Re: [Xen-devel] Re: [pv_ops domU] 2.6.30.5 - unable to handle kernel paging request / refresh_cpu_vm_stats / vmstat_update

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 08/20/09 12:11, Jed Smith wrote:
> Jeremy Fitzhardinge wrote:
>   
>>>> Is it new with 2.6.30.5?
>>>>         
> Perhaps earlier, and we're just now running into it.  I am able to
> reproduce on the v2.6.30 release.  My initial bisect leads me here (from
> bad=v2.6.30 and good=v2.6.29 in linux-2.6.git):
>
> commit 9049a11de73d3ecc623f1903100d099f82ede56c
> Merge: c47c1b1 e4d0407
> Author: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
> Date:   Wed Feb 11 11:52:22 2009 -0800
>
>     Merge commit 'remotes/tip/x86/paravirt' into x86/untangle2
>
> I note astutely, however, that's a pretty large merge commit.
>
>   
>> Have you tried any other distros?  I'll try to repro with a current Xen
>> and my Fedora system.
>>     
> I used an Arch domU to test, as this happens a few steps into init's run
> there.  The process that bugs varies widely, but it's always a few
> scripts in.  We can reproduce this on two versions of our software
> stack, which both run Xen 3.2.1-rc5 (xm info from one):
>
> release                : 2.6.18.8-524-1
> version                : #1 SMP Tue Apr 22 16:31:28 EDT 2008
> machine                : i686
>
> xen_major              : 3
> xen_minor              : 2
> xen_extra              : .1-rc5
> xen_caps               : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32
> hvm-3.0-x86_32p hvm-3.0-x86_64
> xen_scheduler          : credit
> xen_pagesize           : 4096
>
> cc_compiler            : gcc version 4.0.3 (Ubuntu 4.0.3-1ubuntu5)
> cc_compile_date        : Fri Apr 11 11:24:13 EDT 2008
>
> Newer hypervisors starting with v3.3.0 do not exhibit this behavior.
>
> Now then, the bisection --
>
> I ended up at 9049a11 in linux-2.6.git as told above, and I tried to
> identify those patches in xen.git.  I'm not entirely sure my bisection
> from that point was accurate (I could not reproduce a stack trace), and
> I'll let you bisect it given your familiarity with xen.git.
>
> I have a feeling version of hypervisor is important here as, again,
> v3.3.0 and up do not BUG.
>
> What's interesting is that they all stack trace, but the location
> changes.  Here is an example from my bisection at f402a65:
>   

Do you have CONFIG_PARAVIRT_SPINLOCKS enabled?  That uses some
mechanisms that were not well exercised or tested on older versions of
Xen, and some fixes went in for them.

    J

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