From: Askar Safin <safinaskar@gmail.com>
To: wqu@suse.com
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v2 0/3] btrfs: scrub: enhance freezing and signal handling
Date: Fri, 17 Oct 2025 12:39:47 +0300 [thread overview]
Message-ID: <20251017093947.1170945-1-safinaskar@gmail.com> (raw)
In-Reply-To: <cover.1760607566.git.wqu@suse.com>
Qu Wenruo <wqu@suse.com>:
> - Systemd slice freezing
> This is the most complex part that I have not yet fully pinned down,
> but during the tests it looks like systemd is sending some signals to
> the processes under the user slice.
Systemd doesn't send any signals. First it freezes user slices using
cgroup freezer. This happens here:
https://github.com/systemd/systemd/blob/28aa0a1f25470b21fbe3b8af2d9d99e616c000a4/src/sleep/sleep.c#L665
Ultimately this code does cgroup freezing, see "cgroup.freeze" in
https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html .
Then systemd initiates actual kernel-based suspend.
But it is still useful to catch signals, because systemd does
send signals when we poweroff.
(Please, CC me, if you send future versions of this patchset.)
--
Askar Safin
next prev parent reply other threads:[~2025-10-17 9:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-16 9:42 [PATCH v2 0/3] btrfs: scrub: enhance freezing and signal handling Qu Wenruo
2025-10-16 9:42 ` [PATCH v2 1/3] btrfs: scrub: add cancel/pause/removed bg checks for raid56 parity stripes Qu Wenruo
2025-10-16 9:42 ` [PATCH v2 2/3] btrfs: scrub: cancel the run if the process or fs is being frozen Qu Wenruo
2025-10-16 10:02 ` Filipe Manana
2025-10-16 9:42 ` [PATCH v2 3/3] btrfs: scrub: cancel the run if there is a pending signal Qu Wenruo
2025-10-17 9:47 ` Askar Safin
2025-10-17 10:34 ` Qu Wenruo
2025-10-17 9:39 ` Askar Safin [this message]
2025-10-17 13:03 ` [PATCH v2 0/3] btrfs: scrub: enhance freezing and signal handling Askar Safin
2025-10-18 4:16 ` Askar Safin
2025-10-18 4:26 ` Qu Wenruo
2025-10-18 6:43 ` Askar Safin
2025-10-18 7:14 ` Qu Wenruo
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