On 11/11/2015 08:36 AM, Mauro Carvalho Chehab wrote:
> Em Wed, 11 Nov 2015 07:22:47 -0700
> Shuah Khan <shuahkh@xxxxxxxxxxxxxxx> escreveu:
>
>> On 11/11/2015 05:30 AM, Mauro Carvalho Chehab wrote:
>>> Em Mon, 09 Nov 2015 08:55:06 -0700
>>> Shuah Khan <shuahkh@xxxxxxxxxxxxxxx> escreveu:
>>>
>>>> On 11/09/2015 08:51 AM, Shuah Khan wrote:
>>>>> As I mentioned on the IRC, here is the log for the problems I am seeing.
>>>>> I have to do eject HVR 950Q TV stick to see the problem.
>>>>>
>>>>> mc_next_gen.v8.4 branch with no changes.
>>>>>
>>>>> I can test and debug this week.
>>>>>
>>>>> thanks,
>>>>> -- Shuah
>>>>>
>>>>
>>>> Forgot to cc linux-media, just in case others are interested
>>>> and have ideas on debugging.
>>>>
>>>> thanks,
>>>> -- Shuah
>>>
>>>> [ 8.558049] ======================================================
>>>> [ 8.558056] [ INFO: possible circular locking dependency detected ]
>>>> [ 8.558063] 4.2.0-rc2+ #21 Not tainted
>>>> [ 8.558070] -------------------------------------------------------
>>>> [ 8.558077] systemd-udevd/143 is trying to acquire lock:
>>>> [ 8.558084] (init_mutex){+.+.+.}, at: [<ffffffffa0001f36>] acpi_video_get_backlight_type+0x17/0x163 [video]
>>>> [ 8.558104]
>>>> but task is already holding lock:
>>>> [ 8.558114] (&(&backlight_notifier)->rwsem){++++..}, at: [<ffffffff8107fc49>] __blocking_notifier_call_chain+0x39/0x70
>>>> [ 8.558133]
>>>> which lock already depends on the new lock.
>>>>
>>>> [ 8.558147]
>>>> the existing dependency chain (in reverse order) is:
>>>> [ 8.558158]
>>>> -> #1 (&(&backlight_notifier)->rwsem){++++..}:
>>>> [ 8.558170] [<ffffffff810b0c61>] lock_acquire+0xb1/0x130
>>>> [ 8.558180] [<ffffffff817fb006>] down_write+0x36/0x70
>>>> [ 8.558189] [<ffffffff8107fdc1>] blocking_notifier_chain_register+0x21/0xb0
>>>> [ 8.558202] [<ffffffff81424c98>] backlight_register_notifier+0x18/0x20
>>>> [ 8.558212] [<ffffffffa0002019>] acpi_video_get_backlight_type+0xfa/0x163 [video]
>>>> [ 8.558225] [<ffffffffa000167e>] acpi_video_bus_add+0x686/0xdfa [video]
>>>> [ 8.558237] [<ffffffff814371b0>] acpi_device_probe+0x50/0xf7
>>>> [ 8.558247] [<ffffffff814db62d>] driver_probe_device+0x14d/0x470
>>>> [ 8.558257] [<ffffffff814db9e4>] __driver_attach+0x94/0xa0
>>>> [ 8.558266] [<ffffffff814d9366>] bus_for_each_dev+0x66/0xa0
>>>> [ 8.558275] [<ffffffff814daece>] driver_attach+0x1e/0x20
>>>> [ 8.558287] [<ffffffff814daa4e>] bus_add_driver+0x1ee/0x280
>>>> [ 8.558296] [<ffffffff814dc280>] driver_register+0x60/0xe0
>>>> [ 8.558304] [<ffffffff81437936>] acpi_bus_register_driver+0x3b/0x43
>>>> [ 8.558313] [<ffffffffa0000328>] acpi_video_register+0x6e/0x90 [video]
>>>> [ 8.558322] [<ffffffffa000b087>] hid_generic_exit+0x87/0x1000 [hid_generic]
>>>> [ 8.558334] [<ffffffff810002eb>] do_one_initcall+0xab/0x1d0
>>>> [ 8.558344] [<ffffffff817f317e>] do_init_module+0x60/0x1e9
>>>> [ 8.558353] [<ffffffff810f1900>] load_module+0x2170/0x2780
