mount_ns+0x5d/0x170 fs/super.c:1044
 proc_mount+0x4b/0xa0 fs/proc/root.c:101
------------[ cut here ]------------
 mount_fs+0x84/0x26e fs/super.c:1237
WARNING: CPU: 1 PID: 7049 at lib/refcount.c:187 refcount_sub_and_test.cold.13+0x13/0x1c lib/refcount.c:187
 vfs_kern_mount.part.33+0x58/0x3c0 fs/namespace.c:1046
Kernel panic - not syncing: panic_on_warn set ...

 vfs_kern_mount fs/namespace.c:3329 [inline]
 kern_mount_data+0x42/0xa0 fs/namespace.c:3329
 pid_ns_prepare_proc+0x1b/0x60 fs/proc/root.c:222
 alloc_pid+0x930/0xcc0 kernel/pid.c:324
 copy_process.part.37+0x2538/0x66e0 kernel/fork.c:1785
 copy_process kernel/fork.c:1586 [inline]
 _do_fork+0x155/0xbb0 kernel/fork.c:2070
 SYSC_clone kernel/fork.c:2180 [inline]
 SyS_clone+0x14/0x20 kernel/fork.c:2174
 do_syscall_64+0x1c9/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x458c29
RSP: 002b:00007f39779c0c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f39779c0c90 RCX: 0000000000458c29
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 0000802122001ffa
RBP: 000000000073bfa0 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f39779c16d4
R13: 00000000004befd3 R14: 00000000004d0020 R15: 0000000000000003
CPU: 1 PID: 7049 Comm: syz-executor.1 Not tainted 4.14.171-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xf7/0x13b lib/dump_stack.c:58
 panic+0x1b0/0x36a kernel/panic.c:183
 __warn.cold.8+0x25/0x2a kernel/panic.c:547
FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 0
 report_bug+0x1a4/0x1f3 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:177 [inline]
 do_error_trap+0x1bd/0x310 arch/x86/kernel/traps.c:295
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:963
RIP: 0010:refcount_sub_and_test.cold.13+0x13/0x1c lib/refcount.c:187
RSP: 0018:ffff88807dd7faf0 EFLAGS: 00010286
RAX: 0000000000000026 RBX: 0000000000000001 RCX: 0000000000000000
RDX: 0000000000000026 RSI: ffffffff868cb0e0 RDI: ffffed100fbaff55
RBP: ffff88807dd7fb00 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff88807bb76500
R13: dffffc0000000000 R14: ffff888090faa9d8 R15: 0000802122001ffa
 refcount_dec_and_test+0x11/0x20 lib/refcount.c:212
 kref_put include/linux/kref.h:69 [inline]
 put_pid_ns.part.2+0x4f/0x100 kernel/pid_namespace.c:203
 put_pid_ns+0x9/0x10 kernel/pid_namespace.c:198
 free_nsproxy+0xc9/0x190 kernel/nsproxy.c:182
 switch_task_namespaces+0x84/0xa0 kernel/nsproxy.c:229
 exit_task_namespaces+0xb/0x10 kernel/nsproxy.c:234
 copy_process.part.37+0x38de/0x66e0 kernel/fork.c:1971
 copy_process kernel/fork.c:1586 [inline]
 _do_fork+0x155/0xbb0 kernel/fork.c:2070
 SYSC_clone kernel/fork.c:2180 [inline]
 SyS_clone+0x14/0x20 kernel/fork.c:2174
 do_syscall_64+0x1c9/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x458c29
RSP: 002b:00007f21f6596c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f21f6596c90 RCX: 0000000000458c29
RDX: 9999999999999999 RSI: 0000000000000000 RDI: 0000802122001ffa
RBP: 000000000073bf00 R08: ffffffffffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f21f65976d4
R13: 00000000004befd3 R14: 00000000004d0020 R15: 0000000000000004
Kernel Offset: disabled
Rebooting in 86400 seconds..