From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31338C6FD20 for ; Fri, 24 Mar 2023 09:03:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 680CB6B0075; Fri, 24 Mar 2023 05:03:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 632C56B0078; Fri, 24 Mar 2023 05:03:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4F8846B007B; Fri, 24 Mar 2023 05:03:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 3F4AA6B0075 for ; Fri, 24 Mar 2023 05:03:35 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id D94A91206A0 for ; 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WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20230323080443.GC20444@lst.de> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.24] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To dggpemm100009.china.huawei.com (7.185.36.113) X-CFilter-Loop: Reflected X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: E809EC0021 X-Stat-Signature: z8az7fhgdogbqjunyumzie7btz55sphs X-HE-Tag: 1679648610-584523 X-HE-Meta: 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 +ax0Qpyq 4qKLcxQoR8w6Hv2hb8/IxSZJpweBwbHJ5Gy4KGurJ4VE79E7rBb5chV/5ZEg59RT48x7CUXYLaLaFl7fWpUeHa2fy0PBP5aqCJurA90qAuLoh2wfOf+x9LN28uOLn0X2iKereVJAJB2kpoyc+ejen9dKOgpalaSoZtw8+6VgCeXgXIgc= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2023/3/23 16:04, Christoph Hellwig wrote: > On Wed, Mar 22, 2023 at 06:20:06PM +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 >> --- >> mm/zswap.c | 51 +++++++++++++++++++++++++++++++++++++++++---------- >> 1 file changed, 41 insertions(+), 10 deletions(-) >> >> diff --git a/mm/zswap.c b/mm/zswap.c >> index 09fa956920fa..3aed3b26524a 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 *, >> @@ -220,6 +222,9 @@ static bool zswap_init_started; >> /* fatal error during init */ >> static bool zswap_init_failed; >> >> +/* 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; >> >> @@ -272,13 +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; >> } > Please add a cleanup patch to remove this helper first, it just > massivel confuses the reader. I will, thanks. > >> -static void __init zswap_entry_cache_destroy(void) >> +static void zswap_entry_cache_destroy(void) >> { >> kmem_cache_destroy(zswap_entry_cache); >> } > Same here. > >> @@ -663,7 +668,7 @@ 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; >> >> @@ -784,8 +789,15 @@ static int __zswap_param_set(const char *val, const struct kernel_param *kp, >> /* if this is load-time (pre-init) param setting, >> * don't create a pool; that's done during init. >> */ >> - if (!zswap_init_started) >> - return param_set_charp(s, kp); >> + if (!zswap_init_started) { >> + mutex_lock(&zswap_init_lock); >> + if (!zswap_init_started) { >> + ret = param_set_charp(s, kp); >> + mutex_unlock(&zswap_init_lock); >> + return ret; >> + } >> + mutex_unlock(&zswap_init_lock); >> + } > Just take the lock around the whole function. No need to micro-optimize > setting a kernel paramter. I will, thanks. > >> @@ -884,6 +896,15 @@ static int zswap_enabled_param_set(const char *val, >> if (res == *(bool *)kp->arg) >> return 0; >> >> + if (!zswap_init_started && (system_state == SYSTEM_RUNNING)) { > No need for the inner braces. But directly looking at > SYSTEM_RUNNING, especially without a comment is a bit of a mess. > Is there any better way to deal with this? I have no idea about better way. > > Also the zswap_init_started variable name has always been a bit > confusing. If everything around it takes zswap_init_lock now, > it can be replaced with a check for successful zswap initialization > as all the initializtion is covered by the lock. That would really > help to clean up the code. I will, thanks. > >> +static int zswap_debugfs_init(void) >> { >> if (!debugfs_initialized()) >> return -ENODEV; >> @@ -1482,7 +1503,7 @@ static int __init zswap_debugfs_init(void) >> return 0; >> } >> #else >> -static int __init zswap_debugfs_init(void) >> +static int zswap_debugfs_init(void) > Is there any reason to not just always initialize debugfs and > only defer the expensive allocations? It seems there is no need to initialize debugfs if zswap is not used. > > . >