Description:
System randomly freezes for about 40-50 seconds. No pattern could be determined for reproducing issue. However, other similar bug reports on Debian, RedHat and Gentoo seem to point to using applications that use OpenGL.

Some of the symptoms are:
1. Screen freezes.
2. Mouse / keyboard input is frozen. Switching to a TTY is impossible.
3. Music continues playing in the background.
4. ACPI events, like pressing the power button or closing laptop lid are not triggered.

Xorg.0.log shows the following backtrace:

(EE) [mi] EQ overflowing. Additional events will be discarded until existing events are processed.
767 (EE)
768 (EE) Backtrace:
769 (EE) 0: /usr/bin/X (xorg_backtrace+0x36) [0x58a846]
770 (EE) 1: /usr/bin/X (mieqEnqueue+0x26b) [0x56b98b]
771 (EE) 2: /usr/bin/X (0x400000+0x4ca82) [0x44ca82]
772 (EE) 3: /usr/lib/xorg/modules/input/evdev_drv.so (0x7f14245bd000+0x5f74) [0x7f14245c2f74]
773 (EE) 4: /usr/bin/X (0x400000+0x75db7) [0x475db7]
774 (EE) 5: /usr/bin/X (0x400000+0x9f3c8) [0x49f3c8]
775 (EE) 6: /usr/lib/libpthread.so.0 (0x7f142caa7000+0xf1e0) [0x7f142cab61e0]
776 (EE) 7: /usr/lib/libc.so.6 (ioctl+0x7) [0x7f142b9f3657]
777 (EE) 8: /usr/lib/libdrm.so.2 (drmIoctl+0x28) [0x7f142c89e968]
778 (EE) 9: /usr/lib/libdrm.so.2 (drmCommandWriteRead+0x1c) [0x7f142c8a0d9c]
779 (EE) 10: /usr/lib/libdrm_radeon.so.1 (0x7f1427483000+0x2903) [0x7f1427485903]
780 (EE) 11: /usr/lib/xorg/modules/drivers/radeon_drv.so (0x7f142768e000+0x43877) [0x7f14276d1877]
781 (EE) 12: /usr/lib/xorg/modules/drivers/radeon_drv.so (0x7f142768e000+0x43a40) [0x7f14276d1a40]
782 (EE) 13: /usr/bin/X (_CallCallbacks+0x34) [0x43ca14]
783 (EE) 14: /usr/bin/X (FlushAllOutput+0x2b) [0x58df0b]
784 (EE) 15: /usr/bin/X (0x400000+0x37d7b) [0x437d7b]
785 (EE) 16: /usr/bin/X (0x400000+0x2689a) [0x42689a]
786 (EE) 17: /usr/lib/libc.so.6 (__libc_start_main+0xf5) [0x7f142b933a15]
787 (EE) 18: /usr/bin/X (0x400000+0x26bdd) [0x426bdd]
788 (EE)
789 (EE) [mi] These backtraces from mieqEnqueue may point to a culprit higher up the stack.
790 (EE) [mi] mieq is *NOT* the cause. It is a victim.
791 (EE) [mi] EQ overflow continuing. 100 events have been dropped.

The same backtrace is repeatedly printed, with a change in the number of events dropped (goes upto 1000 events dropped)

The same backtrace also occurs in /var/log/kdm.log

I will provide any other information required.

Additional info:
* The libdrm_radeon.so file belongs to xf86-video-ati, which is upgraded to the latest version in [Extra]
* I have [Testing] and [Multilib-Testing] repos enabled.


Steps to reproduce: N/a