Re: [Xen-devel] Live migration leaves page tables read-only?

[John Byrne <john.l.byrne@xxxxxx>]

Ian Pratt wrote:
> > I forgot to mention that a very simple test case I wrote using shared
> > memory and the mprotect call didn't fail. So, the only test case I
> have
> > at the moment is to run SAP.
> What happens if you use non-live relo?
I thought I had tested that way back at the beginning without seeing the 
problem, but I must not have, because I just retested it to be sure and 
it died the same way. (Now I am truly confused and I need to go back and 
re-examine some of my earlier experiments.)
In the meantime, any ideas where to look?

> Also, can you repro on 32b?
I am doing this on behalf of someone else, so I'd have to ask them to do 
the setup if they have the time. I am reluctant to do so at this point.
Thanks,

John

> Thanks,
> Ian
>
>  
> > John Byrne
> >
> > John Byrne wrote:
> > > I have been trying to debug a problem live-migrating SAP on
> Xen-3.0.3
> > > x86-64 (I also tested Xen-unstable changeset 12548) without success.
> > >
> > > SAP seems to run fine on a given host; live-migrating it to another
> host
> > > causes the guest to almost immediately panic in the mprotect() call
> in
> > > the change_pte_range() routine in the set_pte_at() macro because the
> > > page table page it is trying to update is write-protected.
> > >
> > > My attempts at understanding where this is coming from have come to
> > > naught. Any help in running this down would be appreciated. I am
> > > perfectly willing/able to write some debugging code if I am given a
> few
> > > clues what to look for.
> > >
> > > Thanks,
> > >
> > > John Byrne
> > >
> > >
> > >
> > >
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