panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 959
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*220891  98276      0           0  0x4000000    0K syz-executor
  83423  78117      0         0x2        0x1    1  syz-executor
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff834c1037) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff834fed8c,ffffffff8350fc1b,3bf,ffffffff83538b16) at __assert+0x29 sys/kern/subr_prf.c:-1
refcnt_finalize(ffff80003c3f3770,ffffffff834b24f6) at refcnt_finalize+0x1e7 sys/kern/kern_synch.c:960
pppx_if_destroy(ffff800035798000,ffff80003c3f3768) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794
pppxclose(205b9a,1,2000,ffff800045ffca68) at pppxclose+0xa0 sys/net/if_pppx.c:541
spec_close(ffff80002a250650) at spec_close+0x417 sys/kern/spec_vnops.c:-1
VOP_CLOSE(fffffa806075b540,1,fffffa80097fd548,ffff800045ffca68) at VOP_CLOSE+0x132 sys/kern/vfs_vops.c:156
vn_closefile(fffffa806f13ed30,ffff800045ffca68) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:298 [inline]
vn_closefile(fffffa806f13ed30,ffff800045ffca68) at vn_closefile+0x12b sys/kern/vfs_vnops.c:621
fdrop(fffffa806f13ed30,ffff800045ffca68) at fdrop+0x121 sys/kern/kern_descrip.c:1281
closef(fffffa806f13ed30,ffff800045ffca68) at closef+0x192 sys/kern/kern_descrip.c:1265
sys_closefrom(ffff800045ffca68,ffff80002a250920,ffff80002a250870) at sys_closefrom+0x13c sys/kern/kern_descrip.c:1471
syscall(ffff80002a250920) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a250920) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xced6df7acb0, count: 1
https://www.openbsd.org/ddb.html describes the minimum info required in bug
reports.  Insufficient info makes it difficult to find and fix bugs.
ddb{0}> 
ddb{0}> set $lines = 0
ddb{0}> set $maxwidth = 0
ddb{0}> show panic
*cpu0: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 959
ddb{0}>