panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/multicore/kernel/sys/kern/kern_synch.c", line 955
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
  70753  48142      0           0          0    0  syz-executor
*116002  84844      0           0  0x4000000    1K syz-executor
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff834520b4) at panic+0x1e5 sys/kern/subr_prf.c:198
__assert(ffffffff8348ca57,ffffffff83498b2a,3bb,ffffffff834c11b4) at __assert+0x29 sys/kern/subr_prf.c:-1
refcnt_finalize(ffff80002a27f778,ffffffff8344829c) at refcnt_finalize+0x1db sys/kern/kern_synch.c:956
pppx_if_destroy(ffff800035bb2000,ffff80002a27f770) at pppx_if_destroy+0x3d sys/net/if_pppx.c:794
pppxclose(205b9a,2,2000,ffff8000fffeed10) at pppxclose+0xa0 sys/net/if_pppx.c:541
spec_close(ffff80002a249630) at spec_close+0x417 sys/kern/spec_vnops.c:-1
VOP_CLOSE(fffffd805ec06048,2,fffffd80097fd270,ffff8000fffeed10) at VOP_CLOSE+0x132 sys/kern/vfs_vops.c:156
vn_closefile(fffffd806f573968,ffff8000fffeed10) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline]
vn_closefile(fffffd806f573968,ffff8000fffeed10) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615
fdrop(fffffd806f573968,ffff8000fffeed10) at fdrop+0x121 sys/kern/kern_descrip.c:1281
closef(fffffd806f573968,ffff8000fffeed10) at closef+0x192 sys/kern/kern_descrip.c:1265
sys_closefrom(ffff8000fffeed10,ffff80002a249900,ffff80002a249850) at sys_closefrom+0x13c sys/kern/kern_descrip.c:1471
syscall(ffff80002a249900) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80002a249900) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xf282d63f3c0, count: 1
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