Re: [PATCH] mdadm/systemd: change KillMode from none to mixed in service files

On 12/2/21 5:51 AM, NeilBrown wrote:

On Thu, 02 Dec 2021, Coly Li wrote:

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On 12/2/21 12:28 AM, Benjamin Brunner wrote:

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Hi all,

On 01.12.21 17:23, Coly Li wrote:

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On 12/2/21 12:08 AM, mtkaczyk wrote:

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Hi Coly,

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This patch changes KillMode in above listed service files from "none"
to "mixed", to follow systemd recommendation and avoid potential
unnecessary issue.

What about mdmonitor.service? Should we add it there too? Now it is not
defined.

It was overlooked when I did grep KillMode. Yes, I agree
mdmonitor.service should have a KillMode key word as well.

Let me post a v2 version.

JFYI, when KillMode is not set, it defaults to KillMode=control-group,
see https://www.freedesktop.org/software/systemd/man/systemd.kill.html.

Therefore, it shouldn't be necessary to explicitly add it (as long as
control-group is working in case of mdmonitor.service, of course).

Hi Benjamin,

Please correct me if I am wrong, I see the difference of the KillMode is,
-- KillMode=mixed stops the processes more gentally, it kill the main
process with SIGTERM and the remaining processes with SIGKILL.
-- KillMode=control-group kills all in-cgroup processes with SIGKILL,
which I feel a bit cruel for the main process.

There is no point sending SIGTERM to a process which doesn't respond to
it.  mdmon is the only mdadm service which handles SIGTERM.  So it might
make sense to uise KillMode=mixed for that.
For anything else, SIGKILL via KillMode=control-group is perfectly
acceptable.

Hi Neil,

Thanks for the hint. So it seems remove the KillMode= lines from the systemd files might be best choice.

Hi Benjamin,

How do you think about removing the KillMode= lines to use SIGKILL as default action ?

Thanks.

Coly Li