drm_crtc.c WARNING: drm_mode_object_get() called w/o mode_config lock

[Wu Fengguang]

Hi,

I got the following mutex-not-locked warning in linux 2.6.29-rc1.
It appears in a HP 6910p notebook and another G45 desktop.

[  357.150892] pci 0000:00:02.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16
[  357.157653] pci 0000:00:02.0: setting latency timer to 64
[  357.169915] pci 0000:00:02.0: irq 26 for MSI/MSI-X
[  357.497053] ------------[ cut here ]------------
[  357.501715] WARNING: at drivers/gpu/drm/drm_crtc.c:213 drm_mode_object_get+0xb7/0xc0()
[  357.509662] Hardware name:
[  357.513186] drm_mode_object_get called w/o mode_config lock
[  357.518777] Modules linked in: i915(+) fb cfbcopyarea cfbimgblt cfbfillrect snd_hda_codec_intelhdmi snd_hda_codec_idt snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq snd_timer snd_seq_device snd soundcore snd_page_alloc
[  357.539346] Pid: 3364, comm: modprobe Not tainted 2.6.29-rc1 #45
[  357.545377] Call Trace:
[  357.547831]  [<ffffffff810454a0>] warn_slowpath+0xd0/0x130
[  357.553349]  [<ffffffff8106f4aa>] ? trace_hardirqs_on_caller+0x17a/0x1d0
[  357.560073]  [<ffffffff81012e60>] ? native_sched_clock+0x20/0x80
[  357.566118]  [<ffffffff81012ec9>] ? sched_clock+0x9/0x10
[  357.571446]  [<ffffffff81445bcf>] ? _spin_unlock_irqrestore+0x3f/0x70
[  357.577906]  [<ffffffff8106f4aa>] ? trace_hardirqs_on_caller+0x17a/0x1d0
[  357.584625]  [<ffffffff81050d9a>] ? try_to_del_timer_sync+0x5a/0x70
[  357.590914]  [<ffffffff812474c3>] ? drm_mode_connector_update_edid_property+0x63/0x180
[  357.598854]  [<ffffffff810d4339>] ? cache_alloc_debugcheck_after+0x159/0x250
[  357.605919]  [<ffffffff81247407>] drm_mode_object_get+0xb7/0xc0
[  357.611854]  [<ffffffff812474f5>] drm_mode_connector_update_edid_property+0x95/0x180
[  357.619647]  [<ffffffffa00c430d>] intel_ddc_get_modes+0x3d/0x70 [i915]
[  357.626194]  [<ffffffffa00c29a9>] intel_hdmi_get_modes+0x9/0x10 [i915]
[  357.632730]  [<ffffffff8124b216>] drm_helper_probe_single_connector_modes+0xa6/0x2e0
[  357.640493]  [<ffffffff8124b48e>] drm_helper_probe_connector_modes+0x3e/0x70
[  357.647571]  [<ffffffff8124b4fa>] drm_helper_plugged_event+0x3a/0x330
[  357.654032]  [<ffffffff8124b809>] drm_helper_initial_config+0x9/0x10
[  357.660407]  [<ffffffffa00b44db>] i915_driver_load+0x8eb/0xa30 [i915]
[  357.666868]  [<ffffffff81242c7c>] drm_get_dev+0x2fc/0x490
[  357.672308]  [<ffffffff8123d38e>] drm_init+0x9e/0xf0
[  357.677301]  [<ffffffffa0032000>] ? i915_init+0x0/0x4e [i915]
[  357.683070]  [<ffffffffa003204c>] i915_init+0x4c/0x4e [i915]
[  357.688750]  [<ffffffff8100903a>] _stext+0x3a/0x1d0
[  357.693653]  [<ffffffff8106f206>] ? mark_held_locks+0x56/0xa0
[  357.699416]  [<ffffffff81443c46>] ? mutex_lock_nested+0x276/0x370
[  357.705535]  [<ffffffff8106f206>] ? mark_held_locks+0x56/0xa0
[  357.711292]  [<ffffffff81012e60>] ? native_sched_clock+0x20/0x80
[  357.717320]  [<ffffffff81012ec9>] ? sched_clock+0x9/0x10
[  357.722652]  [<ffffffff81445bcf>] ? _spin_unlock_irqrestore+0x3f/0x70
[  357.729114]  [<ffffffff81445bcf>] ? _spin_unlock_irqrestore+0x3f/0x70
[  357.735570]  [<ffffffff8106f4aa>] ? trace_hardirqs_on_caller+0x17a/0x1d0
[  357.742312]  [<ffffffff8106f50d>] ? trace_hardirqs_on+0xd/0x10
[  357.748166]  [<ffffffff811a2a94>] ? __up_read+0x84/0xb0
[  357.753416]  [<ffffffff81061396>] ? up_read+0x26/0x30
[  357.758479]  [<ffffffff81062069>] ? __blocking_notifier_call_chain+0x69/0x90
[  357.765540]  [<ffffffff8107d11f>] sys_init_module+0xaf/0x200
[  357.771220]  [<ffffffff8100c63a>] system_call_fastpath+0x16/0x1b
[  357.777249] ---[ end trace 3c284735efa217aa ]---

Thanks,
Fengguang