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Date:   Mon, 4 Mar 2019 18:02:46 -0500
From:   Mike Snitzer <snitzer@redhat.com>
To:     Alexander Duyck <alexander.duyck@gmail.com>
Cc:     linux-next@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        dm-devel@redhat.com
Subject: Re: x86 VM Boot hang with latest linux-next
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On Sun, Mar 03 2019 at 12:06pm -0500,
Alexander Duyck <alexander.duyck@gmail.com> wrote:

> Thanks. The behavior of it has me wondering if we are looking at
> something like an uninitialized data issue or something like that
> since as I mentioned I don't see this occur on every boot, just on
> most of them. So every now and then I can boot up the VM without any
> issues, but most of the time it will boot and then get stuck waiting
> on jobs that take forever.

The commit in question (1efa3bb79d3 "dm: must allocate dm_noclone for
stacked noclone devices") conditionally allocates the 'struct
dm_noclone' and I can only infer that the change is causing a negative
side-effect in virtualized environments (both x86_64 and s390).

I haven't been able to reproduce on x86_64 kvm with virtio-scsi on
fedora 25 though.  Will try fedora 29 shortly, and also try virtio-blk.

Could you please provide your guest's .config (even if just off-list)?
Also, what kernel are you running on the host?

Thanks,
Mike