Re: [PATCH] Hibernation: Fix lockdep report (v2)

From: Peter Zijlstra
Date: Wed Nov 14 2007 - 16:56:27 EST



On Wed, 2007-11-14 at 22:42 +0000, Pavel Machek wrote:
> On Wed 2007-11-14 22:25:57, Rafael J. Wysocki wrote:
> > [Andrew, please consider this as 2.6.24 material, thanks.]
> > ---
> > From: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
> >
> > Lockdep reports a circular locking dependency in the hibernate code
> > because
> > - during system boot hibernate code (from an initcall) locks pm_mutex
> > and then a sysfs buffer mutex via name_to_dev_t
> > - during regular operation hibernate code locks pm_mutex under a
> > sysfs buffer mutex because it's called from sysfs methods.
> >
> > The deadlock can never happen because during initcall invocation nothing
> > can write to sysfs yet. This removes the lockdep report by marking the
> > initcall locking as being in a different class.
> >
> > Signed-off-by: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
> > Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> > Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>

I guess mine got lost too :-)

Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>

> > Cc: Pavel Machek <pavel@xxxxxx>
>
> ACK...
>

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