Created attachment 189791 [details]
full syslog

Btrfs progs v4.2.1

Could be the same as: https://bugzilla.opensuse.org/show_bug.cgi?id=940212

I have try it with kernel 4.1.6 and btrfs progs 4.2.2 .. the same error

scrub completes without an error

any hint what i can do now or how i can help to solve this problem?

btrfs balance start -m /media/RAID

complete with out any error but the resulte of device usage is confusing me.
Metadata on sdb and sdc are 2 GiB, but on sdd (the new added device) is 4 GiB. And the 2. one that's confusing me, is that sdd has a "System" entry but sdb and sdc dosn't

floyd@nas ~ $ sudo btrfs dev us /media/RAID/
/dev/sdb, ID: 1
   Device size:             2.73TiB
   Data,RAID1:              2.11TiB
   Metadata,RAID1:          2.00GiB
   System,RAID1:           32.00MiB
   Unallocated:           628.49GiB

/dev/sdc, ID: 2
   Device size:             2.73TiB
   Data,RAID1:              2.11TiB
   Metadata,RAID1:          2.00GiB
   Unallocated:           628.52GiB

/dev/sdd, ID: 3
   Device size:             2.73TiB
   Data,RAID1:            792.00GiB
   Metadata,RAID1:          4.00GiB
   System,RAID1:           32.00MiB
   Unallocated:             1.95TiB

I'm must correct me .. sdb and sdd has a "System" entry and "sdc" not

I also see some of this blocks in my syslog: Bug 105791

[ 3840.616538] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 3840.616541]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 3840.616542] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3840.616543] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 3840.616545]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 3840.616547]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 3840.616548]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 3840.616549] Call Trace:
[ 3840.616555]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 3840.616569]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 3840.616572]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 3840.616576]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 3840.616579]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 3840.616584]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 3840.616592]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 3840.616598]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 3840.616604]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 3840.616609]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 3840.616615]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 3840.616621]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 3840.616626]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 3840.616631]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 3840.616636]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 3840.616637]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 3840.616638]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3840.616640]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 3840.616641]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180

dmesg:

