RE: 3.19 kernel: BUG: unable to handle kernel NULL pointer dereference

["Justin Piszcz" <jpiszcz@lucidpixels.com>]

> -----Original Message-----
> From: Justin Piszcz [mailto:jpiszcz@lucidpixels.com]
> Sent: Friday, February 27, 2015 10:54 AM
> To: linux-kernel@vger.kernel.org
> Subject: RE: 3.19 kernel: BUG: unable to handle kernel NULL pointer
> dereference
> 
> 
> 
> > -----Original Message-----
> > From: Justin Piszcz [mailto:jpiszcz@lucidpixels.com]
> > Sent: Friday, February 27, 2015 9:54 AM
> > To: linux-kernel@vger.kernel.org
> > Subject: 3.19 kernel: BUG: unable to handle kernel NULL pointer
> dereference
> >
> > Hello,
> >
> > With kernel 3.15, I do not recall having any issues, with 3.19, I am
> getting
> > a kernel crash when I copy files over NFS from machine A to B.
> > Is this a known issue?
> >
> > I suspect it has to do something with this:
> > Feb 27 09:31:20 remote-host [   15.745342] dmar: DRHD: handling fault
> status
> > reg 2
> > Feb 27 09:31:20 remote-host [   15.745361] dmar: DMAR:[DMA Read]
> Request
> > device [04:00.0] fault addr 0 #012[   15.745361] DMAR:[fault reason 06]
> PTE
> > Read access is not set
> >
> 
> [ .. ]
> 
> Here is another crash with debugging enabled:
> 

[ .. ] 

https://bbs.archlinux.org/viewtopic.php?id=176398
https://forums.opensuse.org/showthread.php/497436-DMAR-errors-with-VT-d-enab
led

I disabled Virtualization in the kernel and this works around the problem.

Justin.