linux-kernel - Re: [RFC PATCH v1 6/9] freezer: Set default freeze priority for zombie tasks

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Message-ID: <9dca7c98-84e5-4d16-af76-93f2b0470243@kylinos.cn>
Date: Tue, 12 Aug 2025 16:07:11 +0800
From: Zihuan Zhang <zhangzihuan@...inos.cn>
To: Oleg Nesterov <oleg@...hat.com>
Cc: "Rafael J . Wysocki" <rafael@...nel.org>,
 Peter Zijlstra <peterz@...radead.org>, David Hildenbrand <david@...hat.com>,
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 "Liam R . Howlett" <Liam.Howlett@...cle.com>,
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 linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v1 6/9] freezer: Set default freeze priority for
 zombie tasks

在 2025/8/8 22:29, Oleg Nesterov 写道:
> On 08/07, Zihuan Zhang wrote:
>> @@ -6980,6 +6981,7 @@ void __noreturn do_task_dead(void)
>>   	current->flags |= PF_NOFREEZE;
>>
>>   	__schedule(SM_NONE);
>> +	freeze_set_default_priority(current, FREEZE_PRIORITY_NEVER);
>>   	BUG();
> But this change has no effect?
>
> Firstly, this last __schedule() should not return, note the BUG() we have.
>
> Secondly, this zombie is already PF_NOFREEZE, freeze_task() will return
> false anyway.

Thanks for pointing that out.
Indeed, I’ve noticed that in the current position the code has no effect.
If we move this code to a more appropriate place, it should improve both 
safety and usefulness compared to the previous implementation.

> Oleg.
>