I am getting call traces in my server log. How do I find the cause of this. Currently running 6.4.0-rc9f 

servernas-diagnostics-20171002-1527.zip

Think your docker img file is corrupt and causing your call traces.  But you might wait for a second opinion on this since I could easily be wrong.  Reading the logs is not terribly easy for me.

Oct  1 22:14:35 ServerNAS kernel: Call Trace:
Oct  1 22:14:35 ServerNAS kernel: close_ctree+0x1bf/0x29c
Oct  1 22:14:35 ServerNAS kernel: ? evict_inodes+0x128/0x137
Oct  1 22:14:35 ServerNAS kernel: btrfs_put_super+0x10/0x12
Oct  1 22:14:35 ServerNAS kernel: generic_shutdown_super+0x6a/0x10b
Oct  1 22:14:35 ServerNAS kernel: kill_anon_super+0xd/0x17
Oct  1 22:14:35 ServerNAS kernel: btrfs_kill_super+0x11/0x94
Oct  1 22:14:35 ServerNAS kernel: deactivate_locked_super+0x30/0x68
Oct  1 22:14:35 ServerNAS kernel: deactivate_super+0x32/0x35
Oct  1 22:14:35 ServerNAS kernel: cleanup_mnt+0x44/0x62
Oct  1 22:14:35 ServerNAS kernel: __cleanup_mnt+0xd/0xf
Oct  1 22:14:35 ServerNAS kernel: task_work_run+0x67/0x7a
Oct  1 22:14:35 ServerNAS kernel: exit_to_usermode_loop+0x55/0x82
Oct  1 22:14:35 ServerNAS kernel: syscall_return_slowpath+0x44/0x57
Oct  1 22:14:35 ServerNAS kernel: entry_SYSCALL_64_fastpath+0xa7/0xa9
Oct  1 22:14:35 ServerNAS kernel: RIP: 0033:0x2b21c29fa357
Oct  1 22:14:35 ServerNAS kernel: RSP: 002b:00007ffdd4aa7658 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
Oct  1 22:14:35 ServerNAS kernel: RAX: 0000000000000000 RBX: 00000000006072b0 RCX: 00002b21c29fa357
Oct  1 22:14:35 ServerNAS kernel: RDX: 0000000000000001 RSI: 0000000000000000 RDI: 000000000060b700
Oct  1 22:14:35 ServerNAS kernel: RBP: 000000000060b700 R08: ffffffffffffff60 R09: 00000000006079a0
Oct  1 22:14:35 ServerNAS kernel: R10: 0000000000000008 R11: 0000000000000246 R12: 00002b21c228de90
Oct  1 22:14:35 ServerNAS kernel: R13: 0000000000000000 R14: 0000000000607490 R15: 0000000000000000
Oct  1 22:14:35 ServerNAS kernel: Code: 0e 00 00 48 39 c2 0f 84 aa 00 00 00 4c 8b a3 38 0e 00 00 49 83 7c 24 90 00 75 10 49 83 7c 24 98 00 75 08 49 83 7c 24 a0 00 74 16 <0f> ff 31 c9 31 d2 48 89 df 49 8d b4 24 78 ff ff ff e8 a0 7a ff 
Oct  1 22:14:35 ServerNAS kernel: ---[ end trace 3adbe9613f5a484e ]---
Oct  1 22:14:35 ServerNAS kernel: BTRFS info (device loop2): space_info 4 has 976306176 free, is not full
Oct  1 22:14:35 ServerNAS kernel: BTRFS info (device loop2): space_info total=1073741824, used=97353728, pinned=0, reserved=16384, may_use=0, readonly=65536
Oct  1 22:14:35 ServerNAS kernel: BTRFS warning (device loop2): page private not zero on page 735363072
Oct  1 22:14:35 ServerNAS kernel: BTRFS warning (device loop2): page private not zero on page 735367168
Oct  1 22:14:35 ServerNAS kernel: BTRFS warning (device loop2): page private not zero on page 735371264
Oct  1 22:14:35 ServerNAS kernel: BTRFS warning (device loop2): page private not zero on page 735375360