linux-kernel - Re: [PATCH -mmotm] fbmem: fix fb_info->lock and mm->mmap

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Message-Id: <200902050249.27244.rjw@sisk.pl>
Date:	Thu, 5 Feb 2009 02:49:25 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Andrea Righi <righi.andrea@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Andrey Borzenkov <arvidjaar@...l.ru>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	"Antonino A. Daplas" <adaplas@...il.com>,
	linux-fbdev-devel@...ts.sourceforge.net,
	linux-pm@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
	Dave Jones <davej@...hat.com>,
	Harvey Harrison <harvey.harrison@...il.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Stefan Richter <stefanr@...6.in-berlin.de>
Subject: Re: [PATCH -mmotm] fbmem: fix fb_info->lock and mm->mmap_sem circular locking dependency

On Thursday 05 February 2009, Rafael J. Wysocki wrote:
> On Wednesday 04 February 2009, Andrea Righi wrote:
> > Fix this circular locking dependencies in the frame buffer console
> > driver pushing down the mutex fb_info->lock.
> > 
> > Circular locking dependecies occur calling the blocking
> > fb_notifier_call_chain() with fb_info->lock held. Notifier callbacks can
> > try to acquire mm->mmap_sem, while fb_mmap() acquires the locks in the
> > reverse order mm->mmap_sem => fb_info->lock.
> 
> Does this fix a Bugzilla bug?  If so, then which one?

Never mind, found it.

Thanks,
Rafael
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