From: Jari Ruusu <jariruusu@users.sourceforge.net>
To: linux-kernel@vger.kernel.org
Cc: Rusty Russell <rusty@rustcorp.com.au>,
Al Viro <viro@zeniv.linux.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: 2.6.35-rc2 module reference counting broken
Date: Mon, 07 Jun 2010 08:20:30 +0300 [thread overview]
Message-ID: <4C0C819E.EA5D6A18@users.sourceforge.net> (raw)
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
next reply other threads:[~2010-06-07 5:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-07 5:20 Jari Ruusu [this message]
2010-06-07 6:44 ` 2.6.35-rc2 module reference counting broken Al Viro
2010-06-08 23:48 ` Al Viro
2010-06-09 7:01 ` Tejun Heo
2010-06-10 6:34 ` Jari Ruusu
2010-06-10 11:31 ` Tejun Heo
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