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5c6c201ccb
linux/drivers/gpu/drm
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Daniel Vetter 5c6c201ccb drm: Paper over locking inversion after registration rework 
drm_connector_register_all requires a few too many locks because our
connector_list locking is busted. Add another FIXME+hack to work
around this. This should address the below lockdep splat:

======================================================
[ INFO: possible circular locking dependency detected ]
4.7.0-rc5+ #524 Tainted: G           O
-------------------------------------------------------
kworker/u8:0/6 is trying to acquire lock:
 (&dev->mode_config.mutex){+.+.+.}, at: [<ffffffff815afde0>] drm_modeset_lock_all+0x40/0x120

but task is already holding lock:
 ((fb_notifier_list).rwsem){++++.+}, at: [<ffffffff810ac195>] __blocking_notifier_call_chain+0x35/0x70

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #1 ((fb_notifier_list).rwsem){++++.+}:
       [<ffffffff810df611>] lock_acquire+0xb1/0x200
       [<ffffffff819a55b4>] down_write+0x44/0x80
       [<ffffffff810abf91>] blocking_notifier_chain_register+0x21/0xb0
       [<ffffffff814c7448>] fb_register_client+0x18/0x20
       [<ffffffff814c6c86>] backlight_device_register+0x136/0x260
       [<ffffffffa0127eb2>] intel_backlight_device_register+0xa2/0x160 [i915]
       [<ffffffffa00f46be>] intel_connector_register+0xe/0x10 [i915]
       [<ffffffffa0112bfb>] intel_dp_connector_register+0x1b/0x80 [i915]
       [<ffffffff8159dfea>] drm_connector_register+0x4a/0x80
       [<ffffffff8159fe44>] drm_connector_register_all+0x64/0xf0
       [<ffffffff815a2a64>] drm_modeset_register_all+0x174/0x1c0
       [<ffffffff81599b72>] drm_dev_register+0xc2/0xd0
       [<ffffffffa00621d7>] i915_driver_load+0x1547/0x2200 [i915]
       [<ffffffffa006d80f>] i915_pci_probe+0x4f/0x70 [i915]
       [<ffffffff814a2135>] local_pci_probe+0x45/0xa0
       [<ffffffff814a349b>] pci_device_probe+0xdb/0x130
       [<ffffffff815c07e3>] driver_probe_device+0x223/0x440
       [<ffffffff815c0ad5>] __driver_attach+0xd5/0x100
       [<ffffffff815be386>] bus_for_each_dev+0x66/0xa0
       [<ffffffff815c002e>] driver_attach+0x1e/0x20
       [<ffffffff815bf9be>] bus_add_driver+0x1ee/0x280
       [<ffffffff815c1810>] driver_register+0x60/0xe0
       [<ffffffff814a1a10>] __pci_register_driver+0x60/0x70
       [<ffffffffa01a905b>] i915_init+0x5b/0x62 [i915]
       [<ffffffff8100042d>] do_one_initcall+0x3d/0x150
       [<ffffffff811a935b>] do_init_module+0x5f/0x1d9
       [<ffffffff81124416>] load_module+0x20e6/0x27e0
       [<ffffffff81124d63>] SYSC_finit_module+0xc3/0xf0
       [<ffffffff81124dae>] SyS_finit_module+0xe/0x10
       [<ffffffff819a83a9>] entry_SYSCALL_64_fastpath+0x1c/0xac

