panic: kernel diagnostic assertion "refs != ~0" failed: file "/syzkaller/managers/main/kernel/sys/kern/kern_synch.c", line 951
Starting stack trace...
panic(ffffffff8342ce90) at panic+0x1ba sys/kern/subr_prf.c:229
__assert(ffffffff833df239,ffffffff83327cc3,3b7,ffffffff833e0f75) at __assert+0x29 sys/kern/subr_prf.c:-1
refcnt_finalize(ffff80003c94eb48,ffffffff8332abb8) at refcnt_finalize+0x1c8 sys/kern/kern_synch.c:952
pppx_if_destroy(205b92,ffff80003c94eb40) at pppx_if_destroy+0x3d sys/net/if_pppx.c:806
pppxclose(205b92,1,2000,ffff800039913210) at pppxclose+0xa0 sys/net/if_pppx.c:553
spec_close(ffff80003c96d340) at spec_close+0x412 sys/kern/spec_vnops.c:-1
VOP_CLOSE(fffffd8060912708,1,fffffd8007bfb958,ffff800039913210) at VOP_CLOSE+0x12a sys/kern/vfs_vops.c:156
vn_closefile(fffffd80644082d0,ffff800039913210) at vn_closefile+0x11d vn_close sys/kern/vfs_vnops.c:292 [inline]
vn_closefile(fffffd80644082d0,ffff800039913210) at vn_closefile+0x11d sys/kern/vfs_vnops.c:615
fdrop(fffffd80644082d0,ffff800039913210) at fdrop+0x126 sys/kern/kern_descrip.c:1267
closef(fffffd80644082d0,ffff800039913210) at closef+0x18d sys/kern/kern_descrip.c:1251
fdfree(ffff800039913210) at fdfree+0x115 sys/kern/kern_descrip.c:1182
exit1(ffff800039913210,0,0,3) at exit1+0x59c sys/kern/kern_exit.c:215
proc_suspend_check_locked(ffff800039913210,0) at proc_suspend_check_locked+0x439 sys/kern/kern_sig.c:2235
userret(ffff800039913210) at userret+0x8c proc_suspend_check sys/kern/kern_sig.c:-1 [inline]
userret(ffff800039913210) at userret+0x8c sys/kern/kern_sig.c:2194
Xsyscall() at Xsyscall+0x156
end of kernel
end trace frame: 0x6fa063776210, count: 242
End of stack trace.