linux-kernel - Re: [PATCH v2 3/5] md: use md_thread api to wake up sync

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Message-ID: <89b8377c-e953-f5c5-0ad9-d7b426f1a371@huaweicloud.com>
Date:   Sat, 18 Mar 2023 10:31:52 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     Yu Kuai <yukuai1@...weicloud.com>,
        kernel test robot <oliver.sang@...el.com>
Cc:     oe-lkp@...ts.linux.dev, lkp@...el.com, linux-raid@...r.kernel.org,
        agk@...hat.com, snitzer@...nel.org, song@...nel.org,
        linux-kernel@...r.kernel.org, yi.zhang@...wei.com,
        yangerkun@...wei.com, logang@...tatee.com, guoqing.jiang@...ux.dev,
        pmenzel@...gen.mpg.de, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH v2 3/5] md: use md_thread api to wake up sync_thread

Hi,

在 2023/03/17 11:30, Yu Kuai 写道:
> Hi,
> 
> 在 2023/03/17 10:30, kernel test robot 写道:
>>
>> Greeting,
>>
>> FYI, we noticed INFO:task_blocked_for_more_than#seconds due to commit 
>> (built with gcc-11):
>>
>> commit: af2203c7e88c00d3ce072f18c18a36e2936372fd ("[PATCH v2 3/5] md: 
>> use md_thread api to wake up sync_thread")
>> url: 
>> https://github.com/intel-lab-lkp/linux/commits/Yu-Kuai/md-pass-a-md_thread-pointer-to-md_register_thread/20230315-142018 
>>
>> base: git://git.kernel.org/cgit/linux/kernel/git/song/md.git md-next
>> patch link: 
>> https://lore.kernel.org/all/20230315061810.653263-4-yukuai1@huaweicloud.com/ 
>>
>> patch subject: [PATCH v2 3/5] md: use md_thread api to wake up 
>> sync_thread
>>
> 
> I don't expect there is any difference between:
> 
> if (mddev->sync_thread)
>      wake_up_process(mddev->sync_thread->tsk);
> 
> and:
> 
> md_wakeup_thread(mddev->sync_thread);

I understand that they are different now.

md_wakeup_thread() only wakeup wait_event() from md_thread(), it will
not wake up 'md_thread->tsk' if it's runing.

Hence this patch is wrong.

Thanks,
Kuai