Comment 73 for bug 1402331

Similar, probalby same problem here.

- I've been running Kubuntu 14.04 for about a year with no problems. Problem started about 3 months ago or so, not entirely sure about the period.
- The screen usually locks up when using Firefox, today it happen when I switched windows from Firefox to Konsole (the GUI app). The screen locked half way switching the window borders from blue to grey. (Could it be the screen candy thingy that also does the wobbly windows, what's the name again?). The konsole window border on my right monitor is was grey, is now locked faint blue and should have turned to full blue. The Firefox window on the left monitor was full blue, is now slightly going to grey and locked right there and then.
- I don't use a Dell computer, but some Intel mother board based system (DG43GT with a Q9550).
- When the system is locked, which happens every two or three weeks, I can sometimes change to text console but not always. Currently I cannot access console, but I can log in to the box through SSH.
- Screen blanking (power save) doesn't work when the screen locked.

Linux diablo 3.13.0-49-generic #83-Ubuntu SMP Fri Apr 10 20:11:33 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

When my box locks up, I usually run full patching before power cycle, some messages in log files may be caused by that. I attached log files and I believe in the past I have some debug headers installed on my system which seems to list somewhat useful information.

[vr mei 15 23:12:46 2015] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck timer elapsed... render ring idle
[vr mei 15 23:15:36 2015] INFO: task Xorg:2243 blocked for more than 120 seconds.
[vr mei 15 23:15:36 2015] Tainted: G OX 3.13.0-49-generic #83-Ubuntu
[vr mei 15 23:15:36 2015] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[vr mei 15 23:15:36 2015] Xorg D ffff88023bd134c0 0 2243 2230 0x00400000
[vr mei 15 23:15:36 2015] ffff8800b29d7a18 0000000000000086 ffff88022a6d1800 ffff8800b29d7fd8
[vr mei 15 23:15:36 2015] 00000000000134c0 00000000000134c0 ffff88022a6d1800 ffff880035523000
[vr mei 15 23:15:36 2015] ffff880035472ad8 ffff880035eda800 ffff880035eda800 ffff8800032da780
[vr mei 15 23:15:36 2015] Call Trace:
[vr mei 15 23:15:36 2015] [<ffffffff81725f49>] schedule+0x29/0x70
[vr mei 15 23:15:36 2015] [<ffffffffa015ea65>] intel_crtc_wait_for_pending_flips+0x75/0x110 [i915]
[vr mei 15 23:15:36 2015] [<ffffffff810ab120>] ? prepare_to_wait_event+0x100/0x100
[vr mei 15 23:15:36 2015] [<ffffffffa017008f>] intel_crtc_set_config+0x7ef/0x9a0 [i915]
[vr mei 15 23:15:36 2015] [<ffffffffa0026eed>] drm_mode_set_config_internal+0x5d/0xe0 [drm]
[vr mei 15 23:15:36 2015] [<ffffffffa00a4561>] drm_fb_helper_set_par+0x71/0xf0 [drm_kms_helper]
[vr mei 15 23:15:36 2015] [<ffffffff813cd181>] fb_set_var+0x191/0x430
[vr mei 15 23:15:36 2015] [<ffffffff810a2f60>] ? update_curr+0x80/0x180
[vr mei 15 23:15:36 2015] [<ffffffff813da161>] fbcon_blank+0x1d1/0x2d0
[vr mei 15 23:15:36 2015] [<ffffffff81462d68>] do_unblank_screen+0xb8/0x1f0
[vr mei 15 23:15:36 2015] [<ffffffff81458aba>] complete_change_console+0x5a/0xe0
[vr mei 15 23:15:36 2015] [<ffffffff81459aea>] vt_ioctl+0xfaa/0x11c0
[vr mei 15 23:15:36 2015] [<ffffffff8144d4cd>] tty_ioctl+0x26d/0xbb0
[vr mei 15 23:15:36 2015] [<ffffffff811ffcd1>] ? fsnotify+0x241/0x320
[vr mei 15 23:15:36 2015] [<ffffffff811d1200>] do_vfs_ioctl+0x2e0/0x4c0
[vr mei 15 23:15:36 2015] [<ffffffff811c0521>] ? __sb_end_write+0x31/0x60
[vr mei 15 23:15:36 2015] [<ffffffff811d1461>] SyS_ioctl+0x81/0xa0
[vr mei 15 23:15:36 2015] [<ffffffff8173263d>] system_call_fastpath+0x1a/0x1f

Some more details in the attached file. I tarred the current /var/log directory so content from other log files is available upon request.

Please advice.