-> #0 (&dev->mode_config.mutex){+.+.+.}:
       [<ffffffff810df0ac>] __lock_acquire+0x10fc/0x1260
       [<ffffffff810df611>] lock_acquire+0xb1/0x200
       [<ffffffff819a3097>] mutex_lock_nested+0x67/0x3c0
       [<ffffffff815afde0>] drm_modeset_lock_all+0x40/0x120
       [<ffffffff8158f79b>] drm_fb_helper_restore_fbdev_mode_unlocked+0x2b/0x80
       [<ffffffff8158f81d>] drm_fb_helper_set_par+0x2d/0x50
       [<ffffffffa0105f7a>] intel_fbdev_set_par+0x1a/0x60 [i915]
       [<ffffffff814c13c6>] fbcon_init+0x586/0x610
       [<ffffffff8154d16a>] visual_init+0xca/0x130
       [<ffffffff8154e611>] do_bind_con_driver+0x1c1/0x3a0
       [<ffffffff8154eaf6>] do_take_over_console+0x116/0x180
       [<ffffffff814bd3a7>] do_fbcon_takeover+0x57/0xb0
       [<ffffffff814c1e48>] fbcon_event_notify+0x658/0x750
       [<ffffffff810abcae>] notifier_call_chain+0x3e/0xb0
       [<ffffffff810ac1ad>] __blocking_notifier_call_chain+0x4d/0x70
       [<ffffffff810ac1e6>] blocking_notifier_call_chain+0x16/0x20
       [<ffffffff814c748b>] fb_notifier_call_chain+0x1b/0x20
       [<ffffffff814c86b1>] register_framebuffer+0x251/0x330
       [<ffffffff8158fa9f>] drm_fb_helper_initial_config+0x25f/0x3f0
       [<ffffffffa0106b48>] intel_fbdev_initial_config+0x18/0x30 [i915]
       [<ffffffff810adfd8>] async_run_entry_fn+0x48/0x150
       [<ffffffff810a3947>] process_one_work+0x1e7/0x750
       [<ffffffff810a3efb>] worker_thread+0x4b/0x4f0
       [<ffffffff810aad4f>] kthread+0xef/0x110
       [<ffffffff819a85ef>] ret_from_fork+0x1f/0x40

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock((fb_notifier_list).rwsem);
                               lock(&dev->mode_config.mutex);
                               lock((fb_notifier_list).rwsem);
  lock(&dev->mode_config.mutex);

 *** DEADLOCK ***

6 locks held by kworker/u8:0/6:
 #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff810a38c9>] process_one_work+0x169/0x750
 #1:  ((&entry->work)){+.+.+.}, at: [<ffffffff810a38c9>] process_one_work+0x169/0x750
 #2:  (registration_lock){+.+.+.}, at: [<ffffffff814c8487>] register_framebuffer+0x27/0x330
 #3:  (console_lock){+.+.+.}, at: [<ffffffff814c86ce>] register_framebuffer+0x26e/0x330
 #4:  (&fb_info->lock){+.+.+.}, at: [<ffffffff814c78dd>] lock_fb_info+0x1d/0x40
 #5:  ((fb_notifier_list).rwsem){++++.+}, at: [<ffffffff810ac195>] __blocking_notifier_call_chain+0x35/0x70

