	if (zswap_init_state != ZSWAP_UNINIT)
+		return 0;
+
 	if (zswap_entry_cache_create()) {
 		pr_err("entry cache creation failed\n");
 		goto cache_fail;
@@ -1534,8 +1555,17 @@ cache_fail:
 	zswap_enabled = false;
 	return -ENOMEM;
 }
+
+static int __init zswap_init(void)
+{
+	/* skip init if zswap is disabled when system startup */
+	if (!zswap_enabled)
+		return 0;
+	return zswap_setup();
+}
+
 /* must be late so crypto has time to come up */
-late_initcall(init_zswap);
+late_initcall(zswap_init);
 
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Seth Jennings <sjennings@variantweb.net>");
_

Patches currently in -mm which might be from liushixin2@huawei.com are

bootmem-remove-the-vmemmap-pages-from-kmemleak-in-put_page_bootmem.patch
mm-zswap-skip-confusing-print-info.patch