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

[Benjamin Brunner <bbrunner@suse.com>]

Hi,

On 05.12.21 14:42, Coly Li wrote:
> On 12/2/21 5:51 AM, NeilBrown wrote:
>> On Thu, 02 Dec 2021, Coly Li wrote:
>>> On 12/2/21 12:28 AM, Benjamin Brunner wrote:
>>>> Hi all,
>>>>
>>>> On 01.12.21 17:23, Coly Li wrote:
>>>>> On 12/2/21 12:08 AM, mtkaczyk wrote:
>>>>>> Hi Coly,
>>>>>>
>>>>>>> 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 ?
> 
 From my PoV, this should be fine. To be on the safe side, I've added 
Franck Bui, our systemd maintainer, to the list of recipients.

Franck, could you have a look as well, please?

Thanks,
Benjamin

> Thanks.
> 
> Coly Li
> 

-- 
Benjamin Brunner
Engineering Manager System Boot and Init
SUSE Software Solutions Germany GmbH
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