[ 3000.613310] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 3000.613314]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 3000.613314] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3000.613315] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 3000.613318]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 3000.613319]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 3000.613321]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 3000.613322] Call Trace:
[ 3000.613327]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 3000.613341]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 3000.613344]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 3000.613349]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 3000.613351]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 3000.613356]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 3000.613364]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 3000.613370]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 3000.613376]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 3000.613382]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 3000.613388]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 3000.613395]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 3000.613400]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 3000.613406]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 3000.613411]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 3000.613412]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 3000.613414]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3000.613415]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 3000.613416]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3120.613665] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 3120.613669]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 3120.613669] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3120.613670] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 3120.613672]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 3120.613674]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 3120.613675]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 3120.613676] Call Trace:
[ 3120.613682]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 3120.613695]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 3120.613698]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 3120.613702]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 3120.613704]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 3120.613709]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 3120.613716]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 3120.613721]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 3120.613727]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 3120.613732]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 3120.613744]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 3120.613749]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 3120.613754]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 3120.613759]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 3120.613764]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 3120.613766]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 3120.613767]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3120.613768]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 3120.613769]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3240.614145] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 3240.614148]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 3240.614149] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3240.614150] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 3240.614152]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 3240.614154]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 3240.614155]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 3240.614156] Call Trace:
[ 3240.614161]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 3240.614174]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 3240.614177]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 3240.614181]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 3240.614183]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 3240.614188]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 3240.614194]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 3240.614200]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 3240.614206]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 3240.614211]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 3240.614217]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 3240.614222]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 3240.614227]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 3240.614232]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 3240.614236]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 3240.614238]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 3240.614239]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3240.614240]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 3240.614241]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3360.614630] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 3360.614634]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 3360.614635] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3360.614636] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 3360.614638]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 3360.614640]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 3360.614641]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 3360.614642] Call Trace:
[ 3360.614647]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 3360.614660]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 3360.614663]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 3360.614667]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 3360.614669]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 3360.614674]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 3360.614681]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 3360.614687]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 3360.614692]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 3360.614698]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 3360.614703]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 3360.614709]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 3360.614713]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 3360.614718]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 3360.614723]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 3360.614724]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 3360.614725]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3360.614727]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 3360.614728]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3480.615115] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 3480.615118]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 3480.615118] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3480.615119] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 3480.615122]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 3480.615124]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 3480.615125]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 3480.615126] Call Trace:
