[Bug 536994] Re: kernel lockups unmounting ext4 lvm2 snapshots

[Kees Cook]

** Description changed:

  I have experienced IO lock-ups when unmounting lvm2 snapshots partitions
  containing ext4.  All IO, sound, etc will hang, though alt-sysrq remains
  responsive (I can do alt-sysrq-b and it reboots, e.g.).
  
  This problem is intermittent, unfortunately, but I see it most often
  when I have performing a package build via sbuild in an LVM based
  snapshot schroot.
  
  Steps to reproduce (probably not the minimal test case...):
  Terminal 1:
  - create an MD device across two physical drives
  - sudo -s
  - vgcreate testvg /dev/md0
  - lvcreate -L10G -n testlv testvg
  - mkfs.ext4 /dev/testvg/testlv
  - mkdir /mnt/test
- - mount /dev/testvg/testlv
+ - mount /dev/testvg/testlv /mnt/test
  - apt-get install ubuntu-dev-tools
  - while :; do cp -a /usr /mnt/test; sleep 1; rm -rf /mnt/test/usr; done
  
  Then in Terminal 2:
  - mk-sbuild --vg=VG karmic
  - cd /tmp
  - dget https://launchpad.net/ubuntu/+archive/primary/+files/dpkg_1.15.4ubuntu2.dsc
  - while :; do sbuild -d karmic dpkg*.dsc"; done &
  - while :; do sbuild -d karmic dpkg*.dsc"; done
  
  ProblemType: Bug
  AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.21.
  AplayDevices:
-  **** List of PLAYBACK Hardware Devices ****
-  card 0: Intel [HDA Intel], device 0: ALC268 Analog [ALC268 Analog]
-    Subdevices: 1/1
-    Subdevice #0: subdevice #0
+  **** List of PLAYBACK Hardware Devices ****
+  card 0: Intel [HDA Intel], device 0: ALC268 Analog [ALC268 Analog]
+    Subdevices: 1/1
+    Subdevice #0: subdevice #0
  Architecture: amd64
  AudioDevicesInUse:
-  USER        PID ACCESS COMMAND
-  /dev/snd/controlC0:  kees       3851 F.... pulseaudio
+  USER        PID ACCESS COMMAND
+  /dev/snd/controlC0:  kees       3851 F.... pulseaudio
  CRDA: Error: [Errno 2] No such file or directory
  Card0.Amixer.info:
-  Card hw:0 'Intel'/'HDA Intel at 0xe0420000 irq 22'
-    Mixer name	: 'Realtek ALC268'
-    Components	: 'HDA:10ec0268,80860000,00100003'
-    Controls      : 17
-    Simple ctrls  : 11
+  Card hw:0 'Intel'/'HDA Intel at 0xe0420000 irq 22'
+    Mixer name	: 'Realtek ALC268'
+    Components	: 'HDA:10ec0268,80860000,00100003'
+    Controls      : 17
+    Simple ctrls  : 11
  Date: Wed Mar 10 15:28:56 2010
  DistroRelease: Ubuntu 10.04
  HibernationDevice: RESUME=/dev/md1
  Package: linux-image-2.6.32-16-generic 2.6.32-16.24
  ProcCmdLine: BOOT_IMAGE=/vmlinuz-2.6.32-16-generic root=/dev/mapper/systemvg-root2lv ro quiet splash
  ProcEnviron:
-  LANGUAGE=en_US:en
-  PATH=(custom, user)
-  LANG=en_US.UTF-8
-  SHELL=/bin/bash
+  LANGUAGE=en_US:en
+  PATH=(custom, user)
+  LANG=en_US.UTF-8
+  SHELL=/bin/bash
  ProcVersionSignature: Ubuntu 2.6.32-16.24-generic
  Regression: Yes
  RelatedPackageVersions: linux-firmware 1.32
  Reproducible: Yes
  RfKill:
-  
+ 
  SourcePackage: linux
  TestedUpstream: No
  Uname: Linux 2.6.32-16-generic x86_64
  WpaSupplicantLog:
-  
+ 
  dmi.bios.date: 09/22/2008
  dmi.bios.vendor: Intel Corp.
  dmi.bios.version: JOQ3510J.86A.0954.2008.0922.2331
  dmi.board.asset.tag: Base Board Asset Tag
  dmi.board.name: DQ35JO
  dmi.board.vendor: Intel Corporation
  dmi.board.version: AAD82085-800
  dmi.chassis.type: 3
  dmi.modalias: dmi:bvnIntelCorp.:bvrJOQ3510J.86A.0954.2008.0922.2331:bd09/22/2008:svn:pn:pvr:rvnIntelCorporation:rnDQ35JO:rvrAAD82085-800:cvn:ct3:cvr:

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kernel lockups unmounting ext4 lvm2 snapshots
https://bugs.launchpad.net/bugs/536994
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