>>>> [ 8.558363] [<ffffffff810f212a>] SyS_finit_module+0x9a/0xc0
>>>> [ 8.558372] [<ffffffff817fd5d7>] entry_SYSCALL_64_fastpath+0x12/0x6f
>>>> [ 8.558381]
>>>> -> #0 (init_mutex){+.+.+.}:
>>>> [ 8.558392] [<ffffffff810aff59>] __lock_acquire+0x1f29/0x1f90
>>>> [ 8.558401] [<ffffffff810b0c61>] lock_acquire+0xb1/0x130
>>>> [ 8.558409] [<ffffffff817f9ceb>] mutex_lock_nested+0x4b/0x340
>>>> [ 8.558417] [<ffffffffa0001f36>] acpi_video_get_backlight_type+0x17/0x163 [video]
>>>> [ 8.558430] [<ffffffffa00020ba>] acpi_video_backlight_notify+0x19/0x2f [video]
>>>> [ 8.558442] [<ffffffff8107faad>] notifier_call_chain+0x5d/0x80
>>>> [ 8.558451] [<ffffffff8107fc61>] __blocking_notifier_call_chain+0x51/0x70
>>>> [ 8.558462] [<ffffffff8107fc96>] blocking_notifier_call_chain+0x16/0x20
>>>> [ 8.558474] [<ffffffff81424ff2>] backlight_device_register+0x1a2/0x260
>>>> [ 8.558483] [<ffffffffa02af70a>] radeon_atom_backlight_init+0xda/0x1d0 [radeon]
>>>> [ 8.558543] [<ffffffffa0254713>] radeon_link_encoder_connector+0xc3/0x130 [radeon]
>>>> [ 8.558585] [<ffffffffa0232b06>] radeon_get_atom_connector_info_from_object_table+0x3a6/0x950 [radeon]
>>>> [ 8.558625] [<ffffffffa0257e4c>] radeon_modeset_init+0x5dc/0xa40 [radeon]
>>>> [ 8.558667] [<ffffffffa0230b0b>] radeon_driver_load_kms+0x12b/0x220 [radeon]
>>>> [ 8.558706] [<ffffffffa0033281>] drm_dev_register+0xb1/0x100 [drm]
>>>> [ 8.558728] [<ffffffffa003605d>] drm_get_pci_dev+0x8d/0x1e0 [drm]
>>>> [ 8.558747] [<ffffffffa022c404>] radeon_pci_probe+0xa4/0xc0 [radeon]
>>>> [ 8.558783] [<ffffffff813f3715>] local_pci_probe+0x45/0xa0
>>>> [ 8.558792] [<ffffffff813f4911>] pci_device_probe+0xd1/0x120
>>>> [ 8.558800] [<ffffffff814db62d>] driver_probe_device+0x14d/0x470
>>>> [ 8.558809] [<ffffffff814db9e4>] __driver_attach+0x94/0xa0
>>>> [ 8.558818] [<ffffffff814d9366>] bus_for_each_dev+0x66/0xa0
>>>> [ 8.558827] [<ffffffff814daece>] driver_attach+0x1e/0x20
>>>> [ 8.558835] [<ffffffff814daa4e>] bus_add_driver+0x1ee/0x280
>>>> [ 8.558844] [<ffffffff814dc280>] driver_register+0x60/0xe0
>>>> [ 8.558852] [<ffffffff813f2fd4>] __pci_register_driver+0x64/0x70
>>>> [ 8.558860] [<ffffffffa0036290>] drm_pci_init+0xe0/0x110 [drm]
>>>> [ 8.558879] [<ffffffffa039d09d>] radeon_init+0x9d/0xb2 [radeon]
>>>> [ 8.558911] [<ffffffff810002eb>] do_one_initcall+0xab/0x1d0
>>>> [ 8.558920] [<ffffffff817f317e>] do_init_module+0x60/0x1e9
>>>> [ 8.558928] [<ffffffff810f1900>] load_module+0x2170/0x2780
>>>> [ 8.558937] [<ffffffff810f212a>] SyS_finit_module+0x9a/0xc0
>>>> [ 8.558945] [<ffffffff817fd5d7>] entry_SYSCALL_64_fastpath+0x12/0x6f
>>>> [ 8.558954]
>>>> other info that might help us debug this:
>>>>
>>>> [ 8.558968] Possible unsafe locking scenario:
>>>>
>>>> [ 8.558978] CPU0 CPU1
>>>> [ 8.558984] ---- ----
>>>> [ 8.558989] lock(&(&backlight_notifier)->rwsem);
>>>> [ 8.558997] lock(init_mutex);
>>>> [ 8.559004] lock(&(&backlight_notifier)->rwsem);
