SCHED_IDLE patch is a source of DoS
Andrea Arcangeli (andrea@e-mind.com)
Sat, 7 Nov 1998 20:23:41 +0100 (CET)
It' s trivial to deadlock the filesystem using the sched_idle patch. A
process in sched_idle policy can be blocked trivially by another CPU eater
process that runs in SCHED_OTHER. You only need to implement a SCHED_IDLE
process that play a lot with a hot piece of filesystem, and run at the
same time the SCHED_OTHER CPU eater process. The buffers used by the
SCHED_IDLE process will remains locked and no other process will be able
to access such part of the FS (nor root of course). Tried it here and
worked (I used `find` as sched_idle process and `primes` as SCHED_OTHER
process).
Andrea Arcangeli
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