panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 944
Starting stack trace...
panic(ffffffff83405a4d) at panic+0x1ba sys/kern/subr_prf.c:229
__assert(ffffffff833af7dc,ffffffff832ffc06,3b0,ffffffff833b8d9a) at __assert+0x29
refcnt_finalize(ffff80002a8e2050,ffffffff832ff175) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:945
pppx_if_destroy(205b9a,ffff80002a8e2048) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806
pppxclose(205b9a,1,2000,ffff80002a8e4018) at pppxclose+0xa0 sys/net/if_pppx.c:553
spec_close(ffff80003c982cd0) at spec_close+0x412
VOP_CLOSE(fffffd8068c1edb0,1,fffffd807f7d7820,ffff80002a8e4018) at VOP_CLOSE+0x12a sys/kern/vfs_vops.c:156
vn_closefile(fffffd806c093cb0,ffff80002a8e4018) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline]
vn_closefile(fffffd806c093cb0,ffff80002a8e4018) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615
fdrop(fffffd806c093cb0,ffff80002a8e4018) at fdrop+0x126 sys/kern/kern_descrip.c:1265
closef(fffffd806c093cb0,ffff80002a8e4018) at closef+0x18d sys/kern/kern_descrip.c:1249
fdfree(ffff80002a8e4018) at fdfree+0x115 sys/kern/kern_descrip.c:1181
exit1(ffff80002a8e4018,0,0,1) at exit1+0x57f sys/kern/kern_exit.c:214
sys_exit(ffff80002a8e4018,ffff80003c983040,ffff80003c982f90) at sys_exit+0x1a
syscall(ffff80003c983040) at syscall+0x97e sys/arch/amd64/amd64/trap.c:577
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x796a62d418c0, count: 242
End of stack trace.