[  907.331854] BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
[  907.331941] IP: [<ffffffffa0587381>] nfs_open_revalidate+0x21/0x220 [nfs]
[  907.332017] PGD 114415067 PUD 10cb11067 PMD 0 
[  907.332070] Oops: 0000 [#1] SMP 
[  907.332108] CPU 0 
[  907.332128] Modules linked in: veth overlayfs nfsd nfs lockd fscache auth_rpcgss nfs_acl sunrpc ip6table_filter ip6_tables ebtable_nat ebtables ipt_MASQUERADE iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 xt_state nf_conntrack ipt_REJECT xt_CHECKSUM iptable_mangle xt_tcpudp iptable_filter ip_tables x_tables kvm_intel kvm bnep rfcomm bluetooth parport_pc ppdev snd_hda_codec_conexant snd_hda_intel snd_hda_codec uvcvideo videodev joydev arc4 bridge v4l2_compat_ioctl32 snd_hwdep stp snd_pcm b43 snd_seq_midi mac80211 dell_laptop snd_rawmidi i915 dcdbas snd_seq_midi_event drm_kms_helper dell_wmi drm snd_seq snd_timer snd_seq_device sparse_keymap cfg80211 psmouse snd serio_raw mac_hid bcma i2c_algo_bit video wmi soundcore snd_page_alloc lp parport r8169 ums_realtek uas ssb usb_storage
[  907.332990] 
[  907.333007] Pid: 21906, comm: ls Not tainted 3.2.0-30-generic #48-Ubuntu Dell Inc. Vostro 1220                     /0X482M
[  907.333104] RIP: 0010:[<ffffffffa0587381>]  [<ffffffffa0587381>] nfs_open_revalidate+0x21/0x220 [nfs]
[  907.333191] RSP: 0018:ffff880117d05ae8  EFLAGS: 00010286
[  907.333235] RAX: ffffffffa05b94c0 RBX: ffff8800b719d3c0 RCX: 0000000000000002
[  907.333290] RDX: ffff880105eef6f8 RSI: 0000000000000000 RDI: ffff8800b719d3c0
[  907.333345] RBP: ffff880117d05b28 R08: 0000000000000002 R09: ffff8800b719d3f8
[  907.333400] R10: ffff8800b719d3c0 R11: 0000000000000000 R12: ffff8801004dc600
[  907.333455] R13: ffff880117d05b88 R14: 0000000000000000 R15: ffff8801091baa80
[  907.333511] FS:  00007fb2a78be7c0(0000) GS:ffff88011fc00000(0000) knlGS:0000000000000000
[  907.333575] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  907.333621] CR2: 0000000000000038 CR3: 00000001079b1000 CR4: 00000000000406f0
[  907.333676] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  907.333732] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[  907.333787] Process ls (pid: 21906, threadinfo ffff880117d04000, task ffff880036da8000)
[  907.333848] Stack:
[  907.333867]  0000000000000000 ffff8801091baa80 ffff880117d05b28 ffff8800b719d3c0
[  907.333942]  ffff8801004dc600 ffff880117d05b88 0000000000000000 ffff8801091baa80
[  907.334016]  ffff880117d05b68 ffffffff81183642 ffff880117d05b68 ffffffff8118389a
[  907.334091] Call Trace:
[  907.334119]  [<ffffffff81183642>] __lookup_hash.part.28+0x92/0xe0
[  907.334169]  [<ffffffff8118389a>] ? inode_permission+0x4a/0x110
[  907.334217]  [<ffffffff81183b6e>] lookup_one_len+0xee/0x120
[  907.334266]  [<ffffffffa055ab50>] ovl_do_lookup+0x190/0x370 [overlayfs]
[  907.334320]  [<ffffffff8118fb00>] ? __d_alloc+0x130/0x180
[  907.334366]  [<ffffffffa055ad41>] ovl_lookup+0x11/0x30 [overlayfs]
[  907.334417]  [<ffffffff81182b15>] d_alloc_and_lookup+0x45/0x90
[  907.334467]  [<ffffffff81190235>] ? d_lookup+0x35/0x60
[  907.334511]  [<ffffffff81184ca2>] do_lookup+0x202/0x310
[  907.334555]  [<ffffffff811869dc>] path_lookupat+0x11c/0x750
[  907.334602]  [<ffffffff813192b7>] ? __strncpy_from_user+0x27/0x60
[  907.334653]  [<ffffffff81132661>] ? kzfree+0x31/0x40
[  907.334695]  [<ffffffff81187041>] do_path_lookup+0x31/0xc0
[  907.334741]  [<ffffffff81187b49>] user_path_at_empty+0x59/0xa0
[  907.334792]  [<ffffffffa055d0a1>] ? ovl_readdir+0xd1/0x380 [overlayfs]
[  907.335680]  [<ffffffff8118a610>] ? fillonedir+0xd0/0xd0
[  907.335680]  [<ffffffff81187ba1>] user_path_at+0x11/0x20
[  907.335680]  [<ffffffff8117cbda>] vfs_fstatat+0x3a/0x70
[  907.335680]  [<ffffffff8117cc2e>] vfs_lstat+0x1e/0x20
[  907.335680]  [<ffffffff8117cdca>] sys_newlstat+0x1a/0x40
[  907.335680]  [<ffffffff81014721>] ? math_state_restore+0x51/0x80
[  907.335680]  [<ffffffff8165b43e>] ? do_device_not_available+0xe/0x10
[  907.335680]  [<ffffffff81664a0b>] ? device_not_available+0x1b/0x20
[  907.335680]  [<ffffffff81662a02>] system_call_fastpath+0x16/0x1b
[  907.335680] Code: 89 c4 eb e2 66 0f 1f 44 00 00 55 48 89 e5 48 83 ec 40 48 89 5d d8 4c 89 65 e0 4c 89 6d e8 4c 89 75 f0 4c 89 7d f8 66 66 66 66 90 <f6> 46 38 40 ba f6 ff ff ff 49 89 fc 48 89 f3 75 28 4c 8b 7f 30 
[  907.335680] RIP  [<ffffffffa0587381>] nfs_open_revalidate+0x21/0x220 [nfs]
[  907.335680]  RSP <ffff880117d05ae8>
[  907.335680] CR2: 0000000000000038
[  907.397644] ---[ end trace 00415a8ed70f20bf ]---