Hi Erez,
We've found a reproducible bug in unionfs when used with NFS. If you
do this:
# mkdir x nfs new-storage
# mount -t nfs SOME-NFS-VOLUME nfs
# modprobe unionfs
# mount -t unionfs -o dirs=./x=rw:./nfs=ro unionfs new-storage
# l new-storage
You'll get the OOPS below (the kernel is a 2.6.24 vanilla with
unionfs patch applied):
"""
Registering unionfs 2.2.3 (for 2.6.24)
BUG: unable to handle kernel NULL pointer dereference at virtual address
00000000
printing eip: 00000000 *pde = 00000000
Oops: 0000 [#1]
Modules linked in: unionfs nfs af_packet snd_seq_dummy snd_seq_oss
snd_seq_midi_event snd_seq ipv6 snd_pcm_oss snd_mixer_oss nfsd lockd nfs_acl
auth_rpcgss sunrpc exportfs binfmt_misc loop dm_mirror dm_mod sata_via libata
scsi_mod floppy cpufreq_ondemand cpufreq_conservative cpufreq_powersave
freq_table parport_pc parport snd_via82xx rtc_cmos gameport rtc_core rtc_lib
snd_ac97_codec ac97_bus snd_pcm snd_timer snd_page_alloc snd_mpu401_uart
snd_rawmidi snd_seq_device snd soundcore pcspkr ehci_hcd i2c_viapro uhci_hcd
8139cp i2c_core ohci1394 ieee1394 usbcore ide_cd cdrom 8139too mii shpchp
firewire_ohci pci_hotplug via_agp firewire_core crc_itu_t agpgart evdev ext3
jbd ide_disk ide_generic via82cxxx ide_core
Pid: 4090, comm: ls Not tainted (2.6.24-1mdv #1)
EIP: 0060:[<00000000>] EFLAGS: 00010282 CPU: 0
EIP is at 0x0
EAX: dc1a3540 EBX: e0e1e6d4 ECX: 00000000 EDX: dc1a29a4
ESI: dc1a29a4 EDI: dc1a2a40 EBP: dd64fc84 ESP: dd64fc68
DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
Process ls (pid: 4090, ti=dd64e000 task=de6aabb0 task.ti=dd64e000)
Stack: c01776ed 00000000 dd64fc90 dc1a3540 dc1a2a40 dd64fc90 dc1a35c8 dd64fca4
c0178937 00000010 1210cd94 00000010 e0d82725 dc1a3540 dc1a2a40 dd64fd14
e0d7e160 dd64fcd4 c01804af dc1a2ab8 dd64fd00 dc18e3ac dc1a2a40 c01800ab
Call Trace:
[<c01054b2>] show_trace_log_lvl+0x1a/0x2f
[<c0105562>] show_stack_log_lvl+0x9b/0xa3
[<c0105610>] show_registers+0xa6/0x178
[<c01057f8>] die+0x116/0x202
[<c02cc070>] do_page_fault+0x561/0x63f
[<c02ca8ba>] error_code+0x6a/0x70
[<c0178937>] lookup_one_len+0x3b/0x42
[<e0d7e160>] is_opaque_dir+0x68/0xab [unionfs]
[<e0d7e706>] unionfs_lookup_backend+0x563/0x9a6 [unionfs]
[<e0d77242>] unionfs_lookup+0x6d/0x180 [unionfs]
[<c0177596>] do_lookup+0xa2/0x13f
[<c017918e>] __link_path_walk+0x740/0xb30
[<c01795c7>] link_path_walk+0x49/0xbc
[<c0179652>] path_walk+0x18/0x1a
[<c01798d3>] do_path_lookup+0x179/0x1dc
[<c017a0b7>] __user_walk_fd+0x32/0x44
[<c0173f7e>] vfs_lstat_fd+0x18/0x3e
[<c017400f>] vfs_lstat+0x11/0x13
[<c0174025>] sys_lstat64+0x14/0x28
[<c0103e02>] sysenter_past_esp+0x6b/0xc9
=======================
Code: Bad EIP value.
EIP: [<00000000>] 0x0 SS:ESP 0068:dd64fc68
---[ end trace 140a045c14fdd94a ]---
"""
--
Luiz Fernando N. Capitulino
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unionfs@mail.fsl.cs.sunysb.edu
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