From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f69.google.com (mail-pa0-f69.google.com [209.85.220.69]) by kanga.kvack.org (Postfix) with ESMTP id 189AE280296 for ; Fri, 11 Nov 2016 17:22:10 -0500 (EST) Received: by mail-pa0-f69.google.com with SMTP id hr10so33247442pac.2 for ; Fri, 11 Nov 2016 14:22:10 -0800 (PST) Received: from mail-pg0-x231.google.com (mail-pg0-x231.google.com. [2607:f8b0:400e:c05::231]) by mx.google.com with ESMTPS id j62si12362559pgc.104.2016.11.11.14.22.09 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 11 Nov 2016 14:22:09 -0800 (PST) Received: by mail-pg0-x231.google.com with SMTP id p66so17520992pga.2 for ; Fri, 11 Nov 2016 14:22:09 -0800 (PST) From: Yu Zhao Subject: [PATCH] zswap: only use CPU notifier when HOTPLUG_CPU=y Date: Fri, 11 Nov 2016 14:21:41 -0800 Message-Id: <1478902901-26889-1-git-send-email-yuzhao@google.com> Sender: owner-linux-mm@kvack.org List-ID: To: Seth Jennings , Dan Streetman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yu Zhao __unregister_cpu_notifier() only removes registered notifier from its linked list when CPU hotplug is configured. If we free registered CPU notifier when HOTPLUG_CPU=n, we corrupt the linked list. To fix the problem, we can either use a static CPU notifier that walks through each pool or just simply disable CPU notifier when CPU hotplug is not configured (which is perfectly safe because the code in question is called after all possible CPUs are online and will remain online until power off). Signed-off-by: Yu Zhao --- mm/zswap.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/mm/zswap.c b/mm/zswap.c index 275b22c..d92d19a 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -118,7 +118,9 @@ struct zswap_pool { struct kref kref; struct list_head list; struct work_struct work; +#ifdef CONFIG_HOTPLUG_CPU struct notifier_block notifier; +#endif char tfm_name[CRYPTO_MAX_ALG_NAME]; }; @@ -448,6 +450,7 @@ static int __zswap_cpu_comp_notifier(struct zswap_pool *pool, return NOTIFY_OK; } +#ifdef CONFIG_HOTPLUG_CPU static int zswap_cpu_comp_notifier(struct notifier_block *nb, unsigned long action, void *pcpu) { @@ -456,21 +459,26 @@ static int zswap_cpu_comp_notifier(struct notifier_block *nb, return __zswap_cpu_comp_notifier(pool, action, cpu); } +#endif static int zswap_cpu_comp_init(struct zswap_pool *pool) { unsigned long cpu; +#ifdef CONFIG_HOTPLUG_CPU memset(&pool->notifier, 0, sizeof(pool->notifier)); pool->notifier.notifier_call = zswap_cpu_comp_notifier; cpu_notifier_register_begin(); +#endif for_each_online_cpu(cpu) if (__zswap_cpu_comp_notifier(pool, CPU_UP_PREPARE, cpu) == NOTIFY_BAD) goto cleanup; +#ifdef CONFIG_HOTPLUG_CPU __register_cpu_notifier(&pool->notifier); cpu_notifier_register_done(); +#endif return 0; cleanup: @@ -484,11 +492,15 @@ static void zswap_cpu_comp_destroy(struct zswap_pool *pool) { unsigned long cpu; +#ifdef CONFIG_HOTPLUG_CPU cpu_notifier_register_begin(); +#endif for_each_online_cpu(cpu) __zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu); +#ifdef CONFIG_HOTPLUG_CPU __unregister_cpu_notifier(&pool->notifier); cpu_notifier_register_done(); +#endif } /********************************* -- 2.8.0.rc3.226.g39d4020 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org