From: Xiao Ni <xni@redhat.com>
To: Yu Kuai <yukuai1@huaweicloud.com>
Cc: guoqing.jiang@linux.dev, agk@redhat.com, snitzer@kernel.org,
dm-devel@redhat.com, song@kernel.org, linux-raid@vger.kernel.org,
yangerkun@huawei.com, linux-kernel@vger.kernel.org,
yi.zhang@huawei.com, "yukuai (C)" <yukuai3@huawei.com>
Subject: Re: [dm-devel] [PATCH -next v2 4/6] md: refactor idle/frozen_sync_thread() to fix deadlock
Date: Wed, 14 Jun 2023 15:12:01 +0800 [thread overview]
Message-ID: <CALTww292gwOe-WEjuBwJn0AXvJC4AbfMZXC43EvVt3GCeBoHfw@mail.gmail.com> (raw)
In-Reply-To: <6e738d9b-6e92-20b7-f9d9-e1cf71d26d73@huaweicloud.com>
On Wed, Jun 14, 2023 at 10:04 AM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>
> Hi,
>
> 在 2023/06/14 9:48, Yu Kuai 写道:
>
>
> >>
> >> In the patch, sync_seq is added in md_reap_sync_thread. In
> >> idle_sync_thread, if sync_seq isn't equal
> >>
> >> mddev->sync_seq, it should mean there is someone that stops the sync
> >> thread already, right? Why do
> >>
> >> you say 'new started sync thread' here?
>
> If someone stops the sync thread, and new sync thread is not started,
> then this sync_seq won't make a difference, above wait_event() will not
> wait because !test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) will pass.
> So 'sync_seq' is only used when the old sync thread stops and new sync
> thread starts, add 'sync_seq' will bypass this case.
Hi
If a new sync thread starts, why can sync_seq be different? sync_seq
is only added in md_reap_sync_thread. And when a new sync request
starts, it can't stop the sync request again?
Af first, the sync_seq is 0
admin1
echo idle > sync_action
idle_sync_thread(sync_seq is 1)
echo resync > sync_action (new sync)
Then admin2 echos idle > sync_action, sync_seq is still 1
Regards
Xiao
>
> Thanks,
> Kuai
>
next prev parent reply other threads:[~2023-06-14 7:13 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
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 [this message]
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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