Messages in this thread | | | Date | Thu, 3 Oct 2013 17:44:01 +0200 | From | Peter Zijlstra <> | Subject | Re: trinity finds ftrace/perf bug. Film at 11. |
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On Thu, Sep 12, 2013 at 02:38:49PM -0400, Dave Jones wrote:
> The current one I'm staring at is this from LIST_DEBUG.. > > list_del corruption. next->prev should be prev (ffff88000fb812b0), but was ffff88000fb812b0. (next=ffff88009df8b7b0). > > The sharp eyed will notice that those first two addresses are actually the same. > So we matched the next->prev != prev test, but at the time we got to the printk that follows > in the WARN, the inverse was true. Smells like a race of some kind.
FWIW, I've not given up on this. I've found one bug in the list_entry handling already -- although not this one.
Today I hit a more revealing error:
[ 8348.150303] list_del corruption. prev->next should be ffff88042839c108, but was 6b6b6b6b6b6b6b6b
And as we all know that 6b is POISON_FREE, so we're staring at a use-after-free here.
Brain did give out for today though.. more staring at reference counts tomorrow.
The sad thing is that reproduction takes forever on my machine; I need to let trinity run for a good hour and then ^C abort the run. Only then will I hit it fairly reliably.
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