Hi,

With CONFIG_PREEMPT=y and hammering away on two different JFFS2 
partitions on a NAND flash I get an oops within ~10 seconds.  This is on 
a BeagleBoard xM (rev A2, with NAND).

I've boiled it down to whether CONFIG_PREEMPT (bug happens) or
CONFIG_PREEMPT_VOLUNTARY (bug doesn't happen) is selected.  Of course,
changing that affects a other things like inline spinlocking.  Turning 
on CONFIG_DEBUG_SPINLOCK reveals nothing.


By changing this option, I've made the bug go away in a 2.6.32 and
2.6.37 setup where it previously happened, and I've made it appear in a
2.6.39 setup where it previously didn't happen.


Pointers on what to look at next are appreciated.  (I've posted this on 
the mtd-utils mailing list too.)  More details below.


Thanks,
Orjan


The setup is simply two JFFS2-formatted partitions, and launching a

   while :; do dd if=/dev/zero of=file bs=800 count=1; done

on each of them.  Sometimes the oops trace originates from the garbage 
collector, sometimes the result is a JFFS2 decompress error.


-- 
Orjan Friberg
FlatFrog Laboratories AB