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Re: [Xen-devel] Re: [PATCH] xen: correctly rebuild mfn list list after m

To: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Re: [PATCH] xen: correctly rebuild mfn list list after migration.
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Thu, 21 Oct 2010 10:10:14 -0700
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 On 10/21/2010 03:10 AM, Ian Campbell wrote:
> On Thu, 2010-10-14 at 19:27 +0100, Jeremy Fitzhardinge wrote:
>> On 10/14/2010 01:51 AM, Ian Campbell wrote:
>>> On Thu, 2010-10-14 at 07:49 +0100, Ian Campbell wrote:
>>>> On Thu, 2010-10-14 at 01:37 +0100, Jeremy Fitzhardinge wrote:
>>>>> I'm getting this triggering at boot:
>>>>> PM: Adding info for No Bus:xen!gntdev
>>>>> ------------[ cut here ]------------
>>>>> kernel BUG at /home/jeremy/git/linux/arch/x86/xen/mmu.c:480! 
>>>> Probably a consequence of the bogus attempt to skip over completely
>>>> empty mid levels which you pointed out in your next mail.
>>>> I guess I should test 64 bit guests and not just PAE ones and I guess
>>>> pre-ballooning is likely to interact as well.
>>> I'm only able to reproduce this by booting ballooned and then ballooning
>>> up, are you doing that or were you seeing it just by booting?
>>> What are your memory and maxmem settings?
>> memory=512, no maxmem.
> The BUG_ON I added to alloc_p2m was wrong (converted an mfn to an
> address in the direct map and then compared it with a virtual address in
> kernel map, IIRC). Here's an update patch which fixes all your previous
> comments, this issue and a few other bits and bobs
> * s/p2m_mid_mfn_p/p2m_top_mfn_p/g
> * Fix BUG_ON in alloc_p2m
> * Skip correct number of pfns when mid == p2m_mid_missing
> * Use correct value p2m_top_mfn[topidx] when mid == p2m_mid_missing

OK, it passed my sniff test - it boots and save/restored a few times.

(I added a S-O-B for you.)


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