Subject: Re: 3.3.0, 3.4-rc1 reproducible tun Oops

From: Simon Kirby <[email-masked]>
Date: Wed, 4 Apr 2012 22:58:19 -0700

On Thu, Apr 05, 2012 at 04:41:04AM +0200, Eric Dumazet wrote:

> On Wed, 2012-04-04 at 15:05 -0700, Simon Kirby wrote:
> > I use an SSH VPN occasionally from home, and since upgrading the
> > remote
> > kernel to 3.3.0, the it now seems to Oops when I ^C the tunnel with
> > sockets still active. If I start the tunnel, log in to a box through
> > it
> > and run "vmstat 1", ^C the tunnel SSH process, and start it up again,
> > I
> > get an Oops like this:
> > 
> > BUG: unable to handle kernel NULL pointer dereference at
> > 00000000000000ff
> > IP: [<ffffffff810ed5fa>] __kmalloc_track_caller+0xaa/0x1b0
> > PGD 12d2bc067 PUD 0
> > Oops: 0000 [#1] SMP
> > CPU 1
> > Modules linked in: nf_conntrack_netlink nfnetlink iptable_mangle
> > ipt_MASQUERADE xt_state xt_conntrack iptable_nat nf_nat
> > nf_conntrack_ipv4 nf_defrag_ipv4 nf_conntrack hwmon_vid ppp_async
> > ppp_generic slhc crc_ccitt tun nvidia(PO) uvcvideo videobuf2_vmalloc
> > videobuf2_memops videobuf2_core e100
> > 
> > Pid: 16156, comm: sshd Tainted: P           O 3.3.0 #32 System
> > manufacturer System Product Name/A8N-VM CSM
> 
> Hmm, is it happening if you remove the nvidia module ?
> 
> If yes, please try to add slub_debug=FZPU
> 
> CONFIG_SLUB_DEBUG=y
> CONFIG_SLUB=y
> # CONFIG_SLUB_DEBUG_ON is not set

Yes it is, and here we go:

[ 3223.596062] =============================================================================
[ 3223.603618] BUG kmalloc-2048 (Not tainted): Redzone overwritten
[ 3223.603618] -----------------------------------------------------------------------------
[ 3223.603618] 
[ 3223.603618] INFO: 0xffff88017499d240-0xffff88017499d240. First byte 0xcb instead of 0xcc
[ 3223.603618] INFO: Allocated in alloc_netdev_mqs+0x62/0x300 age=2919 cpu=1 pid=3929
[ 3223.603618]  __slab_alloc.constprop.65+0x21b/0x25f
[ 3223.603618]  __kmalloc+0x1a7/0x1c0
[ 3223.603618]  alloc_netdev_mqs+0x62/0x300
[ 3223.603618]  __tun_chr_ioctl+0x903/0xc50 [tun]
[ 3223.603618]  tun_chr_compat_ioctl+0x10/0x20 [tun]
[ 3223.603618]  compat_sys_ioctl+0x8f/0x10d0
[ 3223.603618]  ia32_sysret+0x0/0x5
[ 3223.603618] INFO: Freed in skb_release_data+0xe7/0xf0 age=3004 cpu=1 pid=0
[ 3223.603618]  __slab_free+0x2d/0x28a
[ 3223.603618]  kfree+0x114/0x140
[ 3223.603618]  skb_release_data+0xe7/0xf0
[ 3223.603618]  __kfree_skb+0x19/0xa0
[ 3223.603618]  kfree_skb+0x44/0xb0
[ 3223.603618]  ip_rcv_finish+0xd8/0x2c0
[ 3223.603618]  ip_rcv+0x1f5/0x2b0
[ 3223.603618]  __netif_receive_skb+0x32b/0x410
[ 3223.603618]  netif_receive_skb+0x28/0x80
[ 3223.603618]  napi_skb_finish+0x48/0x60
[ 3223.603618]  napi_gro_receive+0xed/0x130
[ 3223.603618]  nv_rx_process_optimized+0x135/0x270
[ 3223.603618]  nv_napi_poll+0x84/0x5f0
[ 3223.603618]  net_rx_action+0x111/0x200
[ 3223.603618]  __do_softirq+0x99/0x210
[ 3223.603618]  call_softirq+0x1c/0x30
[ 3223.603618] INFO: Slab 0xffffea0005d26600 objects=13 used=9 fp=0xffff880174999290 flags=0x8000000000004081
[ 3223.603618] INFO: Object 0xffff88017499ca40 @offset=19008 fp=0xffff880174999290
[ 3223.603618] 
[ 3223.603618] Bytes b4 ffff88017499ca30: 5f 25 0b 00 01 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a  _%......ZZZZZZZZ
[ 3223.603618] Object ffff88017499ca40: 74 75 6e 30 00 00 00 00 00 00 00 00 00 00 00 00  tun0............
