On Mon, Apr 03, 2023 at 08:13:18PM +0800, Liu Shixin wrote:
> Since some users may not use zswap, the zswap_pool is wasted. Save memory
> by delaying the initialization of zswap until enabled.
>
> Signed-off-by: Liu Shixin <liushixin2@xxxxxxxxxx>
> ---
> mm/zswap.c | 56 +++++++++++++++++++++++++++++++++++++++++-------------
> 1 file changed, 43 insertions(+), 13 deletions(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index 9169c2baee87..14db57450bfd 100644
> --- a/mm/zswap.c
> +++ b/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 *,
> @@ -222,6 +224,9 @@ enum zswap_init_type {
>
> static enum zswap_init_type 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;
>
> @@ -654,7 +659,7 @@ static struct zswap_pool *zswap_pool_create(char *type, char *compressor)
> 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;
>
> @@ -763,21 +768,28 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp,
> char *s = strstrip((char *)val);
> int ret;
>
> + mutex_lock(&zswap_init_lock);
> switch (zswap_init_state) {
> case ZSWAP_UNINIT:
> /* if this is load-time (pre-init) param setting,
> * don't create a pool; that's done during init.
> */
> - return param_set_charp(s, kp);
> + ret = param_set_charp(s, kp);
> + mutex_unlock(&zswap_init_lock);
> + return ret;
> case ZSWAP_INIT_SUCCEED:
> /* no change required */
> - if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool)
> + if (!strcmp(s, *(char **)kp->arg) && zswap_has_pool) {
> + mutex_unlock(&zswap_init_lock);
> return 0;
> + }
> break;
> case ZSWAP_INIT_FAILED:
> pr_err("can't set param, initialization failed\n");
> + mutex_unlock(&zswap_init_lock);
> return -ENODEV;
> }
> + mutex_unlock(&zswap_init_lock);
The pattern here looks a bit odd. Can you split the code that
the ZSWAP_INIT_SUCCEED case falls through into a helper, then just
assign ret inside the switch statement, break out and do a single
unlock and return?
> + /*if this is load-time (pre-init) param setting, only set param.*/
missing space after the initial and before the last * here.
But except for these nitpicks this version looks good to me now.
