Re: [PATCH] fb: Rework locking to fix lock ordering on takeover
From: Maarten Lankhorst
Date: Tue Jan 15 2013 - 07:06:26 EST
Hey,
Op 13-01-13 01:02, Borislav Petkov schreef:
> On Sat, Jan 12, 2013 at 01:13:23PM -0800, Andrew Morton wrote:
>> Florian has been taking a month or two's downtime (now expired, I
>> think) so I've been waiting for him to reappear to process this one for
>> 3.8.
>>
>> Meanwhile, I guess we could put it into mainline ;) It has been in
>> -next for a month.
>>
>> From: Alan Cox <alan@xxxxxxxxxxxxxxx>
>> Subject: fb: rework locking to fix lock ordering on takeover
>>
>> Adjust the console layer to allow a take over call where the caller
>> already holds the locks. Make the fb layer lock in order.
>>
>> This is partly a band aid, the fb layer is terminally confused about the
>> locking rules it uses for its notifiers it seems.
>>
>> [akpm@xxxxxxxxxxxxxxxxxxxx: remove stray non-ascii char, tidy comment]
>> [akpm@xxxxxxxxxxxxxxxxxxxx: export do_take_over_console()]
>> Signed-off-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
>> Cc: Florian Tobias Schandinat <FlorianSchandinat@xxxxxx>
>> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
>> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Yes, that's the one, modulo Andrew's fixes, which I've been running.
> Irregardless, I'll run this one tomorrow just in case, because it
> triggers here so easily.
>
Just tested this patch on a macbook pro with i915 and radeon. First I get a nasty lockdep splat, then it locks up completely:
[ 13.507373] fb: conflicting fb hw usage radeondrmfb vs EFI VGA - removing generic driver
[ 13.507412]
[ 13.507413] ======================================================
[ 13.507413] [ INFO: possible circular locking dependency detected ]
[ 13.507414] 3.8.0-rc3-patser+ #910 Not tainted
[ 13.507415] -------------------------------------------------------
[ 13.507415] modprobe/554 is trying to acquire lock:
[ 13.507421] (console_lock){+.+.+.}, at: [<ffffffff813f6ca7>] unbind_con_driver+0x37/0x210
[ 13.507422]
[ 13.507422] but task is already holding lock:
[ 13.507425] ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8106d96d>] __blocking_notifier_call_chain+0x3d/0x80
[ 13.507426]
[ 13.507426] which lock already depends on the new lock.
[ 13.507426]
[ 13.507426]
[ 13.507426] the existing dependency chain (in reverse order) is:
[ 13.507428]
[ 13.507428] -> #1 ((fb_notifier_list).rwsem){.+.+.+}:
[ 13.507431] [<ffffffff8109e946>] lock_acquire+0x96/0xc0
[ 13.507434] [<ffffffff816f8442>] down_read+0x42/0x57
[ 13.507435] [<ffffffff8106d96d>] __blocking_notifier_call_chain+0x3d/0x80
[ 13.507437] [<ffffffff8106d9c1>] blocking_notifier_call_chain+0x11/0x20
[ 13.507439] [<ffffffff8138e816>] fb_notifier_call_chain+0x16/0x20
[ 13.507441] [<ffffffff8138fd23>] register_framebuffer+0x1c3/0x2e0
[ 13.507444] [<ffffffff81cdfabf>] efifb_probe+0x402/0x489
[ 13.507446] [<ffffffff81412e0e>] platform_drv_probe+0x3e/0x70
[ 13.507448] [<ffffffff81410e96>] driver_probe_device+0x76/0x240
[ 13.507450] [<ffffffff81411103>] __driver_attach+0xa3/0xb0