[ 3480.615131]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 3480.615145]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 3480.615148]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 3480.615152]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 3480.615154]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 3480.615159]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 3480.615166]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 3480.615171]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 3480.615177]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 3480.615182]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 3480.615187]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 3480.615193]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 3480.615198]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 3480.615203]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 3480.615207]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 3480.615209]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 3480.615210]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3480.615211]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 3480.615212]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3600.615585] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 3600.615589]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 3600.615589] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3600.615590] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 3600.615593]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 3600.615594]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 3600.615596]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 3600.615597] Call Trace:
[ 3600.615602]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 3600.615616]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 3600.615619]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 3600.615623]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 3600.615625]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 3600.615630]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 3600.615637]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 3600.615642]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 3600.615647]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 3600.615653]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 3600.615658]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 3600.615664]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 3600.615669]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 3600.615673]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 3600.615678]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 3600.615680]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 3600.615681]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3600.615682]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 3600.615683]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3720.616073] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 3720.616076]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 3720.616077] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3720.616078] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 3720.616080]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 3720.616082]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 3720.616083]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 3720.616084] Call Trace:
[ 3720.616089]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 3720.616103]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 3720.616106]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 3720.616111]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 3720.616113]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 3720.616119]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 3720.616127]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 3720.616133]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 3720.616138]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 3720.616144]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 3720.616150]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 3720.616155]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 3720.616161]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 3720.616166]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 3720.616170]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 3720.616172]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 3720.616173]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3720.616175]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 3720.616176]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3840.616538] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 3840.616541]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 3840.616542] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3840.616543] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 3840.616545]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 3840.616547]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 3840.616548]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 3840.616549] Call Trace:
[ 3840.616555]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 3840.616569]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 3840.616572]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 3840.616576]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 3840.616579]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 3840.616584]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 3840.616592]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 3840.616598]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 3840.616604]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 3840.616609]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 3840.616615]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 3840.616621]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 3840.616626]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 3840.616631]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 3840.616636]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 3840.616637]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 3840.616638]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3840.616640]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 3840.616641]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3960.617033] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 3960.617037]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 3960.617037] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 3960.617038] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 3960.617041]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 3960.617042]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 3960.617043]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 3960.617045] Call Trace:
[ 3960.617050]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 3960.617064]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 3960.617067]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 3960.617072]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 3960.617075]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 3960.617081]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 3960.617088]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 3960.617095]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 3960.617101]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 3960.617106]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 3960.617112]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 3960.617118]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 3960.617123]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 3960.617128]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 3960.617133]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 3960.617134]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 3960.617136]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 3960.617137]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 3960.617138]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 4080.617509] INFO: task btrfs-transacti:11423 blocked for more than 120 seconds.
[ 4080.617512]       Tainted: G     U          4.2.3-040203-generic #201510030832
[ 4080.617513] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 4080.617514] btrfs-transacti D 0000000000000000     0 11423      2 0x00000000
[ 4080.617516]  ffff88007bd2bb58 0000000000000046 ffff880215d7e600 ffff8802121d2640
[ 4080.617518]  0000000000000246 ffff88007bd2c000 ffff8801aa607928 ffff8801aa607940
[ 4080.617519]  ffff88007bd2bba8 ffff8801aa607920 ffff88007bd2bb78 ffffffff817a6357
[ 4080.617520] Call Trace:
[ 4080.617525]  [<ffffffff817a6357>] schedule+0x37/0x80
[ 4080.617539]  [<ffffffffc0332038>] btrfs_tree_lock+0x98/0x1c0 [btrfs]
[ 4080.617542]  [<ffffffff810b6fd0>] ? prepare_to_wait_event+0xf0/0xf0
