From: Andrea Righi <righi.andrea@gmail.com>
To: Eric Miao <eric.y.miao@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Krzysztof Helt <krzysztof.h1@poczta.fm>,
Andrew Morton <akpm@linux-foundation.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>,
Andrey Borzenkov <arvidjaar@gmail.com>,
"Antonino A. Daplas" <adaplas@gmail.com>,
linux-fbdev-devel@lists.sourceforge.net,
linux-pm@lists.linux-foundation.org,
Dave Jones <davej@redhat.com>,
Harvey Harrison <harvey.harrison@gmail.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Stefan Richter <stefanr@s5r6.in-berlin.de>
Subject: Re: [REGRESSION] commit 66c1ca0: {fbmem: fix fb_info->lock and mm->mmap_sem ...} causes Xfbdev not working
Date: Thu, 9 Apr 2009 14:58:51 +0200 [thread overview]
Message-ID: <20090409125850.GA2727@linux> (raw)
In-Reply-To: <f17812d70904090436kd03744brca4a4bc4b85bba8@mail.gmail.com>
On Thu, Apr 09, 2009 at 07:36:24PM +0800, Eric Miao wrote:
> This happens on my Marvell PXA310-based Littleton platform with
> Angstrom Distribution. The offending paths are many:
>
> FBIOPUT_VSCREENINFO:
> lock_fb_info()
> --> fb_set_var()
> --> fb_notifier_call_chain() [FBINFO_MISC_USEREVENT]
> --> fbcon_event_notifier() [FB_EVENT_MODE_CHANGE]
> --> lock_fb_info()
>
> OK, now hang. I'd suggest a clean fix to the original assumption of
> circular locking
> issue and revert this commit first.
>
> --
> Cheers
> - eric
I can agree to revert 66c1ca019078220dc1bf968f2bb18421100ef147, since I
don't have a clean fix for this. Pushing down fb_info->lock in
fb_set_var() excluding to call fb_notifier_call_chain with fb_info->lock
held doesn't seem to be so trivial...
However, reverting this will re-introduce the circular locking
dependency fb_info->lock => mm->mmap_sem => fb_info->lock.
-Andrea
next parent reply other threads:[~2009-04-09 12:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <f17812d70904090436kd03744brca4a4bc4b85bba8@mail.gmail.com>
2009-04-09 12:58 ` Andrea Righi [this message]
2009-04-10 20:21 ` [REGRESSION] commit 66c1ca0: {fbmem: fix fb_info->lock and mm->mmap_sem ...} causes Xfbdev not working Krzysztof Helt
2009-04-10 21:16 ` Andrew Morton
2009-04-10 22:05 ` Andrea Righi
2009-04-11 6:04 ` Krzysztof Helt
[not found] ` <49E05C36.9040204@s5r6.in-berlin.de>
2009-04-11 11:08 ` Andrea Righi
2009-04-11 15:04 ` Andrea Righi
[not found] ` <20090411150359.GA8265@linux>
2009-04-11 18:21 ` Andrew Morton
2009-04-11 19:32 ` Andrea Righi
2009-04-13 23:34 ` Andreas Schwab
[not found] ` <20090417182507.0bd85ccc.krzysztof.h1@poczta.fm>
2009-04-17 22:51 ` Andrea Righi
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