Re: [Xen-devel] 2.6.29-rc8 pv_ops dom0 BUG / unable to handle kernel paging request

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Pasi Kärkkäinen wrote:
> On Sun, Mar 22, 2009 at 07:04:23PM +0200, Pasi Kärkkäinen wrote:
>   
> > On Sun, Mar 22, 2009 at 01:51:51PM +0200, Pasi Kärkkäinen wrote:
> >     
> > > On Sat, Mar 21, 2009 at 09:28:55PM -0700, Jeremy Fitzhardinge wrote:
> > >       
> > > > Pasi Kärkkäinen wrote:
> > > >         
> > > > > On Sun, Mar 22, 2009 at 12:50:31AM +0200, Pasi Kärkkäinen wrote:
> > > > >  
> > > > >           
> > > > > > On Sat, Mar 21, 2009 at 10:16:52PM +0200, Pasi Kärkkäinen wrote:
> > > > > >    
> > > > > >             
> > > > > > > > Also, do you see this problem before you've started any other domains?  
> > > > > > > > Or does it only happen once you've run a domU (or only while a domU is 
> > > > > > > > running)?
> > > > > > > >        
> > > > > > > >                 
> > > > > > > I'm not running any other domains.. Only dom0 is running.
> > > > > > >
> > > > > > > Steps to reproduce this BUG on my pv_ops dom0 testbox:
> > > > > > >
> > > > > > > 1) Reboot the box to pv_ops dom0 kernel
> > > > > > > 2) Login to dom0 via ssh
> > > > > > > 3) Start kernel compilation on dom0 (make bzImage && make modules)
> > > > > > > 4) Wait some minutes and pv_ops dom0 kernel BUGs
> > > > > > >
> > > > > > > So no other domains has been or is running when this happens..
> > > > > > >
> > > > > > > I'll try disabling CONFIG_HIGHPTE now, and see if that makes any 
> > > > > > > difference.
> > > > > > >      
> > > > > > >               
> > > > > > CONFIG_HIGHPTE=y and pv_ops dom0 survives up for maybe 30 mins, and then
> > > > > > BUGs (during kernel compilation):
> > > > > > http://pasik.reaktio.net/xen/pv_ops-dom0-debug/pv_ops-dom0-bootlog-22-xen331-linux-2.6.29-rc8-bug-with-highpte.txt
> > > > > >
> > > > > >
> > > > > > CONFIG_HIGHPTE=n and I get BUG during system startup when udev is started:
> > > > > > http://pasik.reaktio.net/xen/pv_ops-dom0-debug/pv_ops-dom0-bootlog-23-xen331-linux-2.6.29-rc8-bug-no-highpte.txt
> > > > > >
> > > > > > Starting udev: BUG: unable to handle kernel paging request at 70007823
> > > > > > IP: [<e30ce245>] pdc_common_ops+0x171/0xfffffcfe [sata_promise]
> > > > > > *pdpt = 000000005f781001 
> > > > > > Oops: 0002 [#1] SMP 
> > > > > >
> > > > > > So yeah..  with CONFIG_HIGHPTE=n it seems to happen when sata_promise is 
> > > > > > loaded.. What should I try next? 
> > > > > >    
> > > > > >             
> > > > > Actually it's not only sata_promise. I tried 2 more times with the
> > > > > CONFIG_HIGHPTE=n pv_ops dom0 kernel:
> > > > >
> > > > > http://pasik.reaktio.net/xen/pv_ops-dom0-debug/pv_ops-dom0-bootlog-23-xen331-linux-2.6.29-rc8-bug-no-highpte.txt
> > > > > http://pasik.reaktio.net/xen/pv_ops-dom0-debug/pv_ops-dom0-bootlog-23-xen331-linux-2.6.29-rc8-bug-no-highpte-2.txt
> > > > > http://pasik.reaktio.net/xen/pv_ops-dom0-debug/pv_ops-dom0-bootlog-23-xen331-linux-2.6.29-rc8-bug-no-highpte-3.txt
> > > > >
> > > > > BUG: unable to handle kernel paging request at a536462c
> > > > > IP: [<e30f4278>] classes+0x688/0xfffffa30 [parport]
> > > > > *pdpt = 000000005f759001 
> > > > > Oops: 0002 [#1] SMP 
> > > > >  
> > > > >           
> > > > Hm, OK.  Something is clearly drastically amiss.  I'll try to repro.
> > > >
> > > >         
> > > Actually it seems CONFIG_HIGHPTE=n kernel fails also on baremetal:
> > > http://pasik.reaktio.net/xen/pv_ops-dom0-debug/pv_ops-dom0-bootlog-24-baremetal-2.6.29-rc8-bug-no-highpte.txt
> > >
> > > Starting udev: invalid opcode: 0000 [#1] SMP 
> > >
> > > Summary:
> > > CONFIG_HIGHPTE=n: both dom0 and baremetal fail during system startup when udev 
> > > is started
> > > CONFIG_HIGHPTE=y: baremetal works OK, dom0 fails with BUG after around 30 mins 
> > > of kernel compilation
> > >
> > >       
> > Please ignore this summary, there was something wrong with my kernel builds or
> > something. 
> >
> > I'll post new summary soon when I'm finished with testing. 
> >
> >     
> Ok, I did new fresh kernel+modules builds and re-tested everything.
>
> New summary:
> CONFIG_HIGHPTE=n: both dom0 and baremetal work OK, both survive kernel 
> compilation.
> CONFIG_HIGHPTE=y: baremetal works OK and survives kernel compilation, but dom0 
> fails with BUG after around 20-30 mins of kernel compilation
>   
Thanks for getting a consistent test result; the other reports looked, 
frankly, scary and I wouldn't want to be on that wild goose chase.
These ones look much more tractable, though I don't really have a theory 
for them.  I'll have a look next week sometime.
   J

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