[ 4080.617546]  [<ffffffffc02d4095>] btrfs_search_slot+0x6e5/0x9c0 [btrfs]
[ 4080.617548]  [<ffffffff81180ef7>] ? __set_page_dirty_nobuffers+0xe7/0x140
[ 4080.617553]  [<ffffffffc02ed8cf>] btrfs_lookup_inode+0x2f/0xa0 [btrfs]
[ 4080.617560]  [<ffffffffc034db13>] ? btrfs_delete_delayed_items+0x313/0x330 [btrfs]
[ 4080.617566]  [<ffffffffc034d484>] ? btrfs_insert_delayed_items+0xa4/0x420 [btrfs]
[ 4080.617571]  [<ffffffffc034dd3a>] __btrfs_update_delayed_inode+0x5a/0x1e0 [btrfs]
[ 4080.617576]  [<ffffffffc034e03c>] __btrfs_run_delayed_items+0x17c/0x210 [btrfs]
[ 4080.617582]  [<ffffffffc034e2e3>] btrfs_run_delayed_items+0x13/0x20 [btrfs]
[ 4080.617587]  [<ffffffffc02f85c8>] btrfs_commit_transaction+0x2c8/0xb10 [btrfs]
[ 4080.617592]  [<ffffffffc02f8ea3>] ? start_transaction+0x93/0x580 [btrfs]
[ 4080.617597]  [<ffffffffc02f395a>] transaction_kthread+0x1ba/0x240 [btrfs]
[ 4080.617601]  [<ffffffffc02f37a0>] ? btrfs_cleanup_transaction+0x540/0x540 [btrfs]
[ 4080.617603]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[ 4080.617604]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[ 4080.617605]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[ 4080.617606]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[44929.058013] ------------[ cut here ]------------
[44929.058035] WARNING: CPU: 0 PID: 39 at /home/kernel/COD/linux/drivers/gpu/drm/i915/intel_uncore.c:70 assert_device_not_suspended.isra.11+0x53/0x60 [i915]()
[44929.058036] Device suspended
[44929.058037] Modules linked in: xt_nat veth xt_conntrack xt_addrtype br_netfilter nvram msr dm_thin_pool dm_persistent_data dm_bio_prison dm_bufio libcrc32c ir_lirc_codec lirc_dev ir_xmp_decoder ir_sony_decoder ir_sharp_decoder ir_mce_kbd_decoder ir_sanyo_decoder ir_rc6_decoder ir_nec_decoder ir_jvc_decoder ir_rc5_decoder rc_rc6_mce xt_CHECKSUM iptable_mangle mceusb ipt_MASQUERADE nf_nat_masquerade_ipv4 rc_core input_leds iptable_nat nf_conntrack_ipv4 joydev nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack xt_tcpudp bridge stp llc iptable_filter ip_tables x_tables autofs4 eeepc_wmi asus_wmi sparse_keymap snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hda_core dm_multipath snd_hwdep scsi_dh snd_pcm intel_rapl iosf_mbi x86_pkg_temp_thermal snd_seq_midi snd_seq_midi_event intel_powerclamp kvm snd_rawmidi crct10dif_pclmul crc32_pclmul snd_seq rfcomm bnep ghash_clmulni_intel bluetooth snd_seq_device cryptd snd_timer serio_raw snd lpc_ich mei_me mei soundcore shpchp mac_hid parport_pc ppdev nct6775 hwmon_vid coretemp lp parport nfsd auth_rpcgss nfs_acl nfs binfmt_misc lockd grace sunrpc fscache btrfs xor raid6_pq nls_iso8859_1 dm_mirror dm_region_hash dm_log hid_generic usbhid hid uas usb_storage psmouse ahci libahci wmi i915 video i2c_algo_bit drm_kms_helper drm e1000e ptp pps_core
[44929.058088] CPU: 0 PID: 39 Comm: kswapd0 Tainted: G     U          4.2.3-040203-generic #201510030832
[44929.058089] Hardware name: ASUS All Series/H87I-PLUS, BIOS 2003 11/05/2014
[44929.058090]  ffffffffc01e5c78 ffff8800d5edb988 ffffffff817a2803 0000000000000000
[44929.058092]  ffff8800d5edb9d8 ffff8800d5edb9c8 ffffffff810771da ffff88020a942d28
[44929.058093]  ffff8802120b0000 0000000000100010 0000000000100010 ffff8802120b0080
[44929.058094] Call Trace:
[44929.058098]  [<ffffffff817a2803>] dump_stack+0x45/0x57
[44929.058100]  [<ffffffff810771da>] warn_slowpath_common+0x8a/0xc0
[44929.058102]  [<ffffffff81077256>] warn_slowpath_fmt+0x46/0x50
[44929.058110]  [<ffffffffc0169cc3>] assert_device_not_suspended.isra.11+0x53/0x60 [i915]
[44929.058116]  [<ffffffffc016b61a>] hsw_write32+0x3a/0x130 [i915]
[44929.058123]  [<ffffffffc0149eb0>] i915_gem_write_fence+0x210/0x520 [i915]
[44929.058125]  [<ffffffff813a5ea1>] ? __sg_free_table+0x71/0x90
[44929.058131]  [<ffffffffc014a266>] i915_gem_object_update_fence+0xa6/0xd0 [i915]
[44929.058137]  [<ffffffffc014a31a>] i915_gem_object_put_fence+0x8a/0xd0 [i915]
[44929.058142]  [<ffffffffc014a4e7>] i915_vma_unbind+0x187/0x230 [i915]
[44929.058148]  [<ffffffffc014d2d6>] i915_gem_shrink+0x156/0x230 [i915]
[44929.058153]  [<ffffffffc014d43d>] i915_gem_shrinker_scan+0x8d/0xa0 [i915]
[44929.058156]  [<ffffffff81186b37>] shrink_slab+0x207/0x380
[44929.058157]  [<ffffffff8118b1f1>] shrink_zone+0x291/0x2b0
[44929.058158]  [<ffffffff8118c160>] kswapd+0x500/0x9b0
[44929.058159]  [<ffffffff8118bc60>] ? mem_cgroup_shrink_node_zone+0x130/0x130
[44929.058160]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[44929.058161]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[44929.058163]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[44929.058164]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[44929.058165] ---[ end trace 975c39f656782ad7 ]---
[44929.058171] ------------[ cut here ]------------
[44929.058179] WARNING: CPU: 0 PID: 39 at /home/kernel/COD/linux/drivers/gpu/drm/i915/intel_uncore.c:620 hsw_unclaimed_reg_debug.isra.14+0x78/0xa0 [i915]()
[44929.058179] Unclaimed register detected before reading register 0x100010
[44929.058180] Modules linked in: xt_nat veth xt_conntrack xt_addrtype br_netfilter nvram msr dm_thin_pool dm_persistent_data dm_bio_prison dm_bufio libcrc32c ir_lirc_codec lirc_dev ir_xmp_decoder ir_sony_decoder ir_sharp_decoder ir_mce_kbd_decoder ir_sanyo_decoder ir_rc6_decoder ir_nec_decoder ir_jvc_decoder ir_rc5_decoder rc_rc6_mce xt_CHECKSUM iptable_mangle mceusb ipt_MASQUERADE nf_nat_masquerade_ipv4 rc_core input_leds iptable_nat nf_conntrack_ipv4 joydev nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack xt_tcpudp bridge stp llc iptable_filter ip_tables x_tables autofs4 eeepc_wmi asus_wmi sparse_keymap snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hda_core dm_multipath snd_hwdep scsi_dh snd_pcm intel_rapl iosf_mbi x86_pkg_temp_thermal snd_seq_midi snd_seq_midi_event intel_powerclamp kvm snd_rawmidi crct10dif_pclmul crc32_pclmul snd_seq rfcomm bnep ghash_clmulni_intel bluetooth snd_seq_device cryptd snd_timer serio_raw snd lpc_ich mei_me mei soundcore shpchp mac_hid parport_pc ppdev nct6775 hwmon_vid coretemp lp parport nfsd auth_rpcgss nfs_acl nfs binfmt_misc lockd grace sunrpc fscache btrfs xor raid6_pq nls_iso8859_1 dm_mirror dm_region_hash dm_log hid_generic usbhid hid uas usb_storage psmouse ahci libahci wmi i915 video i2c_algo_bit drm_kms_helper drm e1000e ptp pps_core
[44929.058204] CPU: 0 PID: 39 Comm: kswapd0 Tainted: G     U  W       4.2.3-040203-generic #201510030832
[44929.058205] Hardware name: ASUS All Series/H87I-PLUS, BIOS 2003 11/05/2014
[44929.058205]  ffffffffc01e5c78 ffff8800d5edb968 ffffffff817a2803 0000000000000000
[44929.058206]  ffff8800d5edb9b8 ffff8800d5edb9a8 ffffffff810771da ffff8800d5edb988
[44929.058207]  ffff8802120b0078 ffff8802120b0000 ffff8802120b0080 ffff8802120b0078
[44929.058208] Call Trace:
[44929.058210]  [<ffffffff817a2803>] dump_stack+0x45/0x57
[44929.058211]  [<ffffffff810771da>] warn_slowpath_common+0x8a/0xc0
[44929.058212]  [<ffffffff81077256>] warn_slowpath_fmt+0x46/0x50
[44929.058219]  [<ffffffffc0169e58>] hsw_unclaimed_reg_debug.isra.14+0x78/0xa0 [i915]
[44929.058225]  [<ffffffffc016bd9f>] gen6_read32+0x5f/0x1a0 [i915]
[44929.058231]  [<ffffffffc016b686>] ? hsw_write32+0xa6/0x130 [i915]
[44929.058237]  [<ffffffffc0149ec0>] i915_gem_write_fence+0x220/0x520 [i915]
[44929.058238]  [<ffffffff813a5ea1>] ? __sg_free_table+0x71/0x90
[44929.058244]  [<ffffffffc014a266>] i915_gem_object_update_fence+0xa6/0xd0 [i915]
[44929.058249]  [<ffffffffc014a31a>] i915_gem_object_put_fence+0x8a/0xd0 [i915]
[44929.058254]  [<ffffffffc014a4e7>] i915_vma_unbind+0x187/0x230 [i915]
[44929.058259]  [<ffffffffc014d2d6>] i915_gem_shrink+0x156/0x230 [i915]
[44929.058264]  [<ffffffffc014d43d>] i915_gem_shrinker_scan+0x8d/0xa0 [i915]
[44929.058266]  [<ffffffff81186b37>] shrink_slab+0x207/0x380
[44929.058267]  [<ffffffff8118b1f1>] shrink_zone+0x291/0x2b0
[44929.058268]  [<ffffffff8118c160>] kswapd+0x500/0x9b0
[44929.058269]  [<ffffffff8118bc60>] ? mem_cgroup_shrink_node_zone+0x130/0x130
[44929.058270]  [<ffffffff81094e69>] kthread+0xc9/0xe0
[44929.058271]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[44929.058272]  [<ffffffff817a9f9f>] ret_from_fork+0x3f/0x70
[44929.058273]  [<ffffffff81094da0>] ? kthread_create_on_node+0x180/0x180
[44929.058274] ---[ end trace 975c39f656782ad8 ]---

