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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E85AEB64D7 for ; Wed, 14 Jun 2023 01:15:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240192AbjFNBPO (ORCPT ); Tue, 13 Jun 2023 21:15:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38364 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230189AbjFNBPN (ORCPT ); Tue, 13 Jun 2023 21:15:13 -0400 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8EE761BE8; Tue, 13 Jun 2023 18:15:11 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4QgnXW2scnz4f3mVx; Wed, 14 Jun 2023 09:15:07 +0800 (CST) Received: from [10.174.176.73] (unknown [10.174.176.73]) by APP4 (Coremail) with SMTP id gCh0CgAHcLOaFIlkEF+bLg--.21440S3; Wed, 14 Jun 2023 09:15:08 +0800 (CST) Subject: Re: [dm-devel] [PATCH -next v2 3/6] md: add a mutex to synchronize idle and frozen in action_store() To: Xiao Ni , Yu Kuai , guoqing.jiang@linux.dev, agk@redhat.com, snitzer@kernel.org, dm-devel@redhat.com, song@kernel.org Cc: yi.zhang@huawei.com, yangerkun@huawei.com, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, "yukuai (C)" References: <20230529132037.2124527-1-yukuai1@huaweicloud.com> <20230529132037.2124527-4-yukuai1@huaweicloud.com> From: Yu Kuai Message-ID: <254fc651-aa75-074d-f567-49bafc437e9c@huaweicloud.com> Date: Wed, 14 Jun 2023 09:15:06 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID: gCh0CgAHcLOaFIlkEF+bLg--.21440S3 X-Coremail-Antispam: 1UD129KBjvJXoWxJw1kJrWfAr1xArW3JrWfGrg_yoW5CFWrpF WktFWrArZ0yws3Xr1UJwsrZay5Xr18KayDKryfGa4UJF13Cr4qqF1jgF4j9FykC3y8Cr1U tw18XFZ3ZF18Xr7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9F14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvEwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2Y2ka 0xkIwI1lc7I2V7IY0VAS07AlzVAYIcxG8wCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7x kEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E 67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCw CI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxKx2IYs7xG6rW3Jr0E 3s1lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcS sGvfC2KfnxnUUI43ZEXa7VUbXdbUUUUUU== X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org Hi, 在 2023/06/13 22:43, Xiao Ni 写道: > > 在 2023/5/29 下午9:20, Yu Kuai 写道: >> From: Yu Kuai >> >> Currently, for idle and frozen, action_store will hold 'reconfig_mutex' >> and call md_reap_sync_thread() to stop sync thread, however, this will >> cause deadlock (explained in the next patch). In order to fix the >> problem, following patch will release 'reconfig_mutex' and wait on >> 'resync_wait', like md_set_readonly() and do_md_stop() does. >> >> Consider that action_store() will set/clear 'MD_RECOVERY_FROZEN' >> unconditionally, which might cause unexpected problems, for example, >> frozen just set 'MD_RECOVERY_FROZEN' and is still in progress, while >> 'idle' clear 'MD_RECOVERY_FROZEN' and new sync thread is started, which >> might starve in progress frozen. A mutex is added to synchronize idle >> and frozen from action_store(). >> >> Signed-off-by: Yu Kuai >> --- >>   drivers/md/md.c | 5 +++++ >>   drivers/md/md.h | 3 +++ >>   2 files changed, 8 insertions(+) >> >> diff --git a/drivers/md/md.c b/drivers/md/md.c >> index 23e8e7eae062..63a993b52cd7 100644 >> --- a/drivers/md/md.c >> +++ b/drivers/md/md.c >> @@ -644,6 +644,7 @@ void mddev_init(struct mddev *mddev) >>       mutex_init(&mddev->open_mutex); >>       mutex_init(&mddev->reconfig_mutex); >>       mutex_init(&mddev->delete_mutex); >> +    mutex_init(&mddev->sync_mutex); >>       mutex_init(&mddev->bitmap_info.mutex); >>       INIT_LIST_HEAD(&mddev->disks); >>       INIT_LIST_HEAD(&mddev->all_mddevs); >> @@ -4785,14 +4786,18 @@ static void stop_sync_thread(struct mddev *mddev) >>   static void idle_sync_thread(struct mddev *mddev) >>   { >> +    mutex_lock(&mddev->sync_mutex); >>       clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery); >>       stop_sync_thread(mddev); >> +    mutex_unlock(&mddev->sync_mutex); >>   } >>   static void frozen_sync_thread(struct mddev *mddev) >>   { >> +    mutex_init(&mddev->delete_mutex); > > > typo error? It should be mutex_lock(&mddev->sync_mutex); ? > Yes, and thanks for spotting this, this looks like I did this while rebasing. Thanks, Kuai > Regards > > Xiao > >>       set_bit(MD_RECOVERY_FROZEN, &mddev->recovery); >>       stop_sync_thread(mddev); >> +    mutex_unlock(&mddev->sync_mutex); >>   } >>   static ssize_t >> diff --git a/drivers/md/md.h b/drivers/md/md.h >> index bfd2306bc750..2fa903de5bd0 100644 >> --- a/drivers/md/md.h >> +++ b/drivers/md/md.h >> @@ -537,6 +537,9 @@ struct mddev { >>       /* Protect the deleting list */ >>       struct mutex            delete_mutex; >> +    /* Used to synchronize idle and frozen for action_store() */ >> +    struct mutex            sync_mutex; >> + >>       bool    has_superblocks:1; >>       bool    fail_last_dev:1; >>       bool    serialize_policy:1; > > . >