[ 3223.603618] Object ffff88017499ca50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ca60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ca70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ca80: 00 00 00 00 00 00 00 00 00 02 20 00 00 00 ad de  .......... .....
[ 3223.603618] Object ffff88017499ca90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499caa0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cab0: 00 00 00 00 00 00 00 00 06 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cac0: 78 36 d8 81 ff ff ff ff 00 02 20 00 00 00 ad de  x6........ .....
[ 3223.603618] Object ffff88017499cad0: d0 ca 99 74 01 88 ff ff d0 ca 99 74 01 88 ff ff  ...t.......t....
[ 3223.603618] Object ffff88017499cae0: e0 ca 99 74 01 88 ff ff e0 ca 99 74 01 88 ff ff  ...t.......t....
[ 3223.603618] Object ffff88017499caf0: 40 40 00 40 00 00 00 00 49 48 1b 40 00 00 00 00  @@.@....IH.@....
[ 3223.603618] Object ffff88017499cb00: 49 48 1b 40 00 00 00 00 20 00 00 00 00 00 00 00  IH.@.... .......
[ 3223.603618] Object ffff88017499cb10: 07 00 00 00 07 00 00 00 0d 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cb20: 0e 00 00 00 00 00 00 00 a4 02 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cb30: 82 0f 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cb40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cb50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cb60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cb70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cb90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cba0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cbb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cbc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cbd0: 00 00 00 00 00 00 00 00 40 89 03 a0 ff ff ff ff  ........@.......
[ 3223.603618] Object ffff88017499cbe0: e0 87 03 a0 ff ff ff ff 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cbf0: 90 10 00 00 00 04 00 00 00 00 00 00 02 00 00 00  ................
[ 3223.603618] Object ffff88017499cc00: dc 05 00 00 fe ff 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cc10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cc20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cc30: 00 00 06 06 00 00 00 00 38 cc 99 74 01 88 ff ff  ........8..t....
[ 3223.603618] Object ffff88017499cc40: 38 cc 99 74 01 88 ff ff 00 00 00 00 00 00 00 00  8..t............
[ 3223.603618] Object ffff88017499cc50: 50 cc 99 74 01 88 ff ff 50 cc 99 74 01 88 ff ff  P..t....P..t....
[ 3223.603618] Object ffff88017499cc60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cc70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cc90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cca0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ccb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ccc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ccd0: d0 cc 99 74 01 88 ff ff d0 cc 99 74 01 88 ff ff  ...t.......t....
[ 3223.603618] Object ffff88017499cce0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ccf0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cd00: 00 00 00 00 00 00 00 00 90 30 4d 76 01 88 ff ff  .........0Mv....
[ 3223.603618] Object ffff88017499cd10: 20 47 2a 79 01 88 ff ff 01 00 00 00 01 00 00 00   G*y............
[ 3223.603618] Object ffff88017499cd20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cd30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cd40: 38 f1 c1 6e 01 88 ff ff 01 00 00 00 01 00 00 00  8..n............
[ 3223.603618] Object ffff88017499cd50: 80 1a c3 81 ff ff ff ff f4 01 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cd60: 03 03 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cd70: 0b 1b 0b 00 01 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cd90: 00 00 00 00 00 00 00 00 00 40 15 7b 01 88 ff ff  .........@.{....
[ 3223.603618] Object ffff88017499cda0: a0 49 6d 81 ff ff ff ff 40 ca 99 74 01 88 ff ff  .Im.....@..t....