[ 13.507451] [<ffffffff8140f2f6>] bus_for_each_dev+0x56/0x90
[ 13.507452] [<ffffffff814109f9>] driver_attach+0x19/0x20
[ 13.507454] [<ffffffff81410598>] bus_add_driver+0x188/0x270
[ 13.507455] [<ffffffff81411635>] driver_register+0x75/0x150
[ 13.507457] [<ffffffff814126a1>] platform_driver_register+0x41/0x50
[ 13.507458] [<ffffffff814126c6>] platform_driver_probe+0x16/0xa0
[ 13.507460] [<ffffffff81cdfdbd>] efifb_init+0x277/0x292
[ 13.507462] [<ffffffff810001fa>] do_one_initcall+0x3a/0x170
[ 13.507464] [<ffffffff816df85d>] kernel_init+0x11d/0x290
[ 13.507466] [<ffffffff817008ac>] ret_from_fork+0x7c/0xb0
[ 13.507467]
[ 13.507467] -> #0 (console_lock){+.+.+.}:
[ 13.507469] [<ffffffff8109dccf>] __lock_acquire+0x168f/0x1d90
[ 13.507471] [<ffffffff8109e946>] lock_acquire+0x96/0xc0
[ 13.507474] [<ffffffff81048dff>] console_lock+0x6f/0x80
[ 13.507475] [<ffffffff813f6ca7>] unbind_con_driver+0x37/0x210
[ 13.507477] [<ffffffff8139dbe7>] fbcon_event_notify+0x477/0x920
[ 13.507478] [<ffffffff816fe318>] notifier_call_chain+0x58/0xb0
[ 13.507479] [<ffffffff8106d983>] __blocking_notifier_call_chain+0x53/0x80
[ 13.507481] [<ffffffff8106d9c1>] blocking_notifier_call_chain+0x11/0x20
[ 13.507482] [<ffffffff8138e816>] fb_notifier_call_chain+0x16/0x20
[ 13.507484] [<ffffffff8138f902>] do_unregister_framebuffer+0x62/0x100
[ 13.507485] [<ffffffff8138fb34>] do_remove_conflicting_framebuffers+0x154/0x180
[ 13.507487] [<ffffffff8138fe7a>] remove_conflicting_framebuffers+0x3a/0x60
[ 13.507501] [<ffffffffa02111a4>] radeon_pci_probe+0x84/0xc0 [radeon]
[ 13.507503] [<ffffffff813745c6>] local_pci_probe+0x46/0x80
[ 13.507505] [<ffffffff81375e19>] pci_device_probe+0xf9/0x120
[ 13.507506] [<ffffffff81410e96>] driver_probe_device+0x76/0x240
[ 13.507507] [<ffffffff81411103>] __driver_attach+0xa3/0xb0
[ 13.507508] [<ffffffff8140f2f6>] bus_for_each_dev+0x56/0x90
[ 13.507510] [<ffffffff814109f9>] driver_attach+0x19/0x20
[ 13.507511] [<ffffffff81410598>] bus_add_driver+0x188/0x270
[ 13.507512] [<ffffffff81411635>] driver_register+0x75/0x150
[ 13.507514] [<ffffffff81374e2f>] __pci_register_driver+0x5f/0x70
[ 13.507520] [<ffffffffa009773a>] drm_pci_init+0x11a/0x130 [drm]
[ 13.507528] [<ffffffffa02f30ec>] radeon_init+0xec/0x1000 [radeon]
[ 13.507530] [<ffffffff810001fa>] do_one_initcall+0x3a/0x170
[ 13.507532] [<ffffffff810a9fd2>] load_module+0x1a52/0x2020
[ 13.507533] [<ffffffff810aa671>] sys_init_module+0xd1/0x100
[ 13.507535] [<ffffffff81700952>] system_call_fastpath+0x16/0x1b
[ 13.507535]
[ 13.507535] other info that might help us debug this:
[ 13.507535]
[ 13.507535] Possible unsafe locking scenario:
[ 13.507535]
[ 13.507536] CPU0 CPU1
[ 13.507536] ---- ----
[ 13.507537] lock((fb_notifier_list).rwsem);
[ 13.507538] lock(console_lock);
[ 13.507538] lock((fb_notifier_list).rwsem);
[ 13.507539] lock(console_lock);
[ 13.507539]
[ 13.507539] *** DEADLOCK ***
[ 13.507539]
[ 13.507540] 5 locks held by modprobe/554:
[ 13.507543] #0: (&__lockdep_no_validate__){......}, at: [<ffffffff814110b3>] __driver_attach+0x53/0xb0
[ 13.507545] #1: (&__lockdep_no_validate__){......}, at: [<ffffffff814110c1>] __driver_attach+0x61/0xb0
