From: Xiao Ni <xni@redhat.com>
To: Yu Kuai <yukuai1@huaweicloud.com>,
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,
yukuai3@huawei.com
Subject: Re: [dm-devel] [PATCH -next v2 3/6] md: add a mutex to synchronize idle and frozen in action_store()
Date: Tue, 13 Jun 2023 22:43:11 +0800 [thread overview]
Message-ID: <c96f2604-e1ef-c3ad-9d15-5e0efa5f222b@redhat.com> (raw)
In-Reply-To: <20230529132037.2124527-4-yukuai1@huaweicloud.com>
在 2023/5/29 下午9:20, Yu Kuai 写道:
> From: Yu Kuai <yukuai3@huawei.com>
>
> 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 <yukuai3@huawei.com>
> ---
> 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); ?
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;
next prev parent reply other threads:[~2023-06-13 14:44 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-29 13:20 [PATCH -next v2 0/6] md: fix that MD_RECOVERY_RUNNING can be cleared while sync_thread is still running Yu Kuai
2023-05-29 13:20 ` [PATCH -next v2 1/6] Revert "md: unlock mddev before reap sync_thread in action_store" Yu Kuai
2023-06-13 6:25 ` Xiao Ni
2023-06-13 11:58 ` Yu Kuai
2023-05-29 13:20 ` [PATCH -next v2 2/6] md: refactor action_store() for 'idle' and 'frozen' Yu Kuai
2023-06-13 8:02 ` [dm-devel] " Xiao Ni
2023-06-13 12:00 ` Yu Kuai
2023-06-13 12:25 ` Xiao Ni
2023-06-13 12:44 ` Yu Kuai
2023-06-13 14:14 ` Xiao Ni
2023-05-29 13:20 ` [PATCH -next v2 3/6] md: add a mutex to synchronize idle and frozen in action_store() Yu Kuai
2023-06-13 14:43 ` Xiao Ni [this message]
2023-06-14 1:15 ` [dm-devel] " Yu Kuai
2023-06-16 6:41 ` Song Liu
2023-05-29 13:20 ` [PATCH -next v2 4/6] md: refactor idle/frozen_sync_thread() to fix deadlock Yu Kuai
2023-06-13 14:50 ` [dm-devel] " Xiao Ni
2023-06-14 1:48 ` Yu Kuai
2023-06-14 2:04 ` Yu Kuai
2023-06-14 7:12 ` Xiao Ni
2023-06-14 7:38 ` Yu Kuai
2023-06-14 7:57 ` Xiao Ni
2023-06-14 8:28 ` Yu Kuai
2023-06-14 9:08 ` Xiao Ni
2023-06-15 1:28 ` Yu Kuai
2023-06-15 8:01 ` Xiao Ni
2023-06-15 8:17 ` Xiao Ni
2023-06-15 9:05 ` Yu Kuai
2023-06-15 9:14 ` Xiao Ni
2023-06-14 3:47 ` Xiao Ni
2023-06-14 6:04 ` Yu Kuai
2023-06-14 6:37 ` Xiao Ni
2023-05-29 13:20 ` [PATCH -next v2 5/6] md: wake up 'resync_wait' at last in md_reap_sync_thread() Yu Kuai
2023-06-14 7:20 ` Xiao Ni
2023-05-29 13:20 ` [PATCH -next v2 6/6] md: enhance checking in md_check_recovery() Yu Kuai
2023-06-14 7:24 ` [dm-devel] " Xiao Ni
2023-06-08 2:41 ` [PATCH -next v2 0/6] md: fix that MD_RECOVERY_RUNNING can be cleared while sync_thread is still running Yu Kuai
2023-06-09 4:44 ` Song Liu
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