Red Hat Bugzilla – Bug 431806
kernel BUG at block/cfq-iosched.c:1147 on USB disconnect
Last modified: 2008-03-19 19:26:49 EDT
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):
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
No kernel bug
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:
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.
This appears to have been resolved in the 184.108.40.206 based kernels, as I can no
longer recreate the problem. Closing.