RBP: 00007fb1a8ffaa90 R08: 0000000020700fff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b75bb
R13: 00007fb1a8ffabc8 R14: 00000000004b75bb 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 1ffa13067 P4D 1ffa13067 PUD 200e19067 PMD 0 
Oops: 0000 [#1] SMP
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 3339 Comm: syz-executor7 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:ffffc90002853e30 EFLAGS: 00010207
RAX: 0000000000000000 RBX: ffff8801ff08c730 RCX: dead000000000200
RDX: 0000000000000000 RSI: 00000000efce5b00 RDI: ffff8801ff08c758
RBP: ffffc90002853e30 R08: 0000000000000001 R09: 0000000000000004
R10: ffffc90002853db0 R11: 0000000000000004 R12: ffffffff830b85a0
R13: ffff88020138c340 R14: 0000000000000000 R15: ffff8802111adab8
FS:  0000000002505940(0000) GS:ffff88021fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000001ffed3004 CR4: 00000000001606f0
DR0: 0000000020001000 DR1: 0000000020001000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600
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: 0033:0x455417
RSP: 002b:0000000000a2d888 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000064 RCX: 0000000000455417
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000a2e9f0
RBP: 0000000000a2e9f0 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000005 R11: 0000000000000206 R12: 000000000250fce0
R13: 0000000000000000 R14: 0000000000016e19 R15: 0000000000000010
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: ffffc90002853e30
CR2: 0000000000000000
---[ end trace c19bdee0b6e9803c ]---