stack backtrace:
CPU: 2 PID: 6 Comm: kworker/u8:0 Tainted: G           O    4.7.0-rc5+ #524
Hardware name: Intel Corp. Broxton P/NOTEBOOK, BIOS APLKRVPA.X64.0138.B33.1606250842 06/25/2016
Workqueue: events_unbound async_run_entry_fn
 0000000000000000 ffff8800758577f0 ffffffff814507a5 ffffffff828b9900
 ffffffff828b9900 ffff880075857830 ffffffff810dc6fa ffff880075857880
 ffff88007584d688 0000000000000005 0000000000000006 ffff88007584d6b0
Call Trace:
 [<ffffffff814507a5>] dump_stack+0x67/0x92
 [<ffffffff810dc6fa>] print_circular_bug+0x1aa/0x200
 [<ffffffff810df0ac>] __lock_acquire+0x10fc/0x1260
 [<ffffffff810df611>] lock_acquire+0xb1/0x200
 [<ffffffff815afde0>] ? drm_modeset_lock_all+0x40/0x120
 [<ffffffff815afde0>] ? drm_modeset_lock_all+0x40/0x120
 [<ffffffff819a3097>] mutex_lock_nested+0x67/0x3c0
 [<ffffffff815afde0>] ? drm_modeset_lock_all+0x40/0x120
 [<ffffffff810fa85f>] ? rcu_read_lock_sched_held+0x7f/0x90
 [<ffffffff81208218>] ? kmem_cache_alloc_trace+0x248/0x2b0
 [<ffffffff815afdc5>] ? drm_modeset_lock_all+0x25/0x120
 [<ffffffff815afde0>] drm_modeset_lock_all+0x40/0x120
 [<ffffffff8158f79b>] drm_fb_helper_restore_fbdev_mode_unlocked+0x2b/0x80
 [<ffffffff8158f81d>] drm_fb_helper_set_par+0x2d/0x50
 [<ffffffffa0105f7a>] intel_fbdev_set_par+0x1a/0x60 [i915]
 [<ffffffff814c13c6>] fbcon_init+0x586/0x610
 [<ffffffff8154d16a>] visual_init+0xca/0x130
 [<ffffffff8154e611>] do_bind_con_driver+0x1c1/0x3a0
 [<ffffffff8154eaf6>] do_take_over_console+0x116/0x180
 [<ffffffff814bd3a7>] do_fbcon_takeover+0x57/0xb0
 [<ffffffff814c1e48>] fbcon_event_notify+0x658/0x750
 [<ffffffff810abcae>] notifier_call_chain+0x3e/0xb0
 [<ffffffff810ac1ad>] __blocking_notifier_call_chain+0x4d/0x70
 [<ffffffff810ac1e6>] blocking_notifier_call_chain+0x16/0x20
 [<ffffffff814c748b>] fb_notifier_call_chain+0x1b/0x20
 [<ffffffff814c86b1>] register_framebuffer+0x251/0x330
 [<ffffffff815b7e8d>] ? vga_switcheroo_client_fb_set+0x5d/0x70
 [<ffffffff8158fa9f>] drm_fb_helper_initial_config+0x25f/0x3f0
 [<ffffffffa0106b48>] intel_fbdev_initial_config+0x18/0x30 [i915]
 [<ffffffff810adfd8>] async_run_entry_fn+0x48/0x150
 [<ffffffff810a3947>] process_one_work+0x1e7/0x750
 [<ffffffff810a38c9>] ? process_one_work+0x169/0x750
 [<ffffffff810a3efb>] worker_thread+0x4b/0x4f0
 [<ffffffff810a3eb0>] ? process_one_work+0x750/0x750
 [<ffffffff810aad4f>] kthread+0xef/0x110
 [<ffffffff819a85ef>] ret_from_fork+0x1f/0x40
 [<ffffffff810aac60>] ? kthread_stop+0x2e0/0x2e0

v2: Rebase onto the right branch (hand-editing patches ftw) and add more
reporters.