[ 3223.603618] Object ffff88017499cdb0: ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cdc0: 00 01 10 00 00 00 ad de 00 02 20 00 00 00 ad de  .......... .....
[ 3223.603618] Object ffff88017499cdd0: 00 00 00 00 00 00 00 00 00 02 20 00 00 00 ad de  .......... .....
[ 3223.603618] Object ffff88017499cde0: e0 cd 99 74 01 88 ff ff e0 cd 99 74 01 88 ff ff  ...t.......t....
[ 3223.603618] Object ffff88017499cdf0: 04 01 00 00 00 00 00 00 f0 6b 03 a0 ff ff ff ff  .........k......
[ 3223.603618] Object ffff88017499ce00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ce10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ce20: 40 d0 c9 6e 01 88 ff ff 80 da a6 73 01 88 ff ff  @..n.......s....
[ 3223.603618] Object ffff88017499ce30: 30 ce 99 74 01 88 ff ff 30 ce 99 74 01 88 ff ff  0..t....0..t....
[ 3223.603618] Object ffff88017499ce40: 00 00 00 00 00 00 00 00 a8 81 06 7b 01 88 ff ff  ...........{....
[ 3223.603618] Object ffff88017499ce50: 20 09 c0 81 ff ff ff ff 00 00 00 00 00 00 00 00   ...............
[ 3223.603618] Object ffff88017499ce60: 00 00 00 00 0d 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ce70: 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499ce80: 80 ce 99 74 01 88 ff ff 80 ce 99 74 01 88 ff ff  ...t.......t....
[ 3223.603618] Object ffff88017499ce90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cea0: 78 ce 99 74 01 88 ff ff 00 00 00 00 00 00 00 00  x..t............
[ 3223.603618] Object ffff88017499ceb0: 00 00 00 00 00 00 00 00 40 ca 99 74 01 88 ff ff  ........@..t....
[ 3223.603618] Object ffff88017499cec0: ff ff ff ff 00 00 00 00 c8 ce 99 74 01 88 ff ff  ...........t....
[ 3223.603618] Object ffff88017499ced0: c8 ce 99 74 01 88 ff ff fe ff ff ff 00 00 00 00  ...t............
[ 3223.603618] Object ffff88017499cee0: 02 02 00 00 00 00 00 00 e8 ce 99 74 01 88 ff ff  ...........t....
[ 3223.603618] Object ffff88017499cef0: e8 ce 99 74 01 88 ff ff 00 00 00 00 00 00 00 00  ...t............
[ 3223.603618] Object ffff88017499cf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cf10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cf20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cf30: 00 00 00 00 00 00 00 00 38 cf 99 74 01 88 ff ff  ........8..t....
[ 3223.603618] Object ffff88017499cf40: 38 cf 99 74 01 88 ff ff 00 00 00 00 00 00 00 00  8..t............
[ 3223.603618] Object ffff88017499cf50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cf60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cf70: 01 01 00 00 00 00 00 00 78 cf 99 74 01 88 ff ff  ........x..t....
[ 3223.603618] Object ffff88017499cf80: 78 cf 99 74 01 88 ff ff 00 00 00 00 00 00 00 00  x..t............
[ 3223.603618] Object ffff88017499cf90: 00 01 10 00 00 00 ad de 00 02 20 00 00 00 ad de  .......... .....
[ 3223.603618] Object ffff88017499cfa0: 00 00 00 00 00 00 00 00 a0 02 c3 81 ff ff ff ff  ................
[ 3223.603618] Object ffff88017499cfb0: c0 cf 99 74 01 88 ff ff 00 00 00 00 00 00 00 00  ...t............
[ 3223.603618] Object ffff88017499cfc0: 20 03 c3 81 ff ff ff ff 00 00 00 00 00 00 00 00   ...............
[ 3223.603618] Object ffff88017499cfd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cfe0: 00 8f 03 a0 ff ff ff ff 00 00 01 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499cff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d080: 00 00 00 00 00 00 00 00 41 00 00 00 ff ff ff ff  ........A.......
