Re: 2.6.26-rc9-git4: Reported regressions from 2.6.25

From: Ingo Molnar
Date: Thu Jul 10 2008 - 14:08:49 EST



* Ingo Molnar <mingo@xxxxxxx> wrote:

> cool! :)
>
> (hm, could anyone please resend Nick's original mail? The original one
> is not in my lkml folder nor on lkml.org - only the quoted one.)

ok, got the mail now now:

| | Annoyed this wasn't a crazy obscure error in the algorithm I could
| | fix :) [...]

Paul recently ran a formal proof against all sorts of RCU details (and
found and fixed a few obscure races that way that no-one ever
triggered), so i'd be quite surprised if we found anything in the core
algorithm :-)

| | [...] I spent all day debugging it and had to make a special test
| | case (rcutorture didn't seem to trigger it), and a big RCU state
| | logging infrastructure to log millions of RCU state transitions and
| | events. Oh well.

nice debugging!

Acked-by: Ingo Molnar <mingo@xxxxxxx>

i'm wondering why rcutorture didnt trigger it. I do run !HOTPLUG +
RCU_PREEMPT kernels and never saw this. Nor did Paul. That aspect is
weird.

Ingo
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