kernel NULL pointer dereference in netback_uevent

["Olivier B." <xen.list@daevel.fr>]

Hi,

I've just compile a new pv_ops 2.6.32.16 pv_ops kernel for my Dom0, it 
works but when I reboot a DomU I obtain that strace :

Jul 24 01:48:08 keron kernel: [ 2108.807624] vlan: port 2(vif2.0) 
entering disabled state
Jul 24 01:48:08 keron kernel: [ 2108.819009] vlan: port 2(vif2.0) 
entering disabled state
Jul 24 01:48:09 keron kernel: [ 2109.869360] BUG: unable to handle 
kernel NULL pointer dereference at 0000000000000150
Jul 24 01:48:09 keron kernel: [ 2109.869457] IP: [<ffffffff811fdfab>] 
netback_uevent+0x8b/0xb9
Jul 24 01:48:09 keron kernel: [ 2109.869515] PGD 3e06d067 PUD 324cc067 
PMD 0
Jul 24 01:48:09 keron kernel: [ 2109.869571] Oops: 0000 [#1] SMP
Jul 24 01:48:09 keron kernel: [ 2109.869620] last sysfs file: 
/sys/devices/vif-3-0/uevent
Jul 24 01:48:09 keron kernel: [ 2109.869670] CPU 3
Jul 24 01:48:09 keron kernel: [ 2109.869711] Modules linked in: 
xt_tcpudp xt_physdev bridge xen_evtchn iptable_filter iptable_mangle 
xenfs iptable_raw ip_tables x_tables authenc esp4 ah4 
xfrm4_mode_transport deflate zlib_deflate ctr twofish twofish_common 
camellia serpent blowfish cast5 des_generic cbc aes_x86_64 aes_generic 
xcbc rmd160 sha256_generic sha1_generic hmac crypto_null af_key xfs 
exportfs 8021q garp stp drbd cn tpm_tis tpm tpm_bios i2c_i801 i2c_core 
snd_pcm snd_timer snd soundcore snd_page_alloc pcspkr joydev evdev 
ioatdma button processor acpi_processor ext3 jbd mbcache dm_mod usbhid 
hid ata_generic uhci_hcd ses sd_mod crc_t10dif enclosure ata_piix 
ehci_hcd libata megaraid_sas usbcore nls_base scsi_mod ixgbe mdio 
thermal thermal_sys igb dca [last unloaded: scsi_wait_scan]
Jul 24 01:48:09 keron kernel: [ 2109.870516] Pid: 8893, comm: udevd Not 
tainted 2.6.32.16-dae-dom0 #1 S5520HC
Jul 24 01:48:09 keron kernel: [ 2109.870571] RIP: 
e030:[<ffffffff811fdfab>]  [<ffffffff811fdfab>] netback_uevent+0x8b/0xb9
Jul 24 01:48:09 keron kernel: [ 2109.870659] RSP: e02b:ffff88003e617e08  
EFLAGS: 00010246
Jul 24 01:48:09 keron kernel: [ 2109.870709] RAX: 01000000000000c1 RBX: 
ffff88003cde9000 RCX: 000000000080007e
Jul 24 01:48:09 keron kernel: [ 2109.870764] RDX: ffff88003d1bfdc0 RSI: 
ffffea0000d5e1c8 RDI: 01000000000002c0
Jul 24 01:48:09 keron kernel: [ 2109.870820] RBP: ffff88003222c000 R08: 
0000000000000000 R09: 0000000000000073
Jul 24 01:48:09 keron kernel: [ 2109.870875] R10: 0000000000000000 R11: 
0000000000000400 R12: 0000000000000000
Jul 24 01:48:09 keron kernel: [ 2109.870931] R13: ffff88003d1bfb00 R14: 
