2.6.35-rc2 module reference counting broken

[Jari Ruusu]

Someone broke block device module reference counting. Problem occours when a
modular block device is mounted and unmounted. Not when it is directly read.
2.6.34 kernel works OK, but 2.6.35-rc2 kernel seems to increase usage count
by one for each mount + umount pair.

# uname -s -r -m
Linux 2.6.35-rc2 i686
# grep CONFIG_SMP /usr/src/linux-2.6.35-rc2/.config
# CONFIG_SMP is not set
# grep CONFIG_MODULE_UNLOAD /usr/src/linux-2.6.35-rc2/.config
CONFIG_MODULE_UNLOAD=y
# grep CONFIG_BLK_DEV_FD /usr/src/linux-2.6.35-rc2/.config
CONFIG_BLK_DEV_FD=m
# lsmod
Module                  Size  Used by
# modprobe floppy
# lsmod
Module                  Size  Used by
floppy                 40029  0
# mount -t ext2 /dev/fd0 /mnt
# umount /mnt
# lsmod
Module                  Size  Used by
floppy                 40029  1
# rmmod floppy
ERROR: Module floppy is in use
# echo $?
1
# 

(reboot)

# uname -s -r -m
Linux 2.6.35-rc2 i686
# lsmod
Module                  Size  Used by
# modprobe floppy
# lsmod
Module                  Size  Used by
floppy                 40029  0
# dd if=/dev/fd0 of=/dev/null bs=4096 count=1 conv=notrunc 2>/dev/null
# lsmod
Module                  Size  Used by
floppy                 40029  0
# rmmod floppy
# echo $?
0
# lsmod
Module                  Size  Used by
# 

-- 
Jari Ruusu  1024R/3A220F51 5B 4B F9 BB D3 3F 52 E9  DB 1D EB E3 24 0E A9 DD
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