syzbot

login: witness: thread 0xffff800020b399e0 exiting with the following locks held:
exclusive rrwlock inode r = 0 (0xfffffd806a587d58) locked @ /syzkaller/managers/multicore/kernel/sys/ufs/ufs/ufs_vnops.c:1547
#0  witness_lock+0x594 sys/kern/subr_witness.c:1205
#1  _rw_enter+0x45d sys/kern/kern_rwlock.c:280
#2  _rrw_enter+0x60 sys/kern/kern_rwlock.c:410
#3  VOP_LOCK+0x57 sys/kern/vfs_vops.c:602
#4  vn_write+0x169 vn_lock sys/kern/vfs_vnops.c:549 [inline]
#4  vn_write+0x169 sys/kern/vfs_vnops.c:393
#5  dofilewritev+0x1b0 sys/kern/sys_generic.c:364
#6  sys_write+0x92 sys/kern/sys_generic.c:284
#7  syscall+0x5b8 mi_syscall sys/sys/syscall_mi.h:99 [inline]
#7  syscall+0x5b8 sys/arch/amd64/amd64/trap.c:574
#8  Xsyscall+0x128
panic: thread 0xffff800020b399e0 cannot exit while holding sleeplocks
Stopped at      db_enter+0x18:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*201819  83779      0     0x14000      0x200    1  reaper
db_enter() at db_enter+0x18 sys/arch/amd64/amd64/db_interface.c:399
panic() at panic+0x174 sys/kern/subr_prf.c:208
witness_thread_exit(ffff800020b399e0) at witness_thread_exit+0x283 sys/kern/subr_witness.c:1422
reaper(ffff800020ac1c20) at reaper+0x14f sys/kern/kern_exit.c:412
end trace frame: 0x0, count: 11
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