scrub device /dev/sdb (id 1) done
	scrub started at Sun Oct 11 00:41:06 2015 and finished after 05:36:43
	total bytes scrubbed: 2.10TiB with 0 errors
scrub device /dev/sdc (id 2) done
	scrub started at Sun Oct 11 00:41:06 2015 and finished after 05:11:29
	total bytes scrubbed: 2.10TiB with 0 errors
scrub device /dev/sdd (id 3) done
	scrub started at Sun Oct 11 00:41:06 2015 and finished after 01:48:51
	total bytes scrubbed: 772.22GiB with 0 errors

sudo btrfs check --readonly /media/RAID

Superblock bytenr is larger than device size
Couldn't open file system

btrfs check --readonly /dev/sdb

http://pastebin.com/UxkeVd7Y

many entrys with "extent buffer leak"

btrfs-show-super -i0 /dev/sd[bcd] 
btrfs-show-super -i1 /dev/sd[bcd] 
btrfs-show-super -i2 /dev/sd[bcd]

sdb: http://pastebin.com/zs7B8827
sdc: http://pastebin.com/Kn1kwgYv
sdd: http://pastebin.com/CHC52ef7

sudo btrfs check --repair /dev/sdb
enabling repair mode
Checking filesystem on /dev/sdb
UUID: cba641be-f5a2-444b-af88-359f7edae8aa
checking extents
Fixed 0 roots.
checking free space cache
cache and super generation don't match, space cache will be invalidated
checking fs roots
checking csums
checking root refs
checking quota groups
found 2770194741781 bytes used err is 0
total csum bytes: 2702120812
total tree bytes: 3223027712
total fs tree bytes: 299204608
total extent tree bytes: 91504640
btree space waste bytes: 175969438
file data blocks allocated: 4480820461568
 referenced 4366171271168
btrfs-progs v4.2.2
extent buffer leak: start 8789296545792 len 16384
extent buffer leak: start 8786100617216 len 16384
extent buffer leak: start 8786447040512 len 16384
extent buffer leak: start 8786639388672 len 16384
extent buffer leak: start 8786665259008 len 16384
extent buffer leak: start 8787662929920 len 16384
extent buffer leak: start 8787663683584 len 16384
extent buffer leak: start 8787663880192 len 16384
extent buffer leak: start 8787663978496 len 16384
extent buffer leak: start 8788232437760 len 16384
extent buffer leak: start 8788232519680 len 16384
extent buffer leak: start 8788232634368 len 16384
extent buffer leak: start 8788232667136 len 16384
extent buffer leak: start 8788232699904 len 16384
extent buffer leak: start 8788232732672 len 16384
extent buffer leak: start 8788232798208 len 16384
extent buffer leak: start 8788232830976 len 16384
extent buffer leak: start 8788232863744 len 16384
extent buffer leak: start 8788611612672 len 16384
extent buffer leak: start 8788612579328 len 16384
extent buffer leak: start 8788614594560 len 16384
extent buffer leak: start 8788692369408 len 16384
extent buffer leak: start 8788692598784 len 16384
extent buffer leak: start 8788693598208 len 16384
extent buffer leak: start 8788693811200 len 16384
extent buffer leak: start 8788693827584 len 16384
extent buffer leak: start 8788693843968 len 16384
extent buffer leak: start 8788693925888 len 16384
extent buffer leak: start 8788701691904 len 16384
extent buffer leak: start 8788702560256 len 16384
extent buffer leak: start 8788703559680 len 16384
extent buffer leak: start 8788721221632 len 16384
extent buffer leak: start 8788722515968 len 16384
extent buffer leak: start 8788724924416 len 16384
extent buffer leak: start 8788728348672 len 16384
extent buffer leak: start 8788731133952 len 16384
extent buffer leak: start 8788732575744 len 16384
extent buffer leak: start 8788734853120 len 16384
extent buffer leak: start 8788739686400 len 16384
extent buffer leak: start 8789296496640 len 16384
extent buffer leak: start 8789296562176 len 16384
extent buffer leak: start 8789296644096 len 16384
extent buffer leak: start 8789296676864 len 16384
extent buffer leak: start 8789296709632 len 16384
extent buffer leak: start 8789296742400 len 16384
extent buffer leak: start 8789296775168 len 16384
extent buffer leak: start 8789296807936 len 16384
extent buffer leak: start 8789296840704 len 16384
extent buffer leak: start 8789296873472 len 16384
extent buffer leak: start 8789296922624 len 16384
extent buffer leak: start 8789296955392 len 16384
extent buffer leak: start 8789306015744 len 16384
extent buffer leak: start 8789306507264 len 16384
extent buffer leak: start 8789306540032 len 16384
extent buffer leak: start 8789306589184 len 16384
extent buffer leak: start 8789331361792 len 16384
extent buffer leak: start 8789340651520 len 16384
extent buffer leak: start 8789340684288 len 16384
extent buffer leak: start 8789340717056 len 16384
extent buffer leak: start 8789340749824 len 16384
extent buffer leak: start 8789340782592 len 16384
extent buffer leak: start 8789340815360 len 16384
extent buffer leak: start 8789340848128 len 16384
extent buffer leak: start 8789340880896 len 16384
extent buffer leak: start 8789340913664 len 16384
extent buffer leak: start 8789340946432 len 16384
extent buffer leak: start 8789340979200 len 16384
extent buffer leak: start 8789353512960 len 16384
extent buffer leak: start 8789827715072 len 16384
extent buffer leak: start 8789828255744 len 16384
extent buffer leak: start 8789828616192 len 16384
extent buffer leak: start 8789829730304 len 16384
extent buffer leak: start 8790050111488 len 16384
extent buffer leak: start 8790050308096 len 16384
extent buffer leak: start 8790050340864 len 16384
extent buffer leak: start 8790050390016 len 16384
extent buffer leak: start 8790050455552 len 16384
extent buffer leak: start 8790050488320 len 16384
extent buffer leak: start 8790050504704 len 16384
extent buffer leak: start 8790050570240 len 16384
extent buffer leak: start 8790050619392 len 16384
extent buffer leak: start 8790050717696 len 16384
extent buffer leak: start 8790050750464 len 16384
extent buffer leak: start 8790104932352 len 16384
extent buffer leak: start 8790113943552 len 16384

Just encountered this on Arch Linux v4.2.3-1 and btrfs-progs v4.2.2-1.

