Re: [git pull] drm for v4.8

[Jiri Kosina <jikos@kernel.org>]

On Mon, 1 Aug 2016, Linus Torvalds wrote:

> > This is the main drm pull request for 4.8, I'm down with a cold at the moment
> > so hopefully this isn't in too bad a state, I finished pulling stuff last
> > week mostly (nouveau fixes just went in today), so only this message should
> > be influenced by illness. Apologies to anyone who's major feature I missed :-)
> >
> > i915:
> >         BXT support enabled by default
> >         GVT-g infrastructure
> >         GuC command submission and fixes
> >         BXT workarounds
> >         SKL/BKL workarounds
> >         Demidlayering device registration
> >         Thundering herd fixes
> >         Missing pci ids
> >         Atomic updates
> 
> Hmm. I did the merge and pushed it out, but testing it on my laptop
> shows some very annoying flickering problem.

In addition to that, what I see with current git (HEAD == 731c7d3a205, 
i.e. the drm merge) is lockdep report during bootup about AB-BA between 
mode_config.mutex and fb_notifier_list rwsem; will probably not have time 
to look into it more (look at the code and / or bisect) until tomorrow, so 
sending out early as a heads-up.

Also, trying to suspend the machine to disk hangs, with the "suspend" LED 
constantly blinking, LCD being blank, but the machine never actually 
powering off. Not sure whether it might not be the very deadlock actually 
triggering for real.


[    8.731638] fbcon: inteldrmfb (fb0) is primary device

[    8.732611] ======================================================
[    8.732612] [ INFO: possible circular locking dependency detected ]
[    8.732614] 4.7.0-10753-g731c7d3 #459 Not tainted
[    8.732614] -------------------------------------------------------
[    8.732615] kworker/u8:3/60 is trying to acquire lock:
[    8.732650]  (&dev->mode_config.mutex){+.+.+.}, at: [<ffffffffc02bfd00>] drm_modeset_lock_all+0x40/0x120 [drm]
[    8.732651] 
but task is already holding lock:
[    8.732657]  ((fb_notifier_list).rwsem){++++.+}, at: [<ffffffff8d08fe2a>] __blocking_notifier_call_chain+0x3a/0x70
[    8.732658] 
which lock already depends on the new lock.

