Warning: Permanently added '10.128.1.123' (ECDSA) to the list of known hosts.
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[   31.132926] refcount_t: underflow; use-after-free.
[   31.138753] ------------[ cut here ]------------
[   31.143506] WARNING: CPU: 0 PID: 8324 at lib/refcount.c:281 refcount_dec_not_one.cold+0x18/0x25
[   31.152480] Kernel panic - not syncing: panic_on_warn set ...
[   31.152480] 
[   31.159822] CPU: 0 PID: 8324 Comm: systemd-udevd Not tainted 4.14.239-syzkaller #0
[   31.167515] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[   31.176852] Call Trace:
[   31.179435]  dump_stack+0x1b2/0x281
[   31.183038]  panic+0x1f9/0x42d
[   31.186220]  ? add_taint.cold+0x16/0x16
[   31.190175]  ? refcount_dec_not_one.cold+0x18/0x25
[   31.195086]  ? refcount_dec_not_one.cold+0x18/0x25
[   31.199989]  __warn.cold+0x20/0x44
[   31.203510]  ? ist_end_non_atomic+0x10/0x10
[   31.207835]  ? refcount_dec_not_one.cold+0x18/0x25
[   31.212792]  report_bug+0x208/0x250
[   31.216399]  do_error_trap+0x195/0x2d0
[   31.220266]  ? math_error+0x2d0/0x2d0
[   31.224048]  ? ___preempt_schedule+0x16/0x18
[   31.228434]  ? trace_hardirqs_off_thunk+0x1a/0x1c
[   31.233291]  invalid_op+0x1b/0x40
[   31.236722] RIP: 0010:refcount_dec_not_one.cold+0x18/0x25
[   31.242242] RSP: 0018:ffff888093e3fc38 EFLAGS: 00010286
[   31.247584] RAX: 0000000000000026 RBX: 0000000000000000 RCX: 0000000000000000
[   31.254940] RDX: 0000000000000000 RSI: ffffffff878bbbc0 RDI: ffffed10127c7f7d
[   31.262183] RBP: ffff8880ac120918 R08: 0000000000000026 R09: 0000000000000000
[   31.269427] R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffff
[   31.276669] R13: 0000000000000000 R14: ffffed10118bf26e R15: ffff8880ac120928
[   31.283959]  ? refcount_dec_not_one.cold+0x18/0x25
[   31.288865]  ? trace_hardirqs_on_caller+0x3a8/0x580
[   31.293862]  refcount_dec_and_mutex_lock+0x1a/0x60
[   31.298769]  nbd_config_put+0x506/0x810
[   31.302720]  nbd_release+0xdf/0x150
[   31.306331]  ? nbd_queue_rq+0xc50/0xc50
[   31.310280]  __blkdev_put+0x5aa/0x800
[   31.314053]  ? revalidate_disk+0x1f0/0x1f0
[   31.318260]  ? locks_remove_file+0x2cd/0x420
[   31.322690]  ? blkdev_put+0x75/0x4c0
[   31.326386]  ? blkdev_put+0x4c0/0x4c0
[   31.330282]  blkdev_close+0x86/0xb0
[   31.333889]  __fput+0x25f/0x7a0
[   31.337155]  task_work_run+0x11f/0x190
[   31.341146]  exit_to_usermode_loop+0x1ad/0x200
[   31.345700]  do_syscall_64+0x4a3/0x640
[   31.349560]  entry_SYSCALL_64_after_hwframe+0x46/0xbb
[   31.354718] RIP: 0033:0x7f0b18e1d270
[   31.358402] RSP: 002b:00007ffe631408f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
[   31.366083] RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007f0b18e1d270
[   31.373593] RDX: 000000000aba9500 RSI: 0000000000000000 RDI: 0000000000000007
[   31.380923] RBP: 00007f0b19cd7710 R08: 000055ca923a1d60 R09: 0000000000000018
[   31.388167] R10: 000055ca9238ce38 R11: 0000000000000246 R12: 0000000000000000
[   31.395413] R13: 000055ca9239e880 R14: 0000000000000003 R15: 000000000000000e
[   31.404248] Kernel Offset: disabled
[   31.407900] Rebooting in 86400 seconds..