I've compiled and ran the test (below) on a virgin 2.4.27 kernel patched 
with uml-patch-2.4.27-1.bz2.

Result: the bug is still readily reproducible and _is not fixed_ in this 
patch.

P.S. Jeff Dike: if CONFIG_NETFILTER=y is set in .config, the patched 
kernel fails to compile.

Blaisorblade wrote:

>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 2.4.27: 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.
>
>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...
>  
>