[ 13.507547] #2: (registration_lock){+.+.+.}, at: [<ffffffff8138fe6b>] remove_conflicting_framebuffers+0x2b/0x60
[ 13.507550] #3: (&fb_info->lock){+.+.+.}, at: [<ffffffff8138ecd1>] lock_fb_info+0x21/0x60
[ 13.507552] #4: ((fb_notifier_list).rwsem){.+.+.+}, at: [<ffffffff8106d96d>] __blocking_notifier_call_chain+0x3d/0x80
[ 13.507552]
[ 13.507552] stack backtrace:
[ 13.507554] Pid: 554, comm: modprobe Not tainted 3.8.0-rc3-patser+ #910
[ 13.507554] Call Trace:
[ 13.507557] [<ffffffff816efd4e>] print_circular_bug+0x1fb/0x20c
[ 13.507559] [<ffffffff8109dccf>] __lock_acquire+0x168f/0x1d90
[ 13.507561] [<ffffffff8109b532>] ? mark_held_locks+0x82/0x130
[ 13.507563] [<ffffffff8109e946>] lock_acquire+0x96/0xc0
[ 13.507565] [<ffffffff813f6ca7>] ? unbind_con_driver+0x37/0x210
[ 13.507566] [<ffffffff8109b7cd>] ? trace_hardirqs_on+0xd/0x10
[ 13.507568] [<ffffffff81048dff>] console_lock+0x6f/0x80
[ 13.507570] [<ffffffff813f6ca7>] ? unbind_con_driver+0x37/0x210
[ 13.507571] [<ffffffff813f6ca7>] unbind_con_driver+0x37/0x210
[ 13.507573] [<ffffffff8109e953>] ? lock_acquire+0xa3/0xc0
[ 13.507574] [<ffffffff8139dbe7>] fbcon_event_notify+0x477/0x920
[ 13.507576] [<ffffffff816fe318>] notifier_call_chain+0x58/0xb0
[ 13.507577] [<ffffffff8106d983>] __blocking_notifier_call_chain+0x53/0x80
[ 13.507579] [<ffffffff8106d9c1>] blocking_notifier_call_chain+0x11/0x20
[ 13.507580] [<ffffffff8138e816>] fb_notifier_call_chain+0x16/0x20
[ 13.507582] [<ffffffff8138f902>] do_unregister_framebuffer+0x62/0x100
[ 13.507584] [<ffffffff8138fb34>] do_remove_conflicting_framebuffers+0x154/0x180
[ 13.507586] [<ffffffff8138fe7a>] remove_conflicting_framebuffers+0x3a/0x60
[ 13.507597] [<ffffffffa02111a4>] radeon_pci_probe+0x84/0xc0 [radeon]
[ 13.507598] [<ffffffff813745c6>] local_pci_probe+0x46/0x80
[ 13.507600] [<ffffffff81375e19>] pci_device_probe+0xf9/0x120
[ 13.507601] [<ffffffff81410e96>] driver_probe_device+0x76/0x240
[ 13.507603] [<ffffffff81411103>] __driver_attach+0xa3/0xb0
[ 13.507604] [<ffffffff81411060>] ? driver_probe_device+0x240/0x240
[ 13.507606] [<ffffffff8140f2f6>] bus_for_each_dev+0x56/0x90
[ 13.507607] [<ffffffff814109f9>] driver_attach+0x19/0x20
[ 13.507608] [<ffffffff81410598>] bus_add_driver+0x188/0x270
[ 13.507610] [<ffffffff81411635>] driver_register+0x75/0x150
[ 13.507612] [<ffffffff81374e2f>] __pci_register_driver+0x5f/0x70
[ 13.507617] [<ffffffffa009773a>] drm_pci_init+0x11a/0x130 [drm]
[ 13.507619] [<ffffffffa02f3000>] ? 0xffffffffa02f2fff
[ 13.507620] [<ffffffffa02f3000>] ? 0xffffffffa02f2fff
[ 13.507628] [<ffffffffa02f30ec>] radeon_init+0xec/0x1000 [radeon]
[ 13.507630] [<ffffffff810001fa>] do_one_initcall+0x3a/0x170
[ 13.507632] [<ffffffff810a9fd2>] load_module+0x1a52/0x2020
[ 13.507633] [<ffffffff810a71b0>] ? get_modinfo.isra.30+0xc0/0xc0
[ 13.507635] [<ffffffff8135166e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[ 13.507637] [<ffffffff810aa671>] sys_init_module+0xd1/0x100
[ 13.507639] [<ffffffff81700952>] system_call_fastpath+0x16/0x1b
<...>
[ 62.505111] INFO: task plymouthd:293 blocked for more than 30 seconds.