[ 3223.603618] Object ffff88017499d090: ff ff ff ff 00 00 00 00 40 ca 99 74 01 88 ff ff  ........@..t....
[ 3223.603618] Object ffff88017499d0a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d0b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d0c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d0d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d0e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d0f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d100: 40 d1 99 74 01 88 ff ff 00 00 00 00 00 00 00 00  @..t............
[ 3223.603618] Object ffff88017499d110: d8 cf b5 73 01 88 ff ff 00 00 00 00 00 00 00 00  ...s............
[ 3223.603618] Object ffff88017499d120: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d130: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d140: 64 64 00 00 00 00 00 00 48 d1 99 74 01 88 ff ff  dd......H..t....
[ 3223.603618] Object ffff88017499d150: 48 d1 99 74 01 88 ff ff 00 00 00 00 00 00 00 00  H..t............
[ 3223.603618] Object ffff88017499d160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d180: 0a 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d190: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d1a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d1b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d1c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d1d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d1e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d1f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d210: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d220: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Object ffff88017499d230: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
[ 3223.603618] Redzone ffff88017499d240: cb cc cc cc cc cc cc cc                          ........
[ 3223.603618] Padding ffff88017499d380: 5a 5a 5a 5a 5a 5a 5a 5a                          ZZZZZZZZ
[ 3223.603618] Pid: 3929, comm: sshd Not tainted 3.4.0-rc1+ #35
[ 3223.603618] Call Trace:
[ 3223.603618]  [<ffffffff810ea1c8>] ? print_section+0x38/0x40
[ 3223.603618]  [<ffffffff810ea913>] print_trailer+0xe3/0x160
[ 3223.603618]  [<ffffffff810eade7>] check_bytes_and_report+0xd7/0x110
[ 3223.603618]  [<ffffffff810eafae>] check_object+0x18e/0x270
[ 3223.603618]  [<ffffffff816cd534>] ? netdev_release+0x34/0x40
[ 3223.603618]  [<ffffffff81819a78>] free_debug_processing+0xf1/0x1e7
[ 3223.603618]  [<ffffffff81819b9b>] __slab_free+0x2d/0x28a
[ 3223.603618]  [<ffffffff810ea48a>] ? set_track+0x5a/0x180
[ 3223.603618]  [<ffffffff816cd534>] ? netdev_release+0x34/0x40
[ 3223.603618]  [<ffffffff810ebd05>] ? init_object+0x45/0x80
[ 3223.603618]  [<ffffffff816cd534>] ? netdev_release+0x34/0x40
[ 3223.603618]  [<ffffffff810ebfa4>] kfree+0x114/0x140
[ 3223.603618]  [<ffffffff816cd534>] netdev_release+0x34/0x40
[ 3223.603618]  [<ffffffff814ded72>] device_release+0x22/0x90
[ 3223.603618]  [<ffffffff8137689c>] kobject_release+0x4c/0xa0
[ 3223.603618]  [<ffffffff8137675c>] kobject_put+0x2c/0x60
[ 3223.603618]  [<ffffffff814debe2>] put_device+0x12/0x20
[ 3223.603618]  [<ffffffff816b6e57>] free_netdev+0xb7/0xf0
[ 3223.603618]  [<ffffffffa0036434>] tun_sock_destruct+0x14/0x20 [tun]
[ 3223.603618]  [<ffffffff816a9af8>] __sk_free+0x18/0x140
[ 3223.603618]  [<ffffffff816a9c9d>] sk_free+0x1d/0x30
[ 3223.603618]  [<ffffffffa003635e>] tun_chr_close+0x5e/0xa0 [tun]
[ 3223.603618]  [<ffffffff810f3242>] fput+0xd2/0x240
[ 3223.603618]  [<ffffffff810efb71>] filp_close+0x61/0x90
[ 3223.603618]  [<ffffffff810efc1b>] sys_close+0x7b/0xd0
[ 3223.603618]  [<ffffffff81825179>] ia32_do_call+0x13/0x13
[ 3223.603618] FIX kmalloc-2048: Restoring 0xffff88017499d240-0xffff88017499d240=0xcc
[ 3223.603618] 

Simon-