From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757575AbcK3VPg (ORCPT ); Wed, 30 Nov 2016 16:15:36 -0500 Received: from mail-pg0-f45.google.com ([74.125.83.45]:33911 "EHLO mail-pg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752872AbcK3VP3 (ORCPT ); Wed, 30 Nov 2016 16:15:29 -0500 From: Yu Zhao To: Seth Jennings , Dan Streetman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Yu Zhao Subject: [PATCH v2] zswap: only use CPU notifier when HOTPLUG_CPU=y Date: Wed, 30 Nov 2016 13:15:16 -0800 Message-Id: <1480540516-6458-1-git-send-email-yuzhao@google.com> X-Mailer: git-send-email 2.8.0.rc3.226.g39d4020 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org __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). v2: #ifdef for cpu_notifier_register_done during cleanup. Signe-off-by: Yu Zhao --- mm/zswap.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/mm/zswap.c b/mm/zswap.c index 275b22c..2915f44 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) { @@ -456,27 +459,34 @@ 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: for_each_online_cpu(cpu) __zswap_cpu_comp_notifier(pool, CPU_UP_CANCELED, cpu); +#ifdef CONFIG_HOTPLUG_CPU cpu_notifier_register_done(); +#endif return -ENOMEM; } @@ -484,11 +494,15 @@ 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