Re: Subject: Re: port-xen/45975: panic: HYPERVISOR_mmu_update failed, ret: -22 on -current MP domU (amd64)

[Cherry G. Mathew <cherry%zyx.in@localhost>]

>>>>> Manuel Bouyer <bouyer%antioche.eu.org@localhost> writes:

    >> On Tue, Feb 14, 2012 at 11:41:02PM +0530, Cherry G. Mathew wrote:

[...]

    >> Isn't a tlb shootdown needed after this, to make sure the old pte
    >> is not referred to in the TLB ?

    >> The pmap code does it. Plus, I suspect that the hypervisor does
    >> tlb flushes itself, to make sure you can't write accidentally to
    >> a ptp page using stale TLB entries.

    >> 
    >> Separately, please note that the tlb shootdown code ignores
    >> requests to shootdown when the pmap is being destroyed.

    >> this shouldn't be a problem.

Perhaps - but if there's a stale entry pointing to the now destroyed
pmap pdir....

Incidentally, it looks like dom0 with MP hits this bug/symptom at boot -
might be easier to trigger + debug. (I don't have a dom0 setup handy).

Cheers,
-- 
Cherry