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

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Date:	Wed, 14 Nov 2007 22:42:00 +0000
From:	Pavel Machek <pavel@....cz>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Johannes Berg <johannes@...solutions.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	LKML <linux-kernel@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: Re: [PATCH] Hibernation: Fix lockdep report (v2)

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@...solutions.net>
> 
> 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@...solutions.net>
> Cc: Alan Stern <stern@...land.harvard.edu>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Pavel Machek <pavel@....cz>

ACK...

-- 
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