Re: lockdep and debug objects together are broken?

From: Ingo Molnar
Date: Wed Jan 21 2009 - 06:55:33 EST



* Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:

> On Wed, 2009-01-21 at 12:42 +0100, Ingo Molnar wrote:
>
> > So by the time you'd rearm, there's a lot of tasks with no proper
> > locking state built up. We might be able to re-arm via
> > stop_machine_run perhaps.
>
> Won't work either, kstopmachine only preempts everybody. We'd require
> something stronger.

indeed - mutexes wont be covered.

> What we need is a point where there's guaranteed no locks held, for
> regular tasks that would be a trip to userspace and back, but for kernel
> tasks that's a bit harder -- does the freezer stuff guarantee this?

yes, that might be doable.

Sounds very fragile though.

Ingo
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