Re: [PATCH v2] md: don't create mddev in md_open

["heming.zhao@suse.com" <heming.zhao@suse.com>]

On 4/1/21 2:17 PM, Christoph Hellwig wrote:
> On Thu, Apr 01, 2021 at 09:34:56AM +0800, Zhao Heming wrote:
>> commit d3374825ce57 ("md: make devices disappear when they are no longer
>> needed.") introduced protection between mddev creating & removing. The
>> md_open shouldn't create mddev when all_mddevs list doesn't contain
>> mddev. With currently code logic, there will be very easy to trigger
>> soft lockup in non-preempt env.
> 
> As mention below, please don't make this even more of a mess than it
> needs to.  We can just pick the two patches doing this from the series
> I sent:
> 

Hi,

I already got your meaning on previously email.
I sent v2 patch for Song's review comment. My patch is bugfix, it may need
to back port into branch maintenance.

Your attachment patch files is partly my patch.
The left part is in md_open (response [PATCH 01/15] md: remove the code to flush
an old instance in md_open)
I still think you directly use bdev->bd_disk->private_data as mddev pointer is not safe.

Let's wait for other guys opinions.

Thanks,
heming