unionfs problems with linux-ubuntu-modules-2.6.22-13-generic_2.6.22-13.34_amd64.deb

[pm13]

Binary package hint: linux-ubuntu-modules-2.6.22-13-generic

I try to test readonly root filesystem on nfs with unionfs. Maybe it is not good description so I paste my script:

#!/bin/sh

mountroot() {
    export rootmnt=/ro
    mkdir -p /ro
    mkdir -p /rw
    . /scripts/nfs
    mountroot
    mount -t tmpfs none /rw
    mount -t unionfs -o dirs=/rw=rw:/ro=ro none /root
    export rootmnt=/root
}

I don't know if it is right (I learn it) but it works with linux-ubuntu-modules-2.6.22-13-generic_2.6.22-13.33_amd64.deb and it doesn't work with linux-ubuntu-modules-2.6.22-13-generic_2.6.22-13.34_amd64.deb.

[pm13 (petr-marhoun)]

The latest version (linux-image-2.6.22-14-generic - 2.6.22-14.43, linux-ubuntu-modules-2.6.22-14-generic - 2.6.22-14.35) has the same problem.

[Jonas Bonn (jonas.bonn)]

Confirmed in 2.6.22-14-generic (amd64), even with 'ro' replaced by 'nfsro'

mount -t unionfs -o dirs=/rw=rw:/ro=nfsro unionfs /root

[Jonas Bonn (jonas.bonn)]

There was a bugfix from Unionfs 2.0 backported to 1.2 as per bug #85145. This problem looks like the problem reported in bug #85145... has that backport been missed in the UnionFS 1.4 that is in Gutsy now?

[Philipp Richter (philipp-ist)]

Same here. Kernel is 2.6.22-14-generic_2.6.22-14.35_i386.

The patch from bug #85145 does NOT solve this problem (took the patch from ubuntu-feisty git tree: a47c7c9186612ad5f59bcca95bd5fac5cb01b287).

We are using ubuntu for our netboot thin clients. Root fs is nfs ro mounted, /etc and /var are mounted as union to a tmpfs in an init script. We have been using this technique since ubuntu dapper and it always has worked.

Here is the oops:

[ 9.664000] BUG: unable to handle kernel NULL pointer dereference at virtual address 00000004
[ 9.664000] printing eip:
[ 9.664000] e01f6c42
[ 9.664000] *pde = 00000000
[ 9.664000] Oops: 0000 [#1]
[ 9.664000] SMP
[ 9.664000] Modules linked in: unionfs netconsole af_packet nfs lockd sunrpc b44 mii ehci_hcd uhci_hcd usbcore raid10 raid456 xor raid1 raid0 multipath linear md_mod dm_mirror dm_snapshot dm_mod thermal processor fan fuse apparmor commoncap
[ 9.668000] CPU: 0
[ 9.668000] EIP: 0060:[<e01f6c42>] Not tainted VLI
[ 9.668000] EFLAGS: 00010246 (2.6.22-14-generic #1)
[ 9.668000] EIP is at nfs_lookup+0xd2/0x260 [nfs]
[ 9.668000] eax: 00000000 ebx: e021aec0 ecx: 00000000 edx: ddc5cb08
[ 9.668000] esi: 00000000 edi: de15f000 ebp: 00000000 esp: deb9bbc4
[ 9.668000] ds: 007b es: 007b fs: 00d8 gs: 0033 ss: 0068
[ 9.668000] Process bash (pid: 2514, ti=deb9a000 task=de3a59f0 task.ti=deb9a000)
[ 9.668000] Stack: deb9bbd8 00000000 00000000 ddc5cb08 0007c89a 00000006 470e2508 00000000
[ 9.668000] 470ccf4c 00000000 470ccf4d 00000000 00000005 0000a1ff 00000001 00000000
[ 9.668000] 00000000 00000025 00000000 00000000 00000000 00000000 00009302 00000000
[ 9.668000] Call Trace:
[ 9.668000] [<e01f656e>] nfs_lookup_revalidate+0x24e/0x450 [nfs]
[ 9.668000] [<e01f75ec>] nfs_access_get_cached+0x1c/0x110 [nfs]
[ 9.668000] [<e01f77c1>] nfs_permission+0xe1/0x1f0 [nfs]
[ 9.668000] [<e016438b>] unionfs_read_inode+0x7b/0xd0 [unionfs]
[ 9.668000] [<c01926d9>] d_alloc+0x109/0x190
[ 9.668000] [<c01896a6>] lookup_one_len_nd+0xe6/0x110
[ 9.672000] [<e016936a>] unionfs_lookup_backend+0x36a/0x880 [unionfs]
[ 9.672000] [<c01925eb>] d_alloc+0x1b/0x190
[ 9.672000] [<c01926d9>] d_alloc+0x109/0x190
[ 9.672000] [<c0187ef8>] do_lookup+0x148/0x190
[ 9.672000] [<c018a017>] __link_path_walk+0x867/0xe70
[ 9.672000] [<c02183b7>] vgacon_scroll+0x107/0x1d0
[ 9.672000] [<c024f3b1>] scrup+0xe1/0xf0
[ 9.672000] [<c018a665>] link_path_walk+0x45/0xc0
[ 9.672000] [<c018a8d7>] do_path_lookup+0x97/0x1d0
[ 9.672000] [<c018b541>] __path_lookup_intent_open+0x51/0xa0
[ 9.672000] [<c018b620>] path_lookup_open+0x20/0x30
[ 9.672000] [<c018b71a>] open_namei+0x5a/0x600
[ 9.672000] [<c016ce18>] __handle_mm_fault+0x288/0xb00
[ 9.672000] [<c017edf3>] do_filp_open+0x33/0x60
[ 9.672000] [<c017ee6e>] do_sys_open+0x4e/0xf0
[ 9.672000] [<c017ef4c>] sys_open+0x1c/0x20
[ 9.672000] [<c01041d2>] sysenter_past_esp+0x6b/0xa9
[ 9.672000] =======================
[ 9.672000] Code: 24 0c 8d 57 1c 89 0c 24 8d 8c 24 a6 00 00 00 ff 53 20 31 d2 83 f8 fe 74 6f 85 c0 89 c6 0f 88 0a 01 00 00 8b 54...

[Sergio Zanchetta (primes2h)]

The 18 month support period for Gutsy Gibbon 7.10 has reached its end of life -
http://www.ubuntu.com/news/ubuntu-7.10-eol . As a result, we are closing the
linux-backports-modules-2.6.22 task. It would be helpful if you could test the
new Jaunty Jackalope 9.04 release and confirm if this issue remains -
http://www.ubuntu.com/getubuntu/releasenotes/904overview. If the issue still exists with the Jaunty
release, please update this report by changing the Status of the "linux (Ubuntu)"
task from "Incomplete" to "New". Thanks in advance.

[Sergio Zanchetta (primes2h)]

Sorry, I meant linux-ubuntu-modules-2.6.22 task.

[Jeremy Foshee (jeremyfoshee)]

This bug report was marked as Incomplete and has not had any updated comments for quite some time. As a result this bug is being closed. Please reopen if this is still an issue in the current Ubuntu release http://www.ubuntu.com/getubuntu/download . Also, please be sure to provide any requested information that may have been missing. To reopen the bug, click on the current status under the Status column and change the status back to "New". Thanks.

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