# Kernel panic after udev upgrade

## johnisevil

Like a lot of people on here, I went through the whole udev/device-mapper fiasco. It seemed to be a pretty straightforward fix and it seemed to have went well. The problems began when I went to reboot. Once the boot process hit the device probing stage it caused a kernel panic and does so at the same point every time. I'm using gentoo-sources-2.6.30 if that helps. I'm not understanding why this is all of a sudden causing kernel panics when this version of the kernel worked fine before these upgrades. I had to boot into an older 2.6.27 kernel which seems to be unaffected by this aside from a warning about disabling SYSFS_DEPRECATED.

Any ideas?

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## johnisevil

So I tried upgrading to 2.6.31 and it seems the problem has went away. But it's still bothering me on why it's causing 2.6.30 to panic yet an older kernel still works just fine.

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## jprobichaud

Well, you're lucky...  

I have a mdadm(raid1) + lvm2 setup and since I did the last upgrade to udev/lvm2 (forcing me to remove device-mapper), I can't boot anymore.

I'm using a setup where my ext-4 root partition is inside a LVM volume and I'm using a custom initrd to  setup everything and mount the volumes (I know I know, I'm asking for trouble....)

I get some strange messages during boot time which loosely look like this (I'm retyping the messages)

```

mdadm: /dev/md2 has been started with 2 drives

initrd: Finding device mapper major and minor numbers (10,62)

initrd: Activating LVM2 volumes

  Failed to find sysfs mount point

  Reading all physical volumes, This may take a while...

md2: unknown partition table

  Found volume group "vg0" using metadata type lvm2

  Failed to find sysfs mount point

  6 logical volume(s) in volume group "vg0" now active

initrd: mounting root filesystem /dev/vg0/root  ro

EXT3-fs: dm-0: couldn't mount because of unsupported optional features (240)

EXT2-fs: dm-0: couldn't mount because of unsupported optional features (240)

EXT4-fs (dm-0): barriers enabled

EXT4-fs (dm-0): delayed allocation enabled

EXT4-fs (dm-0): file extents enabled

EXT4-fs (dm-0):  mballoc enabled

EXT4-fs (dm-0):  mounted filesystem with ordered data mode

initrd: Unmounting /proc

initrd: Changing rootts and proceeding with boot

INIT: version 2.86

...

 * Mounting systs at /sys ... [ok]

...

 * Checking root fileststen:

fsck.ext4: No such file or directory while trying to open /dev/vg0/root

/dev/vg0/root"

The superb lock could not be read...

...

```

Then I get to the rescue console and I can confirm that I can't reach /dev/vg0 ...

any commands I try using lvm fails with the following message:

```

Locking type -1 initialisation failed

```

Now I can actually see the data on my root partition, probably because the lvm tools inside the initrd can still work.

So I'm confused, what to do next?  Boot using a rescue cd, rebuild the kernel and the initrd disk with the new lvm?

What's this sysfs error?

Any help will be greatly appreciated...

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## VoidMage

As for the locking error, there's a bug about it in bugzilla.

As for '/dev/vg0/root', IIRC, device naming scheme has changed.

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## jprobichaud

hum, thanks for the reply, but that doesn't seem to help me ...

I've tried to rebuild my initrd "drive" with the new lvm, hoping that it would help, but to no avail...

I've also changed the root= parameter from 

```

root=/dev/vg0/root

```

 to

```

 root=/dev/mapper/vg0-root

```

but that doesn't help...

I can access everything using the minimal cd.  should I rebuild the kernel since I've updated the lvm2 package?  What else should I try?

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## jprobichaud

I've find this  bug 292833  so I've upgraded lvm2 to 2.02.56-r1 (and rebuild udev and hal) as well as my initrd disk and I still can't boot...

this isn't fun...  it was marked as a stable upgrade....

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## jprobichaud

ok, this is now solved for me.  In the above mentioned bug, there is a comment saying that this is solved with the very latest genkernel,  so in the end I needed:

sys-fs/lvm2-2.02.56-r1

sys-kernel/genkernel-3.4.10.906

edit /etc/genkernel.conf to set:

```

LVM="yes"

DMRAID="yes"

MDADM="yes"

```

edit the kernel .config to make sure that:

```

# CONFIG_SYSFS_DEPRECATED_V2 is not set

# CONFIG_ACPI_SYSFS_POWER is not set

CONFIG_WIRELESS_EXT_SYSFS=y

CONFIG_SYSFS=y

Made the LVM needed modules built in

CONFIG_BLK_DEV_DM=y

CONFIG_DM_DEBUG=y

CONFIG_DM_CRYPT=y

CONFIG_DM_SNAPSHOT=y

CONFIG_DM_MIRROR=y

# CONFIG_DM_LOG_USERSPACE is not set

CONFIG_DM_ZERO=y

CONFIG_DM_MULTIPATH=y

# CONFIG_DM_MULTIPATH_QL is not set

# CONFIG_DM_MULTIPATH_ST is not set

CONFIG_DM_DELAY=m

CONFIG_DM_UEVENT=y

```

run genkernel:

```

genkernel --no-clean --no-mrproper --config=/usr/src/linux/.config --lvm2 --mdadm --loglevel=2 all

```

Setup grub:

```

title Gentoo Linux Take-6 GentooSources-2.6.31-rc5 GK

root (hd0,0)                                         

kernel /kernel-genkernel-x86_64-2.6.31-gentoo-r5-take6 root=/dev/ram0 real_root=/dev/mapper/vg0-root dolvm2 dodmraid

initrd /initramfs-genkernel-x86_64-2.6.31-gentoo-r5-take6   

```

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