Latest working kernel version: 2.6.24.7

Earliest failing kernel version: 2.6.25.6 (also seen on 2.6.25.4)

Distribution: Slackware 12.1 (x86)

Hardware Environment: Intel P4 32-bit, 4GB RAM, Lots of HD space, 1xSATA DVD+RW and 1xIDE DVD+RW

Software Environment: bash ver. 3.1.17(2), mount ver. 2.13.1 (util-linux-ng)

Problem Description:
CD/DVD containing valid data fails to mount in SATA DVD+RW drive when mount(8) command issued from console.  Instead, "medium not found" message is displayed.  After waiting 20-25 seconds and re-issuing mount command, disc mounts fine.

This behavior does _not_ occur on IDE DVD+RW drive on same computer, nor did this behavior occur with 2.6.24[.x] or earlier kernels.

Discs used to reproduce the problem all have valid data and file systems.  Problem can be reproduced with either storebought CDs/DVDs, or CD-R/DVD+/-R containing valid UDF or ISO9660 fs and data.  /etc/fstab and udev are all configured appropriately for mount command issued.

Steps to reproduce:

1.  Ensure no disc is mounted and SATA DVD drive tray is open (extended).  Place CD or DVD on tray.

2.  In shell: $ mount /media/dvd0

3.  Tray closes, but immediately after closing, shell shows message "mount: No medium found" and returns prompt.  Disc is not mounted.

4.  Re-issuing above mount command in shell within a few (2-4) seconds again gets "mount: No medium found" message and a prompt.  Disc remains unmounted.

5.  Wait about 20-25 seconds after first mount command issued and retry.  Mount will then be successful.

Please note that doing the above in 2.6.24.7 (and earlier) would cause the shell to block until the disc was mounted (assuming it was mountable) instead of the "No medium found" messages.  The IDE DVD drive on this computer (yes, two DVD burners on the same PC) does _not_ exhibit this behavior, even when running same kernel.

Below is a BASH script and its output.  /media/dvd0 is the mount point of the SATA drive /dev/sr0, and /media/dvd1 is the mount point of the IDE drive /dev/hdc.

========= demo.sh ==========
#!/bin/sh

for DRIVE in dvd0 dvd1
do
    echo
    while true
    do
        echo "$(date +%s.%N) mount /media/${DRIVE}"
        mount /media/${DRIVE}

        if [ ${?} -eq 0 ]; then
            break
        fi

        sleep 0.5
    done

    echo "$(date +%s.%N) mount succeeded."
    echo
    echo "Contents of /media/${DRIVE} are:"
    echo "$(ls -1 /media/${DRIVE})"
    echo

done
======== End demo.sh ===========

Below is the output of running the above script.  Before the script was run, both drive trays were ejected (open).  A Debian Etch disc 1 DVD was placed in the /media/dvd0 (SATA) tray, and an Etch disc 2 DVD was placed in the /media/dvd1 (IDE) tray.

======== Output of demo.sh ========

1213323099.766990388 mount /media/dvd0
mount: No medium found
1213323101.783767667 mount /media/dvd0
mount: No medium found
1213323102.932494608 mount /media/dvd0
mount: No medium found
1213323104.358153665 mount /media/dvd0
mount: No medium found
1213323105.506916265 mount /media/dvd0
mount: No medium found
1213323106.655628941 mount /media/dvd0
mount: No medium found
1213323107.804383561 mount /media/dvd0
mount: No medium found
1213323108.953112140 mount /media/dvd0
mount: No medium found
1213323110.378777718 mount /media/dvd0
mount: No medium found
1213323111.527538089 mount /media/dvd0
mount: No medium found
1213323112.676269230 mount /media/dvd0
mount: No medium found
1213323113.806000861 mount /media/dvd0
1213323118.829925134 mount succeeded.

Contents of /media/dvd0 are:
README.html
README.mirrors.html
README.mirrors.txt
README.txt
autorun.bat
autorun.inf
debian
dists
doc
install
isolinux
md5sum.txt
pics
pool
tools


1213323118.927907914 mount /media/dvd1
1213323139.241765949 mount succeeded.

Contents of /media/dvd1 are:
README.html
README.mirrors.html
README.mirrors.txt
README.txt
autorun.bat
autorun.inf
boot
debian
dists
md5sum.txt
pics
pool

========== end of output from demo.sh ========

Supporting documentation and debug files can be found at the URLs below:

Kernel config:  http://www.cs.txstate.edu/~pr1037/kernel-debug/2.6.25.6/config-2.6.25.6-DBUG

cpuinfo: http://www.cs.txstate.edu/~pr1037/kernel-debug/2.6.25.6/cpuinfo.txt

/etc/fstab file: http://www.cs.txstate.edu/~pr1037/kernel-debug/2.6.25.6/fstab

iomem: http://www.cs.txstate.edu/~pr1037/kernel-debug/2.6.25.6/iomem.txt

ioports: http://www.cs.txstate.edu/~pr1037/kernel-debug/2.6.25.6/ioports.txt

lspci -vvv (as root): http://www.cs.txstate.edu/~pr1037/kernel-debug/2.6.25.6/lspci-vvv.txt

kernel modules: http://www.cs.txstate.edu/~pr1037/kernel-debug/2.6.25.6/modules.txt

/proc/scsi/scsi: http://www.cs.txstate.edu/~pr1037/kernel-debug/2.6.25.6/scsi.txt

output of ver_linux (in /scripts directory of kernel source): http://www.cs.txstate.edu/~pr1037/kernel-debug/2.6.25.6/ver_linux_output.txt

All the above files can be viewed as a directory listing at http://www.cs.txstate.edu/~pr1037/kernel-debug/2.6.25.6/

Finally, a small request:  I'd like to try to figure this out on my own and propose/submit a patch (assuming this hasn't already been done).  I'm sincerely interested in participating in the kernel development/testing process, but I'm new at it.  Granted, I've used Linux for around 10 years now (exclusively for 4), but now I'd like to get even more involved.  Thank you for your assistance.  

-Patrick A. Read-