My RAID1 array lost a device due to failure recent and went from 4 to 3 devices.  To move data off the missing device I had issued:

btrfs balance start -f -ddevid=4 -mdevid=4 -sdevid=4 /mnt/btrfs

After several hours the system was hung reporting this same bug line.

Btrfs check revealed no problems (log @ https://gist.github.com/8eaa0c23a5e4712476a0 )

It seems that my system triggered the bug by starting a scheduled back-up on the volume that was undergoing the balance.  The system had run for hours balancing without issue until the back-up ran.

Perhaps there is a race condition with the creation/deletion/modification of files while balancing?

I'm experiencing the same issue while removing a device from my system. btrfs check doesn't find any errors. The system completely locks up, I had to use net console to log the error. I'm running kernel "Linux nasbak 4.2.6-040206-generic #201511091832 SMP Mon Nov 9 23:34:22 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux" with the latest btrfs tools compiled from the github repository (btrfs-progs v4.3.1).


[ 2542.444227] ------------[ cut here ]------------
[ 2542.444309] kernel BUG at /home/kernel/COD/linux/fs/btrfs/extent-tree.c:1833!
[ 2542.444408] invalid opcode: 0000 [#1] SMP
[ 2542.444478] Modules linked in: cuse bridge stp llc deflate ctr twofish_generic twofish_x86_64_3way twofish_x86_64 twofish_common camellia_generic dm_thin_pool camellia_x86_64 dm_persistent_data dm_bio_prison dm_bufio libcrc32c serpent_sse2_x86_64 xts serpent_generic lrw gf128mul glue_helper blowfish_generic blowfish_x86_64 blowfish_common cast5_generic cast_common ablk_helper cryptd des_generic cmac xcbc rmd160 crypto_null af_key xfrm_algo nfsd auth_rpcgss nfs_acl nfs lockd grace sunrpc fscache ip6t_REJECT nf_reject_ipv6 dm_crypt xt_hl ip6t_rt nf_conntrack_ipv6 nf_defrag_ipv6 ppdev ipt_REJECT nf_reject_ipv4 xt_comment xt_recent xt_multiport kvm xt_limit xt_tcpudp xt_addrtype ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_conntrack_ipv4 nf_defrag_ipv4 serio_raw xt_conntrack edac_core k10temp edac_mce_amd ip6table_filter i2c_piix4 ip6_tables nf_conntrack_netbios_ns nf_conntrack_broadcast nf_nat_ftp nf_nat nf_conntrack_ftp joydev nf_conntrack iptable_filter snd_hda_codec_via snd_hda_codec_generic snd_hda_codec_hdmi input_leds ip_tables x_tables snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_pcm snd_timer snd soundcore 8250_fintek parport_pc asus_atk0110 shpchp mac_hid netconsole configfs lp parport btrfs xor raid6_pq pata_acpi hid_generic usbhid hid uas usb_storage amdkfd amd_iommu_v2 radeon psmouse i2c_algo_bit pata_atiixp ttm drm_kms_helper r8169 wmi mii drm sata_sil24 ahci libahci
[ 2542.446979] CPU: 0 PID: 142 Comm: kworker/u12:7 Not tainted 4.2.6-040206-generic #201511091832
[ 2542.447090] Hardware name: System manufacturer System Product Name/M4A78LT-M, BIOS 0802    08/24/2010
[ 2542.447237] Workqueue: btrfs-extent-refs btrfs_extent_refs_helper [btrfs]
[ 2542.447329] task: ffff8800c95a9900 ti: ffff880212e4c000 task.ti: ffff880212e4c000
[ 2542.447427] RIP: 0010:[<ffffffffc0350d07>]  [<ffffffffc0350d07>] insert_inline_extent_backref+0xe7/0xf0 [btrfs]
[ 2542.447574] RSP: 0018:ffff880212e4fac8  EFLAGS: 00010293
[ 2542.447646] RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000
[ 2542.447739] RDX: ffff880000000000 RSI: 0000000000000001 RDI: 0000000000000000
[ 2542.447832] RBP: ffff880212e4fb48 R08: 0000000000004000 R09: ffff880212e4f9c0
[ 2542.447925] R10: 0000000000000000 R11: 0000000000000003 R12: ffff8800cb1e1800
[ 2542.448018] R13: ffff88004c4cef30 R14: 0000199d4bff8000 R15: 0000000000000000
[ 2542.448111] FS:  00007ff3c9940700(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
[ 2542.448215] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 2542.448291] CR2: 00007f70ec02ca28 CR3: 00000000bce95000 CR4: 00000000000006f0
[ 2542.448385] Stack:
[ 2542.448416]  0000199d4bff8000 0000000000011711 0000000000000001 0000000000000000
[ 2542.448536]  ffff880200000001 ffffffff811de3aa ffff880212e4fb28 ffffffffc0343e7a
[ 2542.448657]  0000000000003b92 000000000655f589 ffff8802130e3000 0000000000000000
[ 2542.448778] Call Trace:
[ 2542.448818]  [<ffffffff811de3aa>] ? kmem_cache_alloc+0x1ca/0x200
[ 2542.448908]  [<ffffffffc0343e7a>] ? btrfs_alloc_path+0x1a/0x20 [btrfs]
[ 2542.449005]  [<ffffffffc0351219>] __btrfs_inc_extent_ref.isra.52+0xa9/0x270 [btrfs]
[ 2542.449107]  [<ffffffff817db68c>] ? __schedule+0x36c/0x950
[ 2542.449193]  [<ffffffffc03569fc>] __btrfs_run_delayed_refs+0xc6c/0x1080 [btrfs]
[ 2542.449289]  [<ffffffff810a4e2d>] ? ttwu_do_wakeup+0x1d/0xd0
[ 2542.449377]  [<ffffffffc0359b1e>] btrfs_run_delayed_refs.part.73+0x6e/0x270 [btrfs]
[ 2542.449487]  [<ffffffffc0359dbe>] delayed_ref_async_start+0x7e/0x90 [btrfs]
[ 2542.449593]  [<ffffffffc03a036a>] btrfs_scrubparity_helper+0xca/0x290 [btrfs]
[ 2542.449700]  [<ffffffffc03a056e>] btrfs_extent_refs_helper+0xe/0x10 [btrfs]
[ 2542.449792]  [<ffffffff8109413a>] process_one_work+0x1aa/0x440
[ 2542.449871]  [<ffffffff8109441b>] worker_thread+0x4b/0x4c0
[ 2542.449946]  [<ffffffff810943d0>] ? process_one_work+0x440/0x440
[ 2542.450028]  [<ffffffff810943d0>] ? process_one_work+0x440/0x440
[ 2542.450109]  [<ffffffff8109a798>] kthread+0xd8/0xf0
[ 2542.450176]  [<ffffffff8109a6c0>] ? kthread_create_on_node+0x1b0/0x1b0
[ 2542.450263]  [<ffffffff817e011f>] ret_from_fork+0x3f/0x70
[ 2542.450336]  [<ffffffff8109a6c0>] ? kthread_create_on_node+0x1b0/0x1b0
[ 2542.450422] Code: 10 49 89 d9 48 8b 55 c0 4c 89 7c 24 10 4c 89 f1 4c 89 ee 4c 89 e7 89 44 24 08 48 8b 45 20 48 89 04 24 e8 dd d4 ff ff 31 c0 eb ac <0f> 0b e8 92 a4 d2 c0 66 90 0f 1f 44 00 00 55 48 89 e5 41 57 41
[ 2542.451118] RIP  [<ffffffffc0350d07>] insert_inline_extent_backref+0xe7/0xf0 [btrfs]
[ 2542.451238]  RSP <ffff880212e4fac8>
[ 2542.503919] ---[ end trace 35f589f57ae41b90 ]---