>>>> [ 8.559015] lock(init_mutex);
>>>> [ 8.559021]
>>>> *** DEADLOCK ***
>>>>
>>>> [ 8.559035] 4 locks held by systemd-udevd/143:
>>>> [ 8.559041] #0: (&dev->mutex){......}, at: [<ffffffff814db99b>] __driver_attach+0x4b/0xa0
>>>> [ 8.559056] #1: (&dev->mutex){......}, at: [<ffffffff814db9a9>] __driver_attach+0x59/0xa0
>>>> [ 8.559072] #2: (drm_global_mutex){+.+.+.}, at: [<ffffffffa00331f6>] drm_dev_register+0x26/0x100 [drm]
>>>> [ 8.559097] #3: (&(&backlight_notifier)->rwsem){++++..}, at: [<ffffffff8107fc49>] __blocking_notifier_call_chain+0x39/0x70
>>>> [ 8.559113]
>>>> stack backtrace:
>>>> [ 8.559124] CPU: 2 PID: 143 Comm: systemd-udevd Not tainted 4.2.0-rc2+ #21
>>>> [ 8.559132] Hardware name: Hewlett-Packard HP ProBook 6475b/180F, BIOS 68TTU Ver. F.04 08/03/2012
>>>> [ 8.559143] ffffffff8285ace0 ffff88002b09f378 ffffffff817f4254 ffffffff810c155a
>>>> [ 8.559156] ffffffff8285ace0 ffff88002b09f3c8 ffffffff810ac6a3 0000000000000003
>>>> [ 8.559169] ffff88002b09f438 ffff88002b09f3c8 ffff88002b06b398 ffff88002b06a600
>>>> [ 8.559181] Call Trace:
>>>> [ 8.559190] [<ffffffff817f4254>] dump_stack+0x45/0x57
>>>> [ 8.559208] [<ffffffff810c155a>] ? console_unlock+0x1da/0x580
>>>> [ 8.559216] [<ffffffff810ac6a3>] print_circular_bug+0x1e3/0x250
>>>> [ 8.559225] [<ffffffff810aff59>] __lock_acquire+0x1f29/0x1f90
>>>> [ 8.559234] [<ffffffff810b0c61>] lock_acquire+0xb1/0x130
>>>> [ 8.559243] [<ffffffffa0001f36>] ? acpi_video_get_backlight_type+0x17/0x163 [video]
>>>> [ 8.559255] [<ffffffff817f9ceb>] mutex_lock_nested+0x4b/0x340
>>>> [ 8.559264] [<ffffffffa0001f36>] ? acpi_video_get_backlight_type+0x17/0x163 [video]
>>>> [ 8.559277] [<ffffffffa0001f36>] acpi_video_get_backlight_type+0x17/0x163 [video]
>>>> [ 8.559289] [<ffffffffa00020ba>] acpi_video_backlight_notify+0x19/0x2f [video]
>>>> [ 8.559301] [<ffffffff8107faad>] notifier_call_chain+0x5d/0x80
>>>> [ 8.559310] [<ffffffff8107fc61>] __blocking_notifier_call_chain+0x51/0x70
>>>> [ 8.559319] [<ffffffff8107fc96>] blocking_notifier_call_chain+0x16/0x20
>>>> [ 8.559327] [<ffffffff81424ff2>] backlight_device_register+0x1a2/0x260
>>>> [ 8.559374] [<ffffffffa02af70a>] radeon_atom_backlight_init+0xda/0x1d0 [radeon]
>>>> [ 8.559416] [<ffffffffa0254713>] radeon_link_encoder_connector+0xc3/0x130 [radeon]
>>>> [ 8.559455] [<ffffffffa0232b06>] radeon_get_atom_connector_info_from_object_table+0x3a6/0x950 [radeon]
>>>> [ 8.559481] [<ffffffffa0038c1b>] ? drm_mode_crtc_set_gamma_size+0x5b/0x70 [drm]
>>>> [ 8.559523] [<ffffffffa0257e4c>] radeon_modeset_init+0x5dc/0xa40 [radeon]
>>>> [ 8.559566] [<ffffffffa03071d8>] ? radeon_ib_ring_tests+0x58/0xc0 [radeon]
>>>> [ 8.559601] [<ffffffffa0230b0b>] radeon_driver_load_kms+0x12b/0x220 [radeon]
>>>> [ 8.559620] [<ffffffffa0033281>] drm_dev_register+0xb1/0x100 [drm]
>>>> [ 8.559639] [<ffffffffa003605d>] drm_get_pci_dev+0x8d/0x1e0 [drm]
>>>> [ 8.559674] [<ffffffffa022c404>] radeon_pci_probe+0xa4/0xc0 [radeon]
