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Message-ID: <CAKMK7uE2no02kB-m3mKX-0yC_wqh+dvKc-VtT4WscdxjnwwQYg@mail.gmail.com>
Date: Mon, 28 Jan 2013 09:59:15 +0100
From: Daniel Vetter <daniel.vetter@...ll.ch>
To: Miles Lane <miles.lane@...il.com>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: Re: Linus GIT 3.8.0-rc5: INFO: possible circular locking dependency
detected -- ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff81052611>] __blocking_notifier_call_chain+0x49/0x80
Hi Miles,
Dave Airlie has some patches in the works which should fix this all, see
http://cgit.freedesktop.org/~airlied/linux/log/?h=fbcon-locking-fixes
Patches hopefully land in 3.9, they're too risky (meaning, they've
caused deadlocks) for 3.8.
Cheers, Daniel
On Mon, Jan 28, 2013 at 7:38 AM, Miles Lane <miles.lane@...il.com> wrote:
> Hi Daniel,
> At the bottom of this message you will find dmesg output showing this
> problem from the current Linus GIT tree.
> Here is the test of the message you wrote about this
> (http://marc.info/?l=dri-devel&m=135905755124554&w=2):
> --------------------------
> Patches for the know issues around console_lock vs fbdev_notifier are in -mm:
>
> http://ozlabs.org/~akpm/mmots/broken-out/fb-rework-locking-to-fix-lock-ordering-on-takeover.patch
> http://ozlabs.org/~akpm/mmots/broken-out/fb-yet-another-band-aid-for-fixing-lockdep-mess.patch
>
> Unfortunately the patches seem to be stuck there for now despite quite
> a few reports about this (including seemingly relevant background
> noise about hangs in distro bugzillas).
> -Daniel
> ----------------------------------
>
> [ 489.832113] [ INFO: possible circular locking dependency detected ]
> [ 489.832115] 3.8.0-rc5 #99 Not tainted
> [ 489.832116] -------------------------------------------------------
> [ 489.832117] 99video/4306 is trying to acquire lock:
> [ 489.832129] ((fb_notifier_list).rwsem){.+.+.+}, at:
> [<ffffffff81052611>] __blocking_notifier_call_chain+0x49/0x80
> [ 489.832130]
> [ 489.832130] but task is already holding lock:
> [ 489.832136] (console_lock){+.+.+.}, at: [<ffffffff8125d25e>]
> store_fbstate+0x43/0x71
> [ 489.832137]
> [ 489.832137] which lock already depends on the new lock.
> [ 489.832137]
> [ 489.832138]
> [ 489.832138] the existing dependency chain (in reverse order) is:
> [ 489.832141]
> [ 489.832141] -> #1 (console_lock){+.+.+.}:
> [ 489.832146] [<ffffffff81079aa8>] lock_acquire+0xfe/0x14d
> [ 489.832150] [<ffffffff8102f680>] console_lock+0x64/0x66
> [ 489.832154] [<ffffffff812b06ef>] register_con_driver+0x33/0x123
> [ 489.832158] [<ffffffff812b0f13>] take_over_console+0x21/0x266
> [ 489.832161] [<ffffffff812617e0>] fbcon_takeover+0x56/0x98
> [ 489.832165] [<ffffffff812652f4>] fbcon_event_notify+0x3b6/0x6e4
> [ 489.832169] [<ffffffff8147584a>] notifier_call_chain+0x8c/0xc0
> [ 489.832173] [<ffffffff81052627>]
> __blocking_notifier_call_chain+0x5f/0x80
> [ 489.832176] [<ffffffff81052657>] blocking_notifier_call_chain+0xf/0x11
> [ 489.832181] [<ffffffff812582f2>] fb_notifier_call_chain+0x16/0x18
> [ 489.832184] [<ffffffff812595de>] register_framebuffer+0x216/0x27a
> [ 489.832189] [<ffffffff81ac6e48>] vesafb_probe+0x6df/0x75f
> [ 489.832193] [<ffffffff81333d70>] platform_drv_probe+0x34/0x5e
> [ 489.832196] [<ffffffff8133254b>] driver_probe_device+0x90/0x19b
> [ 489.832199] [<ffffffff813326a4>] __driver_attach+0x4e/0x6f
> [ 489.832202] [<ffffffff81330d02>] bus_for_each_dev+0x52/0x85
> [ 489.832205] [<ffffffff8133208a>] driver_attach+0x19/0x1b
> [ 489.832208] [<ffffffff81331d49>] bus_add_driver+0xf7/0x21a
> [ 489.832211] [<ffffffff81332bf3>] driver_register+0x8c/0x110