[ 2542.504213] BUG: unable to handle kernel paging request at ffffffffffffffd8
[ 2542.504327] IP: [<ffffffff8109adc0>] kthread_data+0x10/0x20
[ 2542.504415] PGD 1c0f067 PUD 1c11067 PMD 0
[ 2542.504505] Oops: 0000 [#2] SMP
[ 2542.504574] Modules linked in: cuse bridge stp llc deflate ctr twofish_generic twofish_x86_64_3way twofish_x86_64 twofish_common camellia_generic dm_thin_pool camellia_x86_64 dm_persistent_data dm_bio_prison dm_bufio libcrc32c serpent_sse2_x86_64 xts serpent_generic lrw gf128mul glue_helper blowfish_generic blowfish_x86_64 blowfish_common cast5_generic cast_common ablk_helper cryptd des_generic cmac xcbc rmd160 crypto_null af_key xfrm_algo nfsd auth_rpcgss nfs_acl nfs lockd grace sunrpc fscache ip6t_REJECT nf_reject_ipv6 dm_crypt xt_hl ip6t_rt nf_conntrack_ipv6 nf_defrag_ipv6 ppdev ipt_REJECT nf_reject_ipv4 xt_comment xt_recent xt_multiport kvm xt_limit xt_tcpudp xt_addrtype ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_conntrack_ipv4 nf_defrag_ipv4 serio_raw xt_conntrack edac_core k10temp edac_mce_amd ip6table_filter i2c_piix4 ip6_tables nf_conntrack_netbios_ns nf_conntrack_broadcast nf_nat_ftp nf_nat nf_conntrack_ftp joydev nf_conntrack iptable_filter snd_hda_codec_via snd_hda_codec_generic snd_hda_codec_hdmi input_leds ip_tables x_tables snd_hda_intel snd_hda_codec snd_hda_core snd_hwdep snd_pcm snd_timer snd soundcore 8250_fintek parport_pc asus_atk0110 shpchp mac_hid netconsole configfs lp parport btrfs xor raid6_pq pata_acpi hid_generic usbhid hid uas usb_storage amdkfd amd_iommu_v2 radeon psmouse i2c_algo_bit pata_atiixp ttm drm_kms_helper r8169 wmi mii drm sata_sil24 ahci libahci
[ 2542.507473] CPU: 0 PID: 142 Comm: kworker/u12:7 Tainted: G      D         4.2.6-040206-generic #201511091832
[ 2542.514862] Hardware name: System manufacturer System Product Name/M4A78LT-M, BIOS 0802    08/24/2010
[ 2542.522317] task: ffff8800c95a9900 ti: ffff880212e4c000 task.ti: ffff880212e4c000
[ 2542.529808] RIP: 0010:[<ffffffff8109adc0>]  [<ffffffff8109adc0>] kthread_data+0x10/0x20
[ 2542.537333] RSP: 0018:ffff880212e4f758  EFLAGS: 00010092
[ 2542.544824] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000000e
[ 2542.552401] RDX: 000000000000000e RSI: 0000000000000000 RDI: ffff8800c95a9900
[ 2542.559952] RBP: ffff880212e4f758 R08: 00000000ffffffff R09: 0000000000000000
[ 2542.567482] R10: ffff8802132c9958 R11: 000000000000001a R12: 00000000000164c0
[ 2542.574969] R13: ffff88021fc164c0 R14: ffff8800c95a9900 R15: 0000000000000000
[ 2542.582260] FS:  00007f422fec7740(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
[ 2542.589393] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 2542.596319] CR2: 0000000000000028 CR3: 00000000c3f1f000 CR4: 00000000000006f0
[ 2542.603069] Stack:
[ 2542.609590]  ffff880212e4f778 ffffffff81095465 ffff880212e4f778 ffff88021fc164c0
[ 2542.616041]  ffff880212e4f7c8 ffffffff817db92d ffff880200000000 ffff8800c95a9900
[ 2542.622276]  ffff880212e4f7c8 ffff880212e50000 ffff8800c95a9fc8 ffff880212e4f390
[ 2542.628452] Call Trace:
[ 2542.634519]  [<ffffffff81095465>] wq_worker_sleeping+0x15/0xa0
[ 2542.640610]  [<ffffffff817db92d>] __schedule+0x60d/0x950
[ 2542.646627]  [<ffffffff817dbca7>] schedule+0x37/0x80
[ 2542.652574]  [<ffffffff8107dff2>] do_exit+0x822/0xb10
[ 2542.658494]  [<ffffffff810184a5>] oops_end+0xa5/0xe0
[ 2542.664422]  [<ffffffff8101896b>] die+0x4b/0x70
[ 2542.670325]  [<ffffffff81015251>] do_trap+0xb1/0x140
[ 2542.676228]  [<ffffffff81015609>] do_error_trap+0x89/0x110
[ 2542.682132]  [<ffffffffc0350d07>] ? insert_inline_extent_backref+0xe7/0xf0 [btrfs]
[ 2542.688044]  [<ffffffffc03494d2>] ? btrfs_search_slot+0x952/0xa10 [btrfs]
[ 2542.693940]  [<ffffffffc0387d05>] ? btrfs_get_token_64+0x105/0x120 [btrfs]
[ 2542.699854]  [<ffffffff81015bd0>] do_invalid_op+0x20/0x30
[ 2542.705683]  [<ffffffff817e161e>] invalid_op+0x1e/0x30
[ 2542.711483]  [<ffffffffc0350d07>] ? insert_inline_extent_backref+0xe7/0xf0 [btrfs]
[ 2542.717303]  [<ffffffffc0350c88>] ? insert_inline_extent_backref+0x68/0xf0 [btrfs]
[ 2542.723059]  [<ffffffff811de3aa>] ? kmem_cache_alloc+0x1ca/0x200
[ 2542.728797]  [<ffffffffc0343e7a>] ? btrfs_alloc_path+0x1a/0x20 [btrfs]
[ 2542.734536]  [<ffffffffc0351219>] __btrfs_inc_extent_ref.isra.52+0xa9/0x270 [btrfs]
[ 2542.740294]  [<ffffffff817db68c>] ? __schedule+0x36c/0x950
[ 2542.746037]  [<ffffffffc03569fc>] __btrfs_run_delayed_refs+0xc6c/0x1080 [btrfs]
[ 2542.751794]  [<ffffffff810a4e2d>] ? ttwu_do_wakeup+0x1d/0xd0
[ 2542.757536]  [<ffffffffc0359b1e>] btrfs_run_delayed_refs.part.73+0x6e/0x270 [btrfs]
[ 2542.763305]  [<ffffffffc0359dbe>] delayed_ref_async_start+0x7e/0x90 [btrfs]
[ 2542.769075]  [<ffffffffc03a036a>] btrfs_scrubparity_helper+0xca/0x290 [btrfs]
[ 2542.774843]  [<ffffffffc03a056e>] btrfs_extent_refs_helper+0xe/0x10 [btrfs]
[ 2542.780577]  [<ffffffff8109413a>] process_one_work+0x1aa/0x440
[ 2542.786315]  [<ffffffff8109441b>] worker_thread+0x4b/0x4c0
[ 2542.792038]  [<ffffffff810943d0>] ? process_one_work+0x440/0x440
[ 2542.797773]  [<ffffffff810943d0>] ? process_one_work+0x440/0x440
[ 2542.803470]  [<ffffffff8109a798>] kthread+0xd8/0xf0
[ 2542.809197]  [<ffffffff8109a6c0>] ? kthread_create_on_node+0x1b0/0x1b0
[ 2542.814953]  [<ffffffff817e011f>] ret_from_fork+0x3f/0x70
[ 2542.820693]  [<ffffffff8109a6c0>] ? kthread_create_on_node+0x1b0/0x1b0
[ 2542.826453] Code: ff ff ff be 2b 02 00 00 48 c7 c7 90 9a aa 81 e8 37 07 fe ff e9 a6 fe ff ff 66 90 0f 1f 44 00 00 48 8b 87 08 05 00 00 55 48 89 e5 <48> 8b 40 d8 5d c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00
[ 2542.833162] RIP  [<ffffffff8109adc0>] kthread_data+0x10/0x20
[ 2542.839079]  RSP <ffff880212e4f758>
[ 2542.844798] CR2: ffffffffffffffd8
[ 2542.850465] ---[ end trace 35f589f57ae41b91 ]---
[ 2542.856145] Fixing recursive fault but reboot is needed!

