RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000440509
RDX: 00000000209aaffa RSI: 00000000206c6000 RDI: 00000000206eaff8
RBP: 0000000000000005 R08: 0000000020be9f95 R09: 0000000000003431
R10: 0000000000200002 R11: 0000000000000246 R12: 0000000000401e30
R13: 0000000000401ec0 R14: 0000000000000000 R15: 0000000000000000
BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: __list_del_entry_valid+0x29/0x90 lib/list_debug.c:48
PGD 2167c9067 P4D 2167c9067 PUD 216075067 PMD 0 
Oops: 0000 [#1] SMP
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 3110 Comm: syzkaller793953 Not tainted 4.15.0-rc3-next-20171214+ #67
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__list_del_entry_valid+0x29/0x90 lib/list_debug.c:48
RSP: 0018:ffffc90001843e30 EFLAGS: 00010207
RAX: 0000000000000000 RBX: ffff880214315730 RCX: dead000000000200
RDX: 0000000000000000 RSI: ffffffff83da6a60 RDI: ffff880214315758
RBP: ffffc90001843e30 R08: ffffffff83ad0c70 R09: 0000000000000000
R10: ffffc90001843db0 R11: ffff88021374c780 R12: ffffffff830996e0
R13: ffff88021374c780 R14: 0000000000000000 R15: ffff880214ebf038
FS:  0000000002667880(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000020e9fb003 CR4: 00000000001606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __list_del_entry include/linux/list.h:117 [inline]
 list_del include/linux/list.h:125 [inline]
 unregister_shrinker+0x22/0x70 mm/vmscan.c:285
 deactivate_locked_super+0x45/0x80 fs/super.c:311
 deactivate_super+0x61/0x90 fs/super.c:343
 cleanup_mnt+0x49/0x90 fs/namespace.c:1173
 __cleanup_mnt+0x16/0x20 fs/namespace.c:1180
 task_work_run+0xa3/0xe0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x152/0x160 arch/x86/entry/common.c:165
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x1b4/0x1e0 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x94/0x96
RIP: 0033:0x440509
RSP: 002b:00007ffd08e88fa8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffec RBX: 0000000000000000 RCX: 0000000000440509
RDX: 00000000209aaffa RSI: 00000000206c6000 RDI: 00000000206eaff8
RBP: 00000000006cb018 R08: 0000000020be9f95 R09: 0000000000003431
R10: 0000000000200002 R11: 0000000000000246 R12: 0000000000000005
R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
Code: 00 00 55 48 8b 07 48 b9 00 01 00 00 00 00 ad de 48 8b 57 08 48 89 e5 48 39 c8 74 27 48 b9 00 02 00 00 00 00 ad de 48 39 ca 74 2c <48> 8b 32 48 39 fe 75 35 48 8b 50 08 48 39 f2 75 40 b8 01 00 00 
RIP: __list_del_entry_valid+0x29/0x90 lib/list_debug.c:48 RSP: ffffc90001843e30
CR2: 0000000000000000
---[ end trace 2212e43cc89cd8b4 ]---