From: Mikulas Patocka <mpatocka@redhat.com>
To: Yu Kuai <yukuai1@huaweicloud.com>
Cc: Song Liu <song@kernel.org>, David Jeffery <djeffery@redhat.com>,
Li Nan <linan122@huawei.com>,
dm-devel@lists.linux.dev, linux-raid@vger.kernel.org,
Mike Snitzer <msnitzer@redhat.com>,
Heinz Mauelshagen <heinzm@redhat.com>,
Benjamin Marzinski <bmarzins@redhat.com>,
"yukuai (C)" <yukuai3@huawei.com>
Subject: Re: [PATCH 2/7] md: fix a race condition when stopping the sync thread
Date: Thu, 18 Jan 2024 14:07:31 +0100 (CET) [thread overview]
Message-ID: <66fda537-9d25-77e7-754f-2627e35fb8a4@redhat.com> (raw)
In-Reply-To: <dcf29bba-4762-84ad-f60e-3607cf6779f9@huaweicloud.com>
[-- Attachment #1: Type: text/plain, Size: 738 bytes --]
On Thu, 18 Jan 2024, Yu Kuai wrote:
> Hi,
>
> 在 2024/01/18 2:18, Mikulas Patocka 写道:
> > Note that md_wakeup_thread_directly is racy - it will do nothing if the
> > thread is already running or it may cause spurious wake-up if the thread
> > is blocked in another subsystem.
>
> No, as the comment said, md_wakeup_thread_directly() is just to prevent
> that md_wakeup_thread() can't wake up md_do_sync() if it's waiting for
> metadata update.
Yes - but what happens if you wake up the thread just a few instructions
before it is going to sleep for metadata update? wake_up_process does
nothing on a running process and the thread proceeds with waiting. This is
what I thought could happen when I was making the patch.
Mikulas
next prev parent reply other threads:[~2024-01-18 13:07 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-17 18:16 [PATCH 0/7] MD fixes for the LVM2 testsuite Mikulas Patocka
2024-01-17 18:17 ` [PATCH 1/7] md: Revert fa2bbff7b0b4 ("md: synchronize flush io with array reconfiguration") Mikulas Patocka
2024-01-18 1:27 ` Yu Kuai
2024-01-17 18:18 ` [PATCH 2/7] md: fix a race condition when stopping the sync thread Mikulas Patocka
2024-01-18 1:32 ` Yu Kuai
2024-01-18 13:07 ` Mikulas Patocka [this message]
2024-01-18 13:20 ` Yu Kuai
2024-01-18 13:28 ` Mikulas Patocka
2024-01-17 18:19 ` [PATCH 3/7] md: test for MD_RECOVERY_DONE in stop_sync_thread Mikulas Patocka
2024-01-18 0:19 ` Song Liu
2024-01-18 13:23 ` Mikulas Patocka
2024-01-18 21:10 ` Song Liu
2024-01-22 16:34 ` Mikulas Patocka
2024-01-23 2:31 ` Benjamin Marzinski
2024-01-26 9:17 ` Yu Kuai
2024-01-26 9:37 ` Yu Kuai
2024-01-26 10:29 ` Zdenek Kabelac
2024-01-27 1:13 ` Yu Kuai
2024-01-27 1:19 ` Yu Kuai
2024-01-18 1:35 ` Yu Kuai
2024-01-17 18:20 ` [PATCH 4/7] md: call md_reap_sync_thread from __md_stop_writes Mikulas Patocka
2024-01-18 1:38 ` Yu Kuai
2024-01-17 18:21 ` [PATCH 5/7] md: fix deadlock in shell/lvconvert-raid-reshape-linear_to_raid6-single-type.sh Mikulas Patocka
2024-01-18 1:12 ` Song Liu
2024-01-18 1:51 ` Yu Kuai
2024-01-17 18:22 ` [PATCH 6/7] md: partially revert "md/raid6: use valid sector values to determine if an I/O should wait on the reshape" Mikulas Patocka
2024-01-17 23:56 ` Song Liu
2024-01-17 18:22 ` [PATCH 7/7] md: fix a suspicious RCU usage warning Mikulas Patocka
2024-01-17 23:59 ` Song Liu
2024-01-18 1:56 ` Yu Kuai
2024-01-25 17:31 ` Song Liu
2024-01-17 19:27 ` [PATCH 0/7] MD fixes for the LVM2 testsuite Song Liu
2024-01-18 2:03 ` Yu Kuai
2024-01-27 7:57 ` Yu Kuai
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