Allow zswap to initialize at boot even if it can't create its pool
due to a failure to create a zpool and/or compressor. Allow those
to be created later, from the sysfs module param interface.
Signed-off-by: Dan Streetman <dan.streetman@xxxxxxxxxxxxx>
---
mm/zswap.c | 46 ++++++++++++++++++++++++++++++++++------------
1 file changed, 34 insertions(+), 12 deletions(-)
diff --git a/mm/zswap.c b/mm/zswap.c
index cabf09e..77cb847 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -185,6 +185,9 @@ 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
**********************************/
@@ -424,7 +427,8 @@ 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;
}
@@ -443,7 +447,7 @@ 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();
@@ -459,7 +463,9 @@ 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();
@@ -582,6 +588,9 @@ 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);
}
@@ -639,7 +648,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
}
/* 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,
@@ -685,6 +694,7 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
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
@@ -692,6 +702,15 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
*/
list_add_tail_rcu(&pool->list, &zswap_pools);
put_pool = pool;
+ } else if (!zswap_has_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);
}
spin_unlock(&zswap_pools_lock);
@@ -724,6 +743,10 @@ static int zswap_enabled_param_set(const char *val,
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);
}
@@ -1205,22 +1228,21 @@ static int __init init_zswap(void)
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:
- cpuhp_remove_state_nocalls(CPUHP_MM_ZSWP_POOL_PREPARE);
hp_fail:
cpuhp_remove_state(CPUHP_MM_ZSWP_MEM_PREPARE);
dstmem_fail:
--
2.9.3
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
