From: Russell King <rmk@arm.linux.org.uk>
To: Daniel Vetter <daniel.vetter@ffwll.ch>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>,
linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Dave Airlie <airlied@gmail.com>
Subject: Re: BUG: circular locking dependency detected
Date: Wed, 30 Jan 2013 22:19:46 +0000 [thread overview]
Message-ID: <20130130221946.GA14801@flint.arm.linux.org.uk> (raw)
In-Reply-To: <CAKMK7uHEggaGfLTq4c3MfY7csQSFpb=kRwdbJUQMN9Cz9K=V4A@mail.gmail.com>
On Wed, Jan 30, 2013 at 11:07:16PM +0100, Daniel Vetter wrote:
> On Wed, Jan 30, 2013 at 10:52 PM, Russell King <rmk@arm.linux.org.uk> wrote:
> > Also adding Greg and Daniel to this as Daniel introduced the lockdep
> > checking.
> >
> > This looks extremely horrid to be to solve - the paths are rather deep
> > where the dependency occurs. The two paths between the locks are:
> >
> > console_lock+0x5c/0x70
> > register_con_driver+0x44/0x150
> > take_over_console+0x24/0x3b4
> > fbcon_takeover+0x70/0xd4
> > fbcon_event_notify+0x7c8/0x818
> > notifier_call_chain+0x4c/0x8c
> > __blocking_notifier_call_chain+0x50/0x68
> > blocking_notifier_call_chain+0x20/0x28
> >
> > and
> >
> > __blocking_notifier_call_chain+0x34/0x68
> > blocking_notifier_call_chain+0x20/0x28
> > fb_notifier_call_chain+0x20/0x28
> > fb_blank+0x40/0xac
> > fbcon_blank+0x1f4/0x29c
> > do_blank_screen+0x1b8/0x270
> > console_callback+0x74/0x138
>
> You want Dave Airlie's pile of locking reworks, which fixes all
> currently known offenders around console_lock and fb_notifier. Patches
> won't go into 3.9 since it took a few rounds until they did not cause
> regression by making these deadlocks easier to hit.
>
> http://cgit.freedesktop.org/~airlied/linux/log/?hûcon-locking-fixes
>
> Long term solution would be to abolish the fb_notifier, at least for
> the purpose of linking fbdevs up with the fbcon and just replace those
> with direct function calls. But that requires that we no longer allow
> fbdev drivers and the fbcon to be loaded in any arbitrary order. Or
> just force fbcon to be built-in if enabled, imo the sane choice (no
> one's bothering with config_vt=m either, after all).
So... what you seem to be telling me is that 3.9 is going to be a
release which issues lockdep complaints when the console blanks, and
you think that's acceptable?
Adding Linus and Andrew so they're aware of this issue...
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of:
WARNING: multiple messages have this Message-ID (diff)
From: Russell King <rmk@arm.linux.org.uk>
To: Daniel Vetter <daniel.vetter@ffwll.ch>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>,
linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Dave Airlie <airlied@gmail.com>
Subject: Re: BUG: circular locking dependency detected
Date: Wed, 30 Jan 2013 22:19:46 +0000 [thread overview]
Message-ID: <20130130221946.GA14801@flint.arm.linux.org.uk> (raw)
In-Reply-To: <CAKMK7uHEggaGfLTq4c3MfY7csQSFpb=kRwdbJUQMN9Cz9K=V4A@mail.gmail.com>
On Wed, Jan 30, 2013 at 11:07:16PM +0100, Daniel Vetter wrote:
> On Wed, Jan 30, 2013 at 10:52 PM, Russell King <rmk@arm.linux.org.uk> wrote:
> > Also adding Greg and Daniel to this as Daniel introduced the lockdep
> > checking.
> >
> > This looks extremely horrid to be to solve - the paths are rather deep
> > where the dependency occurs. The two paths between the locks are:
> >
> > console_lock+0x5c/0x70
> > register_con_driver+0x44/0x150
> > take_over_console+0x24/0x3b4
> > fbcon_takeover+0x70/0xd4
> > fbcon_event_notify+0x7c8/0x818
> > notifier_call_chain+0x4c/0x8c
> > __blocking_notifier_call_chain+0x50/0x68
> > blocking_notifier_call_chain+0x20/0x28
> >
> > and
> >
> > __blocking_notifier_call_chain+0x34/0x68
> > blocking_notifier_call_chain+0x20/0x28
> > fb_notifier_call_chain+0x20/0x28
> > fb_blank+0x40/0xac
> > fbcon_blank+0x1f4/0x29c
> > do_blank_screen+0x1b8/0x270
> > console_callback+0x74/0x138
>
> You want Dave Airlie's pile of locking reworks, which fixes all
> currently known offenders around console_lock and fb_notifier. Patches
> won't go into 3.9 since it took a few rounds until they did not cause
> regression by making these deadlocks easier to hit.
>
> http://cgit.freedesktop.org/~airlied/linux/log/?h=fbcon-locking-fixes
>
> Long term solution would be to abolish the fb_notifier, at least for
> the purpose of linking fbdevs up with the fbcon and just replace those
> with direct function calls. But that requires that we no longer allow
> fbdev drivers and the fbcon to be loaded in any arbitrary order. Or
> just force fbcon to be built-in if enabled, imo the sane choice (no
> one's bothering with config_vt=m either, after all).
