If you accidentally start 2 instances of xawtv, one of them gets stuck forever and can't be terminated. This is 100% reproduceable. Here is the stack trace: xawtv D ffff88005d3cd540 0 2712 1 0x00000080 ffff88005d3efb28 0000000000000082 0000000000000202 ffff88000000af00 ffff88005d3efac8 0000000000000202 ffff88005d3efd38 ffff88005d3effd8 ffff88005d3effd8 000000000000f9b0 00000000000157c0 ffff880060e183c8 Call Trace: [<ffffffff81064a7d>] ? prepare_to_wait+0x67/0x74 [<ffffffffa02336a2>] videobuf_waiton+0x145/0x163 [videobuf_core] [<ffffffff8106480b>] ? autoremove_wake_function+0x0/0x34 [<ffffffff810e3b92>] ? vfree+0x29/0x2b [<ffffffffa038765a>] saa7134_dma_free+0x45/0x67 [saa7134] [<ffffffffa038c947>] buffer_release+0x9/0xb [saa7134] [<ffffffffa0233dd7>] videobuf_queue_cancel+0xaf/0xd5 [videobuf_core] [<ffffffffa0233e26>] videobuf_streamoff+0x29/0x39 [videobuf_core] [<ffffffffa038bde1>] saa7134_streamoff+0x35/0x62 [saa7134] [<ffffffffa02b51ea>] __video_do_ioctl+0x13e6/0x3327 [videodev] [<ffffffff8128db87>] ? notify_update+0x31/0x33 [<ffffffff81291bd7>] ? do_con_write+0x1ba3/0x1bea [<ffffffff8142dcf5>] ? atomic_notifier_call_chain+0x13/0x15 [<ffffffff81291bd7>] ? do_con_write+0x1ba3/0x1bea [<ffffffffa02b3a37>] ? might_fault+0x1c/0x1e [videodev] [<ffffffffa02b76e3>] video_ioctl2+0x2d4/0x3a1 [videodev] [<ffffffff8104bc2c>] ? release_console_sem+0x18d/0x1be [<ffffffff81064afd>] ? remove_wait_queue+0x30/0x3b [<ffffffffa02b311c>] v4l2_ioctl+0x38/0x3a [videodev] [<ffffffff8110de87>] vfs_ioctl+0x75/0xa1 [<ffffffff8110e3a8>] do_vfs_ioctl+0x47e/0x4c4 [<ffffffff81101363>] ? fsnotify_modify+0x67/0x6f [<ffffffff8110e43f>] sys_ioctl+0x51/0x74 [<ffffffff81009b02>] system_call_fastpath+0x16/0x1b
Bump kernel version.