Re: 4.4-rc3, KVM, br0 and instant hang

[Jens Axboe]

On 12/05/2015 10:31 AM, John Stoffel wrote:
> > > > > > "John" == John Stoffel <john@xxxxxxxxxxxxxxxxx> writes:
>
> John> On Fri, Dec 04, 2015 at 11:28:33PM -0500, John Stoffel wrote:
> > > Hi all,
>
> > > Anyway, if I try to boot up anything past the 4.2.6 kernel, the system
> > > locks up pretty quickly with an oops message that scrolls off the
> > > screen too far.  I've got some pictures which I'll attach in a bit,
> > > maybe they'll help.  So at first I thought it was something to do with
> > > bad kworker threads, or SCSI or SATA interactions, but as I tried to
> > > configure Netconsole to log to my beaglebone black SBC, I found out
> > > that if I compiled and installed 4.4-rc3, started the bridge up (br0),
> > > even started KVM, but did NOT start my VMs, the system was stable.
>
> I've now figured out that I can disable all my VMs from autostart, and
> the system will come up properly.  Then I can setup netconsole to use
> the br0 interface, do an  "echo t > sysrq" to confirm it's working,
> and start up the VMs.
>
> On my most recent bootup, I thought it was ok, since the VMs worked
> for a while (10 minutes) and I was starting to re-compile the kernel
> again to make more modules compiled in.  No luck, I got the following
> crash dump (partial) on my netconsole box.
>
> [ 1434.266524] ------------[ cut here ]------------
> [ 1434.266643] WARNING: CPU: 2 PID: 179 at block/blk-merge.c:435 blk_rq_map_sg+0x2d9/0x2eb()

This is fixed in current -git, as of a few days ago.

--
Jens Axboe

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