So... what you seem to be telling me is that 3.9 is going to be a
release which issues lockdep complaints when the console blanks, and
you think that's acceptable?
Adding Linus and Andrew so they're aware of this issue...
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of:
WARNING: multiple messages have this Message-ID (diff)
From: Russell King <rmk@arm.linux.org.uk>
To: Daniel Vetter <daniel.vetter@ffwll.ch>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>,
linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Dave Airlie <airlied@gmail.com>
Subject: Re: BUG: circular locking dependency detected
Date: Wed, 30 Jan 2013 22:19:46 +0000 [thread overview]
Message-ID: <20130130221946.GA14801@flint.arm.linux.org.uk> (raw)
In-Reply-To: <CAKMK7uHEggaGfLTq4c3MfY7csQSFpb=kRwdbJUQMN9Cz9K=V4A@mail.gmail.com>
On Wed, Jan 30, 2013 at 11:07:16PM +0100, Daniel Vetter wrote:
> On Wed, Jan 30, 2013 at 10:52 PM, Russell King <rmk@arm.linux.org.uk> wrote:
> > Also adding Greg and Daniel to this as Daniel introduced the lockdep
> > checking.
> >
> > This looks extremely horrid to be to solve - the paths are rather deep
> > where the dependency occurs. The two paths between the locks are:
> >
> > console_lock+0x5c/0x70
> > register_con_driver+0x44/0x150
> > take_over_console+0x24/0x3b4
> > fbcon_takeover+0x70/0xd4
> > fbcon_event_notify+0x7c8/0x818
> > notifier_call_chain+0x4c/0x8c
> > __blocking_notifier_call_chain+0x50/0x68
> > blocking_notifier_call_chain+0x20/0x28
> >
> > and
> >
> > __blocking_notifier_call_chain+0x34/0x68
> > blocking_notifier_call_chain+0x20/0x28
> > fb_notifier_call_chain+0x20/0x28
> > fb_blank+0x40/0xac
> > fbcon_blank+0x1f4/0x29c
> > do_blank_screen+0x1b8/0x270
> > console_callback+0x74/0x138
>
> You want Dave Airlie's pile of locking reworks, which fixes all
> currently known offenders around console_lock and fb_notifier. Patches
> won't go into 3.9 since it took a few rounds until they did not cause
> regression by making these deadlocks easier to hit.
>
> http://cgit.freedesktop.org/~airlied/linux/log/?h=fbcon-locking-fixes
>
> Long term solution would be to abolish the fb_notifier, at least for
> the purpose of linking fbdevs up with the fbcon and just replace those
> with direct function calls. But that requires that we no longer allow
> fbdev drivers and the fbcon to be loaded in any arbitrary order. Or
> just force fbcon to be built-in if enabled, imo the sane choice (no
> one's bothering with config_vt=m either, after all).
So... what you seem to be telling me is that 3.9 is going to be a
release which issues lockdep complaints when the console blanks, and
you think that's acceptable?
Adding Linus and Andrew so they're aware of this issue...
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of:
next prev parent reply other threads:[~2013-01-30 22:19 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-30 20:04 BUG: circular locking dependency detected Russell King
2013-01-30 20:06 ` Russell King
2013-01-30 20:06 ` Russell King
2013-01-30 21:52 ` Russell King
2013-01-30 21:52 ` Russell King
2013-01-30 22:07 ` Daniel Vetter
2013-01-30 22:07 ` Daniel Vetter
2013-01-30 22:19 ` Russell King [this message]
2013-01-30 22:19 ` Russell King
2013-01-30 22:19 ` Russell King
2013-01-30 22:27 ` Daniel Vetter
2013-01-30 22:27 ` Daniel Vetter
2013-01-30 23:52 ` Linus Torvalds
2013-01-30 23:52 ` Linus Torvalds
2013-01-31 0:04 ` Dave Airlie
2013-01-31 0:04 ` Dave Airlie
2013-01-31 0:13 ` Russell King
2013-01-31 0:26 ` Linus Torvalds
2013-01-31 0:26 ` Linus Torvalds
2013-01-31 5:40 ` Greg Kroah-Hartman
2013-01-31 5:40 ` Greg Kroah-Hartman
2013-01-31 8:21 ` Daniel Vetter
2013-01-31 8:21 ` Daniel Vetter
2013-01-31 9:21 ` Greg Kroah-Hartman
2013-01-31 9:21 ` Greg Kroah-Hartman
2013-01-31 9:38 ` Daniel Vetter
2013-01-31 9:38 ` Daniel Vetter
2013-01-31 11:51 ` Dave Airlie
2013-01-31 11:51 ` Dave Airlie
2013-01-31 13:02 ` Greg Kroah-Hartman
2013-01-31 13:02 ` Greg Kroah-Hartman
2013-01-31 13:07 ` Russell King
2013-01-31 0:09 ` Russell King
2013-01-31 10:12 ` Sedat Dilek
2013-01-31 10:12 ` Sedat Dilek
2013-01-31 10:20 ` Sedat Dilek
2013-01-31 10:20 ` Sedat Dilek
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