Subject: Re: x86 VM Boot hang with latest linux-next

From: Mike Snitzer <[email-masked]>
Date: Mon, 4 Mar 2019 18:02:46 -0500

On Sun, Mar 03 2019 at 12:06pm -0500,
Alexander Duyck <[email-masked]> 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