Comment 2 for bug 1316757

It is possible the issue is triggered by virtualbox when using a btrfs backend. After the system hung up, I looked at the syslog and saw these messages:

May 8 10:44:23 ae407001 kernel: [155243.020496] ------------[ cut here ]------------
May 8 10:44:23 ae407001 kernel: [155243.020499] kernel BUG at /build/buildd/linux-3.13.0/fs/btrfs/ctree.c:3166!
May 8 10:44:23 ae407001 kernel: [155243.020501] invalid opcode: 0000 [#1] SMP
May 8 10:44:23 ae407001 kernel: [155243.020502] Modules linked in: joydev pci_stub vboxpci(OF) vboxnetadp(OF) vboxnetflt(OF) vboxdrv(OF) rfcomm b
nep snd_hda_codec_hdmi ip6t_REJECT xt_hl ip6t_rt nf_conntrack_ipv6 nf_defrag_ipv6 ipt_REJECT xt_comment xt_LOG xt_multiport xt_recent xt_limit xt_
tcpudp xt_addrtype nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack snd_hda_codec_realtek eeepc_wmi asus_wmi ip6table_filter sparse_keymap ip6_tables
 mxm_wmi x86_pkg_temp_thermal snd_hda_intel nf_conntrack_netbios_ns intel_powerclamp nf_conntrack_broadcast snd_hda_codec coretemp nf_nat_ftp kvm_
intel snd_hwdep nf_nat kvm arc4 btusb snd_pcm nf_conntrack_ftp bluetooth nf_conntrack crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_page_a
lloc aesni_intel snd_seq_midi iptable_filter ath9k aes_x86_64 snd_seq_midi_event lrw ath9k_common ath9k_hw gf128mul ip_tables glue_helper ablk_hel
per x_tables psmouse ath nvidia(POF) cryptd serio_raw lpc_ich snd_rawmidi mac80211 snd_seq snd_seq_device cfg80211 snd_timer mac_hid snd drm wmi m
ei_me mei soundcore parport_pc ppdev lp parport btrfs xor raid6_pq libcrc32c hid_logitech_dj usbhid hid e1000e ahci ptp libahci pps_core video
May 8 10:44:23 ae407001 kernel: [155243.020537] CPU: 6 PID: 21071 Comm: btrfs-endio-wri Tainted: PF O 3.13.0-24-generic #47-Ubuntu
May 8 10:44:23 ae407001 kernel: [155243.020538] Hardware name: ASUS All Series/Z87-PRO, BIOS 1707 12/13/2013
May 8 10:44:23 ae407001 kernel: [155243.020539] task: ffff8803123c5fc0 ti: ffff880238846000 task.ti: ffff880238846000
May 8 10:44:23 ae407001 kernel: [155243.020540] RIP: 0010:[<ffffffffa00f7a31>] [<ffffffffa00f7a31>] btrfs_set_item_key_safe+0x161/0x170 [btrfs]
May 8 10:44:23 ae407001 kernel: [155243.020549] RSP: 0018:ffff880238847b70 EFLAGS: 00010286
May 8 10:44:23 ae407001 kernel: [155243.020550] RAX: 00000000ffffffff RBX: 000000000000000c RCX: 0000000332b43000
May 8 10:44:23 ae407001 kernel: [155243.020551] RDX: 00000000ffffffff RSI: ffff880238847c76 RDI: ffff880238847b8f
May 8 10:44:23 ae407001 kernel: [155243.020552] RBP: ffff880238847bc8 R08: 0000000000000001 R09: ffff880238847b90
May 8 10:44:23 ae407001 kernel: [155243.020552] R10: 0000000332b4e000 R11: 00000000ffffffff R12: ffff880238847b7e
May 8 10:44:23 ae407001 kernel: [155243.020553] R13: ffff88041c0b7120 R14: ffff880238847c76 R15: ffff88021dcff040