[ 62.505113] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 62.505122] plymouthd D 0000000000000246 0 293 1 0x00000000
[ 62.505130] ffff88016a293b18 0000000000000046 0000000000000000 0000000000000000
[ 62.505135] ffff88015ce12040 ffff88016a293fd8 ffff88016a293fd8 ffff88016a293fd8
[ 62.505141] ffff880153c66040 ffff88015ce12040 ffffffff81c30360 ffffffffa00bb1e0
[ 62.505142] Call Trace:
[ 62.505162] [<ffffffff816f9224>] schedule+0x24/0x70
[ 62.505178] [<ffffffff816f9543>] schedule_preempt_disabled+0x13/0x20
[ 62.505180] [<ffffffff816f5de9>] mutex_lock_nested+0x179/0x390
[ 62.505187] [<ffffffffa00907f4>] ? drm_stub_open+0x54/0x170 [drm]
[ 62.505193] [<ffffffffa00907f4>] drm_stub_open+0x54/0x170 [drm]
[ 62.505195] [<ffffffff8113739c>] chrdev_open+0x9c/0x1a0
[ 62.505197] [<ffffffff81137300>] ? cdev_put+0x30/0x30
[ 62.505200] [<ffffffff81130cae>] do_dentry_open+0x26e/0x310
[ 62.505201] [<ffffffff81130eb0>] finish_open+0x30/0x40
[ 62.505204] [<ffffffff81140fee>] do_last+0x74e/0xea0
[ 62.505206] [<ffffffff8113e00d>] ? link_path_walk+0x23d/0x920
[ 62.505208] [<ffffffff811417ee>] path_openat+0xae/0x4c0
[ 62.505210] [<ffffffff8114237d>] do_filp_open+0x3d/0xa0
[ 62.505213] [<ffffffff8114fd0f>] ? __alloc_fd+0xcf/0x120
[ 62.505215] [<ffffffff811321f9>] do_sys_open+0xf9/0x1e0
[ 62.505216] [<ffffffff811322fc>] sys_open+0x1c/0x20
[ 62.505218] [<ffffffff81700952>] system_call_fastpath+0x16/0x1b
[ 62.505219] INFO: lockdep is turned off.
[ 62.505221] INFO: task modprobe:554 blocked for more than 30 seconds.
