Re: Linux 4.1 reports wrong number of pages to toolstack

[David Vrabel <david.vrabel@citrix.com>]

On 04/09/15 09:53, Ian Campbell wrote:
> On Fri, 2015-09-04 at 01:40 +0100, Wei Liu wrote:
>> Hi David
>>
>> This issue is exposed by the introduction of migration v2. The symptom is that
>> a guest with 32 bit 4.1 kernel can't be restored because it's asking for too
>> many pages.
> 
> FWIW my adhoc tests overnight gave me:
> 
> 37858: b953c0d234bc72e8489d3bf51a276c5c4ec85345 v4.1		Fail
> 37862: 39a8804455fb23f09157341d3ba7db6d7ae6ee76 v4.0		Fail
> 37860: bfa76d49576599a4b9f9b7a71f23d73d6dcff735 v3.19		Fail
> 
> 37872: e36f014edff70fc02b3d3d79cead1d58f289332e v3.19-rc7	Fail
> 37866: 26bc420b59a38e4e6685a73345a0def461136dce v3.19-rc6	Fail
> 37868: ec6f34e5b552fb0a52e6aae1a5afbbb1605cc6cc v3.19-rc5	Fail
> 37864: eaa27f34e91a14cdceed26ed6c6793ec1d186115 v3.19-rc4	Fail *
> 37867: b1940cd21c0f4abdce101253e860feff547291b0 v3.19-rc3	Pass *
> 37865: b7392d2247cfe6771f95d256374f1a8e6a6f48d6 v3.19-rc2	Pass
> 
> 37863: 97bf6af1f928216fd6c5a66e8a57bfa95a659672 v3.19-rc1	Pass
> 
> 37861: b2776bf7149bddd1f4161f14f79520f17fc1d71d v3.18		Pass
> 
> I have set the adhoc bisector working on the ~200 commits between rc3 and
> rc4. It's running in the Citrix instance (which is quieter) so the interim
> results are only visible within our network at http://osstest.xs.citrite.ne
> t/~osstest/testlogs/results-adhoc/bisect/xen-unstable/test-amd64-i386
> -xl..html.
> 
> So far it has confirmed the basis fail and it is now rechecking the basis
> pass.
> 
> Slightly strange though is:
> $ git log --oneline v3.19-rc3..v3.19-rc4 -- drivers/xen/ arch/x86/xen/ include/xen/
> $
> 
> i.e. there are no relevant seeming xen commits in that range. Maybe the
> last one of this is more relevant?

Since this bisect attempt appears to have disappeared into the weeds I
did my own and it fingered:

633d6f17cd91ad5bf2370265946f716e42d388c6 (x86/xen: prepare p2m list for
memory hotplug) which was introduced in 4.0-rc7.

This looks a lot more plausible as the Linux change triggering the
migration failures.

David