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Re: [Xen-devel] pvops-dom0 console freezes after latest ballooning patch

To: Ronny.Hegewald@xxxxxxxxx
Subject: Re: [Xen-devel] pvops-dom0 console freezes after latest ballooning patch (+possible fix)
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Wed, 09 Dec 2009 11:51:38 -0800
Cc: Dave McCracken <dcm@xxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
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On 12/09/09 11:22, Ronny.Hegewald@xxxxxxxxx wrote:
Setup: xen 3.4.1, 32-bit linux dom0 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=0e898d5e9b893324435e0e77b67fe8d2f0523dbe>" 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?


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