syzbot

panic: Thread 0xffff800020b92270 cannot exit while holding sleeplocks

Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
 270548  30025  32767        0x10      0x480    1  syz-executor1
*437706   2930      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(dc844db7986d77fb) 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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ddb{0}> 
ddb{0}> set $lines = 0
ddb{0}> show panic
Thread 0xffff800020b92270 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(dc844db7986d77fb) 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}>