panic: acquiring blockable sleep lock with spinlock or critical section held (kernel_lock) &kernel_lock
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
 304955  77470      0         0x2  0x4000080    1  syz-fuzzer
*344008  39960      0     0x14000      0x200    0  systqmp
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:398
panic(ffffffff823faa33) at panic+0x15c sys/kern/subr_prf.c:207
witness_checkorder(ffffffff828f4e08,9,0) at witness_checkorder+0x10e0 sys/kern/subr_witness.c:821
__mp_lock(ffffffff828f4c00) at __mp_lock+0xa1 read_rflags machine/cpufunc.h:195 [inline]
__mp_lock(ffffffff828f4c00) at __mp_lock+0xa1 intr_disable machine/cpufunc.h:216 [inline]
__mp_lock(ffffffff828f4c00) at __mp_lock+0xa1 sys/kern/kern_lock.c:142
pageflttrap(ffff800020da3680,0) at pageflttrap+0x7f sys/arch/amd64/amd64/trap.c:180
kerntrap(ffff800020da3680) at kerntrap+0xec sys/arch/amd64/amd64/trap.c:302
alltraps_kern_meltdown() at alltraps_kern_meltdown+0x7b
pool_cache_gc(ffffffff828e60d8) at pool_cache_gc+0x138 pool_cache_list_put sys/kern/subr_pool.c:1970 [inline]
pool_cache_gc(ffffffff828e60d8) at pool_cache_gc+0x138 sys/kern/subr_pool.c:2025
pool_gc_pages(0) at pool_gc_pages+0x6c sys/kern/subr_pool.c:1559
taskq_thread(ffffffff82716c40) at taskq_thread+0xec sys/kern/kern_task.c:437
end trace frame: 0x0, count: 5
https://www.openbsd.org/ddb.html describes the minimum info required in bug
reports.  Insufficient info makes it difficult to find and fix bugs.