BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
IPVS: ftp: loaded support on port[0] = 21
PGD 8000000117009067 P4D 8000000117009067 PUD 1170f4067 PMD 0 
Oops: 0000 [#1] SMP PTI
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 171 Comm: kworker/u4:4 Not tainted 4.17.0+ #7
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn
RIP: 0010:dev_name include/linux/device.h:1008 [inline]
RIP: 0010:wb_workfn+0x176/0x1fb0 fs/fs-writeback.c:1937
RSP: 0018:ffff8801d85efb38 EFLAGS: 00010246
RAX: ffff88013f4e9350 RBX: 0000000000000050 RCX: ffff880000000000
RDX: ffff88013f4ed350 RSI: aaaaaaaaaaaab000 RDI: ffffea0000000000
RBP: ffff8801d85efc78 R08: 0000000001080020 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff81df5720 R12: 0000000000000000
R13: ffff88019c3ca000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000050 CR3: 000000010d142000 CR4: 00000000001406f0
DR0: 0000000020000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
Call Trace:
 process_one_work+0x12e4/0x1fa0 kernel/workqueue.c:2145
 process_scheduled_works kernel/workqueue.c:2205 [inline]
 worker_thread+0x1986/0x24f0 kernel/workqueue.c:2284
 kthread+0x4db/0x6c0 kernel/kthread.c:241
 ret_from_fork+0x35/0x40 arch/x86/entry/entry_64.S:412
Code: 31 e1 ff 48 83 38 00 75 5c 44 89 7d d4 4c 8b 3b 48 89 df e8 3d 31 e1 ff 4c 8b 30 44 8b 22 49 8d 5f 50 4d 85 f6 75 47 44 89 65 c8 <4c> 8b 2b 48 89 df e8 1f 31 e1 ff 4c 8b 20 8b 1a 4d 85 e4 74 0b 
RIP: dev_name include/linux/device.h:1008 [inline] RSP: ffff8801d85efb38
RIP: wb_workfn+0x176/0x1fb0 fs/fs-writeback.c:1937 RSP: ffff8801d85efb38
CR2: 0000000000000050
---[ end trace 85a3a32459792e9e ]---