On shutdown: “umount2: Device or resource busy, umount:/dev/sda2 busy - remounted read-only” appears

[tuhu]

I got this message when shutdown:

Unmounting local filesystems...
umount2: Device or resource busy
umount:/dev/sda2 busy - remounted read-only
Will now halt

This message appears every time I shut down my system. This showed up the following time after I updated my Ubuntu 12.04.1 to linux-kernel-3.2.0-36-generic today.

The next booting, there was an orphan inode recovery by fsck.

Any known implication or workaround here?

P.S.: /dev/sda2 is my home partition.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.2.0-36-generic 3.2.0-36.57
ProcVersionSignature: Ubuntu 3.2.0-36.57-generic 3.2.35
Uname: Linux 3.2.0-36-generic x86_64
NonfreeKernelModules: nvidia
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu17.1
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: PCH [HDA Intel PCH], device 0: ALC269VB Analog [ALC269VB Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: apg 2755 F.... pulseaudio
 /dev/snd/controlC0: apg 2755 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'PCH'/'HDA Intel PCH at 0xdf000000 irq 44'
   Mixer name : 'Realtek ALC269VB'
   Components : 'HDA:10ec0269,10431ad3,00100100'
   Controls : 19
   Simple ctrls : 11
Card1.Amixer.info:
 Card hw:1 'NVidia'/'HDA NVidia at 0xdd080000 irq 17'
   Mixer name : 'Nvidia GPU 14 HDMI/DP'
   Components : 'HDA:10de0014,10de0101,00100100'
   Controls : 24
   Simple ctrls : 4
Date: Sat Jan 19 21:10:18 2013
HibernationDevice: RESUME=UUID=d80a18e3-d512-4dc7-a88b-d211cb9a4402
InstallationMedia: Ubuntu 12.04.1 Custom DVD amd64 - Release amd64
MachineType: ASUSTeK Computer Inc. K43SV
MarkForUpload: True
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-36-generic root=UUID=d9007a77-fa58-4282-8eb0-eb71328965eb ro
RelatedPackageVersions:
 linux-restricted-modules-3.2.0-36-generic N/A
 linux-backports-modules-3.2.0-36-generic N/A
 linux-firmware 1.79.1
SourcePackage: linux
StagingDrivers: rts5139 mei
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 07/11/2011
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: K43SV.304
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: K43SV
dmi.board.vendor: ASUSTeK Computer Inc.
dmi.board.version: 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 9
dmi.chassis.vendor: ASUSTeK Computer Inc.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrK43SV.304:bd07/11/2011:svnASUSTeKComputerInc.:pnK43SV:pvr1.0:rvnASUSTeKComputerInc.:rnK43SV:rvr1.0:cvnASUSTeKComputerInc.:ct9:cvr1.0:
dmi.product.name: K43SV
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK Computer Inc.

[Brad Figg (brad-figg)]

This change was made by a bot.

[andschuster (andreas-schuster2)]

I observed the following: After upgrading to kernel 2.3.0-36 on my desktop and on my laptop I often see that fsck clears orphaned inodes on ext4-filesystems when I reboot. I didn't saw that before the upgrade. After returning to 2.3.0-35 this problem disappeared on both machines.

[markusj (markusj)]

I can confirm this issue, it appeared after upgrading from 3.2.0-35 to 3.2.0-36. The quantal kernel (3.5.0-22) is also affected. Selecting the old kernel in grub makes the warnings go away.

I tried to locate the cause of this problem but during unmount no handles remain open. Somehow the kernel blocks the /home filesystem internally ...

lsof reports no open files in /home
fuser -v -a -m reports no open files in /home
losetup reports no open loop files in /home
there are not swap-files in /home
-> there is no reason why the kernel blocks unmounting.

For debugging purposes, you might use the attached script and put it into /etc/rc0.d and /etc/rc6.d, i have found it in some forum and adopted it slightly.

[Paulo Matias (paulo-matias)]

Perhaps duplicate of LP: #1101355.

[markusj (markusj)]

Yes, this sounds identical. If the proposed patch works, hopefully it gets applied fast to the older kernels, too.

Quite interesting, if i boot into runlevel 1 directly, i can mount/unmount /home as often as i like ...

[Joseph Salisbury (jsalisbury)]

This may be a duplicate of bug 1101666

[Joseph Salisbury (jsalisbury)]

Would it be possible for folks affected by this bug to test the 3.2.0-36.56 kernel and see if it also exhibits this bug. It can be downloaded from:

https://launchpad.net/ubuntu/+source/linux/3.2.0-36.56

From that link, select your particular arch under the "Builds" section.

Thanks in advance!

[Joseph Salisbury (jsalisbury)]

One additional request in addition to testing 3.2.0-36.56. Can folks affected by this bug also test the v3.2.0-35 kernel, which can downloaded from:

https://launchpad.net/ubuntu/+source/linux/3.2.0-35.55

Again, from that link, select your particular arch under the "Builds" section.

Thanks in advance!

[markusj (markusj)]

@jsalisbury: As stated in #4: Yes, 3.2.0-36 is also affected, it introduced the bug into the 3.2 kernel line. The previuous kernel, 3.2.0-35 is (still) working fine.