Reported-by: Imre Deak <imre.deak@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Reported-by: Jiri Kosina <jikos@kernel.org>
Cc: Jiri Kosina <jikos@kernel.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2016-08-08 16:08:25 +10:00
..
amd Merge tag 'drm-for-v4.8' of git://people.freedesktop.org/~airlied/linux 2016-08-01 21:44:08 -04:00
arc drm/arc: Remove redundant dev_err call in arcpgu_load() 2016-07-19 15:33:50 -04:00
arm drm/arm: mali-dp: Fix error return code in malidp_bind() 2016-07-28 12:59:56 +02:00
armada Merge tag 'drm-for-v4.8' of git://people.freedesktop.org/~airlied/linux 2016-08-01 21:44:08 -04:00
ast Merge remote-tracking branch 'airlied/drm-next' into topic/drm-misc 2016-07-19 09:27:29 +02:00
atmel-hlcdc Merge remote-tracking branch 'airlied/drm-next' into topic/drm-misc 2016-07-19 09:27:29 +02:00
bochs Merge remote-tracking branch 'airlied/drm-next' into topic/drm-misc 2016-07-19 09:27:29 +02:00
bridge Merge tag 'topic/drm-misc-2016-07-28' of git://anongit.freedesktop.org/drm-intel into drm-next 2016-07-30 05:26:07 +10:00
cirrus Merge remote-tracking branch 'airlied/drm-next' into topic/drm-misc 2016-07-19 09:27:29 +02:00
etnaviv Merge tag 'drm-for-v4.8' of git://people.freedesktop.org/~airlied/linux 2016-08-01 21:44:08 -04:00
exynos Merge tag 'drm-for-v4.8-zpos' of git://people.freedesktop.org/~airlied/linux 2016-08-07 16:35:08 -07:00
fsl-dcu Merge tag 'topic/drm-misc-2016-07-22' of git://anongit.freedesktop.org/drm-intel into drm-next 2016-07-27 10:33:08 +10:00
gma500 drm/gma500: remove unnecessary stub for fb_ioctl() 2016-07-28 10:04:03 +02:00
hisilicon drm/hisilicon: Fix ADE vblank on/off handling 2016-07-12 14:17:03 +02:00
i2c drm/i2c: adv7511: Move to bridge folder 2016-07-13 14:24:35 +05:30
i810
i915 drm: i915: fix build when DEBUG_FS is disabled 2016-08-03 18:11:24 -04:00
imx imx-drm ldb mode set fix 2016-07-30 05:45:30 +10:00
mediatek dma-mapping: use unsigned long for dma_attrs 2016-08-04 08:50:07 -04:00
mga
mgag200 drm/mgag200: Delete an unnecessary check before drm_gem_object_unreference_unlocked() 2016-07-22 11:23:39 -04:00
msm dma-mapping: use unsigned long for dma_attrs 2016-08-04 08:50:07 -04:00
nouveau dma-mapping: use unsigned long for dma_attrs 2016-08-04 08:50:07 -04:00
omapdrm Merge tag 'drm-for-v4.8' of git://people.freedesktop.org/~airlied/linux 2016-08-01 21:44:08 -04:00
panel drm/panel: simple: Add support for Starry KR122EA0SRA panel 2016-07-11 14:30:43 +02:00
qxl drm/qxl: Delete an unnecessary check before drm_gem_object_unreference_unlocked() 2016-07-22 11:23:39 -04:00
r128
radeon drm/radeon: Remove deprecated create_singlethread_workqueue 2016-07-29 14:36:55 -04:00
rcar-du drm: rcar-du: Link HDMI encoder with bridge 2016-08-08 15:27:11 +10:00
rockchip dma-mapping: use unsigned long for dma_attrs 2016-08-04 08:50:07 -04:00
savage
shmobile drm/shmobile: make fbdev support really optional 2016-07-18 09:11:37 +02:00
sis drm: Move master pointer from drm_minor to drm_device 2016-06-21 21:43:24 +02:00
sti Merge branch 'generic-zpos-v8' of http://git.linaro.org/people/benjamin.gaignard/kernel into drm-next 2016-08-03 08:40:24 +10:00
sun4i Merge tag 'topic/drm-misc-2016-07-22' of git://anongit.freedesktop.org/drm-intel into drm-next 2016-07-27 10:33:08 +10:00
tdfx
tegra Merge remote-tracking branch 'airlied/drm-next' into topic/drm-misc 2016-07-19 09:27:29 +02:00
tilcdc drm/tilcdc: make fbdev support really optional 2016-07-18 09:11:38 +02:00
ttm Merge tag 'drm-for-v4.8' of git://people.freedesktop.org/~airlied/linux 2016-08-01 21:44:08 -04:00
udl drm/udl: make fbdev support really optional 2016-07-18 09:11:40 +02:00
vc4 Merge remote-tracking branch 'airlied/drm-next' into topic/drm-misc 2016-07-19 09:27:29 +02:00
