Bug 431806 - kernel BUG at block/cfq-iosched.c:1147 on USB disconnect
kernel BUG at block/cfq-iosched.c:1147 on USB disconnect
Product: Fedora
Classification: Fedora
Component: kernel (Show other bugs)
i686 Linux
low Severity medium
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Assigned To: Kernel Maintainer List
Fedora Extras Quality Assurance
Depends On:
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Reported: 2008-02-06 20:22 EST by Mace Moneta
Modified: 2008-03-19 19:26 EDT (History)
1 user (show)

See Also:
Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2008-03-19 19:26:49 EDT
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RHEL 7.3 requirements from Atomic Host:
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Attachments (Terms of Use)
Applicable /var/log/messages entries (5.83 KB, text/plain)
2008-02-06 20:22 EST, Mace Moneta
no flags Details

  None (edit)
Description Mace Moneta 2008-02-06 20:22:52 EST
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):

How reproducible:


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.
Comment 1 Mace Moneta 2008-02-06 20:22:52 EST
Created attachment 294180 [details]
Applicable /var/log/messages entries
Comment 2 Mace Moneta 2008-02-06 21:00:58 EST
Just a note: Googling around, it looks like someone else has reported the same
issue in a Debian 2.6.23 kernel here:


Comment 3 Chuck Ebbert 2008-02-07 19:27:22 EST
       BUG_ON(atomic_read(&cfqq->ref) <= 0);
Comment 4 Mace Moneta 2008-02-09 15:16:29 EST
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.

Comment 5 Mace Moneta 2008-03-19 19:26:49 EDT
This appears to have been resolved in the based kernels, as I can no
longer recreate the problem.  Closing.

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