ffff88003e54c000 R15: ffffffff8149c020
Jul 24 01:48:09 keron kernel: [ 2109.870988] FS:  00007f6b21e877a0(0000) 
GS:ffff88000345f000(0000) knlGS:0000000000000000
Jul 24 01:48:09 keron kernel: [ 2109.871074] CS:  e033 DS: 0000 ES: 0000 
CR0: 000000008005003b
Jul 24 01:48:09 keron kernel: [ 2109.871124] CR2: 0000000000000150 CR3: 
00000000338f6000 CR4: 0000000000002660
Jul 24 01:48:09 keron kernel: [ 2109.871180] DR0: 0000000000000000 DR1: 
0000000000000000 DR2: 0000000000000000
Jul 24 01:48:09 keron kernel: [ 2109.871235] DR3: 0000000000000000 DR6: 
00000000ffff0ff0 DR7: 0000000000000400
Jul 24 01:48:09 keron kernel: [ 2109.871291] Process udevd (pid: 8893, 
threadinfo ffff88003e616000, task ffff88003d541c00)
Jul 24 01:48:09 keron kernel: [ 2109.871376] Stack:
Jul 24 01:48:09 keron kernel: [ 2109.871414]  00000000000080d0 
ffff88003cde9040 ffff88003222c000 ffff88003fc2d840
Jul 24 01:48:09 keron kernel: [ 2109.871479] <0> ffff88003cde9050 
ffffffff8122a313 ffff88003e617f58 ffff88003fc2d840
Jul 24 01:48:09 keron kernel: [ 2109.871579] <0> ffff88003cde9050 
0000000000000000 ffff88003222c000 ffffffff8122afda
Jul 24 01:48:09 keron kernel: [ 2109.871709] Call Trace:
Jul 24 01:48:09 keron kernel: [ 2109.871752]  [<ffffffff8122a313>] ? 
dev_uevent+0xff/0x141
Jul 24 01:48:09 keron kernel: [ 2109.871803]  [<ffffffff8122afda>] ? 
show_uevent+0x7e/0xd0
Jul 24 01:48:09 keron kernel: [ 2109.871854]  [<ffffffff81229ff9>] ? 
dev_attr_show+0x1e/0x44
Jul 24 01:48:09 keron kernel: [ 2109.871907]  [<ffffffff810b8aeb>] ? 
__get_free_pages+0x9/0x47
Jul 24 01:48:09 keron kernel: [ 2109.871959]  [<ffffffff8113ce84>] ? 
sysfs_read_file+0xab/0x131
Jul 24 01:48:09 keron kernel: [ 2109.872011]  [<ffffffff810eda9d>] ? 
vfs_read+0xa1/0xfc
Jul 24 01:48:09 keron kernel: [ 2109.872061]  [<ffffffff810edbab>] ? 
sys_read+0x45/0x6b
Jul 24 01:48:09 keron kernel: [ 2109.872111]  [<ffffffff81011a82>] ? 
system_call_fastpath+0x16/0x1b
Jul 24 01:48:09 keron kernel: [ 2109.872163] Code: c7 c6 a2 7a 3e 81 31 
c0 48 89 ef e8 8c fe f8 ff 85 c0 74 0f 4c 89 ef bd f4 ff ff ff e8 c3 7b 
ee ff eb 2c 4c 89 ef e8 b9 7b ee ff <49> 8b 94 24 50 01 00 00 48 89 ef 
31 c0 48 c7 c6 ac 7a 3e 81 bd
Jul 24 01:48:09 keron kernel: [ 2109.872583] RIP  [<ffffffff811fdfab>] 
netback_uevent+0x8b/0xb9
Jul 24 01:48:09 keron kernel: [ 2109.872637]  RSP <ffff88003e617e08>
Jul 24 01:48:09 keron kernel: [ 2109.872681] CR2: 0000000000000150
Jul 24 01:48:09 keron kernel: [ 2109.873013] ---[ end trace 
7c91c1bde16ffdaa ]---

Note : I'm running Xen 4.0.1~rc3-1 from Debian Squeeze.
Do you need more info ?

Thanks,
Olivier