[Bug 833891] Re: lvscan often times out during boot

[Boris Devouge]

So the same deadlock issue was hit again:

root      1378     1  0  1031   560   0 17:28 ?        00:00:00 /lib/udev/watershed sh -c /sbin/lvm vgscan; /sbin/lvm vgchange -a y
root      1379  1378  0  1055   588   0 17:28 ?        00:00:00 sh -c /sbin/lvm vgscan; /sbin/lvm vgchange -a y
root      1381  1379  0  8719 14080   0 17:28 ?        00:00:00 /sbin/lvm vgchange -a y
root      1387     1  0  1031   324   0 17:28 ?        00:00:00 /lib/udev/watershed sh -c /sbin/lvm vgscan; /sbin/lvm vgchange -a y

There is clearly 2 incarnations of the udev rule being triggered.

The vgchange command took the LVM lock and waits for some udev event:
(gdb) bt
#0  0x00007fd37e8750f7 in semop () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007fd37ed3863c in dm_udev_wait () from /lib/libdevmapper.so.1.02.1
#2  0x0000000000476d8b in ?? ()
#3  0x0000000000477a9e in dev_manager_activate ()
#4  0x000000000042f15c in ?? ()
#5  0x000000000043069b in ?? ()
#6  0x00000000004311ee in lv_activate_with_filter ()
#7  0x000000000047c5c1 in ?? ()
#8  0x000000000044e8a8 in ?? ()
#9  0x000000000044f4a6 in lock_vol ()
#10 0x0000000000428103 in ?? ()
#11 0x0000000000424036 in ?? ()
#12 0x0000000000424ddd in process_each_vg ()
#13 0x000000000041acd9 in lvm_run_command ()
#14 0x000000000041b4d4 in lvm2_main ()
#15 0x00007fd37e7abeff in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6
#16 0x000000000040f1a9 in _start ()
 
Apparently the udev event does not arrive, because the second rule instance also triggered vgscan/vgchange, and those cannot proceed because of the flock() taken by the first vgchange.

Any views?  What version of liblvm do we plan to ship in 11.10 Oneiric?
(2.02.66 seems dated)

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https://bugs.launchpad.net/bugs/833891

Title:
  lvscan often times out during boot

Status in “udev” package in Ubuntu:
  Confirmed

Bug description:
  I'm not 100% certain that mountall is the problem, but seems a good
  place to start.

  I have some LVM partitions on my laptop, and some filesystems on there
  are mounted through fstab:

  /dev/schroots/schroots /srv/devel ext3 defaults,relatime 0 0
  /dev/schroots/isos /iso ext4 defaults,relatime 0 0

  Often (1/3 of the time?) boot hangs, and after a minute or so I get a
  message saying something about watershed and lvscan timing out.  Then
  it proceeds to mount everything readonly.

  Other times boot proceeds with no problem.

  ProblemType: Bug
  DistroRelease: Ubuntu 11.10
  Package: mountall 2.31
  ProcVersionSignature: Ubuntu 3.0.0-9.12-generic 3.0.3
  Uname: Linux 3.0.0-9-generic x86_64
  NonfreeKernelModules: nvidia
  Architecture: amd64
  Date: Thu Aug 25 10:56:52 2011
  InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Alpha amd64 (20110627.1)
  ProcEnviron:
   PATH=(custom, user)
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  SourcePackage: mountall
  UpgradeStatus: No upgrade log present (probably fresh install)

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