kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
   (ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 6055 Comm: syz-executor5 Not tainted 4.15.0-rc3+ #226
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__list_del_entry_valid+0x7e/0x150 lib/list_debug.c:51
RSP: 0018:ffff8801cebef908 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff8801d92433d8 RDI: ffff8801d92433e0
RBP: ffff8801cebef920 R08: 1ffff10039d7de55 R09: 0000000000000004
R10: ffff8801cebef770 R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: 1ffff10039d7df45 R15: ffff8801d92433d8
FS:  00007fc46f5ff700(0000) GS:ffff8801db400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000209a3ff4 CR3: 00000001c3371006 CR4: 00000000001626f0
DR0: 0000000020000000 DR1: 0000000020000000 DR2: 0000000020000000
DR3: 0000000020000000 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+0x79/0x300 mm/vmscan.c:301
 deactivate_locked_super+0x64/0xd0 fs/super.c:311
 deactivate_super+0x141/0x1b0 fs/super.c:343
 cleanup_mnt+0xb2/0x150 fs/namespace.c:1173
 mntput_no_expire+0x6e0/0xa90 fs/namespace.c:1237
 mntput fs/namespace.c:1247 [inline]
 kern_unmount+0x9c/0xd0 fs/namespace.c:3000
 mq_put_mnt+0x37/0x50 ipc/mqueue.c:1609
 put_ipc_ns+0x4d/0x150 ipc/namespace.c:163
 create_new_namespaces+0x5dd/0x880 kernel/nsproxy.c:122
 unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206
 SYSC_unshare kernel/fork.c:2366 [inline]
 SyS_unshare+0x653/0xfa0 kernel/fork.c:2316
 entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x452a09
RSP: 002b:00007fc46f5fec58 EFLAGS: 00000212 ORIG_RAX: 0000000000000110
RAX: ffffffffffffffda RBX: 00007fc46f5feaa0 RCX: 0000000000452a09
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000028060400
RBP: 00007fc46f5fea90 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000004b75bb
R13: 00007fc46f5febc8 R14: 00000000004b75bb R15: 0000000000000000
Code: 00 00 00 00 ad de 49 39 c4 74 66 48 b8 00 02 00 00 00 00 ad de 48 89 da 48 39 c3 74 65 48 c1 ea 03 48 b8 00 00 00 00 00 fc ff df <80> 3c 02 00 75 7b 48 8b 13 48 39 f2 75 57 49 8d 7c 24 08 48 b8 
RIP: __list_del_entry_valid+0x7e/0x150 lib/list_debug.c:51 RSP: ffff8801cebef908
---[ end trace 9222cdda70ba5730 ]---