From: no-reply@sashiko.virtuozzo.com
To: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>,
alexander.ivanov@virtuozzo.com, khorenko@virtuozzo.com
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 v6 5/7] dm/push_backup: arm deadline timer under pb->lock
Date: Wed, 4 Nov 2026 08:48:04 +0000 [thread overview]
Message-ID: <010701a1a5be7488-9cfc6ee9-21ff-43a0-978c-4c8f731f2377-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261104083818.856720-6-andrey.zhadchenko@virtuozzo.com>
> Both pb_timer_func() and postpone_if_required_for_backup() decide
> whether to arm the timer under pb->lock but call mod_timer() after
> dropping it, so the decisions can be applied out of order:
>
> CPU1 pb_timer_func() CPU2 postpone_if_required_for_backup()
> lock; deadline = S64_MAX
> unlock
> lock; nr_delayed = 1
> deadline_jiffies = now + timeout
> unlock
> mod_timer(timeout)
> mod_timer(from S64_MAX)
>
> The late mod_timer() of the callback overwrites the fresh deadline, and
> the write is delayed with the timer parked in a very distant future.
> [ ... ]
> Fixes: 62e07487348e ("dm: Add push backup driver")
> https://virtuozzo.atlassian.net/browse/VSTOR-152912
>
> Feature: dm-backup: push backup target driver
> Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko@virtuozzo.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261104083818.856720-1-andrey.zhadchenko@virtuozzo.com?part=5
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next prev parent reply other threads:[~2026-11-04 8:49 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-04 8:38 [Devel] [PATCH hci-8.1 v6 0/7] dm/push_backup: event fd interface and fixes Andrey Zhadchenko
2026-11-04 8:38 ` [Devel] [PATCH hci-8.1 v6 1/7] dm/push_backup: correct initialization Andrey Zhadchenko
2026-11-04 8:45 ` no-reply
2026-11-04 8:38 ` [Devel] [PATCH hci-8.1 v6 2/7] dm/push_backup: return error if workqueue allocation fails Andrey Zhadchenko
2026-11-04 8:46 ` no-reply
2026-11-04 8:38 ` [Devel] [PATCH hci-8.1 v6 3/7] dm/push_backup: clear pb->alive under pb->lock Andrey Zhadchenko
2026-11-04 8:46 ` no-reply
2026-11-04 8:38 ` [Devel] [PATCH hci-8.1 v6 4/7] dm/push_backup: fix mod_timer() usage Andrey Zhadchenko
2026-11-04 8:47 ` no-reply
2026-11-04 8:38 ` [Devel] [PATCH hci-8.1 v6 5/7] dm/push_backup: arm deadline timer under pb->lock Andrey Zhadchenko
2026-11-04 8:48 ` no-reply [this message]
2026-11-04 8:38 ` [Devel] [PATCH hci-8.1 v6 6/7] dm/push_backup: do not re-arm deadline timer in push_backup_write() Andrey Zhadchenko
2026-11-04 8:50 ` no-reply
2026-11-04 8:38 ` [Devel] [PATCH hci-8.1 v6 7/7] dm/push_backup: add event file descriptor interface Andrey Zhadchenko
2026-11-04 8:52 ` no-reply
2026-11-04 18:46 ` [Devel] [PATCH hci-8.1 v6 0/7] dm/push_backup: event fd interface and fixes Konstantin Khorenko
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