Re: [Xen-devel] pvops-dom0 console freezes after latest ballooning patch (+possible fix)

[Dave McCracken <dcm@xxxxxxxx>]

On Wednesday 09 December 2009, Jeremy Fitzhardinge wrote:
> On 12/09/09 11:22, Ronny.Hegewald@xxxxxxxxx wrote:
> > Setup: xen 3.4.1, 32-bit linux dom0 2.6.31.6 from pvops-git tree from
> > 2009-12-03
> >
> >
> > Since the latest ballooning patch "Add hugepage support to balloon
> > driver
> > <http://git.kernel.org/?p=linux/kernel/git/jeremy/xen.git;a=commit;h=0e89
> >8d5e9b893324435e0e77b67fe8d2f0523dbe>" i experience dom0 console freezes.
> > Additional to that there is a stacktrace about a kernel-bug in
> > drivers/xen/balloon.c in line 346, invalide opcode 0000 (i can send the
> > full stacktrace if someone is interested).
> 
> Yes, please.  Presumably its from the BUG_ON testing the hypercall
> return status?
> 
> > The cause for that seems to be that in the
> > decrease_reservation-funtion the PageHighMem - check is not executed
> > on the assocciated page for the current pfn. Its always the last page
> > that got allocated in the for-loop before, when all the pages are
> > allocated.
> >
> > With the attached patch that crashes dont occur anymore. But im not a
> > kernel-developer so im not sure that this is the correct fix.
> 
> It looks reasonable to me.  Dave?
> 
>      J

Yes, absolutely.  It's the correct fix.  Good catch.

Dave McCracken
Oracle Corp.

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