[ 62.505221] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 62.505223] modprobe D 0000000000000000 0 554 539 0x00000002
[ 62.505225] ffff88015cf155a8 0000000000000046 0000000000000000 ffffffff81070dad
[ 62.505227] ffff88016a284040 ffff88015cf15fd8 ffff88015cf15fd8 ffff88015cf15fd8
[ 62.505228] ffffffff81c13440 ffff88016a284040 ffff88016fdfdf48 ffffffff81c220e0
[ 62.505228] Call Trace:
[ 62.505231] [<ffffffff81070dad>] ? __wake_up+0x2d/0x70
[ 62.505233] [<ffffffff816f9224>] schedule+0x24/0x70
[ 62.505234] [<ffffffff816f57e5>] schedule_timeout+0x175/0x1b0
[ 62.505237] [<ffffffff81009996>] ? native_sched_clock+0x26/0x90
[ 62.505239] [<ffffffff816f84ee>] __down_common+0x97/0xe8
[ 62.505241] [<ffffffff816f859e>] __down+0x18/0x1a
[ 62.505242] [<ffffffff8106d81c>] down+0x3c/0x50
[ 62.505246] [<ffffffff81048db7>] console_lock+0x27/0x80
[ 62.505248] [<ffffffff8139b196>] set_con2fb_map+0x116/0x4c0
[ 62.505250] [<ffffffff8139d9bb>] fbcon_event_notify+0x24b/0x920
[ 62.505252] [<ffffffff816fe318>] notifier_call_chain+0x58/0xb0
[ 62.505254] [<ffffffff8106d983>] __blocking_notifier_call_chain+0x53/0x80
[ 62.505255] [<ffffffff8106d9c1>] blocking_notifier_call_chain+0x11/0x20
[ 62.505257] [<ffffffff8138e816>] fb_notifier_call_chain+0x16/0x20
[ 62.505259] [<ffffffff8138fd23>] register_framebuffer+0x1c3/0x2e0
[ 62.505262] [<ffffffffa0115e7b>] drm_fb_helper_single_fb_probe+0x1eb/0x320 [drm_kms_helper]
[ 62.505265] [<ffffffffa0116183>] drm_fb_helper_initial_config+0x1d3/0x260 [drm_kms_helper]
[ 62.505268] [<ffffffff8109b7cd>] ? trace_hardirqs_on+0xd/0x10
[ 62.505288] [<ffffffffa0253e1a>] radeon_fbdev_init+0xaa/0xf0 [radeon]
[ 62.505301] [<ffffffffa024e95b>] radeon_modeset_init+0x37b/0xa50 [radeon]
[ 62.505313] [<ffffffffa022b5c8>] radeon_driver_load_kms+0xe8/0x150 [radeon]
[ 62.505319] [<ffffffffa00974f9>] drm_get_pci_dev+0x179/0x2a0 [drm]
[ 62.505331] [<ffffffffa02111be>] radeon_pci_probe+0x9e/0xc0 [radeon]
[ 62.505333] [<ffffffff813745c6>] local_pci_probe+0x46/0x80
[ 62.505335] [<ffffffff81375e19>] pci_device_probe+0xf9/0x120
[ 62.505337] [<ffffffff81410e96>] driver_probe_device+0x76/0x240
[ 62.505339] [<ffffffff81411103>] __driver_attach+0xa3/0xb0
[ 62.505341] [<ffffffff81411060>] ? driver_probe_device+0x240/0x240
[ 62.505342] [<ffffffff8140f2f6>] bus_for_each_dev+0x56/0x90
[ 62.505344] [<ffffffff814109f9>] driver_attach+0x19/0x20
[ 62.505345] [<ffffffff81410598>] bus_add_driver+0x188/0x270
[ 62.505347] [<ffffffff81411635>] driver_register+0x75/0x150
[ 62.505349] [<ffffffff81374e2f>] __pci_register_driver+0x5f/0x70
[ 62.505354] [<ffffffffa009773a>] drm_pci_init+0x11a/0x130 [drm]
[ 62.505356] [<ffffffffa02f3000>] ? 0xffffffffa02f2fff
[ 62.505358] [<ffffffffa02f3000>] ? 0xffffffffa02f2fff
[ 62.505367] [<ffffffffa02f30ec>] radeon_init+0xec/0x1000 [radeon]
[ 62.505369] [<ffffffff810001fa>] do_one_initcall+0x3a/0x170
[ 62.505372] [<ffffffff810a9fd2>] load_module+0x1a52/0x2020
[ 62.505373] [<ffffffff810a71b0>] ? get_modinfo.isra.30+0xc0/0xc0
[ 62.505375] [<ffffffff8135166e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[ 62.505377] [<ffffffff810aa671>] sys_init_module+0xd1/0x100
[ 62.505379] [<ffffffff81700952>] system_call_fastpath+0x16/0x1b
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