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Re: [Xen-devel] Possible shadow bug

To: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Subject: Re: [Xen-devel] Possible shadow bug
From: Igor Mammedov <imammedo@xxxxxxxxxx>
Date: Fri, 10 Jun 2011 17:38:58 +0200
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Keir Fraser <keir@xxxxxxx>, Stabellini <stefano.stabellini@xxxxxxxxxxxxx>, "containers@xxxxxxxxxxxxxxxxxxxxxxxxxx" <containers@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Li Zefan <lizf@xxxxxxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, Michal Hocko <mhocko@xxxxxxx>, "linux-mm@xxxxxxxxx" <linux-mm@xxxxxxxxx>, Keir Fraser <keir.xen@xxxxxxxxx>, Paul Menage <menage@xxxxxxxxxx>, "balbir@xxxxxxxxxxxxxxxxxx" <balbir@xxxxxxxxxxxxxxxxxx>, "akpm@xxxxxxxxxxxxxxxxxxxx" <akpm@xxxxxxxxxxxxxxxxxxxx>, Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>, Hiroyuki Kamezawa <kamezawa.hiroyuki@xxxxxxxxx>
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User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110419 Red Hat/3.1.10-1.el6_0 Lightning/1.0b2 Thunderbird/3.1.10
On 06/10/2011 02:40 PM, Tim Deegan wrote:
At 14:48 +0300 on 10 Jun (1307717301), Pasi K?rkk?inen wrote:
On Fri, Jun 10, 2011 at 11:10:11AM +0100, Tim Deegan wrote:
At 11:01 +0100 on 10 Jun (1307703699), Tim Deegan wrote:
ISTR that even though the RHEL xen reports a 3.0.x version it has quite
a lot of backports in it.  Does it have this patch?
http://hg.uk.xensource.com/xen-3.1-testing.hg/rev/e8fca4c42d05
Oops, that URL doesn't work; I meant this:
http://xenbits.xen.org/xen-3.1-testing.hg/rev/e8fca4c42d05

RHEL5 Xen (hypervisor) reports version as 3.1.2-xyz..
Based on a quick scrobble through the CentOS 5.6 SRPMs it looks like a
3.1.0 hypervisor with a bunch of extra patches, but not this one.  This
is very likely the cause of the crash in mem_cgroup_create(), and
probably the corruptions too.  That would explain why they didn't happen
on a 4.0.x SLES11 Xen, but not really why the original patch in this
thread made it go away.

Maybe it changes timing so that imul is executed with correct memory content? Putting extra printk inside zone loop or flushing tlb before it also make problem
go away. Or may be problem just becomes invisible and memory is corrupted at
another place.

PS:
Well, never mind. I do not know what I'm talking about.
Cheers,

Tim.



--
Thanks,
 Igor


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