Re: Need help debugging kernel oops ( BUG: unable to handle page fault for address ? )

["J. Roeleveld" <joost@xxxxxxxxxxxx>]

On Tuesday, 4 August 2020 06:24:44 CEST Jürgen Groß wrote:
> On 03.08.20 08:27, J. Roeleveld wrote:
> > Hi All,
> > 
> > I have had a few oopses in the past week already and am trying to find
> > out what the likely cause is and, more importantly, how to resolve this.
> 
> Could you please apply the attached patch to your kernel? This is
> for an issue I've found recently and I have the vague feeling it could
> repair the issue you are seeing.
> 
> I and others have hit the very same problem as you did in very rare
> cases, but we were never able to reproduce it at will. So if you are
> hitting it on a regular basis it would help a lot to verify whether
> my patch is helping to solve this issue, too.
> 
> 
> Juergen

I am hitting it, but not predictably, which is rather annoying.
I am currently doing my best to force this and documenting what I am trying. 
When I do manage to force the issue, I will definitely try the patch.

Looking at the patch, I am wondering if setting "CONFIG_PREEMPT" might not 
also prevent this?

Or, more likely, the "server" option is "CONFIG_PREEMPT_NONE", which might 
prevent this particular situation all together?

I currently have "CONFIG_PREEMPT_VOLUNTARY" set in my config.

Is there any documentation about which of these three is actually recommended 
for the Xen Domain0?

--
Joost