Re: [Xen-devel] Xen BUG at mm-locks.h:118 in 4.2.1 - mm locking order violation - Dom0 reboot

[Sylvain Munaut <s.munaut@xxxxxxxxxxxxxxxxxxxx>]

Hi all,

Thanks for the feedback, let me try to answer the various questions.


> Did you make any changes to Xen before you built it, or were you just
> building your own to get 4.2?

It's based on the official .tar.bz2 from the website, and built using
the debian/ from the 4.2.0 debian package. There are some patches
applied in the debian build but I don't see any that patch the actual
code, just small adaptation to the build and install system to follow
the debian conventions.

So it should be functionally equivalent to an official 4.2.1 . I can
put the compiled binary online if needed.


> Please can you share the domain configuration. Are you running PV
> drivers (esp. ballooning) within it?

There is no xen driver running in there.

Here's the config which is based on the example hvm config:

---------
builder = "hvm"
name   = "wxp-00"
vcpus = 2
memory = 1536
maxmem = 2048
viridian = 1
vif = [ 'type=ioemu,bridge=br0,mac=00:16:3e:35:ad:12' ]
disk = [ '/dev/xen-disks/wxp-00-test,raw,xvda,w', ]
on_poweroff = 'destroy'
on_reboot   = 'restart'
on_crash    = 'restart'
vnc=1
vncunused=0
vnclisten = '0.0.0.0'
vncdisplay=0
vncconsole=1
vncpasswd='xxx'
--------


> Do you by any chance have the xen-syms file from when you built Xen?
> That would let us see exactly what's happened.

You can get it at http://ge.tt/7DBEjmY/v/0


> In the meantime, perhaps you could try the attached (untested) patch.
> If my guess is right, it ought to stop the crashes but you might find
> the VM's performance suffers.

I'll try it and report here.


> From the stack trace, I assume that the guest is running in shadow mode
> ?  Can you confirm this?

Sorry, no idea what this means. How can I check / test ?  I didn't
configure anything relative to "shadow mode" at least.


Cheers,

    Sylvain

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