vgem drm/vgem: Fix non static symbol warning 2016-07-19 15:01:52 +02:00
via drm: Move master pointer from drm_minor to drm_device 2016-06-21 21:43:24 +02:00
virtio drm/virtio: Fix non static symbol warning 2016-07-19 15:44:10 -04:00
vmwgfx Merge tag 'topic/drm-misc-2016-07-28' of git://anongit.freedesktop.org/drm-intel into drm-next 2016-07-30 05:26:07 +10:00
ati_pcigart.c
drm_agpsupport.c
drm_atomic_helper.c drm: add generic zpos property 2016-07-29 09:59:30 +02:00
drm_atomic.c drm: add generic zpos property 2016-07-29 09:59:30 +02:00
drm_auth.c drm: document drm_auth.c 2016-06-21 22:10:55 +02:00
drm_blend.c drm: add generic zpos property 2016-07-29 09:59:30 +02:00
drm_bridge.c
drm_bufs.c drm: Move master pointer from drm_minor to drm_device 2016-06-21 21:43:24 +02:00
drm_cache.c drm: Restore double clflush on the last partial cacheline 2016-07-12 15:57:13 +02:00
drm_context.c
drm_crtc_helper.c Linux 4.7-rc5 2016-07-02 15:56:01 +10:00
drm_crtc_internal.h drm: add generic zpos property 2016-07-29 09:59:30 +02:00
drm_crtc.c drm: Paper over locking inversion after registration rework 2016-08-08 16:08:25 +10:00
drm_debugfs.c drm: Nuke legacy maps debugfs files 2016-06-16 10:16:11 +02:00
drm_dma.c
drm_dp_aux_dev.c drm_aux-dev: fix error handling in drm_dp_aux_dev_init() 2016-07-12 14:10:57 +02:00
drm_dp_dual_mode_helper.c
drm_dp_helper.c drm/dp: Add drm_dp_psr_setup_time() 2016-08-03 07:06:28 +10:00
drm_dp_mst_topology.c drm/dp-mst: Missing kernel doc 2016-07-19 10:31:53 +02:00
drm_drv.c drm: Do a full device unregister when unplugging 2016-07-12 13:01:49 +02:00
drm_edid_load.c
drm_edid.c
drm_encoder_slave.c
drm_fb_cma_helper.c Merge branch 'for-next' of http://git.agner.ch/git/linux-drm-fsl-dcu into drm-next 2016-07-02 16:21:35 +10:00
drm_fb_helper.c drm/fb-helper: Reduce READ_ONCE(master) to lockless_dereference 2016-06-22 10:07:28 +02:00
drm_flip_work.c
drm_fops.c drm: Clean up drm_crtc.h 2016-06-21 21:43:28 +02:00
drm_fourcc.c
drm_gem_cma_helper.c
drm_gem.c Merge tag 'drm-for-v4.8' of git://people.freedesktop.org/~airlied/linux 2016-08-01 21:44:08 -04:00
drm_global.c
drm_hashtab.c
drm_info.c drm: Extract drm_is_current_master 2016-06-21 21:58:12 +02:00
drm_internal.h drm: Nuke SET_UNIQUE ioctl 2016-06-21 21:43:46 +02:00
drm_ioc32.c
drm_ioctl.c drm: Don't overwrite user ioctl arg unless requested 2016-07-14 10:12:50 +02:00
drm_irq.c drm: Extract&Document drm_irq.h 2016-07-19 10:29:47 +02:00
drm_kms_helper_common.c
drm_legacy.h drm: Hide hw.lock cleanup in filp->release better 2016-06-16 10:16:37 +02:00
drm_lock.c drm: Extract drm_is_current_master 2016-06-21 21:58:12 +02:00
drm_memory.c drm: Fix broken use of _PAGE_NO_CACHE on powerpc 2016-07-12 13:20:39 +02:00
drm_mipi_dsi.c drm/dsi: Make set_tear_scanline command consistent 2016-07-12 13:19:26 +02:00
drm_mm.c
drm_modes.c
drm_modeset_lock.c
drm_of.c
drm_panel.c
drm_pci.c drm: Nuke SET_UNIQUE ioctl 2016-06-21 21:43:46 +02:00
drm_plane_helper.c drm: Deal with rotation in drm_plane_helper_check_update() 2016-06-17 16:41:25 +02:00
drm_platform.c drm: Lobotomize set_busid nonsense for !pci drivers 2016-06-21 21:56:23 +02:00
drm_prime.c drm/prime: fix error path deadlock fail 2016-06-13 17:32:18 +02:00
drm_probe_helper.c
drm_rect.c
drm_scatter.c drm: Fix broken use of _PAGE_NO_CACHE on powerpc 2016-07-12 13:20:39 +02:00
drm_simple_kms_helper.c drm: Deal with rotation in drm_plane_helper_check_update() 2016-06-17 16:41:25 +02:00
drm_sysfs.c
drm_trace_points.c
drm_trace.h
drm_vm.c drm: Fix broken use of _PAGE_NO_CACHE on powerpc 2016-07-12 13:20:39 +02:00
drm_vma_manager.c
Kconfig
Makefile drm: add generic zpos property 2016-07-29 09:59:30 +02:00