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

From: Justin Piszcz
Date: Sat Feb 28 2015 - 17:19:15 EST




> -----Original Message-----
> From: Justin Piszcz [mailto:jpiszcz@xxxxxxxxxxxxxxx]
> Sent: Friday, February 27, 2015 10:54 AM
> To: linux-kernel@xxxxxxxxxxxxxxx
> Subject: RE: 3.19 kernel: BUG: unable to handle kernel NULL pointer
> dereference
>
>
>
> > -----Original Message-----
> > From: Justin Piszcz [mailto:jpiszcz@xxxxxxxxxxxxxxx]
> > Sent: Friday, February 27, 2015 9:54 AM
> > To: linux-kernel@xxxxxxxxxxxxxxx
> > 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.

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