[    8.732658] 
the existing dependency chain (in reverse order) is:
[    8.732661] 
-> #1 ((fb_notifier_list).rwsem){++++.+}:
[    8.732665]        [<ffffffff8d0c22d0>] lock_acquire+0xb0/0x1e0
[    8.732669]        [<ffffffff8d6a0b25>] down_write+0x55/0xc0
[    8.732671]        [<ffffffff8d08ffb1>] blocking_notifier_chain_register+0x21/0xb0
[    8.732674]        [<ffffffff8d3d1318>] fb_register_client+0x18/0x20
[    8.732676]        [<ffffffff8d3d0b88>] backlight_device_register+0x138/0x250
[    8.732746]        [<ffffffffc0568912>] intel_backlight_device_register+0xa2/0x160 [i915]
[    8.732791]        [<ffffffffc053735e>] intel_connector_register+0xe/0x10 [i915]
[    8.732809]        [<ffffffffc02ae389>] drm_connector_register+0x49/0x80 [drm]
[    8.732827]        [<ffffffffc02b28a0>] drm_modeset_register_all+0x1d0/0x260 [drm]
[    8.732843]        [<ffffffffc02a9c22>] drm_dev_register+0xc2/0xd0 [drm]
[    8.732878]        [<ffffffffc04a6ce5>] i915_driver_load+0x745/0x13e0 [i915]
[    8.732914]        [<ffffffffc04b173f>] i915_pci_probe+0x4f/0x70 [i915]
[    8.732917]        [<ffffffff8d3af7d5>] local_pci_probe+0x45/0xa0
[    8.732920]        [<ffffffff8d3b0bf1>] pci_device_probe+0xe1/0x130
[    8.732923]        [<ffffffff8d489be8>] driver_probe_device+0x1a8/0x460
[    8.732925]        [<ffffffff8d489f6d>] __driver_attach+0xcd/0xf0
[    8.732927]        [<ffffffff8d4878a4>] bus_for_each_dev+0x64/0xa0
[    8.732929]        [<ffffffff8d4894ee>] driver_attach+0x1e/0x20
[    8.732931]        [<ffffffff8d488f83>] bus_add_driver+0x1d3/0x290
[    8.732933]        [<ffffffff8d48ad30>] driver_register+0x60/0xe0
[    8.732935]        [<ffffffff8d3af100>] __pci_register_driver+0x60/0x70
[    8.732972]        [<ffffffffc05ec05d>] i915_init+0x5d/0x64 [i915]
[    8.732975]        [<ffffffff8d00041d>] do_one_initcall+0x3d/0x160
[    8.732979]        [<ffffffff8d182bfd>] do_init_module+0x60/0x1dc
[    8.732982]        [<ffffffff8d107a5e>] load_module+0x142e/0x1bf0
[    8.732984]        [<ffffffff8d108449>] SYSC_finit_module+0xa9/0xd0
[    8.732986]        [<ffffffff8d10848e>] SyS_finit_module+0xe/0x10
[    8.732989]        [<ffffffff8d6a38e9>] entry_SYSCALL_64_fastpath+0x1c/0xac
[    8.732992] 
-> #0 (&dev->mode_config.mutex){+.+.+.}:
[    8.732995]        [<ffffffff8d0c1e7c>] __lock_acquire+0x16cc/0x1700
[    8.732997]        [<ffffffff8d0c22d0>] lock_acquire+0xb0/0x1e0
[    8.732999]        [<ffffffff8d69f2d1>] mutex_lock_nested+0x71/0x390
[    8.733019]        [<ffffffffc02bfd00>] drm_modeset_lock_all+0x40/0x120 [drm]
[    8.733034]        [<ffffffffc047640b>] drm_fb_helper_restore_fbdev_mode_unlocked+0x2b/0x80 [drm_kms_helper]
[    8.733043]        [<ffffffffc047648c>] drm_fb_helper_set_par+0x2c/0x50 [drm_kms_helper]
[    8.733088]        [<ffffffffc05476aa>] intel_fbdev_set_par+0x1a/0x60 [i915]
[    8.733091]        [<ffffffff8d3ce2b8>] fbcon_init+0x4d8/0x550
[    8.733094]        [<ffffffff8d450526>] visual_init+0xd6/0x130
[    8.733097]        [<ffffffff8d452ab6>] do_bind_con_driver+0x146/0x310
[    8.733099]        [<ffffffff8d452f66>] do_take_over_console+0x106/0x180
[    8.733101]        [<ffffffff8d3c9777>] do_fbcon_takeover+0x57/0xb0
[    8.733104]        [<ffffffff8d3cedd6>] fbcon_event_notify+0x726/0x870
[    8.733106]        [<ffffffff8d08fbfe>] notifier_call_chain+0x4e/0xa0
[    8.733109]        [<ffffffff8d08fe43>] __blocking_notifier_call_chain+0x53/0x70
[    8.733111]        [<ffffffff8d08fe76>] blocking_notifier_call_chain+0x16/0x20
[    8.733113]        [<ffffffff8d3d135b>] fb_notifier_call_chain+0x1b/0x20
[    8.733116]        [<ffffffff8d3d3379>] register_framebuffer+0x239/0x320
[    8.733126]        [<ffffffffc047670a>] drm_fb_helper_initial_config+0x25a/0x3a3 [drm_kms_helper]
[    8.733169]        [<ffffffffc0548938>] intel_fbdev_initial_config+0x18/0x30 [i915]
[    8.733172]        [<ffffffff8d091aaa>] async_run_entry_fn+0x4a/0x140
[    8.733174]        [<ffffffff8d08771e>] process_one_work+0x1de/0x670
[    8.733176]        [<ffffffff8d087cd5>] worker_thread+0x125/0x4a0
[    8.733178]        [<ffffffff8d08e7e2>] kthread+0xf2/0x110
[    8.733181]        [<ffffffff8d6a3b2f>] ret_from_fork+0x1f/0x40
[    8.733181] 
other info that might help us debug this:

[    8.733182]  Possible unsafe locking scenario:

[    8.733183]        CPU0                    CPU1
[    8.733183]        ----                    ----
[    8.733185]   lock((fb_notifier_list).rwsem);
[    8.733186]                                lock(&dev->mode_config.mutex);
[    8.733187]                                lock((fb_notifier_list).rwsem);
[    8.733188]   lock(&dev->mode_config.mutex);
[    8.733189] 
 *** DEADLOCK ***