May 8 10:44:23 ae407001 kernel: [155243.020554] FS: 0000000000000000(0000) GS:ffff88041ed80000(0000) knlGS:0000000000000000
May 8 10:44:23 ae407001 kernel: [155243.020555] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
May 8 10:44:23 ae407001 kernel: [155243.020556] CR2: 00007f3308eee000 CR3: 000000041dc0e000 CR4: 00000000001427e0
May 8 10:44:23 ae407001 kernel: [155243.020557] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
May 8 10:44:23 ae407001 kernel: [155243.020557] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
May 8 10:44:23 ae407001 kernel: [155243.020558] Stack:
May 8 10:44:23 ae407001 kernel: [155243.020558] ffff880402660800 ac55ffffa0130989 006c00000000000a 550000000332b2f0
May 8 10:44:23 ae407001 kernel: [155243.020561] 6c00000000000aac 0000000332b2f000 ffff88021dcff040 0000000332b43000
May 8 10:44:23 ae407001 kernel: [155243.020563] 0000000000000000 0000000000000d4f ffff88041c0b7120 ffff880238847cc0
May 8 10:44:23 ae407001 kernel: [155243.020564] Call Trace:
May 8 10:44:23 ae407001 kernel: [155243.020574] [<ffffffffa012db11>] __btrfs_drop_extents+0x421/0xad0 [btrfs]
May 8 10:44:23 ae407001 kernel: [155243.020583] [<ffffffffa012ed40>] btrfs_drop_extents+0x60/0x90 [btrfs]
May 8 10:44:23 ae407001 kernel: [155243.020590] [<ffffffffa011e8fc>] insert_reserved_file_extent.constprop.53+0x6c/0x290 [btrfs]
May 8 10:44:23 ae407001 kernel: [155243.020597] [<ffffffffa01243a5>] btrfs_finish_ordered_io+0x2e5/0x570 [btrfs]
May 8 10:44:23 ae407001 kernel: [155243.020600] [<ffffffff810741e0>] ? ftrace_raw_output_tick_stop+0x70/0x70
May 8 10:44:23 ae407001 kernel: [155243.020606] [<ffffffffa01248b5>] finish_ordered_fn+0x15/0x20 [btrfs]
May 8 10:44:23 ae407001 kernel: [155243.020614] [<ffffffffa01481ca>] worker_loop+0x15a/0x5c0 [btrfs]
May 8 10:44:23 ae407001 kernel: [155243.020621] [<ffffffffa0148070>] ? btrfs_queue_worker+0x310/0x310 [btrfs]
May 8 10:44:23 ae407001 kernel: [155243.020623] [<ffffffff8108b312>] kthread+0xd2/0xf0
May 8 10:44:23 ae407001 kernel: [155243.020625] [<ffffffff8108b240>] ? kthread_create_on_node+0x1d0/0x1d0
May 8 10:44:23 ae407001 kernel: [155243.020627] [<ffffffff817263fc>] ret_from_fork+0x7c/0xb0
May 8 10:44:23 ae407001 kernel: [155243.020629] [<ffffffff8108b240>] ? kthread_create_on_node+0x1d0/0x1d0
May 8 10:44:23 ae407001 kernel: [155243.020629] Code: 48 8b 45 bf 48 8d 7d c7 4c 89 f6 48 89 45 d0 0f b6 45 be 88 45 cf 48 8b 45 b6 48 89 45 c7 e
8 97 f2 ff ff 85 c0 0f 8f 48 ff ff ff <0f> 0b 0f 0b 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55
May 8 10:44:23 ae407001 kernel: [155243.020645] RIP [<ffffffffa00f7a31>] btrfs_set_item_key_safe+0x161/0x170 [btrfs]
May 8 10:44:23 ae407001 kernel: [155243.020650] RSP <ffff880238847b70>
May 8 10:44:23 ae407001 kernel: [155243.020651] ---[ end trace 503c10c857c3210d ]---