Subject: Re: [PATCH-next v2 2/2] scsi: fix iscsi rescan fails to create block
 device
To:     jejb@linux.ibm.com, Zhong Jinghua <zhongjinghua@huawei.com>,
        gregkh@linuxfoundation.org, martin.petersen@oracle.com,
        hare@suse.de, bvanassche@acm.org, emilne@redhat.com
Cc:     linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
        yi.zhang@huawei.com, "yukuai (C)" <yukuai3@huawei.com>
References: <20230128094146.205858-1-zhongjinghua@huawei.com>
 <20230128094146.205858-3-zhongjinghua@huawei.com>
 <1b466057ed2e91b05388afbb5791639eb8abdd59.camel@linux.ibm.com>
From:   Yu Kuai <yukuai1@huaweicloud.com>
Message-ID: <c3e58056-942a-f829-ecf6-1342c65b6865@huaweicloud.com>
Date:   Mon, 30 Jan 2023 11:07:08 +0800
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Hi,

在 2023/01/30 1:30, James Bottomley 写道:
> On Sat, 2023-01-28 at 17:41 +0800, Zhong Jinghua wrote:
>> This error will cause a warning:
>> kobject_add_internal failed for block (error: -2 parent: 1:0:0:1).
>> In the lower version (such as 5.10), there is no corresponding error
>> handling, continuing
>> to go down will trigger a kernel panic, so cc stable.
> 
> Is this is important point and what you're saying is that this only
> panics on kernels before 5.10 or so because after that it's correctly
> failed by block device error handling so there's nothing to fix in
> later kernels?
> 
> In that case, isn't the correct fix to look at backporting the block
> device error handling:

This is the last commit that support error handling, and there are many
relied patches, and there are lots of refactor in block layer. It's not
a good idea to backport error handling to lower version.

Althrough error handling can prevent kernel crash in this case, I still
think it make sense to make sure kobject is deleted in order, parent
should not be deleted before child.

Thanks,
Kuai
> 
> commit 83cbce9574462c6b4eed6797bdaf18fae6859ab3
> Author: Luis Chamberlain <mcgrof@kernel.org>
> Date:   Wed Aug 18 16:45:40 2021 +0200
> 
>      block: add error handling for device_add_disk / add_disk
> 
> ?
> 
> James
> 
> .
>