Re: [uml-devel] 2.4.27 guest bug reconfirmed Re bug report [ 745826 ] run cat /dev/urandom

[Blaisorblade <blaisorblade_spam@yahoo.it>]

On Sunday 14 November 2004 11:47, Struan Bartlett wrote:
> I've now tested for this bug using a simplified methodology on the
> latest patched-versions of the host (2.4.27 and 2.6.8) and guest (2.4.27
> and 2.6.9).

> _New methodology_

> My Debian guest system raises two xterms at startup. On each I log in as
> root. On one, I enter:

> while true; do echo >/dev/null; done

> On the second, I enter:

> cat /dev/urandom

> The devastating symptom: within 5 seconds the guest kernel has paniced
> and exited with the message (below) "kernel BUG at sched.c:564!".
>
> _Findings_

> guest 2.6.9: patched with uml-2.6.9-bb2.patch.bz2 - I am pleased to say
> I have not so far been able to reproduce this bug on this configuration.

> guest 2.4.27: patched with uml-2.4.27-bs1.patch and
> uml-patch-2.4.24-1base.patch - no change; this bug is readily
> reproducible and so IS NOT FIXED, regardless of whether the guest is run
> on host 2.4.27 or 2.6.8

> _Conclusion_
>
> If such a simple pair of commands as this causes such devastating
> consequences, it seems the 2.4.27 kernel sched.c line 564 needs to be
> taken a look at - unless, that is, Jeff Dike's recent post about
> uml-patch-2.4.27-1 "a nasty scheduler race fixed" addresses this bug.
I may be wrong, but I think I should have picked that patch into 2.4.27-bs1.

> Jeff: where can I get your uml-patch-2.4.27-1 ?
It's at http://user-mode-linux.sourceforge.net/dl-ists.html

I'll take a look at your report - there is one patch applied on 2.6 that 
seemed unneeded on 2.4 until now - this may be reconsidered...
> Struan

-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729



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