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Date:   Thu, 23 Mar 2023 15:11:12 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Shiyang Ruan <ruansy.fnst@fujitsu.com>
Cc:     <linux-fsdevel@vger.kernel.org>, <nvdimm@lists.linux.dev>,
        <dan.j.williams@intel.com>, <willy@infradead.org>, <jack@suse.cz>,
        <djwong@kernel.org>
Subject: Re: [PATCH] fsdax: unshare: zero destination if srcmap is HOLE or
 UNWRITTEN
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On Thu, 23 Mar 2023 14:50:38 +0800 Shiyang Ruan <ruansy.fnst@fujitsu.com> wrote:

> 
> 
> 在 2023/3/23 7:03, Andrew Morton 写道:
> > On Wed, 22 Mar 2023 11:11:09 +0000 Shiyang Ruan <ruansy.fnst@fujitsu.com> wrote:
> > 
> >> unshare copies data from source to destination. But if the source is
> >> HOLE or UNWRITTEN extents, we should zero the destination, otherwise the
> >> result will be unexpectable.
> > 
> > Please provide much more detail on the user-visible effects of the bug.
> > For example, are we leaking kernel memory contents to userspace?
> 
> This fixes fail of generic/649.

OK, but this doesn't really help.  I'm trying to determine whether this
fix should be backported into -stable kernels and whether it should be
fast-tracked into Linus's current -rc tree.

But to determine this I (and others) need to know what effect the bug
has upon our users.