Re: Linux 3.0 oopses when pulling a USB CDROM

Alan Stern
2011-07-04T16:04:55Z

On Mon, 4 Jul 2011, Heiko Carstens wrote:

> On Sat, Jul 02, 2011 at 01:37:59PM -0400, Alan Stern wrote:
> > The second bug, which hit me but apparently not any of you, is that the
> > request_queue's elevator gets deallocated while it is still in use.
> > That's because __scsi_remove_device() calls scsi_free_queue(), which
> > does blk_cleanup_queue(), which calls elevator_exit(), even though the
> > device file is still open and more requests will be submitted when the
> > file is closed.
> >
> > I'm not sure of the right fix for this. One possibility is to move the
> > scsi_free_queue() call to scsi_device_dev_release_usercontext(). Or
> > maybe the elevator_exit() call should be moved to blk_release_queue().
> >
> > Also, I have no idea why this shows up with USB drives but not other
> > SCSI transports. A fluke of timing?
>
> FWIW, I reported a bug where the request_queue's elevator got deallocated
> while it was still in use (fc transport with device hotplug):
>
> http://www.spinics.net/lists/linux-scsi/msg52879.html

That does sound like the second bug I encountered. Can you reproduce
it? Does the patch here:

http://marc.info/?l=linux-kernel&m=130963676907731&w=2

fix the problem?

Alan Stern