Dear all,
I seem to have the same issue. BTRFS was running stable for a long time now. But today I try to remove a device from my system and my home server keeps freezing after some minutes. Managed to relocate about 0.09TiB with 4 freezes/reboots from devid 4 now.
	devid    1 size 3.64TiB used 3.17TiB path /dev/mapper/hitachi4tb1
	devid    4 size 3.64TiB used 2.75TiB path /dev/mapper/hitachi4tb2
	devid    5 size 5.46TiB used 4.57TiB path /dev/mapper/wdred6tb
	devid    6 size 5.46TiB used 2.45TiB path /dev/mapper/wdred6tb2
btrfs-progs v4.0
Linux server 4.2.0-19-generic #23-Ubuntu SMP Wed Nov 11 11:39:30 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

sudo btrfs device delete /dev/mapper/hitachi4tb2 /data
->
Dec 15 13:00:03 server kernel: [ 1097.041852] BTRFS info (device dm-4): found 1698 extents
Dec 15 13:00:08 server kernel: [ 1101.186721] BTRFS info (device dm-4): relocating block group 32640841285632 flags 1
Dec 15 13:00:28 server kernel: [ 1122.113340] BTRFS info (device dm-4): found 1771 extents
Dec 15 13:02:29 server kernel: [ 1242.331160] BTRFS info (device dm-4): found 1771 extents
Dec 15 13:02:33 server kernel: [ 1246.890472] BTRFS info (device dm-4): relocating block group 32638693801984 flags 1
Dec 15 13:02:57 server kernel: [ 1270.455640] BTRFS info (device dm-4): found 1739 extents
Dec 15 13:03:30 server kernel: [ 1303.367707] ------------[ cut here ]------------
Dec 15 13:03:30 server kernel: [ 1303.367728] kernel BUG at /build/linux-26_gwp/linux-4.2.0/fs/btrfs/extent-tree.c:1833!
Dec 15 13:03:30 server kernel: [ 1303.367751] invalid opcode: 0000 [#1] SMP 
Dec 15 13:03:30 server kernel: [ 1303.367766] Modules linked in: cls_fw xt_length xt_owner ip6table_mangle ip6_tables xt_tcpudp xt_mark sch_sfq sch_htb iptable_mangle iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_filter ip_tables x_tables bridge stp llc intel_rapl iosf_mbi x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm snd_hda_codec_hdmi serio_raw snd_hda_intel snd_hda_codec lpc_ich joydev input_leds snd_hda_core snd_hwdep snd_pcm mei_me mei snd_timer snd soundcore shpchp 8250_fintek tpm_infineon mac_hid nfsd auth_rpcgss nfs_acl lockd grace sunrpc autofs4 btrfs xor raid6_pq drbg ansi_cprng xts gf128mul algif_skcipher af_alg dm_crypt hid_generic mxm_wmi pata_acpi crct10dif_pclmul crc32_pclmul usbhid i915 ahci i2c_algo_bit drm_kms_helper cryptd psmouse pata_marvell libahci hid drm r8169 mii wmi video
Dec 15 13:03:30 server kernel: [ 1303.368061] CPU: 1 PID: 154 Comm: kworker/u4:9 Not tainted 4.2.0-19-generic #23-Ubuntu
Dec 15 13:03:30 server kernel: [ 1303.368084] Hardware name: MSI MS-7817/H81M-P33 (MS-7817), BIOS V1.2 09/17/2013
Dec 15 13:03:30 server kernel: [ 1303.368120] Workqueue: btrfs-extent-refs btrfs_extent_refs_helper [btrfs]
Dec 15 13:03:30 server kernel: [ 1303.368141] task: ffff88030c6e9980 ti: ffff88030c764000 task.ti: ffff88030c764000
Dec 15 13:03:30 server kernel: [ 1303.368162] RIP: 0010:[<ffffffffc0333d07>]  [<ffffffffc0333d07>] insert_inline_extent_backref+0xe7/0xf0 [btrfs]
Dec 15 13:03:30 server kernel: [ 1303.368197] RSP: 0018:ffff88030c767ac8  EFLAGS: 00010293
Dec 15 13:03:30 server kernel: [ 1303.368212] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
Dec 15 13:03:30 server kernel: [ 1303.368232] RDX: ffff880000000000 RSI: 0000000000000001 RDI: 0000000000000000
Dec 15 13:03:30 server kernel: [ 1303.368252] RBP: ffff88030c767b48 R08: 0000000000004000 R09: ffff88030c7679c0
Dec 15 13:03:30 server kernel: [ 1303.368272] R10: 0000000000000000 R11: 0000000000000002 R12: ffff88030bd36800
Dec 15 13:03:30 server kernel: [ 1303.368292] R13: ffff8801907a0120 R14: 0000000000000000 R15: 0000000000000000
Dec 15 13:03:30 server kernel: [ 1303.368313] FS:  0000000000000000(0000) GS:ffff88031fb00000(0000) knlGS:0000000000000000
Dec 15 13:03:30 server kernel: [ 1303.368335] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Dec 15 13:03:30 server kernel: [ 1303.368352] CR2: 00007fe2b3038680 CR3: 00000002358a6000 CR4: 00000000000406e0
Dec 15 13:03:30 server kernel: [ 1303.368372] Stack:
Dec 15 13:03:30 server kernel: [ 1303.368378]  0000000000000000 0000000000000005 0000000000000000 0000000000000000
Dec 15 13:03:30 server kernel: [ 1303.368403]  0000000000000001 ffffffff811de5ea 0000000000270026 ffffffffc0326e7a
Dec 15 13:03:30 server kernel: [ 1303.368428]  0000000000002e0f 000000003e01e9b6 ffff88030bd34800 0000000000000000
Dec 15 13:03:30 server kernel: [ 1303.368453] Call Trace:
Dec 15 13:03:30 server kernel: [ 1303.368464]  [<ffffffff811de5ea>] ? kmem_cache_alloc+0x1ca/0x200
Dec 15 13:03:30 server kernel: [ 1303.368486]  [<ffffffffc0326e7a>] ? btrfs_alloc_path+0x1a/0x20 [btrfs]
Dec 15 13:03:30 server kernel: [ 1303.368509]  [<ffffffffc0334219>] __btrfs_inc_extent_ref.isra.52+0xa9/0x270 [btrfs]
Dec 15 13:03:30 server kernel: [ 1303.368536]  [<ffffffffc03399fc>] __btrfs_run_delayed_refs+0xc6c/0x1080 [btrfs]
Dec 15 13:03:30 server kernel: [ 1303.368562]  [<ffffffffc033cb1e>] btrfs_run_delayed_refs.part.73+0x6e/0x270 [btrfs]
Dec 15 13:03:30 server kernel: [ 1303.368588]  [<ffffffffc033cdbe>] delayed_ref_async_start+0x7e/0x90 [btrfs]
Dec 15 13:03:30 server kernel: [ 1303.368617]  [<ffffffffc038336a>] btrfs_scrubparity_helper+0xca/0x290 [btrfs]
Dec 15 13:03:30 server kernel: [ 1303.368644]  [<ffffffffc038356e>] btrfs_extent_refs_helper+0xe/0x10 
[remaining lost due to freeze]

btrfs-progs v4.0
Data, single: total=12.92TiB, used=12.71TiB
System, single: total=32.00MiB, used=1.59MiB
Metadata, single: total=26.00GiB, used=20.56GiB
GlobalReserve, single: total=512.00MiB, used=0.00B
[/dev/mapper/hitachi4tb1].write_io_errs   0
[/dev/mapper/hitachi4tb1].read_io_errs    0
[/dev/mapper/hitachi4tb1].flush_io_errs   0
[/dev/mapper/hitachi4tb1].corruption_errs 0
[/dev/mapper/hitachi4tb1].generation_errs 0
[/dev/mapper/hitachi4tb2].write_io_errs   0
[/dev/mapper/hitachi4tb2].read_io_errs    0
[/dev/mapper/hitachi4tb2].flush_io_errs   0
[/dev/mapper/hitachi4tb2].corruption_errs 0
[/dev/mapper/hitachi4tb2].generation_errs 0
[/dev/mapper/wdred6tb].write_io_errs   0
[/dev/mapper/wdred6tb].read_io_errs    0
[/dev/mapper/wdred6tb].flush_io_errs   0
[/dev/mapper/wdred6tb].corruption_errs 0
[/dev/mapper/wdred6tb].generation_errs 0
[/dev/mapper/wdred6tb2].write_io_errs   0
[/dev/mapper/wdred6tb2].read_io_errs    0
[/dev/mapper/wdred6tb2].flush_io_errs   0
[/dev/mapper/wdred6tb2].corruption_errs 0
[/dev/mapper/wdred6tb2].generation_errs 0

For me the fix was upgrading to the latest 4.4. Kernel (still in release candidate status)

This issue already seemed to be fixed. Unfortunately I can't remember the name of the patch.

(In reply to bugzilla.kernel.org from comment #17)
> For me the fix was upgrading to the latest 4.4. Kernel (still in release
> candidate status)
> This issue already seemed to be fixed. Unfortunately I can't remember the
> name of the patch.

Thank you very much for that hint! Installed kernel 4.4rc5 and the "device delete" is now running fine since almost one hour.

Seems to be a good idea for the future to try new kernels when there is a bug...