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Subject: Re: [PATCH v5 01/14] md: don't ignore suspended array in
 md_check_recovery()
To: Xiao Ni <xni@redhat.com>, Yu Kuai <yukuai1@huaweicloud.com>
Cc: mpatocka@redhat.com, heinzm@redhat.com, blazej.kucman@linux.intel.com,
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 yi.zhang@huawei.com, yangerkun@huawei.com, "yukuai (C)" <yukuai3@huawei.com>
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From: Yu Kuai <yukuai1@huaweicloud.com>
Message-ID: <c1195efd-dd83-317e-3067-cd4891ae013e@huaweicloud.com>
Date: Sun, 18 Feb 2024 10:34:08 +0800
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Hi,

在 2024/02/18 10:27, Xiao Ni 写道:
> On Sun, Feb 18, 2024 at 9:46 AM Yu Kuai <yukuai1@huaweicloud.com> wrote:
>>
>> Hi,
>>
>> 在 2024/02/18 9:33, Xiao Ni 写道:
>>> The deadlock problem mentioned in this patch should not be right?
>>
>> No, I think it's right. Looks like you are expecting other problems,
>> like mentioned in patch 6, to be fixed by this patch.
> 
> Hi Kuai
> 
> Could you explain why step1 and step2 from this comment can happen
> simultaneously? From the log, the process should be
> The process is :
> dev_remove->dm_destroy->__dm_destroy->dm_table_postsuspend_targets(raid_postsuspend)
> -> dm_table_destroy(raid_dtr).
> After suspending the array, it calls raid_dtr. So these two functions
> can't happen simultaneously.

You're removing the target directly, however, dm can suspend the disk
directly, you can simplily:

1) dmsetup suspend xxx
2) dmsetup remove xxx

Please also take a look at other patches, why step 1) can't stop sync
thread.

Thanks,
Kuai

> 
> 
>>
>> Noted that this patch just fix one case that MD_RECOVERY_RUNNING can't
>> be cleared, I you are testing this patch alone, please make sure that
>> you still triggered the exactly same case:
>>
>> - MD_RCOVERY_RUNNING can't be cleared while array is suspended.
> 
> I'm not testing this patch. I want to understand the patch well. So I
> need to understand the issue first. I can't understand how this
> deadlock (step1,step2) happens.
> 
> Regards
> Xiao
>>
>> Thanks,
>> Kuai
>>
> 
> .
>