> [ 489.832214] [<ffffffff81333805>] platform_driver_register+0x41/0x43
> [ 489.832217] [<ffffffff8133381f>] platform_driver_probe+0x18/0x8a
> [ 489.832220] [<ffffffff81ac6726>] vesafb_init+0x215/0x258
> [ 489.832224] [<ffffffff81000232>] do_one_initcall+0x7a/0x130
> [ 489.832228] [<ffffffff81aa4bfb>] kernel_init_freeable+0x109/0x191
> [ 489.832233] [<ffffffff8145d421>] kernel_init+0x9/0xd1
> [ 489.832236] [<ffffffff814786ec>] ret_from_fork+0x7c/0xb0
> [ 489.832240]
> [ 489.832240] -> #0 ((fb_notifier_list).rwsem){.+.+.+}:
> [ 489.832242] [<ffffffff8107925d>] __lock_acquire+0xacc/0xe0c
> [ 489.832245] [<ffffffff81079aa8>] lock_acquire+0xfe/0x14d
> [ 489.832249] [<ffffffff81470d7a>] down_read+0x3f/0x4b
> [ 489.832253] [<ffffffff81052611>]
> __blocking_notifier_call_chain+0x49/0x80
> [ 489.832257] [<ffffffff81052657>] blocking_notifier_call_chain+0xf/0x11
> [ 489.832260] [<ffffffff812582f2>] fb_notifier_call_chain+0x16/0x18
> [ 489.832263] [<ffffffff812586d9>] fb_set_suspend+0x22/0x4b
> [ 489.832266] [<ffffffff8125d269>] store_fbstate+0x4e/0x71
> [ 489.832270] [<ffffffff8132e98f>] dev_attr_store+0x13/0x1f
> [ 489.832274] [<ffffffff81163064>] sysfs_write_file+0xe9/0x121
> [ 489.832278] [<ffffffff81106546>] vfs_write+0x91/0xd0
> [ 489.832281] [<ffffffff81106738>] sys_write+0x5a/0x8b
> [ 489.832284] [<ffffffff81478792>] system_call_fastpath+0x16/0x1b
> [ 489.832285]
> [ 489.832285] other info that might help us debug this:
> [ 489.832285]
> [ 489.832286] Possible unsafe locking scenario:
> [ 489.832286]
> [ 489.832287] CPU0 CPU1
> [ 489.832288] ---- ----
> [ 489.832290] lock(console_lock);
> [ 489.832292] lock((fb_notifier_list).rwsem);
> [ 489.832294] lock(console_lock);
> [ 489.832296] lock((fb_notifier_list).rwsem);
> [ 489.832297]
> [ 489.832297] *** DEADLOCK ***
> [ 489.832297]
> [ 489.832298] 4 locks held by 99video/4306:
> [ 489.832304] #0: (&buffer->mutex){+.+.+.}, at:
> [<ffffffff81162fb2>] sysfs_write_file+0x37/0x121
> [ 489.832310] #1: (s_active#204){.+.+.+}, at: [<ffffffff8116304c>]
> sysfs_write_file+0xd1/0x121
> [ 489.832315] #2: (&fb_info->lock){+.+.+.}, at:
> [<ffffffff81258698>] lock_fb_info+0x18/0x37
> [ 489.832321] #3: (console_lock){+.+.+.}, at: [<ffffffff8125d25e>]
> store_fbstate+0x43/0x71
> [ 489.832321]
> [ 489.832321] stack backtrace:
> [ 489.832324] Pid: 4306, comm: 99video Not tainted 3.8.0-rc5 #99
> [ 489.832325] Call Trace:
> [ 489.832330] [<ffffffff8146aca7>] print_circular_bug+0x1f6/0x204
> [ 489.832333] [<ffffffff8107925d>] __lock_acquire+0xacc/0xe0c
> [ 489.832337] [<ffffffff81079aa8>] lock_acquire+0xfe/0x14d
> [ 489.832341] [<ffffffff81052611>] ? __blocking_notifier_call_chain+0x49/0x80
> [ 489.832345] [<ffffffff81470d7a>] down_read+0x3f/0x4b
> [ 489.832348] [<ffffffff81052611>] ? __blocking_notifier_call_chain+0x49/0x80
> [ 489.832352] [<ffffffff81052611>] __blocking_notifier_call_chain+0x49/0x80
> [ 489.832356] [<ffffffff81052657>] blocking_notifier_call_chain+0xf/0x11
> [ 489.832359] [<ffffffff812582f2>] fb_notifier_call_chain+0x16/0x18
> [ 489.832362] [<ffffffff812586d9>] fb_set_suspend+0x22/0x4b
> [ 489.832365] [<ffffffff8102f680>] ? console_lock+0x64/0x66
> [ 489.832368] [<ffffffff8125d269>] store_fbstate+0x4e/0x71
> [ 489.832372] [<ffffffff8132e98f>] dev_attr_store+0x13/0x1f
> [ 489.832375] [<ffffffff81163064>] sysfs_write_file+0xe9/0x121
> [ 489.832378] [<ffffffff81106546>] vfs_write+0x91/0xd0
> [ 489.832381] [<ffffffff81106738>] sys_write+0x5a/0x8b
> [ 489.832385] [<ffffffff81478792>] system_call_fastpath+0x16/0x1b
> [ 490.115770] PM: Syncing filesystems ... done.
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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