Description of problem: I plugged in an external USB drive, mounted it, performed a backup, unmounted it, then disconnected it. Kernel bug appears in the log. Version-Release number of selected component (if applicable): 2.6.23.14-107.fc8 How reproducible: intermittent Steps to Reproduce: 1.Plug in external USB 2.0 drive 2.Mount external drive 3.Write to external drive 4.Unmount external drive 5.Unplug external drive Actual results: Kernel bug Expected results: No kernel bug Additional info: A reboot is needed before USB devices can be used again.
Created attachment 294180 [details] Applicable /var/log/messages entries
Just a note: Googling around, it looks like someone else has reported the same issue in a Debian 2.6.23 kernel here: http://groups.google.com/group/linux.debian.kernel/browse_thread/thread/34fb55a26f15ae88
cfq-iosched.c: BUG_ON(atomic_read(&cfqq->ref) <= 0);
I found kernel bug 9180 discusses this problem (two issues in the bug report). I was running ioniced at the time, so this looks like a good match. A patch to correct it is supposed to be available. http://bugzilla.kernel.org/show_bug.cgi?id=9180
This appears to have been resolved in the 2.6.24.3 based kernels, as I can no longer recreate the problem. Closing.