[Mauiusers] Too many property requests

Michel Béland michel.beland at rqchp.qc.ca
Thu Jun 30 10:04:31 MDT 2011


Hi,

With Maui 3.3.1, I encountered a segmentation fault after I submitted a 
job requesting this:

qsub 
-lnodes=3:ibleafs01:ibcable30m:c1:ppn=12+3:ibleafs08:ibcable30m:c2:ppn=12+3:ibleafs20:ibcable30m:e1:ppn=12+3:ibleafs25:ibcable30m:e2:ppn=12+3:ibleafs29:ibcable30m:e3:ppn=12+3:ibleafs32:ibcable30m:e4:ppn=12 
  script

Stepping through the code with gdb, I realized that MAX_MREQ_PER_JOB and 
probably MMAX_REQ_PER_JOB, in msched.h, needed to be increased for Maui 
to behave properly, otherwise there is an array overflow. For good 
measure I set both of them to 64, which I believe should work for all 
sensible use cases at our site.

What worries me though is that anybody can craft a job with as many 
property request as needed and make Maui crash. There is no test in Maui 
to prevent the array overflow. I think that this should be fixed...

-- 
Michel Béland, analyste en calcul scientifique
michel.beland at rqchp.qc.ca
bureau S-250, pavillon Roger-Gaudry (principal), Université de Montréal
téléphone : 514 343-6111 poste 3892     télécopieur : 514 343-2155
RQCHP (Réseau québécois de calcul de haute performance)  www.rqchp.ca
Calcul Canada (computecanada.org)


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