syzbot

panic: acquiring blockable sleep lock with spinlock or critical section held (kernel_lock) &kernel_lock
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
 290216  16442      0           0          0    1  syz-executor
*235205   7755      0     0x14000      0x200    0  systqmp
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff835572bd) at panic+0x1e5 sys/kern/subr_prf.c:198
witness_checkorder(ffffffff83a7eac0,9,0) at witness_checkorder+0x11ee sys/kern/subr_witness.c:847
__mp_lock(ffffffff83a7e2c0) at __mp_lock+0xe1 read_rflags sys/arch/amd64/compile/SYZKALLER/obj/machine/cpufunc.h:212 [inline]
__mp_lock(ffffffff83a7e2c0) at __mp_lock+0xe1 intr_disable sys/arch/amd64/compile/SYZKALLER/obj/machine/cpufunc.h:233 [inline]
__mp_lock(ffffffff83a7e2c0) at __mp_lock+0xe1 sys/kern/kern_lock.c:168
selwakeup(ffff800001617a90) at selwakeup+0x23 sys/kern/sys_generic.c:836
ptsstart(ffff8000015a2e00) at ptsstart+0x120 ptcwakeup sys/kern/tty_pty.c:391 [inline]
ptsstart(ffff8000015a2e00) at ptsstart+0x120 sys/kern/tty_pty.c:358
tputchar(70,ffff8000015a2e00) at tputchar+0x17b ttstart sys/kern/tty.c:1367 [inline]
tputchar(70,ffff8000015a2e00) at tputchar+0x17b sys/kern/tty.c:2301
kputchar(70,1,0) at kputchar+0x10e sys/kern/subr_prf.c:360
kprintf() at kprintf+0x223 sys/kern/subr_prf.c:723
log(5,ffffffff83521847) at log+0x1f8 sys/kern/subr_prf.c:292
pf_purge_expired_fragments() at pf_purge_expired_fragments+0x148 sys/net/pf_norm.c:214
pf_purge(0) at pf_purge+0x248 sys/net/pf.c:1979
taskq_thread(ffffffff839405b0) at taskq_thread+0x157 sys/kern/kern_task.c:446
end trace frame: 0x0, count: 2
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