From: Yu Kuai <yukuai1@huaweicloud.com>
To: Xiao Ni <xni@redhat.com>, 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,
"yukuai (C)" <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: Wed, 14 Jun 2023 09:15:06 +0800 [thread overview]
Message-ID: <254fc651-aa75-074d-f567-49bafc437e9c@huaweicloud.com> (raw)
In-Reply-To: <c96f2604-e1ef-c3ad-9d15-5e0efa5f222b@redhat.com>
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 <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); ?
>
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;
>
> .
>
next prev parent reply other threads:[~2023-06-14 1:15 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 ` [dm-devel] " Xiao Ni
2023-06-14 1:15 ` Yu Kuai [this message]
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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