[    8.733190] 6 locks held by kworker/u8:3/60:
[    8.733194]  #0:  ("events_unbound"){.+.+.+}, at: [<ffffffff8d08769f>] process_one_work+0x15f/0x670
[    8.733198]  #1:  ((&entry->work)){+.+.+.}, at: [<ffffffff8d08769f>] process_one_work+0x15f/0x670
[    8.733201]  #2:  (registration_lock){+.+.+.}, at: [<ffffffff8d3d3167>] register_framebuffer+0x27/0x320
[    8.733205]  #3:  (console_lock){+.+.+.}, at: [<ffffffff8d3d3396>] register_framebuffer+0x256/0x320
[    8.733208]  #4:  (&fb_info->lock){+.+.+.}, at: [<ffffffff8d3d178d>] lock_fb_info+0x1d/0x40
[    8.733212]  #5:  ((fb_notifier_list).rwsem){++++.+}, at: [<ffffffff8d08fe2a>] __blocking_notifier_call_chain+0x3a/0x70
[    8.733212] 
stack backtrace:
[    8.733214] CPU: 1 PID: 60 Comm: kworker/u8:3 Not tainted 4.7.0-10753-g731c7d3 #459
[    8.733215] Hardware name: LENOVO 7470BN2/7470BN2, BIOS 6DET38WW (2.02 ) 12/19/2008
[    8.733218] Workqueue: events_unbound async_run_entry_fn
[    8.733221]  0000000000000000 ffff95f0b77537d8 ffffffff8d36c09e ffffffff8e822d00
[    8.733224]  ffffffff8e822d00 ffff95f0b7753818 ffffffff8d18205b ffff95f0b7753850
[    8.733226]  ffff95f0b774d718 0000000000000005 0000000000000006 ffff95f0b774cd40
[    8.733227] Call Trace:
[    8.733230]  [<ffffffff8d36c09e>] dump_stack+0x67/0x99
[    8.733232]  [<ffffffff8d18205b>] print_circular_bug+0x200/0x20e
[    8.733235]  [<ffffffff8d0c1e7c>] __lock_acquire+0x16cc/0x1700
[    8.733238]  [<ffffffff8d0a17c8>] ? sched_clock_local+0x18/0x80
[    8.733240]  [<ffffffff8d0c22d0>] lock_acquire+0xb0/0x1e0
[    8.733260]  [<ffffffffc02bfd00>] ? drm_modeset_lock_all+0x40/0x120 [drm]
[    8.733262]  [<ffffffff8d69f2d1>] mutex_lock_nested+0x71/0x390
[    8.733281]  [<ffffffffc02bfd00>] ? drm_modeset_lock_all+0x40/0x120 [drm]
[    8.733301]  [<ffffffffc02bfd00>] ? drm_modeset_lock_all+0x40/0x120 [drm]
[    8.733304]  [<ffffffff8d1ec87c>] ? kmem_cache_alloc_trace+0x25c/0x320
[    8.733322]  [<ffffffffc02bfce5>] ? drm_modeset_lock_all+0x25/0x120 [drm]
[    8.733341]  [<ffffffffc02bfd00>] drm_modeset_lock_all+0x40/0x120 [drm]
[    8.733351]  [<ffffffffc047640b>] drm_fb_helper_restore_fbdev_mode_unlocked+0x2b/0x80 [drm_kms_helper]
[    8.733360]  [<ffffffffc047648c>] drm_fb_helper_set_par+0x2c/0x50 [drm_kms_helper]
[    8.733403]  [<ffffffffc05476aa>] intel_fbdev_set_par+0x1a/0x60 [i915]
[    8.733406]  [<ffffffff8d3ce2b8>] fbcon_init+0x4d8/0x550
[    8.733408]  [<ffffffff8d450526>] visual_init+0xd6/0x130
[    8.733410]  [<ffffffff8d452ab6>] do_bind_con_driver+0x146/0x310
[    8.733413]  [<ffffffff8d452f66>] do_take_over_console+0x106/0x180
[    8.733415]  [<ffffffff8d3c9777>] do_fbcon_takeover+0x57/0xb0
[    8.733417]  [<ffffffff8d3cedd6>] fbcon_event_notify+0x726/0x870
[    8.733419]  [<ffffffff8d08fbfe>] notifier_call_chain+0x4e/0xa0
[    8.733422]  [<ffffffff8d08fe43>] __blocking_notifier_call_chain+0x53/0x70
[    8.733424]  [<ffffffff8d08fe76>] blocking_notifier_call_chain+0x16/0x20
[    8.733426]  [<ffffffff8d3d135b>] fb_notifier_call_chain+0x1b/0x20
[    8.733427]  [<ffffffff8d3d3379>] register_framebuffer+0x239/0x320
[    8.733430]  [<ffffffff8d4817c0>] ? vga_switcheroo_client_fb_set+0x60/0x70
[    8.733440]  [<ffffffffc047670a>] drm_fb_helper_initial_config+0x25a/0x3a3 [drm_kms_helper]
[    8.733483]  [<ffffffffc0548938>] intel_fbdev_initial_config+0x18/0x30 [i915]
[    8.733484]  [<ffffffff8d091aaa>] async_run_entry_fn+0x4a/0x140
[    8.733486]  [<ffffffff8d08771e>] process_one_work+0x1de/0x670
[    8.733488]  [<ffffffff8d08769f>] ? process_one_work+0x15f/0x670
[    8.733490]  [<ffffffff8d087cd5>] worker_thread+0x125/0x4a0
[    8.733492]  [<ffffffff8d087bb0>] ? process_one_work+0x670/0x670
[    8.733494]  [<ffffffff8d08e7e2>] kthread+0xf2/0x110
[    8.733497]  [<ffffffff8d6a3b2f>] ret_from_fork+0x1f/0x40
[    8.733499]  [<ffffffff8d08e6f0>] ? kthread_create_on_node+0x220/0x220

-- 
Jiri Kosina
SUSE Labs