>>>> [ 8.559683] [<ffffffff813f3715>] local_pci_probe+0x45/0xa0
>>>> [ 8.559691] [<ffffffff813f47d0>] ? pci_match_device+0xe0/0x110
>>>> [ 8.559699] [<ffffffff813f4911>] pci_device_probe+0xd1/0x120
>>>> [ 8.559708] [<ffffffff814db62d>] driver_probe_device+0x14d/0x470
>>>> [ 8.559717] [<ffffffff814db9e4>] __driver_attach+0x94/0xa0
>>>> [ 8.559726] [<ffffffff814db950>] ? driver_probe_device+0x470/0x470
>>>> [ 8.559734] [<ffffffff814d9366>] bus_for_each_dev+0x66/0xa0
>>>> [ 8.559743] [<ffffffff814daece>] driver_attach+0x1e/0x20
>>>> [ 8.559752] [<ffffffff814daa4e>] bus_add_driver+0x1ee/0x280
>>>> [ 8.559760] [<ffffffff814dc280>] driver_register+0x60/0xe0
>>>> [ 8.559767] [<ffffffff813f2fd4>] __pci_register_driver+0x64/0x70
>>>> [ 8.559786] [<ffffffffa0036290>] drm_pci_init+0xe0/0x110 [drm]
>>>> [ 8.559794] [<ffffffffa039d000>] ? 0xffffffffa039d000
>>>> [ 8.559825] [<ffffffffa039d09d>] radeon_init+0x9d/0xb2 [radeon]
>>>> [ 8.559834] [<ffffffff810002eb>] do_one_initcall+0xab/0x1d0
>>>> [ 8.559843] [<ffffffff817f3146>] ? do_init_module+0x28/0x1e9
>>>> [ 8.559852] [<ffffffff811c5c3b>] ? kmem_cache_alloc_trace+0xbb/0x160
>>>> [ 8.559862] [<ffffffff817f317e>] do_init_module+0x60/0x1e9
>>>> [ 8.559870] [<ffffffff810f1900>] load_module+0x2170/0x2780
>>>> [ 8.559878] [<ffffffff810edd30>] ? __symbol_put+0x40/0x40
>>>> [ 8.559888] [<ffffffff810f212a>] SyS_finit_module+0x9a/0xc0
>>>> [ 8.559897] [<ffffffff817fd5d7>] entry_SYSCALL_64_fastpath+0x12/0x6f
>>>
>>> Sorry, but I fail to see how this is related to the V4L2 subsystem.
>>>
>>> At least on my eyes, it seems that the bug is somewhere at the Radeon
>>> driver.
>>>
>>
>> Mauro,
>>
>> I think you didn't look down the dmesg far enough. The following is the
>> problem I am talking about and you will see media_device_unregister()
>> on the stack. This occurs as soon as the device is removed.
>
> Shuah,
>
> I saw that, but it is clear, from the above log, that the Radeon
> driver is broken and it has some bad lock dependencies with the
> driver_attach locks. Any other bad lock report related to the
> Radeon driver or driver binding/unbiding code are very likely
> related to the above bug.
>
> You should either fix the bad lock at the Radeon driver or not
> load it at all, in order to be able to get any reliable results
> about possible locking troubles with the MC drivers with the Kernel
> lock tests.
>
Yeah Radeon driver bug could be making things worse. Did you see
any problems with device removal during your testing?
ok found the following commit that fixes the problem:
7231ed1a813e0a9d249bbbe58e66ca058aee83e1
This went into 4.2-rc4 or rc5. I will test applying just this
one patch to mc_next_gen.v8.4 branch and see if device removal
problem also goes away.
thanks,
-- Shuah
--
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@xxxxxxxxxxxxxxx | (970) 217-8978
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