panic: Thread 0xffff800020b92bd0 cannot exit while holding sleeplocks

Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
  10923  34859      0         0x2      0x480    1  syz-executor1
*228503  60997      0     0x14000      0x200    0  reaper
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399
panic() at panic+0x16c sys/kern/subr_prf.c:208
witness_thread_exit(37530971dfcc38ae) at witness_thread_exit+0x244 sys/kern/subr_witness.c:1377
reaper(0) at reaper+0x14f sys/kern/kern_exit.c:412
end trace frame: 0x0, count: 11
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reports.  Insufficient info makes it difficult to find and fix bugs.
ddb{0}> 
ddb{0}> set $lines = 0
ddb{0}> show panic
Thread 0xffff800020b92bd0 cannot exit while holding sleeplocks

ddb{0}> trace
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399
panic() at panic+0x16c sys/kern/subr_prf.c:208
witness_thread_exit(37530971dfcc38ae) at witness_thread_exit+0x244 sys/kern/subr_witness.c:1377
reaper(0) at reaper+0x14f sys/kern/kern_exit.c:412
end trace frame: 0x0, count: -4
ddb{0}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff800020b673d0
rbx               0xffff800020b67470
rdx               0xffffffff81ec577a    cmd0646_9_tim_udma+0x16395
rcx                            0x201
rax                              0x1
r8                0xffffffff81788154    kprintf+0x174
r9                               0x1
r10               0x48f78ee6edb2a303
r11               0xa339bb86623064e0
r12                     0x3000000008
r13               0xffff800020b673e0
r14                            0x100
r15                              0x1
rip               0xffffffff81107618    db_enter+0x18
cs                               0x8
rflags                         0x246
rsp               0xffff800020b673c0
ss                              0x10
db_enter+0x18:  addq    $0x8,%rsp
ddb{0}>