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From: Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Subject: Re: [PATCH -next 8/8] block: fix null-pointer dereference in
 ioc_pd_init
Date: Wed, 30 Nov 2022 07:59:41 -0800
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To: Yu Kuai <yukuai1-XF6JlduFytWkHkcT6e4Xnw@public.gmane.org>
Cc: Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, Li Nan <linan122-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>, tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, josef-DigfWCa+lFGyeJad7bwFQA@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, yi.zhang-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, "yukuai (C)" <yukuai3-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>

On Wed, Nov 30, 2022 at 09:32:58AM +0800, Yu Kuai wrote:
> > No, that now means it is removed to later.  You need to add proper
> > synchronization.
> > .
> > 
> 
> Can you explain a bit more? Maybe I'm being noob, here disk is about to
> be freed, and I can think of any contention.

Right now we need synchronization with e.g. open_mutex and a check
for a dead disk, which I suggst to add insted of creating a lifetime
imbalance.